Saudi Prometric Pharmacist Pharmacology and Therapeutics — Questions and Answers
Question 1: What is the mechanism of action of omeprazole (proton pump inhibitor)?
- Blocks histamine H2 receptors
- Irreversibly inhibits the H+/K+ ATPase enzyme system (proton pump) in gastric parietal cells (Correct answer)
- Neutralizes stomach acid directly
- Stimulates bicarbonate secretion
Correct answer: Irreversibly inhibits the H+/K+ ATPase enzyme system (proton pump) in gastric parietal cells
Omeprazole irreversibly blocks the hydrogen-potassium ATPase enzyme (proton pump) on the apical surface of parietal cells, preventing the final step of acid secretion. This provides superior acid suppression compared to H2 blockers.
Question 2: Which antihypertensive class is contraindicated in pregnancy?
- Calcium channel blockers
- ACE inhibitors and ARBs (Correct answer)
- Methyldopa
- Labetalol
Correct answer: ACE inhibitors and ARBs
ACE inhibitors and ARBs are absolutely contraindicated in pregnancy due to teratogenic effects including renal dysgenesis, oligohydramnios, skull defects, and fetal death. Methyldopa and labetalol are the preferred antihypertensives during pregnancy.
Question 3: What is the primary concern when dispensing methotrexate for a patient?
- It causes weight gain
- Ensure correct dosing frequency (usually weekly, NOT daily for autoimmune conditions), and verify hepatic/renal function and CBC (Correct answer)
- It has no significant side effects
- It should be taken with dairy products
Correct answer: Ensure correct dosing frequency (usually weekly, NOT daily for autoimmune conditions), and verify hepatic/renal function and CBC
Methotrexate dosing errors (daily instead of weekly) have caused fatal toxicity. Pharmacists must verify: weekly dosing for autoimmune conditions, baseline and monitoring labs (CBC, LFTs, renal function), folic acid supplementation, pregnancy prevention, and drug interactions.
Question 4: What is the clinical significance of the CYP3A4 enzyme system in drug interactions?
- It has no clinical significance
- CYP3A4 metabolizes approximately 50% of all drugs, so inhibitors and inducers significantly alter drug levels (Correct answer)
- It only affects antibiotics
- It only works in the kidneys
Correct answer: CYP3A4 metabolizes approximately 50% of all drugs, so inhibitors and inducers significantly alter drug levels
CYP3A4 is the most abundant CYP enzyme, metabolizing ~50% of medications. Inhibitors (ketoconazole, grapefruit juice, ritonavir) increase drug levels (toxicity risk). Inducers (rifampicin, carbamazepine, St. John's Wort) decrease drug levels (therapeutic failure).
Question 5: What monitoring is required for a patient starting statin therapy?
- Only cholesterol levels
- Baseline and periodic liver function tests (ALT), lipid profile, and assessment for myopathy symptoms (muscle pain/weakness) (Correct answer)
- Blood pressure only
- No monitoring needed
Correct answer: Baseline and periodic liver function tests (ALT), lipid profile, and assessment for myopathy symptoms (muscle pain/weakness)
Statin monitoring includes: baseline LFTs before initiation, fasting lipid profile at baseline and 4-12 weeks after starting, assess for myopathy (muscle pain, weakness, elevated CK), monitor for rhabdomyolysis symptoms, and assess diabetes risk (statins can increase blood glucose).
Question 6: What is the appropriate first-line treatment for community-acquired pneumonia in an otherwise healthy adult in Saudi Arabia?
- IV vancomycin
- Oral amoxicillin or a macrolide (azithromycin) for outpatient treatment (Correct answer)
- IV meropenem
- Oral metronidazole
Correct answer: Oral amoxicillin or a macrolide (azithromycin) for outpatient treatment
For mild CAP in healthy adults without comorbidities, Saudi and international guidelines recommend oral amoxicillin or macrolides (azithromycin/clarithromycin). Broader spectrum antibiotics are reserved for patients with comorbidities, severe disease, or hospital admission.
Saudi Prometric Pharmacist Pharmacology and Therapeutics
What is the mechanism of action of omeprazole (proton pump inhibitor)?