Intro to Pharmacology Flashcards
Pharmacokinetics
the study of how the body absorbs, distributes, metabolizes, and eliminates drugs
Pharmacodynamics
the analysis of what the drug does to the body, including the mechanism by which the drug exerts its effect on the target tissue.
Threshold dose
Minimum dose to elicit effect
Ceiling effect
maximal effect of the drug
Narrow therapeutic index drugs
difference between effective and toxic dose is small.
First Pass Metabolism
Drugs are transported to the liver, via the portal vein, where significant amounts of the drug can be metabolized and destroyed before reaching the intended site of action
Bioavailability (F)
The extent to which a drug reaches the systemic circulation, first pass metabolism affects a drugs bioavailability
Volume of Distribution (Vd)
Ratio of the amount of drug administered to the concentration of drug in the plasma
Storage Sites for drugs
Adipose
Bone
Muscle
Organs
Drug Excretion
Via drug metabolism, drugs are transformed to polar, water-soluble metabolites get trapped in the nephron and are excreted in the urine
Other routes: lungs and GI tract
Clearance
The tissue’s ability to eliminate a drug
Most often hepatic or renal
Half-life
The amount of time required for 50% of the drug remaining in the body to be eliminated
Accounts for Vd and clearance
5 half-lives is considered eliminated
Helps determine dosing intervals
Affinity
the amount of attraction between a drug and a receptor
Drugs with high affinity bind to open receptors even at low concentrations
Selectivity
Highly selective drug affects only one type of tissue or cell
No drug is 100% selective for the target tissue
Agonist
Drug can bind to a receptor and initiate a change in the cell function
Affinity and efficacy
Antagonist
Drug will bind to receptor, but will not cause a direct change or function
Blocks the chemical response
Affinity only
Partial Agonist
Does not evoke to maximum response compared to a strong agonist, can have high affinity, only partially activates the receptor
Competitive Antagonists
Competes for receptor
Weak bond
Highest concentration will ‘win’ the receptor
Noncompetitive Antagonists
Forms a permanent bond with receptor, high affinity, will last for the receptors lifespan
