ADMINISTRATION ROUTES:
PO, NG
ALTERNATIVE NAMES:
Rocaltrol
ICU INDICATIONS:
- Post-menopausal osteoporosis
- Renal osteodystrophy
- Secondary hyperparathyroidism
- Hypoparathyroidism
- Prevention of corticosteroid-induced osteoporosis
Note: initiation of calcitriol in ICU is rarely indicated and this therapy is often withheld while patients are critically ill (see PRECAUTIONS)
PRESENTATION AND ADMINISTRATION:
PO / NG
Calcitriol-AFT 0.25 mcg capsules (orange)
Rocaltrol solution 1 mcg/mL (colourless to slightly yellowish oily solution). Mix with a drink (eg orange juice). Liquid is available if NG administration is deemed necessary.
DOSAGE:
The optimal daily dose of calcitriol must be carefully determined for each patient. Calcitriol can be administered orally either as a capsule or as an oral solution.
Calcitriol therapy should always be started at the lowest possible dose and should not be increased without careful monitoring of serum calcium.
PO:
0.25 mcg once per day, increasing to up to 0.5 mcg twice daily if required
DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:
Dose as in normal renal function
DOSAGE IN PAEDIATRICS:
PO:
0.02 mcg/kg once daily oral, increasing by 0.02 mcg/kg every 4-8 weeks according to serum calcium (usual maximum 0.1 mcg/kg)
CLINICAL PHARMACOLOGY:
Calcitriol is a synthetic vitamin D analog which is active in the regulation of the absorption of calcium from the gastrointestinal tract and its utilization in the body.
CONTRAINDICATIONS:
-
Hypercalcaemia
-
Evidence of vitamin D toxicity
-
Known hypersensitivity to calcitriol
WARNINGS:
Calcitriol is the most potent metabolite of vitamin D available. Excessive dosing can cause hypercalcaemia, hypercalciuria, and hyperphosphataemia.
Calcitriol increases inorganic phosphate levels in serum. While this is desirable in patients with hypophosphataemia, caution is called for in patients with renal failure because of the danger of ectopic calcification. A non-aluminium phosphate-binding compound and a low-phosphate diet should be used to control serum phosphorus levels in patients undergoing dialysis.
PRECAUTIONS:
General:
Excessive dosage of calcitriol induces hypercalcaemia. Should hypercalcaemia develop, treatment with calcitriol should be stopped immediately. Immobilised patients, e.g., the critically ill, are particularly exposed to the risk of hypercalcaemia which is why this medication is often withheld in ICU.
Laboratory Tests:
No tests in addition to routine ICU tests are required
Drug/Laboratory Test Interactions:
None known
IMPORTANT DRUG INTERACTIONS IN ICU:
Thiazides:
Thiazides are known to induce hypercalcaemia by the reduction of calcium excretion in urine. Some reports have shown that the concomitant administration of thiazides with calcitriol causes hypercalcaemia. Therefore, precaution should be taken when co- administration is necessary.
Digitalis:
Calcitriol dosage must be determined with care in patients undergoing treatment with digitalis, as hypercalcaemia in such patients may precipitate cardiac arrhythmias.
ADVERSE REACTIONS:
Since calcitriol is believed to be the active hormone which exerts vitamin D activity in the body, adverse effects are, in general, similar to those encountered with excessive vitamin D intake, i.e., hypercalcaemia syndrome or calcium intoxication (depending on the severity and duration of hypercalcaemia) (see WARNINGS). The early and late signs and symptoms of vitamin D intoxication associated with hypercalcaemia include:
Early:
Weakness, headache, somnolence, nausea, vomiting, dry mouth, constipation, muscle pain, bone pain, metallic taste, and anorexia.
Late:
Polyuria, polydipsia, anorexia, weight loss, nocturia, conjunctivitis (calcific), pancreatitis, photophobia, rhinorrhea, pruritus, hyperthermia, decreased libido, elevated Cr, albuminuria, hypercholesterolemia, elevated AST and ALT, ectopic calcification, nephrocalcinosis, hypertension, cardiac arrhythmias, dystrophy, sensory disturbances, dehydration, apathy, arrested growth, urinary tract infections, and, rarely, overt psychosis