Pharmacodynamics Flashcards
Pharmacodynamics
The study of the biochemical and physiological effects of drugs on the body and their mechanism of action
Receptors
Bind with the drug to produce a drug-receptor complex and and effect
Pharmacodynamic Response
Describe the effect of the drug on the body.
Quantal dose-response relationship
plots fraction of population that respond to give drug dose as function of dose.
Effectiveness, toxicity, and lethality
Graded dose- response curve
Demonstrates the effect of a drug as function of its concentration.
Efficacy
Maximal response produced by a drug
Potency
The amount of drug needed to elicit a give response. the lower he dose required the more potent the drug.
Slope of dose
Response curve -> steep slope ->small increase in dose produces large changes in response
Active Receptor
Binds the drug
Inactive receptor
unable to bind the drug
Agonist
Binds receptors and activates
Partial agonist
binds receptor at active site and produces only a partial response even when all the receptors are bound by the partial agonist.
SERMS
Act as a partial agonist to estrogen receptors in bone and an antagonist to estrogen receptor in the breast
Buprenorphine
Partial agonist with high affinity for Mu-opoid receptor maybe be more potent but less efficacious then full agonist (morphine)
Pindolol
Often classified as a beta blocker but is actually a partial agonist that produces intermediate response.
Resting heart rate and blood pressure no reduced as well as pure antagonists, but pindolol inhibits potentially dangerous increases that would occur w/ sympathetic stimulation.
Antagonist
Inhibits the action of an agonist. Has no effect in the absence of the agonist.
Chemical antagonists
Inactivate agonist before it has the opportunity to act
Physiological antagonists
cause a physiologic effect opposite to that induced by the agonist
Competitive antagonist
Binds, reversibly to the active site of a receptor, and does not cause activation. Shifts to right
Noncompetitive antagonist
Bind to either active or allosteric site of receptor. If bound to active site the binding is irreversible and cannot be outcompeted by agonist. Allosteric agonist acts by preventing receptor activation. Maximal efficacy of agonist is reduced.
Therapeutic window
Range of doses of drug that elicits therapeutic response without unacceptable toxicity.
Drug-drug interactions
Drugs w/ similar characteristics may produce an exaggerated response.
Drugs w/ opposing pharmacodynamic effects may cause a diminished or lack of response.
