Nuts and Bolts of Therapeutics Flashcards
Drug-receptor interactions depend on…
- Chemical composition
- Stereochemical disposition (chirality)
- Ability for drug to reach receptor binding zone
Affinity
Probability of the the drug occupting a receptor at any given time - affected by other drugs, ageing and genetic mutations
Selectivity
The degree to which a drug acts on a given site relative to other sites
Efficacy
The relative ability of a drug-receptor complex to produce the maximum functional response
Agonist
Chemical binds to a receptor and activates it to produce a biological response
Partial Agonist
Chemical still binds to receptor but only has partial efficacy
Antagonist
Chemical binds and blocks/dampens agonist-mediated responses rather than provoking a biological response
Potency
Measure of drug activity - the amount required to produce an effect of given intensity
Tolerance
Decreased response to drug with repeated doses
Mechanisms of tolerance
- Decreased receptor numbers (downregulation)
- Decreased receptor binding affinity
- Modulation of downstream response to initial signal
On-target response
Drug intended to modulate the function of a specific receptor in a particular tissue
Off-target response
Drug and/or metabollites modulate the function of a target for which it was not intended
Therapeutic index
Ratio of the dose that produces toxicity to the dose that produces a clinically desired or effective response in a group of individuals
Dose
Total quantity of an active agent taken in or absorbed at any one time
Main routes of drug administration
- Enteral - substance given by GIT - desired effect is systemic (oral, NG, ND, enema)
- IV - 100% availability
- Parental - desired effect is systemic but drug not given via GIT (transdermal, tansmucousal, inhalation)
- Topical - local effect (transcutaneous/cream, inhalation)