Nursing fundamentals: pharmacology
Secondary effects of a drug
Severe effects usually resulting in the discontinuation of the medications
Pharmacology
The study of drugs and their interactions with living systems or the science of drug affects
Cytochrome P-450 system
-family of enzymes within liver responsible drug metabolism -ethnic variations -drugs and other substances may be either enzyme inducers or inhibitors -drugs affecting p450 are responsible for many drug interactions
Primary/therapeutic drug effects
-predicted -intended -desired -dose related
Allergic reactions/ immune system response
-the body interprets the drug as a foreign substance and forms antibodies against the drug *anaphylaxis is most severe form of allergic reaction involves The entire body resulting in wheezing, hypotension, nausea, vomiting and edema
Secondary drug effects
-unintended -non therapeutic -dose related
Idiosyncratic effects
-unique, unusual -may be opposite of the intended therapeutic effect (paradoxical)
Rights of medication administration
1. Right patient 2. Right drug 3. Right dose 4. Right route 5. Right time 6. Right documentation
How are drugs classified
According to shared characteristics. Chemical ingredients, physiological effects on the body, therapeutic medications desired effect or use in therapy
Topical
Also bypasses the G.I. tract, includes skin or mucous membranes, installations, irrigations, inhalations
Advantages of topical route
Applied to circumscribed area of body, multiple preparations, local or systemic effects, local irritation, always wear gloves when administering, safe disposal of patches
parenteral route
Bypasses the G.I. track and avoids the first pass effect, fast absorption rapid onset, breaks skin barrier involves sterile technique, patient anxiety, expensive
Toxic effects
Carry the risk of permanent damage to an organ or system
Parenteral
Circumvents the G.I. tract, injections, intravenous
What factors affect metabolism of a drug
Drug is converted to a less active form which can be excreted from the body Metabolism occurs primarily in the liver by cytochrome p-450 enzymes Factors that effect metabolism: Liver dysfunction, immature systems (neonates, children) may slow metabolism and pt at increased risk for adverse drug effects
Therapeutic range
Drugs with a wide therapeutic range are safer to administer than drugs with a narrow therapeutic range.
Pharmacodynamics
Effects of the drug on the body
Negative synergistic effect
Example: EtOH an aspirin increase risk of G.I. bleeding, EtOH from drugs that cause CNS depression
Most common causes of medication error
Lack of knowledge Miscommunication Drug name confusion
Advantages of oral route
Most common, safest, least expensive, subject to the first pass effect, multiple preparations.
Antagonist effect
One drug interferes with the actions of another and decreases the effect of the other drug
Timing of drug response and effectiveness
Onset of action; the time needed for a drug concentration to reach a high enough blood level for its affect to appear. Duration of action; the links of time that the drug concentration is sufficient to elicit a pharmacological response. Serum drug level; peak level occurs when the drug is at its highest concentration, trough level occurs when the truck is at its lowest concentration
What is the first pass effect
Portion of the med is diverted to liver before it hits the bloodstream metabolism more significant with first dose
What factors affect distribution of a drug
Protein binding capabilities of a drug can alter the drugs distribution, blood flow to the target tissues, drugs ability to enter the target tissue through the capillary membrane
First pass effect
Rapid hepatic inactivation of some oral drugs on their first pass through the liver before they reach the systemic circulation. Highly metabolize drugs lose much of their therapeutic effectiveness quickly especially oral medications such as nitroglycerin Highly metabolized, oral medications may be given the another route to bypass the liver
Excretion
Removal of the drug from the body. Factors affecting excretion is age and kidney function. Labs used to valuate kidney functioning food creatinine, B UN, EGFR, creatinine clearance
What factors affect absorption of a drug
Route of administration, solubility of the drug, PH and Ionization, blood flow to the site of the drug administration
Pharmacodynamics
Study of biological, chemical, and physiological actions of a drug within the body
Enteral
The G.I. tract is used for ingestion and absorption of drugs(oral,NG,G tube)
Half-life of a drug
The amount of time it takes to remove 50% of the drug from the blood (half life is the result of metabolism and excretion)
Minimum effective concentration (MEC)
The concentration of drug which must be present in the body to produce therapeutic effect. Plasma drug levels below the MEC May not produce a therapeutic effect. The goal is to dose drugs so that the plasma concentration is above the MEC but below the plasma level at which adverse affects or toxicity occurs also known as the ... **Therapeutic range**
Pharmacotherapeutics
The desired or therapeutic effect of the drug, the indication for giving a drug
Pharmacokinetics
The study of the changes that occur to the drug while it is inside of the body. Four phases, absorption, distribution, metabolism, excretion
Synergistic effect
Two or more drugs are combined in the vector both drugs going together is greater than the individual drug given alone.