Pharmacology and Therapeutics Flashcards

What is the mechanism of action of omeprazole (proton pump inhibitor)?

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.

Which antihypertensive class is contraindicated in pregnancy?

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.

What is the primary concern when dispensing methotrexate for a patient?

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.

What is the clinical significance of the CYP3A4 enzyme system in drug interactions?

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).

What monitoring is required for a patient starting statin therapy?

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).

What is the appropriate first-line treatment for community-acquired pneumonia in an otherwise healthy adult in Saudi Arabia?

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.