Paper II — 2025 March (Supplementary (SAY)) (2019 Scheme) — Q9
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Paper II
2025 March (Supplementary (SAY)) (2019 Scheme) · 100 marks · 180 min
Question
A 60-year-old lady presents with back pain and in the legs. She also complains of a recent fracture in the
right wrist joint. After investigation, the physician made a diagnosis of Osteoporosis. She was prescribed
Alendronate. Explain the mechanism of action and adverse effects of Alendronate. (4+2)
Q96 marksShort Essays
Answer
Alendronate is a nitrogen-containing bisphosphonate, appropriate for this patient’s osteoporotic wrist fracture.
Mechanism of action: binds hydroxyapatite in bone with high affinity and is taken up by osteoclasts during bone resorption; inhibits farnesyl pyrophosphate synthase in the mevalonate pathway, disrupting osteoclast cytoskeletal function and inducing osteoclast apoptosis — reducing bone resorption and increasing net bone mineral density over time.
Adverse effects: esophagitis/esophageal ulceration (must be taken with a full glass of water, sitting upright, on an empty stomach, remaining upright for 30 minutes afterward), osteonecrosis of the jaw (rare, associated with dental procedures during therapy), atypical femoral fractures with long-term use, acute-phase reaction (fever, myalgia — more common with IV bisphosphonates), hypocalcemia.
