drug-drug interactions Flashcards
(24 cards)
what is a drug interaction?
the modification of a drugs effect by prior or concomitant (naturally accompanying) administration of another Drug, Herb, Foodstuff, Drink
what is the evidence that a drug interaction has occurred?
the pharmacological effect of two or more drugs given together is not just a direct function of their individual effects
types of drug interactions
drug with:
- drug
- food
- herbal
- drink
pharmacogenetic interactions
pharmacogenetics
study of inherited genetic differences in drug metabolic pathways which can affect individual responses to drugs, both in terms of therapeutic effect as well as adverse effects.
what is an object drug?
the drug whose activity is effected by such a drug other compound interaction
precipitant
the agent which precipitates a drug interaction
diseases whose treatment is reliant on drug interactions
- hypertension
- Parkinson’s
why is therapeutic drug monitoring carried when treating with drugs involved with serious interaction?
these drugs have narrow therapeutic indexes so any interactions can induce profound toxicity
which groups of patients are susceptible to drug interactions?
-patients on many drugs (polypharmacy)
-the elderly
-the young
-the critically ill
patients undergoing complicated surgical procedures
-patients with some chronic conditions
chronic conditions which will increase drug interactions
- liver disease
- renal impairment
- diabetes mellitus
- epilepsy
- asthma
additive interactions
drug effects are added together
antagonistic interactions
drug effects cancel each other out
what effects can a drug have in the gut?
- Formation of insoluble complexes
- Altered PH.
- Altered bacterial flora.
- Altered GIT motility.
what do drug interactions in the gut cause (in terms of absorption)?
changes in absorption rate
what type of antibiotics destroy normal gut flora?
broad spectrum
what is the rate limiting step in oral medicines absorption?
gastric emptying
what does the displacement of a drug from plasma protein result in?
increased bioavailability as only unbound drug is pharmacologically active
what are drug interactions involving metabolism?
occur when one drug induces or inhibits the metabolism of another
what is the common metabolic enzyme family that is induced or inhibited by other drugs?
cytochrome P-450
pharmacodynamics
the mechanism of a drugs action
main ways in which a drug can alter the action of another drug
- altering absorption
- altering distribution
- altering metabolism
- altering excretion
- altering pharmacodynamic interactions
direct antagonism
drug will block the binding site of another drug
synergistic interactions
two drugs with the same pharmacological effect acting on the same receptor concurrently
types of pharmacological interactions
- direct antagonism
- indirect antagonism
- indirect agonism/synergy
- direct agonism/synergy
