General Information

Hectoral (doxercalciferol) is a synthetic vitamin D2 analog.

Hectoral is specifically indicated for the following:

• Hectoral capsules are indicated for the treatment of secondary hyperparathyroidism in adult patients with Stage 3 or Stage 4 chronic kidney disease (CKD) and adult patients with CKD on dialysis
• Hectoral injection is indicated for the treatment of secondary hyperparathyroidism in adult patients with CKD on dialysis

The recommended dosing is as follows:

Dosage for Hectoral capsules in patients with:

• Stage 3 or 4 CKD: Initiate dosing at 1 mcg orally once daily. Maximum dose is 3.5 mcg once daily.
• CKD on dialysis: Initiate dosing at 10 mcg orally three times weekly at dialysis (no more frequently than every other day). Maximum dose is 20 mcg three times weekly for a total of 60 mcg weekly.

Dosage for Hectoral injection in patients with CKD on dialysis:

• Initiate dosing at 4 mcg by bolus intravenous administration three times weekly at the end of dialysis (no more frequently than every other day). Maximum dose is 18 mcg weekly. Target the maintenance dose of Hectoral to intact parathyroid hormone (PTH) levels within the desired therapeutic range and serum calcium within normal limits

Mechanism of Action

Calcitriol regulates blood calcium at levels required for essential body functions. Specifically, the biologically active vitamin D metabolites control the intestinal absorption of dietary calcium, the tubular reabsorption of calcium by the kidney and, in conjunction with parathyroid hormone (PTH), the mobilization of calcium from the skeleton. They act directly on bone cells (osteoblasts) to stimulate skeletal growth, and on the parathyroid glands to suppress PTH synthesis and secretion. These functions are mediated by the interaction of these biologically active metabolites with specific receptor proteins in the various target tissues. In uremic patients, deficient production of biologically active vitamin D metabolites (due to lack of or insufficient 25-hydroxyvitamin D-1-alpha-hydroxylase activity) leads to secondary hyperparathyroidism, which contributes to the development of metabolic bone disease in patients with renal failure. 

Side Effects

Adverse effects associated with the use of Hectorol may include, but are not limited to, the following:

• Headache
• Malaise
• Dizziness
• Edema
• Nausea/vomiting
• Dyspnea (abnormal breathing [pattern, rate, etc.])

Hectorol is contraindicated in patients with a history of hypercalcemia or evidence of vitamin D toxicity.

Hectorol should not be administered while the patient is taking other forms of vitamin D, since vitamin D overdose is dangerous.

Clinical Trial Results

Two clinical studies investigated the effects of Hectorol Injection. The 70 patients involved in the studies all had chronic renal disease and were on hemodialysis. All of these patients had been treated with Hectorol Capsules in previous clinical studies. The patients were given the investigational drug in an open-label manner over a 12-week period. The drug was administered following each of 3 dialysis sessions a week at a rate of 4.0 mcg per injection. However, the dosage was adjusted in order to reach the targeted iPTH levels of 150 to 300 pg/mL.

The Hectorol Injection resulted in statistically significant decreases from baseline in mean iPTH levels. 92% of the participants experienced at least a 30% decrease.

Approximately 74% of the patients treated achieved iPTH levels less than or equal to 300 pg/mL. 51% of the patients had iPTH levels less than 150 pg/mL at least on point in the study. However, the dosages were decreased when this occurred.

In the first study, mean weekly doses ranged from 8.9 mcg to 12.5 mcg. In the second, the mean dosage range was from 9.1 mcg to 11.6 mcg.