Clin Pharm Exam 2

Drug-drug interactions

What is the most common category of drug interaction tested clinically?

Target drug

What is the term for the drug whose effect is altered by another drug?

Pharmacokinetic interaction

What type of interaction alters absorption, distribution, metabolism, or excretion?

Pharmacodynamic interaction

What type of interaction alters drug effects directly at receptors or physiologic systems?

Synergism

What interaction occurs when the combined effect is greater than the sum of individual effects?

Clopidogrel + aspirin

What is a classic example of synergism?

Additive effect

What interaction occurs when the combined effect equals the sum of the individual effects?

Aspirin + acetaminophen

What is a classic example of an additive interaction?

Antagonism

What interaction occurs when one drug reduces the effect of another?

Naloxone + opioids

What is a classic example of antagonism?

Flumazenil + benzodiazepines

What is a classic example of antagonism?

Permissive effect

What interaction occurs when one drug requires another to exert its full effect?

Tachyphylaxis

What term describes decreased response after repeated doses?

Potentiation

What interaction occurs when a drug with little effect enhances another drug’s action?

Carbidopa + levodopa

What is a classic example of potentiation?

Ketoconazole

What drug requires an acidic gastric pH for absorption?

Famotidine

What medication can decrease ketoconazole absorption by increasing gastric pH?

Ferrous sulfate

What medication has decreased absorption when gastric pH is increased?

Metoclopramide (Reglan)

What medication increases gastric emptying and speeds absorption?

Anticholinergics

What drug class slows GI motility and delays absorption?

Calcium, magnesium, and aluminum antacids

What substances decrease absorption of tetracyclines and fluoroquinolones?

Tetracyclines

What antibiotic class is chelated by calcium-containing products?

Fluoroquinolones

What antibiotic class is chelated by antacids and dairy products?

Cholestyramine and colestipol

What medications bind many drugs and reduce absorption?

2 hours before or 4-6 hours after

How should most drugs be administered around bile acid sequestrants?

Erythromycin + digoxin

What antibiotic interaction increases digoxin bioavailability?

Antibiotics + oral contraceptives

What interaction may reduce enterohepatic recycling of estrogen?

Albumin

What plasma protein preferentially binds acidic drugs?

Warfarin

What classic acidic drug is highly albumin bound?

Alpha-1 acid glycoprotein

What plasma protein preferentially binds lipophilic basic drugs?

Propranolol

What drug is commonly bound by alpha-1 acid glycoprotein?

Free (unbound) drug

What form of a drug is pharmacologically active?

Phenytoin + warfarin

What classic protein-binding displacement interaction increases bleeding risk?

Narrow therapeutic index

What drug characteristic makes protein displacement clinically important?

Greater than 90% protein binding

What level of protein binding increases risk of displacement interactions?

Liver

What is the major site of drug metabolism?

Small intestine

What extrahepatic organ plays an important role in drug metabolism?

CYP3A4

What CYP enzyme metabolizes the largest percentage of drugs?

Poor metabolizer

What patient is at risk for increased drug accumulation and toxicity?

Ultra-metabolizer

What patient may have reduced drug efficacy due to rapid metabolism?

Prodrug

What type of drug requires metabolism to become active?

Enzyme inhibition

What metabolic interaction increases drug concentrations?

Enzyme induction

What metabolic interaction decreases drug concentrations?

Competitive inhibition

What occurs when two drugs compete for the same enzyme binding site?

Noncompetitive inhibition

What occurs when a drug blocks an enzyme without being metabolized by it?

Quinidine

What drug competitively occupies CYP2D6 but is metabolized by CYP3A4?

Fluconazole

What antifungal inhibits CYP enzymes and increases warfarin levels?

TMP-SMX (Bactrim)

What antibiotic inhibits CYP2C9 and increases INR in warfarin users?

Ketoconazole + simvastatin

What interaction increases risk of rhabdomyolysis?

Omeprazole + clopidogrel

What interaction decreases clopidogrel effectiveness?

Amiodarone

What antiarrhythmic is a major CYP inhibitor that increases warfarin levels?

FAB5

What mnemonic identifies major CYP inhibitors that increase warfarin levels?

Fluconazole, Fluoroquinolones, Flagyl

What does the F in FAB5 represent?

Amiodarone

What does the A in FAB5 represent?

Bactrim

What does the B in FAB5 represent?

Fluoroquinolones

What drug class is represented by the second F in FAB5?

Flagyl (metronidazole)

What does the 5th component of FAB5 represent?

Rifampin

What is the classic CYP inducer tested on exams?

Carbamazepine

What anticonvulsant is both a CYP inducer and autoinducer?

Phenytoin

What anticonvulsant is a major CYP inducer?

Phenobarbital

What barbiturate is a major CYP inducer?

Rifampin + warfarin

What interaction decreases warfarin effectiveness?

Carbamazepine

What drug exhibits autoinduction?

Amiodarone

What drug’s long half-life can prolong inhibition for weeks?

Acidic drugs in alkaline urine

What drug form becomes trapped and excreted?

Aspirin overdose

What poisoning is treated with urinary alkalinization?

Sodium bicarbonate

What treatment enhances excretion of aspirin?

Basic drugs in acidic urine

What drug form becomes trapped and excreted?

Digoxin + verapamil

What excretion interaction increases risk of digoxin toxicity?

Traffic jam effect

What occurs when two drugs compete for the same renal transport pathway?

P-glycoprotein

What transporter pumps drugs out of intestinal, liver, and kidney cells?

Verapamil

What drug inhibits P-glycoprotein and increases digoxin levels?

Rifampin

What drug induces P-glycoprotein and decreases digoxin levels?

Grapefruit juice

What food inhibits intestinal CYP3A4?

Felodipine

What medication is classically increased by grapefruit juice?

Statins

What drug class commonly interacts with grapefruit juice?

Azithromycin

What antibiotic should be taken on an empty stomach because food decreases bioavailability?

Fluoroquinolones + milk

What classic drug-food interaction reduces antibiotic absorption?

Vitamin K-rich foods

What foods reduce warfarin effectiveness?

Leafy green vegetables

What foods are most associated with reduced anticoagulation from warfarin?

Pyridoxine (vitamin B6)

What vitamin decreases levodopa efficacy?

Levodopa

What Parkinson medication is affected by vitamin B6?

Metformin

What medication may cause vitamin B12 deficiency?

Isoniazid

What medication can cause vitamin B6 deficiency and neuropathy?

Loop diuretics

What diuretic class wastes potassium and calcium?

Thiazide diuretics

What diuretic class wastes potassium but spares calcium?

Spironolactone

What diuretic spares potassium?

Low sodium diet + lithium

What interaction increases lithium toxicity?

St. John's Wort

What herb induces CYP450 enzymes?

Gastric bypass surgery

What condition commonly causes vitamin B12 deficiency?

Heart failure

What disease can decrease oral drug absorption because of bowel edema?

Diabetes mellitus

What disease can delay gastric emptying and alter absorption?

Cirrhosis

What disease impairs drug metabolism?

Renal insufficiency

What disease state commonly requires dose adjustment?

Lithium

What drug commonly requires renal dose adjustment?

Famotidine

What H2 blocker commonly requires renal dose adjustment?

Ciprofloxacin

What fluoroquinolone commonly requires renal dose adjustment?

Side effect

What is a predictable secondary effect occurring at therapeutic doses?

Adverse drug reaction (ADR)

What is a noxious unintended response at normal doses?

Diphenhydramine causing drowsiness

What is an example of a side effect?