Pharmaceutics Practice Test

A 60-year-old male (weight 82 kg) with GERD reports persistent symptoms despite taking omeprazole delayed-release capsules 20 mg by mouth daily; he also takes calcium carbonate chewable tablets as needed and metformin immediate-release tablets 500 mg twice daily. He recently started taking omeprazole by opening the capsule and sprinkling contents into hot coffee to "help it dissolve." Labs: SCr 1.0 mg/dL (0.6–1.3), AST 26 U/L (10–40), ALT 24 U/L (7–56), Na 138 mEq/L (135–145), K 4.2 mEq/L (3.5–5.0). The pharmacist suspects reduced exposure due to improper dosage-form handling. Which factor most affects this drug's bioavailability?

A 52-year-old woman (70 kg) with Roux-en-Y gastric bypass 2 years ago presents for uncontrolled hypothyroid symptoms. Current medications: levothyroxine 100 mcg tablet daily, calcium citrate 600 mg PO BID, omeprazole 20 mg delayed-release capsule daily. Labs: TSH 9.8 mIU/L (0.4–4.5), SCr 0.9 mg/dL (0.6–1.3), AST 20 U/L (10–40), ALT 19 U/L (7–56), Na 139 mEq/L (135–145), K 4.0 mEq/L (3.5–5.0). The pharmacist suspects reduced absorption related to formulation and GI anatomy. Which factor most affects this drug's bioavailability in this patient?