A randomized controlled trial of oral phosphate binders in the treatment of pseudoxanthoma elasticum.

BACKGROUND: Pseudoxanthoma elasticum (PXE) is a rare connective tissue disorder involving fragmentation and mineralization of elastic fibers predominantly in the skin, eyes, and cardiovascular system. OBJECTIVE: The objective of this study was to assess the efficacy of sevelamer hydrochloride on the reversal of elastic fiber calcification and clinical lesions of PXE. METHODS: This was a randomized, double-blind, placebo-controlled, two-part prospective study. In the first year, 40 patients with PXE were randomized to receive either sevelamer hydrochloride (800 mg by mouth three times daily) or placebo in a 1:1 ratio. In the second year, all patients received sevelamer hydrochloride (800 mg by mouth three times daily). RESULTS: In the first year, the placebo and treatment groups' mean calcium scores decreased from 29.52 to 15.97 (41.93% mean improvement) and 27.48 to 16.75 (38.37% mean improvement), respectively. In the second year, the mean calcium scores decreased to 13.36 (53.94%) and 14.03 (51.35%) in these groups. The mean clinical score in the placebo group decreased from 6.25 to 6.05 at year 1 (2% improvement) whereas the mean clinical score in the sevelamer hydrochloride group decreased from 7.10 to 6.55 (7% improvement). In year 2, the scores in the original placebo and sevelamer hydrochloride groups decreased to 5.33 (14% improvement) and 5.72 (19% improvement), respectively. LIMITATIONS: Magnesium stearate in our placebo and active drugs may have played a confounding role in this study, contributing to the small differences observed in these two groups. CONCLUSION: Sevelamer hydrochloride produced a reduction in both calcification levels and clinical scores; however, this difference was not statistically significant compared with placebo. Future clinical studies should examine the inhibitory role and potential therapeutic effect of magnesium in PXE.

Oral phosphate binders in the treatment of pseudoxanthoma elasticum.

BACKGROUND: Pseudoxanthoma elasticum (PXE) is a systemic connective tissue disorder involving elastic fiber calcification and fragmentation with major clinical manifestations occurring in the cutaneous, ocular, and cardiovascular systems. Normalization of the serum calcium-phosphate product through hemodialysis in a previous patient with perforating periumbilical PXE and elevated serum phosphate resulted in regression of skin lesions. OBJECTIVE: We sought to study the effect of pharmacologically limiting the intestinal absorption of phosphate in patients with PXE. METHODS: Patients received baseline skin examinations, target skin lesion evaluation, and photography; renal function tests and serum calcium and phosphate levels; urine calcium, phosphate, and creatinine levels; skin biopsy; and eye examinations and indocyanine-green angiography. Patients were treated with aluminium hydroxide tablets or liquid and returned every 2 to 4 months for skin photography and lesion evaluation. Repeated skin biopsies were performed on clinically improved target sites. Ophthalmologic evaluation was obtained at yearly intervals. RESULTS: Of 6 patients, 3 showed significant clinical improvement of skin lesions and all 3 of these patients showed histopathologic regression of disease in their target lesions. No deterioration of eye disease was seen in any of the 6 patients at 1-year follow-up. CONCLUSION: Our results demonstrate that the calcification seen in PXE may be reversible in some patients. This could hold true for eye and vascular lesions and for skin. Further studies supporting these results could reveal the first real treatment option for PXE.