Alfacalcidol

Additional information

Alfacalcidol (1α-OH vitamin D) is metabolized by hydroxylation in the liver to the biologically active form of vitamin D (calcitriol; 1α,25(OH)2; 1,25-dihydroxycalciferol) [1].

For additional information on vitamin D, please see separate document.

Pharmacokinetics and dosing

No studies with a clinically relevant sex analysis regarding pharmacokinetics of alfacalcidol have been found.

Effects

In the prospective, controlled, randomized, open phase 3 study of alfacalcidol efficacy in the treatment of secondary hyperparathyroidism in patients with chronic renal failure (100 men, 42 (30%) women) there was no evidence of significant sex difference of the proportion of patients achieving the primary response criterion (≥ 30% reduction in the iPTH). 71 of 100 men (71%) and 36 of 42 women (86%) achieved primary response [2].

A Cochrane review from 2014 on vitamin D and its analogues for preventing fractures in post-menopausal women and older men, concludes that most of the trials with alfacalcidol recruited women only [3]. In the largest study (187 men, 191 women, age >70 years), a randomized, double-blind, placebo-controlled trial, there was no significant difference between women and men in the efficacy of alfacalcidol on reduction of number of individuals falling [4]. Changes of serum calcium and phosphate were similar in men and women.

A meta-analysis of alfacalcidol and calcitriol effects in primary and corticosteroid-induced osteoporosis on bone mineral density and fracture rate [5], suggest that studies involving only women show the same results as the Hayashi study [6] involving both men and women. However, in Hayashi the study population was mostly women (666 (90%) women, 74 men) and the incidence of vertebral fractures was analyzed in women only. Thus, it is impossible to draw conclusions on differences between men and women from this study.

There was no sex difference in the effect of alfacalcidol on bone mineral density in glucocorticoid treated patients (11 men, 22 women) with ophthalmologic disease [7].

Adverse effects

No studies with a clinically relevant sex analysis regarding adverse effects of alfacalcidol have been found.

Reproductive health issues

Regarding teratogenic aspects, please consult Janusmed Drugs and Birth Defects (in Swedish, Janusmed fosterpåverkan).

Other information

The addition of alfacalcidol to interferon-ribavirin therapy for treatment of chronic Hepatitis C in elderly (14 men, 16 women) has been studied [8]. In women the rate of sustained virological response (SVR, HCV-RNA-undetectable status) in the alfacalcidol group (87.5%, 7 of 8 women) was higher than in the control group (25.0%, 2 of 8 women). SVR in alfacalcidol treated men did not reach statistical significance. Alfacalcidol treated women had also statistically significant decrease in relapse rate (detectable HCV-RNA level) (12.5%, 1/8) compared to control (71.4%, 5 of 7) [8].