During the 8-week double-blind phase, more patients achieved and maintained the target range of values for iPTH with Hectorol than with placebo.

Pre-dialysis

The safety and effectiveness of Hectorol were evaluated in two clinical studies in 55 patients with Stage 3 or Stage 4 chronic kidney disease. Eighty-two percent of the patients were male, the average age was 64.6 years, 51% were Caucasian, 40% African-American, and the average serum iPTH level at baseline was 194.6 pg/mL. While levels of 25-(OH) vitamin D were not evaluated at baseline, retrospective assessments of stored serum revealed that the mean ± SD serum 25-(OH)vitamin D was 18.5 ± 8.1 ng/mL (range: < 5 to 54 ng/mL) in the study population.

After randomization to two groups, eligible patients underwent an 8-week washout period during which no vitamin D derivatives were administered to either group. Subsequently, one group received Hectorol and the other placebo during a double-blind period of 24 weeks. The initial dose of Hectorol was 1 mcg per day. The dosage of Hectorol was adjusted as necessary by the investigator in order to reduce intact parathyroid hormone (iPTH) levels to a target of ≥ 30% below post-washout baseline. The maximum dosage was limited to 3.5 mcg per day. If at any time during the trial iPTH fell below 15 pg/mL, Hectorol was immediately suspended and restarted at a lower dosage the following week.

Results

Decreases in the mean plasma iPTH from baseline values were calculated using as baseline the average of the last 2 values obtained during the 8-week washout phase. In analyses of pooled data from the two studies, iPTH levels decreased from baseline by an average of 101.4 pg/mL in the Hectorol group and by 4.4 pg/mL in the placebo group (p < 0.001). Greater reductions of iPTH with Hectorol compared to placebo were observed in each study. Twenty (74%) of 27 subjects in the Hectorol group achieved mean plasma iPTH suppression of ≥ 30% from baseline for the last four weeks of treatment, whereas two (7%) of the 28 subjects treated with placebo achieved this level of iPTH suppression. In the Hectorol-treated patients, the reductions in plasma iPTH were associated with a reduction in serum bone-specific alkaline phosphatase.

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