Drug Interactions Flashcards
What the drug does to the body
Pharmodynamics
Aminoglycosides, such as tobramycin, can potentiate the effect of ____ and _____, causing prolonged neuromuscular blockade
Succinylcholine and tubocurarine
Drug/drug and drug/food interactions can occur at _______ phases of drug disposition
All
Altered by pH, transport, chelation, and biotransformation
Absorption
When co-administered with a tetracycline, such as doxycycline, may bind to the antibiotic and cause decreased absorption
Antacid
Calcium, magnesium, or aluminum present in ____ binds with tetracycline
Antacid
Cholestyramine binds _____ to decrease bioavailability
Digoxin
_______ and ________ binds Mycophenolate mofetil causing a decreased effect of the immunosuppressant
Ferrous sulfate and calcium
Precipitant drugs that decrease gastric motility, may affect the rate, but not the extent of _______ of object drugs
Absorption
________ decrease gastric motility and rate of absorption
Anticholinergics (amitriptyline)
Slow gastric motility
Opiates (morphine)
Precipitant drugs that increase gastric motility result in a shorter time and greater peak effect, but do not change extent of
Absorption
Stimulates gastric motility
Metoclopramide
H2 blockers (cimetidine and ranitidine) increase stomach pH and decrease ________ absorption
Ketoconazole
________ cause decreased atazanavir and itraconazole absorption
Proton pump inhibitors (omeprazole)
Inhibition of P-glycoprotein (PGP) in apical membrane of enterocytes will ___________ absorption of drugs that are normally excreted by this transporter
Increase
Many substrates for _____ are also substrates for PGP
CYP3A4
Ketoconazole is an inhibitor of
PGP/CYP3A4
Inhibits CYP3A4 and activates PGP (counteracts some of the CYP450 inhibition)
Grapefruit juice
Partially converted to an inactive form by normal flora in the gut. Antibiotics may reduce normal flora, causing higher serum levels of this drug
Digoxin
Bactrim can displace protein bound
Warfarin
Induces increased metabolism of asthmatic agent theophylline when exposed to aromatic hydrocarbons in smokers
CYP1A2
Metabolism of 50% of clinically useful drugs
CYP3A4
Metabolism of 30% of clinically useful drugs, including SSRIs, beta blockers, and pain relievers
CYP2D6
May increase drug levels of the drug has active metabolites
Enzyme induction
Phenytoin, rifampin, and carbamazepine
Major inducers
Reduces drug metabolism, causing increased drug concentrations that may lead to an increased therapeutic reponse and/or toxicity
Enzyme inhibition
Ketoconazole, cimetidine, erythromycin, and grapefruit juice (due to naringi)
Enzyme inhibitors
Phenobarbital induces the metabolism of
Diazepam (altered pharmacokinetics)
