CINACALCET EFFECTIVE FOR PRIMARY HYPERPARATHYROIDISM

NEW YORK (Reuters Health) Dec 31 - In patients with primary hyperparathyroidism, treatment with the calcimimetic agent cinacalcet for up to 5.5 years maintains normocalcemia and reduces parathyroid hormone levels, according to a report in the December Journal of Clinical Endocrinology & Metabolism.

Parathyroidectomy usually cures the disease, but what of patients who are not candidates for surgery or who don't wish to undergo it? "Medical therapies capable of reducing serum calcium and parathyroid hormone concentrations and increasing bone mass in primary hyperparathyroidism patients are needed," the authors maintain.

Dr. Munro Peacock from Indiana University School of Medicine, Indianapolis, and colleagues assessed the long-term tolerability, safety, and efficacy of cinacalcet in 45 patients with mild to moderate primary hyperparathyroidism who completed a 1-year placebo-controlled trial and then continued for another 4.5 years in an open-label extension phase.

During the original study, serum calcium levels normalized in patients who received cinacalcet. When patients who had been in the placebo group took cinacalcet in the extension phase, their serum calcium levels normalized as well. Mean serum calcium levels remained in the normal range in all subjects throughout the remainder of the extension.

Parathyroid hormone levels followed a similar pattern in both groups, the authors report, although they never reached normal levels.

Mean levels of serum phosphate and total alkaline phosphatase increased within the normal range throughout the study with administration of cinacalcet.

Mean areal bone mineral density remained in the normal range for the duration of the study, the researchers note, and there were no significant changes in T-scores or Z-scores.

More than 98% of patients experienced at least one mild to moderate adverse event, with similar rates in both groups of the original study. Thirteen patients had treatment-related adverse events, none of which was serious, life-threatening, or fatal; most (9/13) lasted less than one month.

"Cinacalcet is useful in the management of primary hyperparathyroidism in patients in whom parathyroidectomy is contraindicated or who have failed surgical correction of their primary hyperparathyroidism," the investigators conclude.

J Clin Endocrinol Metab 2009;94:4860-4867.