2.1 Prior to Initiation of Doxercalciferol Injection

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Ensure serum calcium is not above the upper limit of normal before initiating treatment with Doxercalciferol Injection [see Warnings and Precautions (5.1)].

2.2 Important Administration Instructions for Doxercalciferol Injection

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Administer Doxercalciferol Injection intravenously as a bolus dose at the end of dialysis.

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Inspect Doxercalciferol Injection visually prior to administration; the solution should appear clear and colorless. Do not use if the solution is not clear or particles are present.

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After initial vial use, store opened multiple-dose vial for up to 14 days at room temperature. Discard unused portion of multiple-dose vial after 14 days [see How Supplied/Storage and Handling (16)].

2.3 Dosage Recommendations for Doxercalciferol Injection

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Initiate Doxercalciferol Injection at a dose of 4 mcg given by bolus intravenous administration three times weekly at the end of dialysis (no more frequently than every other day).

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Target the maintenance dose of Doxercalciferol Injection to intact parathyroid hormone (PTH) levels within the desired therapeutic range and serum calcium within normal limits.

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Monitor serum calcium, phosphorus, and intact PTH levels weekly after initiation of therapy or dose adjustment.

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Titrate the dose of Doxercalciferol Injection based on intact PTH. The dose may be increased at 8-week intervals by 1 mcg to 2 mcg if intact PTH is not lowered by 50% and fails to reach the target range. The maximum dose is 18 mcg weekly. Prior to raising the dose, ensure serum calcium is within normal limits.

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Suspend or decrease the dose if intact PTH is persistently and abnormally low to reduce the risk of adynamic bone disease [see Warnings and Precautions (5.4)] or if serum calcium is consistently above the normal range to reduce the risk of hypercalcemia [see Warnings and Precautions (5.1)]. If suspended, the drug should be restarted one week later at a dose that is at least 1 mcg lower.

2.4 Drug Interactions that May Require Dosage Adjustments of Doxercalciferol Injection

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Increased monitoring of serum calcium and dose adjustment of Doxercalciferol Injection may be necessary when given concomitantly with drugs that may increase the risk of hypercalcemia [see Drug Interactions (7)].

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Increased monitoring of both serum calcium and intact PTH as well as dose adjustment of Doxercalciferol Injection may be necessary when given concomitantly with cytochrome P450 inhibitors or enzyme inducers [see Drug Interactions (7)].

5.1 Hypercalcemia

Hypercalcemia may occur during Doxercalciferol Injection treatment. Acute hypercalcemia may increase the risk of cardiac arrhythmias and seizures and may potentiate the effect of digitalis on the heart [see Warnings and Precautions (5.2)]. Chronic hypercalcemia can lead to generalized vascular calcification and other soft-tissue calcification. Severe hypercalcemia may require emergency attention.

Hypercalcemia may be exacerbated by concomitant administration of high doses of calcium-containing preparations, thiazide diuretics, or other vitamin D compounds [see Drug Interactions (7)]. In addition, high intake of calcium and phosphate concomitantly with vitamin D compounds may lead to hypercalciuria and hyperphosphatemia. Patients with a history of hypercalcemia prior to initiating therapy may be at increased risk for development of hypercalcemia with Doxercalciferol Injection. In these circumstances, frequent serum calcium monitoring and Doxercalciferol Injection dose adjustments may be required.

When initiating Doxercalciferol Injection or adjusting Doxercalciferol Injection dose, measure serum calcium weekly. Once a maintenance dose has been established, measure serum calcium monthly for 3 months and then every 3 months. If hypercalcemia occurs, reduce the dose or discontinue Doxercalciferol Injection until serum calcium is normal [see Dosage and Administration (2)].

Inform patients about the symptoms of elevated calcium (feeling tired, difficulty thinking clearly, loss of appetite, nausea, vomiting, constipation, increased thirst, increased urination and weight loss) and instruct them to report new or worsening symptoms when they occur.

5.2 Digitalis Toxicity

Doxercalciferol Injection can cause hypercalcemia [see Warnings and Precautions (5.1)] which increases the risk of digitalis toxicity. In patients using Doxercalciferol Injection concomitantly with digitalis compounds, monitor both serum calcium and patients for signs and symptoms of digitalis toxicity. Increase the frequency of monitoring when initiating or adjusting the dose of Doxercalciferol Injection [see Drug Interactions (7)].

5.3 Serious Hypersensitivity Reactions

Serious hypersensitivity reactions, including fatal outcome, have been reported post marketing in patients on hemodialysis following administration of Doxercalciferol Injection. Hypersensitivity reactions include anaphylaxis with symptoms of angioedema (involving face, lips, tongue and airways), hypotension, unresponsiveness, chest discomfort, shortness of breath, and cardiopulmonary arrest. These reactions may occur separately or together.

Monitor patients receiving Doxercalciferol Injection upon initiation of treatment for hypersensitivity reactions. Should a hypersensitivity reaction occur, discontinue Doxercalciferol Injection, monitor and treat if indicated [see Contraindications (4)].

5.4 Adynamic Bone Disease

Adynamic bone disease with subsequent increased risk of fractures may develop if intact PTH levels are suppressed by Doxercalciferol Injection to abnormally low levels. Monitor intact PTH levels to avoid oversuppression and adjust the Doxercalciferol Injection dose, if needed [see Dosage and Administration (2)].

6.1 Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The safety of Doxercalciferol Injection has been established from adequate and well-controlled studies of doxercalciferol capsules and from studies of another doxercalciferol injection product (doxercalciferol injection) [see Clinical Studies (14)]. Below is a display of the adverse reactions of doxercalciferol capsules and doxercalciferol injection from these studies.

Doxercalciferol capsules for oral use were evaluated in two placebo-controlled, double-blind studies in patients with CKD on hemodialysis. Patients were treated with doxercalciferol capsules (n=61) or placebo (n=61). 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, all patients received doxercalciferol capsules in an open-label fashion for 16 weeks followed by a double-blind period of 8 weeks during which patients received either doxercalciferol capsules or placebo. Adverse reactions occurring in the doxercalciferol capsules groups at a frequency of 2% or greater, and more frequently than in the placebo group are presented in Table 1.

Doxercalciferol injection was studied in 70 patients with CKD on hemodialysis in two 12-week, open-label, single-arm, multi-center studies [see Clinical Studies (14)]. The incidence of hypercalcemia and hyperphosphatemia increased during therapy with doxercalciferol injection. Patients with higher pre-treatment serum levels of calcium (>10.5 mg/dL) or phosphorus (>6.9 mg/dL) were more likely to experience hypercalcemia or hyperphosphatemia.

There was no placebo group included in the studies of doxercalciferol injection. Adverse reactions in patients with CKD on hemodialysis receiving Doxercalciferol Injection are expected to be similar to those reported in placebo-controlled studies of doxercalciferol capsules presented in Table 1.

6.2 Postmarketing Experience

The following adverse reactions have been identified during postapproval use of Doxercalciferol Injection. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to estimate their frequency or to establish a causal relationship to drug exposure.

Hypersensitivity reactions, including fatal outcome, have been reported in patients on hemodialysis following administration of Doxercalciferol Injection. Hypersensitivity reactions include anaphylaxis with symptoms of angioedema (involving face, lips, tongue and airways), hypotension, unresponsiveness, chest discomfort, shortness of breath, cardiopulmonary arrest, pruritus, and skin burning sensation.

8.1 Pregnancy

8.2 Lactation

8.4 Pediatric Use

Safety and efficacy of Doxercalciferol Injection in pediatric patients have not been established.

8.5 Geriatric Use

Clinical studies of doxercalciferol injection did not include sufficient numbers of patients 65 years or over to determine whether they respond differently from younger subjects. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic or cardiac function, and of concomitant disease or other drug therapy.

8.6 Hepatic Impairment

Patients with hepatic impairment may not metabolize Doxercalciferol Injection appropriately. More frequent monitoring of intact PTH, calcium, and phosphorus levels should be done in patients with hepatic impairment.

12.1 Mechanism of Action

Doxercalciferol is a synthetic vitamin D2 analog that requires metabolic activation to form the active 1α,25-(OH)2D2 metabolite, which binds to the vitamin D receptor (VDR) to result in the selective activation of vitamin D responsive pathways. Vitamin D and doxercalciferol have been shown to reduce PTH levels by inhibiting PTH synthesis and secretion.

12.3 Pharmacokinetics

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

In a 104-week carcinogenicity study in rats, there was an increased incidence of benign and malignant adrenal pheochromocytomas in both males and females at oral doses of 0.04, 0.13, and 0.39 mcg/kg/day (less than the maximum recommended human oral dose of 60 mcg/week based on mcg/m2 body surface area). This increased incidence of pheochromocytomas in rats may be due to altered calcium homeostasis by doxercalciferol. No evidence of genetic toxicity was observed in an in vitro bacterial mutagenicity assay (Ames test) or a mouse lymphoma gene mutation assay. Doxercalciferol caused structural chromatid and chromosome aberrations in an in vitro human lymphocyte clastogenicity assay with metabolic activation. However, doxercalciferol was negative in an in vivo mouse micronucleus clastogenicity assay.

Doxercalciferol had no effect on male or female fertility in rats at oral doses up to 2.5 mcg/kg/day (approximately 3 times the maximum recommended human oral dose of 60 mcg/week based on mcg/m2 body surface area).

Storage

Store multiple-dose vials at 20°C to 25°C (68°F to 77°F) [see USP controlled room temperature].

Protect from light. Store unopened vial in original carton. Discard vial 14 days after opening.

Hypercalcemia

Advise patients to contact a health care provider if they develop symptoms of elevated calcium (e.g. feeling tired, difficulty thinking clearly, loss of appetite, nausea, vomiting, constipation, increased thirst, increased urination and weight loss) [see Warnings and Precautions (5.1)].

Hypersensitivity

Inform patients that hypersensitivity reactions can occur with Doxercalciferol Injection [see Warnings and Precautions (5.3)].

Monitoring

Inform patients that they will need routine monitoring of laboratory parameters such as calcium and intact PTH while receiving Doxercalciferol Injection. Inform patients that more frequent monitoring is necessary during the initiation of therapy, following dose changes or when potentially interacting medications are started or discontinued [see Dosage and Administration (2), Drug Interactions (7)].

Drug Interactions

Advise patients to inform their physician of all medications, including prescription and nonprescription drugs, and supplements they are taking. Advise patients to also inform their physician that they are receiving Doxercalciferol Injection if a new medication is prescribed [see Drug Interactions (7)].