pharma bone

Rickets vs. Osteomalacia

Both involve a faulty bone mineralization process due to Vitamin D, Phosphate, or Calcium defects. Rickets occurs in children; Osteomalacia occurs in adults.

Nutritional vs. Renal Rickets Treatment

Nutritional is treated with Calcium + Vitamin D. Renal rickets (failure to activate Vit D) is treated with Calcium + Calcitriol or Alfacalcidiol.

Osteoporosis Definition

Decreased bone mass that increases fracture risk, but the remaining bone has normal mineralization.

Osteoporosis Causes (5 Main)

Estrogen/androgen deficiency, Cushing's disease, Thyrotoxicosis, Chronic drug use (heparin, phenytoin, PPIs), and Immobilization.

Bisphosphonates Mechanism

First-line antiresorptives that decrease osteoclast activity by inducing apoptosis and inhibiting their cholesterol pathway.

Bisphosphonates Adverse Effects

Gastric and esophageal irritation (take sitting upright with water), renal impairment risk, and high risk of jaw osteonecrosis.

Denosumab Mechanism

Monoclonal antibody that binds and inhibits RANKL, blocking osteoclast formation and function.

Denosumab Adverse Effects

Increased infection risk, dermatological reactions, hypocalcemia, and atypical fractures after stopping the drug.

Calcitonin

Reduces bone resorption but is less effective than bisphosphonates; side effects include facial flushing and nasal irritation (if spray).

Estrogens & Raloxifene

Estrogens inhibit resorption but increase cancer risk. Raloxifene is a SERM that protects bone without breast/uterus cancer risk, but causes hot flashes and thrombosis risk.

Bazedoxifene

A Tissue Specific Estrogen Complex (TSEC) that increases bone density and decreases LDL, but is antiestrogenic in the uterus to prevent hyperplasia.

Teriparatide

Recombinant PTH given via subcutaneous injection; intermittent exposure promotes bone formation by stimulating osteoblasts.

Romosozumab

Humanized monoclonal antibody that inhibits sclerostin, preventing its anti-anabolic effects on bone formation.

Abaloparatide

PTH-related protein (PTHrP) analog that regulates bone development and increases bone formation via continuous administration.

Strontium

Dual-action drug that increases bone formation (calcimimetic) and inhibits bone resorption; may induce myocardial infarction.

Cinacalcet

Calcimimetic that increases the sensitivity of calcium-sensing receptors, decreasing PTH secretion (used for hyperparathyroidism).

Vitamin D Mechanism in Bone vs. Kidneys

In bone, it stimulates osteoblasts and calcium deposition (normal/rickets). In kidneys, it increases calcium and phosphate proximal tubular reabsorption.

Calcitriol vs. Alfacalcidiol

Active forms of Vitamin D that do not require renal activation; used specifically in renal rickets and renal failure.