Describe the Pharmaceutic phase.
-The drug becomes a solution so that it can cross the biologic membrane.
-The tablet must disintegrate into small particles to dissolve a liquid (dissolution).
-Enteric coated drugs resist in the gastric acid of the stomach, so disintegration does not occur until the drug reaches the alkaline environment of the small intestine.
-When the drug is administered parenterally by subcutaneous (subQ), intramuscular (IM), or intravenous (IV) routes, there is no pharmaceutic phase.
Describe the Pharmacodynamics phase.
Study of the way drugs affect the body. Primary and secondary effects, primary is desirable and the secondary may be desirable or undesirable.
Describe the Pharmacokinetic phase.
Is the process of drug movement to achieve drug action.
What are the four processes of pharmacokinetics?
Absorption, Distribution, Metabolism or Biotransformation, Excretion or elimination
Describe the process of absorption.
Absorption is the movement of drug particles from the GI tract to body fluids by passive absorption, active absorption, or pinocytosis.
Passive absorption is usually achieved by?
What does active absorption require?
Requires a carrier such as an enzyme or protein to move the drug against a concentration gradient.
What is pinocytosis?
A process by which cells carry a drug across their membrane by engulfing the drug particles.
What factors can alter drug absorption?
Can be altered by blood flow, pain, stress, hunger, fasting, food, pH, and method of administration.
What is the first-pass effect?
The process in which the drug passes to the liver first, where it is either metabolized to an inactive form or a drug metabolite.
What is bioavailability?
Is the percentage of the administered drug dose that reaches the systemic circulation.
What factors can alter bioavailability?
The drug form, route of administration, GI mucosa and motility, food and other drugs, and changes in liver metabolism.
Describe the distribution process.
The process by which the drug becomes available to body fluids and body tissues.
What factors can influence drug distribution?
Is influenced by blood flow, the drug’s affinity to the tissue, and the protein-binding effect.
What is the difference between inactive and active drugs?
As drugs are distributed in the plasma, many are bound to varying degrees (percentages) with protein (primarily albumin). The portion of the drug that is bound is inactive because it is not available to receptors, and the portion that remains unbound is free, active drug.
Describe the metabolism process.
Is the process by which the body inactivates or biotransforms drugs. Drugs can be metabolized in several organs; however, the liver is the primary site of metabolism.
What are the routes of drug elimination?
The main route of drug elimination is through the kidneys (urine). Other routes include bile, feces, lungs, saliva, sweat, and breast milk.
What are the common tests used to determine renal function?
Creatinine clearance (CLcr) and blood urea nitrogen (BUN).
What is dose response?
Response is the relationship between the minimal versus the maximal amount of drug dose needed to produce the desired drug response.
What is an agonist?
Drugs that produce a response.
What is an antagonist?
Drugs that block a response.
What are the four categories of drug actions?
Stimulation or depression, replacement, inhibition or killing of organisms, and irritation.
In drug actions that stimulate, what happens to the cell activity and secretions from the gland increase or decrease?
The rate of cell activity or the secretion from a gland increases.
In drug action that depresses, cell activity and function of a specific organ increase or decrease?
Cell activity and function of a specific organ are reduced.
Replacement drugs replace what?
Replacement drugs replace essential body compounds.
What do druge that inhibit or kill organisms interfere with?
Drugs that inhibit or kill organisms interfere with bacterial cell growth.
What does the therapeutic index measure?
The therapeutic index (TI) estimates the margin of safety of a drug through the use of a ratio that measures the effective (therapeutic) dose (ED) in 50% of people (ED50) and the lethal dose (LD) in 50% of people (LD50).
What does the therapeutic range measure?
The therapeutic range (therapeutic window) of a drug concentration in plasma is the level of drug between the minimum effective concentration in the plasma for obtaining desired drug action and the minimum toxic concentration (the toxic effect).
What does the peaks and trough drug levels indicate?
Peak drug levels indicate the rate of absorption of the drug, and trough drug levels indicate the rate of elimination of the drug. Peak and trough levels are requested for drugs that have a narrow therapeutic index and are considered toxic.
What are side effects?
Side effects are physiologic effects not related to desired drug effects.
What are adverse reactions?
Adverse reactions are more severe than side effects
Toxic effects, or toxicity, of a drug can be identified by monitoring the plasma (serum) therapeutic range of the drug. When the drug level exceeds the therapeutic range, toxic effects are likely to occur from overdosing or drug accumulation.
What is pharmacogenetics?
Pharmacogenetics is the scientific discipline studying how the effect of a drug action varies from a predicted drug response because of genetic factors or hereditary influence.
What is tolerance?
Tolerance refers to a decreased responsiveness over the course of therapy.
What is tachyphylaxis?
Tachyphylaxis refers to a rapid decrease in response to the drug.
To avoid toxic effects, what should the nurse know about the drugs she/he is about to administer?
To avoid toxic effects, the nurse must know the half-life, protein-binding percentage, normal side effects, and therapeutic ranges of the drug.
Why should the nurse assess for signs and symptoms of drug toxicity when giving 2 drugs that are highly protein-bound?
The drugs compete for protein-binding sites, and displacement of drugs occurs. More free drug is in circulation because there are not enough protein-binding sites. Too much of a free drug can result in drug toxicity.
What is ethnopharmacology?
Ethnopharmacology is the study of drug responses that may be unique to an individual owing to social, cultural, and biologic phenomena.