Alfacalcidol

1alpha-hydroxyvitamin D3 Alphacalcidol 1-hydroxycholecalciferol 1alpha-hydroxycholecalciferol

Interactions

Active ingredient Alfacalcidol interacts in the following cases:

Anticonvulsants

Anticonvulsants (e.g. barbiturates, phenytoin, carbamazepine or primidone) have enzyme-inducing effects resulting in an increased metabolism of alfacalcidol. Patients taking anticonvulsants may require larger doses of alfacalcidol.

Magnesium-containing antacids

Absorption of magnesium-containing antacids may be enhanced by alfacalcidol, increasing the risk of hypermagnesaemia.

Aluminium-containing preparations

Alfacalcidol may increase the serum concentration of aluminium. Patients taking aluminium-containing preparations (e.g. aluminium hydroxide, sucralfate) should be monitored for signs of aluminium related toxicities.

Cardiac glycosides

Alfacalcidol should be used with caution for patients being treated with cardioactive glycosides or digitalis as hypercalcaemia may lead to arrhythmia in such patients. 2

Sarcoidosis

Alfacalcidol should be used with caution in patients with granulomatous diseases such as sarcoidosis where the sensitivity to vitamin D is increased due to increased hydroxylation activity.

Breast-feeding

Although it has not been established, it is likely that increased amounts of 1,25-dihydroxyvitamin D will be found in the milk of lactating mothers treated with alfacalcidol. This may influence calcium metabolism in the infant.
Consequently, breast-fed infants of alfacalcidol-using mothers should be monitored closely for hypercalcaemia.

Thiazide diuretics and calcium containing preparations

Concurrent use of alfacalcidol and thiazide diuretics or calcium containing preparations may enhance the risk of hypercalcaemia. Calcium levels should be monitored.

Colestyramine

Concomitant oral administration of bile acid sequestrants such as cholestyramine may impair the intestinal absorption of oral alfacalcidol formulations. Alfacalcidol should be administered at least 1 hour before, or 4 to 6 hours after the intake of the bile acid sequestrant in order to minimise the potential risk of interaction.

Vitamin D containing preparations

Concurrent use of alfacalcidol and other vitamin D containing preparations may enhance the risk of hypercalcaemia. Use of multiple vitamin D analogues should be avoided.

Arteriosclerosis, cardiac valve sclerosis, nephrolithiasis

Prolonged hypercalcaemia may aggravate arteriosclerosis, cardiac valve sclerosis or nephrolithiasis and therefore prolonged hypercalcaemia should be avoided when alfacalcidol is used in these patients. Transient or even long-lasting deterioration of kidney function has been observed. Alfacalcidol should also be used with caution in patients with calcification of pulmonary tissue as this may result in cardiac disease.

Effects on ability to drive and use machines

Alfacalcidol has no or negligible direct influence on the ability to drive and use machines. However, the patient should be informed that dizziness may occur during treatment and take this into account while driving or using machines.

Pregnancy

There is a limited amount of data from the use of alfacalcidol in pregnant women. Studies in animals have shown reproductive toxicity at high doses.

Therefore, alfacalcidol is not recommended during pregnancy and in women of child-bearing potential not using contraception.

Nursing Mothers

Although it has not been established, it is likely that increased amounts of 1,25-dihydroxyvitamin D will be found in the milk of lactating mothers treated with alfacalcidol. This may influence calcium metabolism in the infant.

Consequently, breast-fed infants of alfacalcidol-using mothers should be monitored closely for hypercalcaemia.

Carcinogenesis, Mutagenesis and Fertility

Fertility

There are no clinical studies on the effect of alfacalcidol on fertility. A pre-clinical study did not show an effect on fertility in rats.

Effects on Ability to Drive and Use Machines

Alfacalcidol has no or negligible direct influence on the ability to drive and use machines. However, the patient should be informed that dizziness may occur during treatment and take this into account while driving or using machines.