PTCB Pharmacology #5 3 — Questions and Answers
Question 1: Which drug is the antidote for heparin overdose?
- Vitamin K
- Fresh frozen plasma
- Protamine sulfate (Correct answer)
- Phytonadione
Correct answer: Protamine sulfate
Protamine sulfate reverses unfractionated heparin toxicity. It is a positively charged protein that binds the negatively charged heparin, forming a stable complex that neutralizes anticoagulant activity.
Question 2: Which class of drug do "-zosin" suffix drugs (e.g., tamsulosin, doxazosin) belong to?
- Beta-blockers
- ACE inhibitors
- Alpha-1 adrenergic blockers (Correct answer)
- Calcium channel blockers
Correct answer: Alpha-1 adrenergic blockers
Alpha-1 blockers end in "-zosin" (tamsulosin, doxazosin, prazosin, terazosin). They relax smooth muscle in blood vessels and the prostate/bladder neck, used for hypertension and BPH.
Question 3: Varenicline (Chantix) is used for smoking cessation because it:
- Is a nicotine replacement providing low-dose nicotine
- Partially activates nicotinic acetylcholine receptors while blocking nicotine binding (Correct answer)
- Blocks dopamine receptors to reduce reward from smoking
- Increases nicotine metabolism to reduce cravings
Correct answer: Partially activates nicotinic acetylcholine receptors while blocking nicotine binding
Varenicline is a partial agonist at alpha4-beta2 nicotinic acetylcholine receptors. It provides mild dopamine release (reducing cravings/withdrawal) while blocking nicotine's full receptor activation (reducing reinforcement from smoking).
Question 4: Drug-induced lupus (DIL) is most commonly associated with which drug?
- Aspirin
- Hydralazine (Correct answer)
- Metoprolol
- Omeprazole
Correct answer: Hydralazine
Hydralazine, procainamide, and isoniazid are the classic drugs most commonly causing drug-induced lupus. The syndrome typically resolves upon drug discontinuation.
Question 5: Which of the following is the primary reason why grapefruit juice interacts with simvastatin?
- It inhibits renal excretion of simvastatin
- It induces CYP2D6 metabolism
- It inhibits intestinal CYP3A4, increasing simvastatin bioavailability and myopathy risk (Correct answer)
- It decreases gastric pH, increasing absorption
Correct answer: It inhibits intestinal CYP3A4, increasing simvastatin bioavailability and myopathy risk
Grapefruit juice inhibits CYP3A4 in the intestinal wall (irreversibly), dramatically increasing simvastatin bioavailability. This raises plasma levels significantly, increasing the risk of myopathy and rhabdomyolysis.
Question 6: What is the mechanism of action of memantine (Namenda), used in Alzheimer's disease?
- Acetylcholinesterase inhibition
- Beta-amyloid plaque reduction
- NMDA receptor antagonism (Correct answer)
- Dopamine agonism
Correct answer: NMDA receptor antagonism
Memantine is a non-competitive NMDA (N-methyl-D-aspartate) glutamate receptor antagonist. By blocking excessive glutamate activity, it reduces excitotoxicity thought to contribute to Alzheimer's neurodegeneration. It is used for moderate-to-severe Alzheimer's disease.
PTCB Pharmacology #5 3
Which drug is the antidote for heparin overdose?