Osteoporosis and Calcium Metabolism MCQs

Paget’s disease is characterized by excessive bone resorption, poorly organized bone formation, and hypercalcemia. Bisphosphonates and calcitonin are first-line treatments. Pamidronate is a powerful bisphosphonate used parenterally to treat hypercalcemia. Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg. no. 793

The active metabolites of vitamin D increase serum calcium and phosphate by promoting calcium and phosphate uptake from the gastrointestinal tract, increasing bone resorption, and decreasing renal excretion of both electrolytes. They inhibit, rather than stimulate, PTH formation. Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg. no. 781

Nitrogen-containingbisphosphonates (alendronate, risedronate, zoledronate) cause inhibition of the enzyme farnesyl pyrophosphatesynthase → disturbance of osteoclast metabolism and signaling → reduced osteoclast function and promotion of osteoclast apoptosis. Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg. no. 698

Teriparatide: parathyroid hormone analogue Mechanism of action: increases osteoblastic activity →increased bone growth Mainly used for the treatment of osteoporosis and as an alternative for severe osteoporosis (T-score ≤ -3.5) or for patients with contraindications to bisphosphonates Administered in a pulsatile fashion Side effects : Hypercalcemia (usually transitory) Increased risk of osteosarcoma in patients with Paget disease of the bone (or an unexplained elevation of alkaline phosphatases) and Prior cancers or radiation therapy Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg. no. 790

Osteoporosis The second and third generation BPNs (e.g. alendronate, ibandronate, risedronate) are effective in preventing and treating postmenopausal osteoporosis in women as well as age related, idiopathic and steroid induced osteoporosis in both men and women. Alendronate is equally or more effective than HRT or raloxifene in conserving bone mineral density BPNs are more effective than calcitonin and continue to afford protection for at least 5 years of continuous use. Thus, theyare the first choice drugs now for osteoporosis. Since the t 1/2 of alendronate in bone is ~ 10 years, treatment beyond 5 years is considered unnecessary.

Denosumab (monoclonal antibody against RANKL) Mechanism of action: targets the RANKL by mimicking osteoprotegerin → interference in osteoclast maturation → ↓ osteoclast activity Indicated in patients with impaired renal function or in whom bisphosphonates therapy failed Reference: Basic & clinical Pharmacology by Bertram G. Katzung, 15 th Edition, pg no. 807