Calcium salt can be used in the prevention and treatment of calcium deficiency states or negative calcium balance. It is also used as an adjunct in the prevention and treatment of osteoporosis.
Calcitriol promotes calcium absorption in the intestines and retention at the kidneys thus increasing serum calcium levels. It also increases renal tubule phosphate resorption consequently decreasing serum phosphatase levels, PTH levels and bone resorption.
Dosage & Administration
Hyperparathyroidism in renal failure: 0.25 mcg/day or alternate day. May increase slowly.
Hypoparathyroidism or pseudohypoparathyroidism: 0.5-2 mcg once daily.
Vitamin D dependent rickets: 0.015-0.02 mcg/kg/day. Maintenance: 0.03-0.06 mcg/kg/day. Max: 2 mcg/day.
Hyperparathyroidism in dialysis patients: 0.5-4 mcg 3 times/wk. Max: 8 mcg 3 times/wk.
Hyperparathyroidism in renal failure: 0.5 mcg 3 times/wk, may increase by 0.25-0.5 mcg at 2-4 wk intervals. Maintenance: 0.5-3 mcg 3 times/wk.
Calcium: Co-administration with thiazide diuretics or vit D may lead to milk-alkali syndrome and hypercalcaemia. Decreased absorption with corticosteroids. Decreases absorption of tetracyclines, atenolol, iron, quinolones, alendronate, Na fluoride, Zn and calcium-channel blockers. Enhances cardiac effects of digitalis glycosides and may precipitate digitalis intoxication.
Calcitriol: Hypermagnesaemia may develop in patients on chronic renal dialysis. Hypercalcaemia in patients on digitalis may precipitate cardiac arrhythmias. Intestinal absorption of calcitriol may be reduced by cholestyramine and colestipol. Phenytoin, barbiturates may decrease the T1/2 of calcitriol. May develop hypercalcaemia with thiazide diuretics.