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.