Name: Human calcitonin (Cibacalcin, Calcimar)
Class: Hormone
Mechanism: Inhibition of both bone resorption and renal tubular reabsorption of calcium and phosphate. Secretion stim by serum calcium. Net result = ¯¯calcium, ¯¯phosphate.
Absorption: SC, IM. Nasal is variable and often poor.
Dist.:
Metabolism.: Inactivated by proteolysis in kidneys and blood.
Excretion, t½: Minutes.
Toxicity/S.E.s: Flushing of face and hands w/in min. of injxn (16-21%). Nausea/vomiting w/in 30 min. of use (14-21%); usu. diminishes w/continued therapy. Bedtime admin. can minimize effects. Urinary frequency (5-10%)
Utility: Initial treatment of hypercalcemia. Diseases characterized by increased skeletal remodeling (e.g., Paget’s disease of bone). Recently approved for treatment of postmenopausal osteoporosis.
Special Features: Effects begin after several hours, persist for up to 10 hr. Salmon calcitonin has a longer t½ and duration and is 50x more potent. However, 30-50% of long-term patients develop antibodies to salmon calcitonin.