Calcitriol is indicated for- Established postmenopausal osteoporosis, Renal osteodystrophy in patients with chronic renal failure, particularly those undergoing haemodialysis, Postsurgical hypoparathyroidism, Idiopathic hypoparathyroidism, Pseudohypoparathyroidism, Vitamin D dependent rickets, Hypophosphataemic vitamin D resistant rickets.
Vitamin in bone formation, Vitamin-D preparations
Calcitriol is one of the most important active metabolites of vitamin D3. It is normally formed in the kidneys from its precursor, 25-hydroxycholecalciferol. Calcitriol promotes intestinal absorption of calcium and regulates bone mineralization. The pharmacological effect of a single dose of Calcitriol lasts about 3-5 days.The key role of calcitriol is the regulation of calcium homeostasis, which includes stimulation effects on osteoblastic activity in the skeleton.
: Hypocalcaemia: For patients undergoing chronic renal dialysis: 1 mcg (0.02 mcg/kg) to 2 mcg 3 times wkly, approx every other day. If no satisfactory response observed, increase by 0.5-1 mcg at 2-4 wk intervals. Individualise and commensurate incremental dosing with PTH, serum Ca and phosphorus levels.
Oral: Postmenopausal osteoporosis: 0.25 mcg bid.
Oral: Renal osteodystrophy: For correction of Ca and phosphorus metabolism abnormalities: Initially, 0.25 mcg daily. Patient with normal or slightly reduced Ca levels: 0.25 mcg every other day. If no response w/in 2-4 wk, increase daily dose by 0.25 mcg at 2-4 wk intervals. Immediately stop treatment if serum Ca levels rise to 1 mg/100 mL (250 μmol/L) above normal (9-11 mg/100 mL or 2,250-2,750 μmol/L), or serum creatinine rises to >120 μmol/L.
Uncontrolled intake of additional calcium containing preparations should be avoided. Concomitant treatment with a thiazide diuretc increases the risk of hypercalcemia. Calcitriol dosage must be determined with care in patients undergoing treatment with digitalis, as hypercalcemia in such patients may precipitate cardiac arrhythmias. Magnesium containing drugs (eg. antacids) may cause hypermagnesemia. The dosage of phosphate binding agents must be adjusted in accordance with the serum phosphate concentration.
Calcitriol is contraindicated in patients with known hypersensitivity to any of its ingredients. Calcitriol is also contraindicated in all diseases associated with hypercalcemia.
Since Calcitriol exerts vitamin D activity, adverse effects may occur which are similar to those found when an excessive dose of vitamin D is taken, i.e. hypercalcaemia syndrome or calcium intoxication (depending on the severity and duration of hypercalcaemia). Occasional acute symptoms include anorexia, headache, nausea, vomiting, abdominal pain or stomach ache and constipation.
Pregnancy category C. Calcitriol has been found to be teratogenic in rabbits. There are no adequate and well-controlled studies in pregnant women. Calcitriol should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Immobilised patients, e.g. those who have undergone surgery, are particularly exposed to the risk of hypercalcaemia. Patients with normal renal function who are taking Calcitriol should avoid dehydration. Adequate fluid intake should be maintained. Caution should be taken in patient with malabsorption syndrome, Renal or hepatic impairment, Pregnancy and lactation.
Administration of Calcitriol to patients in excess of their daily requirements can cause hypercalcaemia, hypercalciuria and hyperphospatemia. Since Calcitriol is a derivative of vitamin D, the signs and symptoms of overdose are the same as for an overdose of vitamin D.
Elderly patients: No specific dosage modifications are required in elderly patients.
Store between 15-30° C. Protect from moisture, heat and light. Do not freeze.