Alfacalcidol in men with osteoporosis: a prospective, observational, 2-year trial on 214 patients

Due to pleiotropic-synergistic actions on bone, muscle, gut, brain and different other non-skeletal tissues, alfacalcidol is an interesting drug for treating osteoporosis. In studies on glucocorticoid-induced osteoporosis, men have always been treated with calcitriol or this active D-hormone prodrug, but there is no study of male patients only in the literature. The AIM-Trial (Alfacalcidol In Men) is an extension of the control group (n = 158) of our former risedronate study in male osteoporosis (Ringe et al. in Rheumatol Int 29:311-315, 2009). In that study, we treated daily those controls with prevalent vertebral fractures with 1 μg alfacalcidol + 500 mg calcium (group A) and those without prevalent vertebral fractures with 1,000 IU plain vitamin D (Vit. D) + 1,000 mg calcium (group B). Subsequently, we added an additional 56 pairs of patients to these two groups: 28 with and 28 without prevalent vertebral fractures, reaching a total of 214 cases. That means with this design, we are comparing two groups with a different risk at onset. Due to the prevalent vertebral fractures and lower average bone mineral density (BMD) values, there was a higher risk of incident fractures in group A. After 2 years, we found significantly higher increases in lumbar spine BMD (+3.2 vs. +0.8 %) and total hip BMD (+1.9 vs. -0.9 %) in group A and B, respectively. Eighteen incident falls were recorded in the alfacalcidol group and 38 in the group treated with Vit. D (p = 0.041). There were significantly lower rates of patients with new vertebral and non-vertebral fractures in group A than in group B. Back pain was significantly reduced only with alfacalcidol. Concerning the incidence of new non-vertebral fractures, we found that there was a relation to renal function in the two groups. The advantage for alfacalcidol was mainly due to a higher non-vertebral fracture-reducing potency in patients with a creatinine clearance (CrCl) below 60 ml/min (p = 0.0019). There were no serious adverse events (SAE), and the numbers of mild-to-moderate adverse events (AE) were not different between groups. Despite the higher initial fracture risk in the alfacalcidol group, 2-year treatment with this active D-hormone prodrug showed a higher therapeutic efficacy in terms of BMD, falls and fractures. One important advantage of alfacalcidol may be that it is effective even in patients with mild-to-moderate renal insufficiency.