Ch. 12: Principles of Pharmacology

Cardiac Glycosides:

-Cardiac glycosides are a class of medications derived from plants. -These drugs block certain ionic pumps in the heart cell membranes, which indirectly increases calcium concentrations. -Cardiac glycosides generally have a small therapeutic index (margin of safety) and are associated with numerous side effects.

C:

-Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal or other) and there are no controlled studies in women, or studies in women and animals are not available. -Drugs should be given only if the potential benefit justifies the potential risk to the fetus.

Drugs Affecting the Cardiovascular System:

-A chronotropic effect is one that affects the heart rate. -An inotropic effect changes the force of contraction. -A dromotropic effect is when a drug alters the velocity of the conduction of electricity through the heart.

Stimulants:

-A common group of CNS agents is stimulants, which exert their action by excitation of the CNS. -The CNS can be stimulated in one of two ways: >By increasing excitatory neurotransmitters >By decreasing inhibitory neurotransmitters Caffeine, cocaine, and amphetamines (prescription and illicit) are examples of CNS stimulants. -They increase the release of dopamine and norepinephrine to increase wakefulness and awareness and reduce drowsiness and fatigue. -They also increase tachycardia and hypertension and can cause seizures and psychosis. -High doses of these agents can cause increased nervousness, irritability, tremors, and headache. Some people may also experience withdrawal symptoms when they stop taking stimulants.

Gels:

-A gel is a semiliquid substance that is administered orally through capsules or plastic tubes. -Gels usually have the consistency of pastes or creams but are transparent. -Depending on your local protocol, as an AEMT you may give oral glucose in gel form to a conscious patient with a low blood glucose level.

Factors Influencing Medication Interactions:

-A medication interaction occurs whenever the actions of one drug on the body are in some way modified by another chemical substance. -Many patients, especially elderly patients, may take several medications each day (polypharmacy). -Warning labels on prescription bottles warn against the substances that may cause interactions.

Metered-Dose Inhalers:

-A metered-dose inhaler (MDI) is a miniature spray canister used to direct substances through the mouth and into the lungs. -An MDI delivers the same amount of medication each time it is used. -Because an inhaled medication usually is a suspension, the MDI must be shaken vigorously before the medication is administered. -Patients with respiratory illnesses such as asthma and emphysema often use MDIs.

Anticonvulsnts:

-A seizure is a state of neurologic hyperactivity. Active seizures generally require treatment in the prehospital setting because of the complications associated with them. -Although the exact mechanism behind anticonvulsant medications is not completely clear, these drugs are believed to work by inhibiting the influx of sodium into cells. -This halt of sodium transport decreases the cells' ability to depolarize and propagate the seizures. -Several other types of drugs are used as anticonvulsants, including benzodiazepines, barbiturates, hydantoins, and valproic acids.

Liquid Drugs:

-A solution is a liquid mixture of one or more substances that cannot be separated by filtering or allowing the mixture to stand. -Solutions can be given by almost any route. -When given by mouth, solutions may be absorbed from the stomach rather quickly because the medication is already dissolved. -Solutions that irritate the stomach may be applied topically to the skin, sprayed SL, or inhaled. -Many solutions can be given as an IV, intramuscular (IM), or subcutaneous injection. -Many substances do not dissolve well in liquids. -Some of these can be ground into fine particles and evenly distributed throughout a liquid by shaking or stirring. -This type of mixture is called a suspension. -An example of a suspension is activated charcoal, which you may give to patients who have taken overdoses of certain medications or ingested certain poisons. -Tinctures are liquid preparations that are alcohol based. -The name of the material contained in the tincture other than alcohol is added to the name of the tincture, such as tincture of iodine. -Spirits are alcohol solutions that are volatile. -Elixirs constitute one of the most common types of medicinal preparations taken orally in liquid form and are made up of a sweetened, aromatic, hydroalcoholic liquid. -Syrups are mixtures with a high sugar content that are designed to disguise the taste of the medication. -These are most commonly used for children's medications. -An emulsion is a mixture of two liquids that are not mutually soluble. -Emulsions are generally a mixture of water and oil that must be thoroughly shaken to mix.

Drugs affecting the pancreas:

-A variety of hypoglycemic medications are available to affect the pancreas. -Others may not act on the pancreas directly, but instead alter the way insulin (produced by the pancreas) is used by the body. -In the absence of pancreatic function, patients may take insulin injections. -To directly affect the pancreas, sulfonylureas increase insulin secretion from the pancreatic beta cells. -This medication is effective only if patients have residual beta cell function. -Insulin sensitivity is increased by thiazolidinediones and biguanides, which are oral hypoglycemic agents.

Intraosseous (IO) Injection:

-Absorption Rate: Immediate -Medications that are given by intraosseous (IO) injection reach the bloodstream through the bone marrow. -Giving a medication by this route requires drilling a needle into the outer layer of the bone. -Because this is painful, the IO route is used most often in patients who are unconscious as a result of cardiac arrest or extreme shock. -Often, the IO route is used for children who have fewer available (or difficult to access) IV sites.

Intravenous (IV) Injection:

-Absorption Rate: Immediate -Medications that need to enter the bloodstream immediately may be injected directly into a vein, known as an intravenous (IV) injection. -This is the fastest way to deliver a chemical substance, but the IV route cannot be used for all chemicals. -Aspirin, oxygen, and charcoal cannot be given by the IV route.

Intramuscular (IM) Injection:

-Absorption Rate: Moderate -Usually, medications that are administered by intramuscular (IM) injection are absorbed quickly because muscles have a lot of blood vessels. -Some types of medications are designed for a slower, sustained release from the muscle. -Possible problems with IM injections include the following: >Damage to muscle tissue >Uneven, unreliable absorption, especially in people with decreased tissue perfusion or who are in shock

Inhalation:

-Absorption Rate: Rapid -Drugs are aerosolized and drawn into the lungs through the mouth or nose. -Include nebulized medications and MDIs -Inhalation helps to minimize the effects of the medication in other body tissues. -Inhaled medications come in the form of: >Aerosols >Fine powders >Sprays

Intranasal (IN):

-Absorption Rate: Rapid -In the intranasal (IN) route, liquid medication is pushed through a specialized device called a mucosal atomizer device (MAD). -The medication is aerosolized and is administered into a nostril. -Absorption is quick. -Naloxone can be administered via this route to some overdose patients.

Sublingual (SL):

-Absorption Rate: Rapid -Medications given by the sublingual (SL) route enter through the oral mucosa under the tongue and are absorbed into the bloodstream within minutes. -This route is faster than the oral route and protects medications from chemicals in the digestive system, such as acids that can weaken or inactivate them.

Subcutaneous (SC) Injection:

-Absorption Rate: Slow -A subcutaneous (SC) injection is given into the fatty tissue between the skin and the muscle. -Because there is less blood here than in the muscles, medications that are given by this route are generally absorbed more slowly, and their effects last longer. -An SC injection is a useful way to give medications that cannot be taken by mouth, as long as they do not irritate or damage the tissue. -Daily insulin shots and epinephrine are given this way.

Transcutaneous (transdermal):

-Absorption Rate: Slow -Medication is absorbed through the layers of the skin and into the bloodstream. -On occasion, a medication that also comes in another form is administered transcutaneously to achieve a longer-lasting effect. -An example is an adhesive patch containing nitroglycerin.

Routes of Administration:

-Absorption is the process by which medications travel through body tissues until they reach the bloodstream. -Enteral medications enter the body through the digestive system. -They include: >Oral. Many medications are taken by mouth, per os (PO), and enter the bloodstream through the digestive system. This process can take as long as 1 hour. >Rectal. Per rectum (PR) means "by rectum." There are no AEMT medications that are administered rectally, with the possible exception of 50% dextrose (D50) if allowed by local protocols, and only as a last resort. -Parenteral medications enter the body by a route other than the digestive tract.

The Food, Drug, and Cosmetic Act (1938, amended in 1952 and 1962):

-Added several new provisions: >Required drug makers to label their products, indicating whether they contain potentially habit-forming substances and to include warnings about possible side effects >Authorized the creation of the FDA >Mandated that dangerous drugs could be dispensed only with a prescription from a physician, dentist, or veterinarian

Drug Storage and Security of Controlled Substances:

-All drug boxes should be locked and secured within the ambulance. -Local protocols determine the manner in which the drugs are maintained. -If controlled substances, such as narcotics, are administered, the records must be kept separate from other paperwork. -If drugs are lost or stolen, notify the supervisor and law enforcement personnel immediately. -The potency of medications is affected by: >Temperature >Light >Moisture >Shelf life >Exposure to air -Destroy all expired controlled substances. -The destruction must be witnessed by two employees and documented on the proper forms.

Iatrogenic Responses:

-An iatrogenic response is an adverse condition inadvertently induced in a patient by the treatment given. -One example is a urinary tract infection that develops in a patient after insertion of an indwelling catheter (such as a Foley catheter). -When the administration of medications results in symptoms that mimic naturally occurring disease states, it is known as an iatrogenic medication response.

Animal Studies:

-Animal studies are designed to learn more about the properties of a drug and to identify tissues and organs that are sensitive to the actions of the drug. -Testing in at least two animal species is required by law. -After successful completion of animal studies, an investigational new drug may enter clinical trials in humans.

Antidysrhythmics:

-Antidysrhythmic medications have long been used in the prehospital setting to treat and prevent cardiac rhythm disorders. -These medications can have direct and indirect effects on cardiac tissue. -Antidysrhythmics are further classified into the following four groups according to their fundamental mode of action on the heart: >Sodium channel blockers slow the conduction through the heart; in other words, they have a negative dromotropic effect. >Beta blockers reduce the adrenergic stimulation of the beta receptors. >Potassium channel blockers increase the heart's contractility (positive inotropy) and work against the reentry of blocked impulses. >Calcium channel blockers block the inflow of calcium into the cardiac cells, thereby decreasing the force of contraction and automaticity. They may also decrease the conduction velocity (negative dromotropic effect).

Predictable Responses:

-Because of the extensive research that goes into developing and testing a medication before it is approved, there is common knowledge about what effect a particular medication will have on the patient. -Side effects are any actions of a medication other than the desired ones. -Side effects may occur even when a medication is administered properly and under the appropriate circumstances. -For example, giving epinephrine to a patient who is having an allergic reaction should dilate the bronchioles and decrease wheezing. -However, two side effects of epinephrine are cardiac stimulation and constriction of the arteries, which may elevate the patient's heart rate and blood pressure. These side effects are predictable.

Pregnant Patients:

-Before you administer any medications to a female of childbearing age, ask the patient whether she could be pregnant. -In an emergency situation, the health of the woman is the priority. -However, before using any drug during pregnancy, you need to consider the expected benefits against the possible risk to the fetus. -Drugs, whether prescription or OTC, have the potential to harm the fetus by crossing the placental barrier, as well as through lactation. -A teratogenic drug is one that poses a risk to the normal development or health of the unborn fetus. -Changes in a pregnant woman's body also affect the way drugs are processed and may increase the chance of harm to the fetus. -Metabolism of drugs in the liver decreases during pregnancy, along with an increased rate of excretion owing to increased cardiac output. -The FDA has established a scale with the categories A, B, C, D, and X to indicate drugs that have documented problems in animals and/or humans during pregnancy. -Category A drugs pose the least risk to the fetus, while Category X drugs pose the greatest risk. -This system is being replaced by a more detailed system that uses narrative summaries to convey prescribing information related to pregnancy (including labor and delivery), lactation, and the risks of a medication to male and female users with reproductive potential. -There are many drugs used with unknown effects during pregnancy, so it is better to delay pharmacologic treatments for pregnant patients until they reach the hospital, except in life-threatening situations. When in doubt, contact medical control to discuss the situation.

Blood flow to the site of administration:

-Blood flow to a particular area regulates how fast the medication is absorbed into the central circulation. -This is why administering medications intramuscularly to a patient having a seizure produces a minimal effect. -Because of the seizure activity, blood flow to the extremities is diminished. -Medications introduced intramuscularly tend to stay in the tissues until the seizure activity stops. -When blood flow resumes, the patient may experience the effects of an overdose if multiple doses were given.

Methods of Drug Classifications:

-Classifications of drugs are based on the effect the drugs have on a particular part of the body or on a specific condition. -Many medications fall into more than one classification. Drugs/medications are classified by: >Body system >Classification by body system is simply categorizing by the system affected by that drug. >Nitroglycerin is a vasodilator that is used predominantly for cardiac ischemia; therefore, it is classified as a cardiac drug. >Understanding which systems are affected by which drugs will help you make the appropriate decisions for patient care. >Class of agent >The class of a medication tells how it affects the system. >For example, an antipyretic is given to reduce fever, and an antiemetic is used to control vomiting. >Mechanism of action >The mechanism of action is the particular action by which the drug creates its desired effect on an organism. >For example, nitroglycerin is a potent vasodilator given for cardiac ischemia because it opens the vessels to allow oxygenated blood to pass through.

Clinical Trials:

-Clinical trials proceed in four phases: >Phase I. The new drug is tested in healthy volunteers to compare human data with those in animals to determine safe doses of the drug and to assess its safety. >Phase II. These trials are performed in homogeneous populations of patients (50 to 300 patients). In double-blind studies, one group receives the drug and the other group receives a placebo. These studies are designed to evaluate the efficacy and safety of the drug and to establish which form is the most effective dose. >Phase III. In these clinical trials, the drug is made available to a larger group of patients (several thousand). These studies, which usually last several years, evaluate the efficacy of the drug and monitor the nature and incidence of side effects. >Phase IV. After successful completion of Phase III clinical trials, the drug company can apply to the FDA for approval to market the drug. Phase IV trials compare the new drug with others on the market and examine the drug's long-term efficacy and cost-effectiveness.

A:

-Controlled studies in women fail to demonstrate a risk to the fetus in the first trimester (and there is no evidence of a risk in later trimesters), and the possibility of fetal harm appears remote.

Scope of Practice:

-Drug administration must be safe and therapeutically effective. -Keep a field guide or other medication reference handy to look up medications that are unfamiliar to you. -Follow the standardized national guidelines listed in the table when providing drug therapy.

Components of a Drug Profile:

-Drug names: generic, trade, and chemical name -Classification: What type of drug is this? What is it used for? -Mechanisms of Action: How does the drug work? What is its intended purpose? -Indications: What are the reasons for taking this drug? -Contraindications: When should the drug not be given? Does it affect certain medical conditions or react with other medications adversely? -Pharmacokinetics: How is the drug absorbed, metabolized, and so forth? What is its half-life? -Side and Adverse Effects: Are there any side effects? What are the adverse effects? -Routes of Administration: How is this drug given? -How Supplied: What is the total quantity of the medication? What form? -Dosages: generally includes proper dosages for adult, pediatric, and special considerations, such as when to modify the dosage based on the patient's history -Special Considerations: considerations for certain groups such as pediatric, geriatric, and pregnant patients, etc. -Other: may include any other information that is vital to the user

Sources of Drug Information:

-Drug reference sources include: >The American Medical Association (AMA) Drug Evaluations >The Physicians' Desk Reference (PDR) >Hospital formularies -Medications come packaged with drug inserts that give information specific to: >Preparation >Dosage >Effects >Possible side effects >Other information

Drug-Related Legislation:

-Drug-related laws and regulations are designed to: >Protect consumers >Prohibit manufacturers from making false claims >Prohibit advising patients on the administration of the drugs >Protect patients from drugs that might cause harm >Outline standards for drug manufacture to ensure that drugs produced by different manufacturers are uniform in strength and purity.

Drug Distribution:

-Drugs pass freely and quickly out of the vascular space and into the interstitial fluid, so blood flow to the area determines the amount of a drug reaching a particular part of the body. -Most drugs tend to pass fairly easily from the intravascular compartment, through the interstitial spaces, and on to their target tissue. -These drugs tend to have a rapid onset and a short duration of action. -Other drugs become bound to serum proteins in the blood and are not immediately available to act on receptor sites. -With the drug bound to the protein, it cannot produce an effect in a receptor site or diffuse through the tissues. -Some areas of the body, such as the brain and placenta, are less accessible to certain drugs than others. -Drugs that are protein-bound or in an ionized form are weak penetrators of the blood-brain barrier. -The blood-brain barrier and the placental barrier are both less permeable to provide protection to the brain and fetus, respectively.

Antianxiety, sedative, and hypnotic drugs:

-Drugs that produce sedation are used to help a patient sleep through a medical procedure. -Drugs that create sedation and hypnosis include the following: >Benzodiazepines are the sedatives most commonly used to prepare patients for invasive procedures. Although their exact mechanism of action is not fully understood, these drugs are believed to affect the neurotransmitter gamma-aminobutyric acid (GABA) in the brain. Benzodiazepine molecules bind to a receptor near GABA binding sites, which is thought to enhance their affinity for GABA. This increased affinity causes brain activity to slow. >Barbiturates are believed to work similarly to benzodiazepines by increasing the affinity between receptor sites and the neurotransmitter GABA. >Opioid agonists >Nonbarbiturate hypnotics have almost identical properties to benzodiazepines and barbiturates in how they affect GABA receptors. The difference is that nonbarbiturate hypnotics tend to have comparatively fewer side effects, particularly regarding cardiovascular compromise. -There are currently no drugs in these categories that are within the scope of practice of the AEMT.

B:

-Either animal reproduction studies have not demonstrated a fetal risk but there are no controlled studies in pregnant women, or animal reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the first trimester (and there is no evidence of a risk in later trimesters.)

Drug Elimination:

-Excretion is the elimination of waste products from the body. -Drugs are eliminated in their original forms or as metabolites. -Organs of excretion include the kidneys via the urine, the intestines through the feces, the lungs via respiration, the salivary glands through sweat, and the mammary glands through breast milk. -The rate of elimination varies with the amount of drug in the body and the underlying condition of the excretion organs. -During shock, when the kidneys are poorly perfused, drugs may remain in the circulation for longer periods. -This also holds true for geriatric patients whose kidneys may not function as well owing to the normal deterioration associated with aging and for patients with chronic kidney disease. -A patient's poor ability to eliminate a drug may result in an accumulation of the drug if subsequent doses are given, resulting in toxic effects.

Drug Regulations:

-Federal legislation guarantees standardization of doses. -Standardization assures patients that when they take a medication with a stated amount of the active ingredient, they will receive that amount of the drug.

Dosage Form:

-Form has a lot to do with the speed of absorption. -A liquid will be absorbed much more quickly than a pill, which must be dissolved before it is absorbed.

Gases:

-Gaseous medications are neither solid nor liquid and often are delivered in an operating room. -The medication that is most commonly used in gas form in the prehospital setting is oxygen. -You usually administer oxygen through a nasal cannula, a nonrebreathing mask, or a bag-mask device when ventilating a patient. -Nitrous oxide is also used in the prehospital environment. -It is an analgesic that may be administered by AEMTs to reduce pain. -Nitrous oxide is administered by inhalation through a mask and has both analgesic and euphoric effects.

Routes of Administration:

-IV administration is the most rapid route for delivering drugs in the prehospital environment. -The medication bypasses the gastrointestinal absorption process because it is introduced directly into the vascular system. -Intramuscular and subcutaneous routes are much slower because they depend on the blood flow to the area in which the medication is administered.

Controlled Substances Act (1970):

-In 1970, Congress enacted the Controlled Substances Act, comprehensive legislation dealing with narcotic and nonnarcotic drugs that have potential for abuse. -This act specifies requirements for registration, procurement, storage, distribution, and record keeping for these drugs and penalties for failure to comply with these requirements. -The drugs covered by the Controlled Substances Act are classified into five categories, or schedules, according to their abuse potential. -Schedule I drugs have the highest abuse potential and a propensity for severe drug dependence; none of them have any accepted medical application. -In general, Schedule I drugs are completely outlawed. On rare occasions, and under the strictest control by the FDA and Drug Enforcement Agency (DEA), these drugs may be used for research, analysis, and instruction only. -Some states have enacted their own laws or regulations related to the use, storage, and handling of controlled substances. -If the state law is more stringent than the federal law, the state law takes precedence.

Topical Medications:

-Lotions, creams, and ointments all are topical medications that are applied to the surface of the skin and affect only that area. -Lotions contain the largest amount of water and are absorbed the quickest. -Creams are absorbed more slowly than lotions, but faster than ointments. -Ointments contain the smallest amount of water, resulting in a slower rate of absorption of the medication.

Biotransformation:

-Many drugs only become active once they have been absorbed and converted into an active form in the blood or by the target tissue. -The chemical alteration that a substance undergoes in the body is known as biotransformation. -The primary organ for biotransformation is the liver. -If the liver is diseased, inactivation (detoxification) of drugs may be impaired. -This will also increase elimination time of the drug from the body, possibly resulting in toxic blood levels. -The liver performs synthetic reactions that yield inactive products (metabolites) that can be secreted by the kidneys, and nonsynthetic reactions, which may result in products that are more active, charged in activity, or less active. -The drugs that are biotransformed to an inactive metabolite very quickly have limited effects on the body and must be administered frequently to continue the effect. -Epinephrine (administered by paramedics) during a cardiac arrest is an example of a drug that is rendered inactive very quickly and must be administered every 3 to 5 minutes as needed or alternatively as a continuous infusion.

Antihypertensives:

-Medications administered to treat hypertension, known as antihypertensives, have the following treatment goals: >Keep blood pressure within normal limits >Maintain or improve blood flow >Reduce the stress placed on the heart -Diuretic medications cause the kidneys to remove excess amounts of salt and water in the body. By lowering the total fluid volume, they reduce the level of stress placed on the cardiovascular system. In particular, diuretics lower the preload on the heart and decrease the stroke volume. -Vasodilator medications act on the smooth muscles of the arterioles and veins. This explains why nitroglycerin, a vasodilator, is so beneficial in treating myocardial ischemia. Unfortunately, the dilation of these vessels prompts a response from the sympathetic nervous system. Consequently, when vasodilators are used to lower blood pressure, the patient must also take medications that inhibit the sympathetic nervous system. -Sympathetic blocking agents include beta blockers and adrenergic inhibitors. Beta blockers compete with epinephrine to bind with available receptor sites, diminishing the effects of beta stimulation. -Angiotensin-converting enzyme (ACE) inhibitors target the renin-angiotensin-aldosterone system, which partially controls blood pressure. ACE inhibitors suppress the conversion of angiotensin I to angiotensin II, decreasing blood pressure. -Angiotensin II is a potent vasoconstrictor that promotes smooth muscle contraction in the arterioles throughout the body. This constriction raises the blood pressure by increasing peripheral resistance. -Calcium channel blockers have antidysrhythmic and antihypertensive properties. By causing the dilation of coronary arteries, calcium channel blockers enable more oxygen to reach the heart via coronary artery dilation. In addition, they prevent the contraction of smooth vascular muscle, which reduces resistance in the peripheral vascular system.

Pediatric Patients:

-Medications have different effects in adults than they do in children. -Young infants have a sharply reduced metabolic capacity. -The incomplete development of the gastrointestinal tract in young infants slows absorption of oral medications and delays elimination, so the same medication may be more potent in an infant than in an adult. -Children can metabolize some medications much more quickly than adults do, so they may require higher doses or more frequent administration of some medications. -Also, the products of metabolism in children can vary from those seen in adults, which may sometimes result in unexpected responses.

Medication Names:

-Medications usually have several names. -The trade name is the brand name that a manufacturer gives to a medication. -A trade name is a proper noun and begins with a capital letter. -A medication may have many different trade names, depending on how many companies manufacture it. -The generic name is its original chemical name suggested by the manufacturer. -It is not capitalized. -All medications that are licensed for use in the United States are listed by their generic names in the United States Pharmacopeia (USP). -The chemical name of a medication is a precise description of the drug's chemical composition and molecular structure. -The official name is the name assigned by the USP. In most cases, the official name is the generic name followed by "USP." -Examples of the four names for a drug are as follows: >Chemical name: 9-chloro-11β,17,21-trihydroxy- 16β-methylpregna-1,4-diene-3,20-dione 17,21-dipropionate >Generic name: beclomethasone dipropionate >Trade name: Vanceril >Official name: beclomethasone dipropionate, USP -Prescription medications are distributed to patients only by pharmacists according to a physician's order. -Over-the-counter (OTC) medications may be purchased directly, without a prescription. -Ask patients about any and all medications they take.

Opioid Agonists:

-Most common class of medications used for analgesia in the prehospital setting -Opioid agonists, which are similar to or derived from the opium plant, bind to opiate receptors and prevent the neurons from sending pain signals. -These medications are also CNS depressants. -Fentanyl (Sublimaze) is a popular opioid agonist because it is rapid acting, is very potent, and has a relatively short duration of action. -The patient experiences analgesia within approximately 90 seconds, and the drug's effective duration is approximately 30 minutes. -Morphine is a popular option for prehospital analgesia. In addition to analgesia, morphine has a tendency to cause a euphoric feeling.

Solid Drugs:

-Most medications that are given by mouth to adult patients are in tablet or capsule form. -Capsules are gelatin shells filled with powdered or liquid medication. -If the capsule contains liquid, the shell is sealed and usually soft. -If the capsule contains powder, the shell can usually be pulled apart. -Tablets often contain other materials that are mixed with the medication and compressed under high pressure. -Some tablets are designed to dissolve very quickly in small amounts of liquid so that they can be given sublingually (SL) and absorbed rapidly. -An example is the SL nitroglycerin tablet used for chest pain by patients with cardiac conditions. -These medications are especially useful in emergency situations. -Tablets may also be ground into a powder, allowing them to be absorbed more quickly. -Generally, a medication that must be swallowed is less useful in an emergency because the digestive tract provides a slower route of delivery. -Pills are solid drugs that are shaped into a ball or oval to be swallowed. -They are often coated to disguise an unpleasant taste. -Suppositories are another form of solid drugs that are administered by inserting them into the rectum. -These medications are more rapidly absorbed through the rectal mucosa than those that must travel through the upper portion of the digestive tract. -Suppositories are not administered by AEMTs.

Psychotherapeutic Drugs:

-Most psychotherapeutic drugs work by blocking dopamine receptors in the brain. -Schizophrenia is often treated with medications that fit into the phenothiazine and butyrophenone classifications. -These medications are associated with a host of side effects, which may include: >Extrapyramidal symptoms >Orthostatic hypotension >Sedation >Sexual dysfunction -Extrapyramidal symptoms include a wide array of symptoms such as involuntary movements, tremors, rigidity, muscle contractions, restlessness, and changes in breathing and heart rate. -Depression is often treated with selective serotonin reuptake inhibitors and monoamine oxidase inhibitors, which block the metabolism of monoamines in the brain. _Although their popularity is waning, tricyclic antidepressants are still occasionally used as antidepressants.

Opioid Agonist-Antagonists:

-Opioid agonist-antagonists have agonistic and antagonistic properties. -They are often preferred because they can decrease pain but do not diminish the function of the respiratory system or result in dependence or addiction, unlike some other analgesics.

Opioid Antagonists:

-Opioid antagonists reverse the effects of opioid drugs. -They bind with the opiate receptors in an antagonistic manner; as a result, the opioid molecules cannot get to the receptor, and the receptor cannot initiate its action. -The most common opioid antagonist used in the prehospital setting is naloxone (Narcan).

Drugs affecting the respiratory system:

-Oxygen is the most commonly used medication in the prehospital setting. -During the cold and influenza seasons, use of OTC decongestant medications is common. -Patients may take antihistamines during allergy season. -Try to find out which medications your patient is taking and know the effects that these drugs may have on other medications and the signs and symptoms they can produce. -Although each decongestant varies slightly in its mechanism of action, all such medications seek to reduce tissue edema, facilitate drainage, and maintain the patency of the sinuses. -People looking to get high have been known to overdose on pseudoephedrine (a decongestant), dextromethorphan (an antitussive), or diphenhydramine (an antihistamine). -Serious respiratory emergencies can arise from severe narrowing of any portion of the respiratory tract. -Many respiratory emergency treatments attempt to expand the respiratory tract by using sympathomimetic medications. -Complications arise when patients with respiratory emergencies experience decreased amounts of oxygen to the vital organs, including the heart. -Stimulation of the beta-2 receptors, which produces bronchodilation and vasodilation, is the most beneficial to patients with respiratory emergencies. -These drugs produce smaller increases in heart rate and force of contraction, which in turn decreases the amount of oxygen needed for the myocardium to function. -A second-line treatment in a respiratory emergency is from xanthines. -This class of drugs relieves airway constriction by relaxing the smooth muscles of the bronchioles and stimulating cardiac muscles to work harder, increasing blood flow. -These drugs also stimulate the CNS—one notable xanthine is caffeine, a well-known CNS stimulant. -Other respiratory medications suppress the inflammatory response that typically causes acute distress for patients with restrictive airway diseases. -In the acute care setting, corticosteroids—including methylprednisolone (Solu-Medrol) and dexamethasone (Decadron)—can be administered for this purpose.

Parasympatholytics:

-Parasympatholytics are also called anticholinergic medications; they block the two types of cholinergic receptors: -Muscarinic cholinergic antagonists block ACh exclusively at the muscarinic receptors. -Atropine, for example, is a muscarinic cholinergic antagonist; it decreases secretions, increases the heart rate, dilates the pupils, and decreases gastrointestinal system activity. -Nicotinic cholinergic antagonists block ACh exclusively at the nicotinic receptors. -This inhibition effectively disables the ANS, so it is virtually never used.

Parasympathomimetics:

-Parasympathomimetics are also called cholinergic medications because they stimulate the cholinergic receptors, to which acetylcholine (ACh) normally binds. -ACh is an important neurotransmitter in the parasympathetic nervous system. -Cholinergic medications may act directly or indirectly on cholinergic receptors. -A drug that has direct action binds with cholinergic receptors, blocking ACh. -If it acts to prevent activation of the receptor by binding, its function is described as anticholinergic. -A drug that has indirect action interacts with acetylcholinesterase (AChE), which normally deactivates ACh. -When a drug interacts with AChE, deactivation of ACh does not occur. -If excessive cholinergics are present, the patient may exhibit the SLUDGEM symptoms: >Salivation, sweating >Lacrimation (excessive tearing of the eyes) >Urination >Defecation, drooling, diarrhea >Gastrointestinal upset and cramps >Emesis (vomiting) >Muscle twitching/miosis (pinpoint pupils) -Patients exposed to certain fertilizers, insecticides, VX (a nerve agent), and sarin gas exhibit SLUDGEM symptoms because all of these substances have cholinergic properties.

Depressants:

-Patients may be prescribed CNS depressants. -These agents are used to slow brain activity. -They may be prescribed to treat anxiety, muscle tension, pain, insomnia, stress, panic attacks, and, in some cases, seizures. -Some other CNS depressants are used as anesthetics. -Examples of CNS depressants include: >Lorazepam (Ativan) >Triazolam (Halcion) >Chlordiazepoxide (Librium) >Diazepam (Valium) >Alprazolam (Xanax) >Zolpidem tartrate (Ambien)

Drugs affecting the immunologic system:

-Patients who undergo organ transplantation or have an autoimmune disease are often prescribed immunosuppressant medications, which are intended to inhibit the body's ability to attack the "foreign" organ or, in the case of autoimmune diseases, the medications inhibit the body's attack on itself. -These drugs are generally derived from fungi or bacteria and tend to have a complicated mechanism of action. They inhibit lymphocytes and T cells from carrying out their immune functions.

Drug Terminology:

-Pharmacology is the study of the properties and effects of drugs and medications on the body. -Drugs are chemical agents used in the diagnosis, treatment, and prevention of disease. -A medication is a chemical substance that is used to treat or prevent disease or relieve pain. -The dose of the medication is the amount that is given. -The action is the therapeutic effect or intended effect that a medication is expected to have on the body. -Unintended effects are the effects that are undesirable but pose little risk to the patient. -Untoward effects are the effects that can be harmful to the patient. -Toxicity is the risk that a substance will pose a health hazard to an individual or organism. -Indications are the therapeutic uses for a particular medication. -Contraindications are situations when you should not give a patient medication, even if it is usually indicated for that person's condition.

Anticoagulants, fibrinolytics, and blood components:

-Platelets repair damage in the blood vessels. Abnormal thrombi (clots) can cause a life-threatening crisis such as acute coronary syndrome or stroke. -A variety of medications are used to prevent or minimize the detrimental effects of thrombi: >Antiplatelet agents interfere with the aggregation, or collection, of platelets. They do not break down aggregated platelets but simply prevent further buildup of these blood cells. >Notably, salicylic acid (aspirin) has substantial antiplatelet properties and has proved important in the prehospital setting because of its ability to minimize the damage to the myocardium in acute coronary syndrome. >Anticoagulant drugs work against coagulation, preventing thrombi from forming. >Some patients can be prescribed anticoagulants on a long-term basis as a preventive measure. You need to be aware of anticoagulant use, particularly when patients have sustained a traumatic injury. Just as anticoagulants prevent blood coagulation in the vascular system, they can also prevent the life-saving coagulation needed to prevent blood loss. -After a blood clot has formed, a fibrinolytic agent may be administered to dissolve the thrombus and prevent it from breaking off and entering the bloodstream, where it might do further damage. -Fibrinolytic agents promote the digestion of fibrin (the protein involved in forming a blood clot). -The use of fibrinolytic medications in the prehospital setting remains controversial, and, in some circumstances, other forms of reperfusion therapy may be indicated.

The Harrison Narcotic Act (1914) and the Narcotic Control Act (1956):

-Regulated the import, manufacture, prescription, and sale of several nonnarcotic drugs and cocaine, opium, and their derivatives -Required precise record keeping about the dispensing of controlled drugs and registration of distributors, such as pharmacists -Specified penalties—namely, fines and imprisonment—for illegal possession or distribution of controlled drugs The Narcotic Control Act (1956) increased the penalties for violation of the Harrison Act, made the possession of heroin illegal, and outlawed the acquisition and transportation of marijuana.

Nonopioid Analgesics:

-Several nonopioid analgesics exist, many of which are available as OTC drugs. -Many of these have antipyretic properties, meaning they can reduce the patient's fever. -All of these medications alter the production of prostaglandins and cyclooxygenase (COX) to produce their effects. -Three forms of nonopioid analgesics are particularly popular: >Salicylates (such as aspirin) >Nonsteroidal anti-inflammatory drugs (NSAIDs, such as ibuprofen) >NSAIDs are designed to reduce pain, inflammation, and fever. -They work by inhibiting the COX enzymes, which produce the chemical prostaglandin; prostaglandin promotes pain, inflammation, and fever. -Para-aminophenol derivatives (such as acetaminophen [Tylenol]). -Aspirin differs slightly from other NSAIDs in that it targets the COX-1 enzymes to reduce platelet aggregation, which provides benefit in patients with suspected myocardial infarction by helping to keep clots from forming and propagating. -This also explains why you cannot substitute another NSAID such as ibuprofen, which is a nonselective COX inhibitor, for aspirin in this situation.

Fluids and Electrolytes:

-Several types of IV fluids may be administered to patients. -Crystalloid solutions are typically used in the prehospital setting and can be isotonic, hypotonic, or hypertonic. -Isotonic solutions provide a stable medium for the administration of medication and provide effective fluid and electrolyte replacement. -Hypertonic solutions help provide nutrition. -Hypotonic solutions are beneficial in dehydration situations but not in hypovolemic cases. -In addition to crystalloids, you may administer colloid solutions to your patients.

Nature of absorbing surface:

-Some surfaces are highly permeable. -It is much easier for a drug to travel through a single layer of cells than through multiple layers. -The greater the surface area exposed to the substance, the greater the absorption.

X:

-Studies in animals or humans have demonstrated fetal abnormalities, there is evidence of fetal risk based on human experience, or both, and the risk of the use of the drug in pregnant women clearly outweighs any possible benefit. -The drug is contraindicated in women who are or may become pregnant.

Drug Enforcement Agency (DEA):

-The DEA, formerly the Bureau of Narcotics and Dangerous Drugs, was created by the Federal Controlled Substances Act of 1970. -The DEA, which is a division of the Justice Department, is responsible for executing the provisions of the Controlled Substances Act, including the registration of physicians who are permitted to dispense controlled substances.

Food and Drug Administration (FDA):

-The FDA enforces the Food, Drug, and Cosmetic Act. -As part of its responsibilities, the FDA is charged with determining the safety and efficacy of drugs before they are allowed to enter the US market.

Federal Trade Commission (FTC):

-The Federal Trade Commission (FTC) monitors drug advertising and ensures that it is not misleading or inappropriate. -The FTC has become involved in making recommendations to the FDA regarding direct-to-consumer (DTC) advertisements. -The FTC found that DTC advertisements "generally benefit consumers" but stated that DTC ads should contain a "major statement of drug risks along with adequate provision for more complete risk information."

Public Health Services:

-The Public Health Service regulates biologic products—that is, medications made from living organisms—such as antitoxins and vaccines.

The Drug Approval Process:

-The average time for a drug to be developed, tested, and approved is approximately 9 years. -All new drugs must go through animal studies and clinical trials in humans before they are approved for distribution.

Buccal:

-The buccal route is similar to the SL route. -The medication is placed between the cheek and gums. -This is a common route for glucose get.

Geriatric Patients:

-The changes in pharmacokinetics in geriatric patients are comparable to those observed in young children. -In elderly people, hepatic functions and gastrointestinal activity slow, which delays absorption and elimination. -In addition, geriatric patients are often taking several medications; these concomitant therapies may interact and modify the effects of each medication. -Because geriatric patients may take a large number of medications and may have alterations in their normal mental status, they may unintentionally overdose on a particular drug or forget to take it.

Drug-response Relationship:

-The drug-response relationship correlates the amount of medication given and the response it causes. -When administering a medication, you need to know: >The onset of action >The duration of action >The termination of action (the amount of time after the concentration level falls below the minimum level to the time it is eliminated from the body) -All of these factors affect the therapeutic index—the ratio of a drug's lethal dose for 50% of the population (LD50) to its effective dose for 50% of the population (ED50). -The therapeutic index gives an indication of a medication's margin of safety. -Each medication also has a biologic half-life—the time it takes the body to eliminate one-half of the drug. -For example, the half-life of naloxone is typically 45 minutes. -The minimum concentration required to produce the desired response is referred to as the therapeutic threshold or the minimum effective concentration. -A concentration lower than the therapeutic threshold will not induce a clinical response. -A concentration higher than the therapeutic threshold may be detrimental and possibly fatal. -The goal of drug therapy is to give the minimum concentration of a drug that will produce the desired effects. The table lists factors that alter drug responses.

Pharmacokinetics: Movement of Drugs Through the Body:

-The effectiveness of a drug relates to its: >Pharmaceutical properties >Pharmacokinetics >Pharmacodynamics -Pharmaceutical properties determine a drug's concentration at its site of action. -Once administered, drugs go through four stages: >Absorption >Distribution >Metabolism >Excretion

The Pure Food and Drug Act (1906):

-The first federal legislation in the United States aimed at protecting the public from mislabeled, poisonous, or otherwise harmful foods, medications, and alcoholic beverages. -It required little more than the labeling of drugs, and it was replaced by more comprehensive legislation in 1938.

Drugs Affecting the Sympathetic Nervous System:

-The hormones released by sympathetic system stimulation cause their intended effects by acting directly on hormone receptors. -Adrenergic receptors are located throughout the body and, after stimulation by the appropriate hormone, cause a response in the target organ. -Sympathomimetics are drugs that produce the same effects on a body system as the hormones of the sympathetic nervous system -Sympatholytics (also known as antiadrenergics) inhibit the sympathetic nervous system. -Antagonists are drugs that counteract the action of something else. -Agonists are drugs that bind to a receptor and cause a response. -Medication that is an agonist of an alpha-1 receptor stimulates the receptor, causing vasoconstriction of the vessels, increasing blood pressure, cardiac preload, and afterload. -Beta blockers work by filling a portion of the beta receptor sites, preventing beta effects. -Beta-2-selective drugs cause bronchodilation with little effect on the heart.

Principles of pharmacokinetics:

-The medication dose, route of administration, and clinical status of a patient will largely determine the duration and effectiveness of the medication (pharmacodynamics). -The pharmacokinetics section of medication profiles states the onset of action, peak, and duration of action for most medications. These values vary by route of administration and may have a broad range, depending on characteristics of individual patients. -The onset and peak of a medication are related to absorption and distribution. -A minimum dose or concentration of medication must be present at certain sites in the body for clinical effects to occur. -The duration of action is generally related to medication metabolism and elimination. -As the amount of a medication near cell receptors (or other site of action) decreases, the clinical effects caused by the medication begin to decrease and normal function resumes. -If a medication permanently binds with a receptor site or irreversibly alters the function of a cell, the duration of the medication is determined by the body's ability to regenerate cells. -In these cases, the duration of action of a medication may be almost entirely unrelated to the dose or concentration present in the body. -A single dose of aspirin, for example, is rapidly eliminated by the body, usually within several hours, but can cause an inhibition of platelet activity lasting for 3 to 10 days.

Drug Concentration:

-The more of a drug available for absorption, the more that will be absorbed and the more that will remain in the system. -Often, a loading dose (bolus) of a medication is given, followed by a continuous infusion to maintain a constant therapeutic level.

Solubility of the drug:

-The more soluble (dissolvable) the drug, the faster it enters the circulatory system.

Allergic Reactions:

-The most common unpredictable response encountered in the prehospital setting is an allergic reaction. -An allergy develops when a person has previously been exposed to a particular antigen and develops antibodies against that substance (sensitization). -After a person has become sensitized, subsequent exposure to that same substance results in hypersensitivity. -Because the patient is hypersensitive, the medication activates the immune system. -Allergic reactions are unpredictable—unless the patient has had an allergic reaction to the same medication in the past—and may result in life-threatening anaphylaxis. -Anaphylaxis is an acute systemic reaction that is usually life threatening. -An allergic reaction may be immediate or delayed. -Before administering any medication, if possible, question the patient carefully about any known medication allergies. -Remain alert for an allergic reaction after administering any medication.

Nervous System Classifications:

-The nervous system is the body's principal control system and is composed of: >The central nervous system, made up of the brain and spinal cord >The peripheral nervous system, including all nervous tissue outside the CNS >The peripheral nervous system contains the autonomic nervous system (ANS).

pH

-The pH of the body and that of the drug can affect the rate of absorption. -Some medications are coated to keep them from being absorbed before they reach the small intestine because the acid environment of the stomach can destroy the drug.

Parasympathetic Nervous System:

-The parasympathetic nervous system relaxes the body and controls automatic functions during nonstressful times, so it is referred to as the "rest and relax" division. -Stimulation of the parasympathetic nervous system results in effects opposite from those of the sympathetic nervous system: >Heart and respiratory rates decrease >Blood pressure lowers >Pupils constrict >Digestive system activity increases

Drug Absorption:

-The passage of a substance through some surface of the body into body fluids and tissues is known as absorption. -Numerous variables affect drug absorption, including: >The nature of the absorbing surface >Blood flow to the site of administration >Solubility of the drug >pH >Drug concentration >Dosage form >Route of administration >Bioavailability >Diffusion >Osmosis >Filtration

Sympathetic Nervous System:

-The sympathetic nervous system is responsible for the body's response to shock and stress and is known as the "fight-or-flight" division. -This response is associated with the release of adrenaline from the adrenal glands. -The sympathetic nervous system response is called adrenergic because special adrenergic nerve fibers ultimately cause the release of the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline). -Sympathetic responses include: >Shunting of blood from the extremities to the vital core organs >Increasing the heart rate and respirations >Increasing blood pressure >Dilation of the pupils >Reduction of digestive system activity

D:

-There is positive evidence of human fetal risk, but the benefits from use in pregnant women may be acceptable despite the risk (eg, if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective).

Mechanism of Action:

-To produce optimal desired or therapeutic effects, a drug must reach appropriate concentrations at its site of action. -The magnitude of the response depends on the dose and the time that it takes the drug to travel in the body. -Drugs may produce their effects locally, systemically, or both. -Local effects are those that result from the direct application of a drug to a tissue. -An example of a local effect would be when cortisone cream is applied to the skin to relieve itching. -Systemic effects occur after the drug is absorbed by any route and distributed by the bloodstream. -Systemic effects almost always involve more than one organ, although the response of one or another organ may predominate. -Medications cause their action on the body by the following four mechanisms: >They may bind to a receptor site. >They may change the physical properties of cells—typically, by changing the osmotic balance. >They may chemically combine with other chemicals (such as with the goal of turning the substance into a nonproblematic chemical). >They may alter a normal metabolic pathway (such as by interrupting the normal growth process of cells). -Medications that bind to a receptor site are the most prevalent, particularly in the prehospital setting. -The medication molecule must have a higher affinity for the receptor than the naturally occurring chemical mediator does, or it must be present in a higher concentration. -More than one medication may vie for the same receptor. -After the medication binds to the receptor site, it initiates a chemical change. -In some cases, this change is the intended effect. In other cases, the initial chemical change releases a second compound (known as a second messenger) that causes the intended effect.

Transcutaneous Medications:

-Transcutaneous or transdermal medications are designed to be absorbed through the skin, or transcutaneously. -These medications can affect other areas of the body. -An example is nitroglycerin paste, which has properties or delivery systems that help to dilate the blood vessels in the skin, speeding absorption into the bloodstream. -In contrast to most topical medicines, which work directly on the application site, transcutaneous medications are usually intended for systemic effects.

Vitamins and Minerals:

-Vitamins and minerals are necessary substances that allow for normal metabolism, growth and development, and cellular function. -Patients may be taking vitamin and mineral supplements to replace deficient items or as a preventive measure. -Vitamins affect a wide variety of functions, but one particular vitamin used in the prehospital setting is thiamine (vitamin B1). -Thiamine aids in converting carbohydrates into energy. People with alcoholism, among others, tend to be deficient in this vitamin.

Beta 2 response:

-bronchodilation -vasodilation

Beta 1 response:

-increased heart rate -increased automaticity -increased contractility -increased conductivity

Alpha 1 response:

-peripheral vasoconstriction

Alpha 2 respose:

-peripheral vasodilation -little or no bronchoconstriction

Pregnancy (includes labor and delivery):

-pregnancy exposure registry -risk summary -clinical considerations -data

Female and Male users with reproductive potential:

-pregnancy testing -contraception -infertility

Lactation (includes nursing mothers):

-risk summary -clinical considerations -data

Osmosis:

-the movement of a solvent (fluid) from an area of lower solute concentration to an area of higher solute concentration

Diffusion:

-the movement of solutes (molecules) from an area of higher concentration to an area of lower concentration

Bioavalaibility:

-the rate and extent to which an active drug enters the general circulation, permitting access to the site of action -It is determined by measurement of the concentration of the drug in body fluids.

Filtration:

-the removal of particles from a solution by allowing the liquid portion to pass through a membrane or other partial barrier -the semipermeability of the membrane allows fluid to pass through, but the openings are small for solid particles.