Zemplar

>10%

Nausea (13%)

1-10%

Vomiting

Edema

Palpitation

Chills

Pneumonia

Lightheadedness

GI bleeding

Flulike symptoms

Sepsis

Hypokalemia

Hypercalcemia

Increase in blood creatinine

Postmarketing Reports

Angioedema

Headache

Constipation

Abdominal pain

Hyperphosphatemia

Paricalcitol, USP, the active ingredient in Zemplar Injection, is a synthetically manufactured analog of calcitriol, the metabolically active form of vitamin D indicated for the prevention and treatment of secondary hyperparathyroidism associated with chronic kidney disease(CKD) Stage 5. Zemplar is available as a sterile, clear, colorless, aqueous solution for intravenous injection. Each mL contains paricalcitol, 2 mcg or 5 mcg and the following inactive ingredients: alcohol, 20% (v/v) and propylene glycol, 30% (v/v).

Paricalcitol is a white powder chemically designated as 19-nor-1α,3β,25-trihydroxy-9,10-secoergosta-5(Z),7(E),22(E)-triene and has the following structural formula:

Molecular formula is C27H44O3.

Molecular weight is 416.64.

Tell your doctor about all your current medicines and any you start or stop using, especially:

• conivaptan;

• digoxin (digitalis);

• nefazodone;

• an antibiotic--clarithromycin, telithromycin;

• antifungal medicine--itraconazole, ketoconazole, posaconazole, voriconazole; or

• antiviral medicine to treat hepatitis C or HIV/AIDS--atazanavir, boceprevir, cobicistat, delavirdine, fosamprenavir, indinavir, lopinavir, nelfinavir, ritonavir, saquinavir, telaprevir.

This list is not complete. Other drugs may interact with paricalcitol, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

A synthetic vitamin D analog.110 111 112 113 117

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Appropriate studies have not been performed on the relationship of age to the effects of paricalcitol in children younger than 10 years of age. Safety and efficacy have not been established.

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of paricalcitol in the elderly.

Pregnancy

Breast Feeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with Medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Ketoconazole

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Bone disease or
• Heart rhythm problems (eg, arrhythmia) or
• Hypercalciuria (high calcium in the urine) or
• Hyperphosphatemia (high phosphate in the blood) or
• Seizures—Use with caution. May make these conditions worse.

• Hypercalcemia (high calcium in the blood) or
• Vitamin D overdose—Should not be used in patients with these conditions.

It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly. Blood and urine tests may be needed to check for unwanted effects.

Do not take other medicines unless they have been discussed with your doctor. Taking other medicines (especially digoxin, Lanoxin®) together with paricalcitol may require your doctor to change the dose of one of the medicines or paricalcitol.

This medicine may increase the calcium in your blood (hypercalcemia). The symptoms of high calcium may include abdominal or stomach pain, confusion, constipation, depression, dry mouth, headache, incoherent speech, increased urination, loss of appetite, metallic taste, muscle weakness, nausea, thirst, unusual tiredness, vomiting, or weight loss. If you have any of these symptoms, check with your doctor immediately.

This medicine may increase the aluminum in your blood and may cause harm to your bones if used in combination with any products containing aluminum (eg, antacids or phosphate binders). Ask your doctor before you take any of these products.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

• Blurred vision
• cough or hoarseness
• difficulty with swallowing
• dizziness
• fever or chills
• headache
• hives
• itching
• lower back or side pain
• nervousness
• pain
• painful or difficult urination
• pounding in the ears
• puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
• shortness of breath
• skin rash
• slow or fast heartbeat
• swelling
• tightness in the chest
• unusual tiredness or weakness

• Abdominal or stomach pain
• abnormal growth filled with fluid or semisolid material
• ammonia-like breath odor
• anxiety
• bladder pain
• bloating or swelling of the face, arms, hands, lower legs, or feet
• bloody or cloudy urine
• burning, tingling, numbness or pain in the hands, arms, feet, or legs
• chest pain or discomfort
• cold sweats
• coma
• confusion
• convulsions
• cool, pale skin
• decreased urine
• depression
• dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
• drowsiness
• dry mouth
• fainting
• frequent urge to urinate
• general feeling of discomfort or illness
• increase in heart rate
• increased hunger
• increased thirst
• irregular heartbeat
• joint pain
• lightheadedness
• loss of appetite
• muscle aches and pains
• nausea or vomiting
• nightmares
• numbness or tingling in the hands, feet, or lips
• pain or discomfort in the arms, jaw, back, or neck
• rapid breathing
• rapid weight gain
• runny nose
• sensation of pins and needles
• shakiness
• shivering
• slurred speech
• sneezing
• sore throat
• stabbing pain
• sunken eyes
• sweating
• thirst
• trouble sleeping
• troubled breathing
• unusual weight gain or loss
• weight loss
• wrinkled skin

• Large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
• slow or irregular breathing

Get emergency help immediately if any of the following symptoms of overdose occur:

• Abdominal or stomach cramps
• constipation
• depression
• high urine levels of calcium
• incoherent speech
• increased urination
• metallic taste
• muscle cramps in the hands, arms, feet, legs, or face
• muscle weakness
• tremor

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

• Acid or sour stomach
• back pain
• belching
• bloody nose
• bruising
• change in vision
• cough producing mucus
• difficulty with moving
• feeling of constant movement of self or surroundings
• heartburn
• impaired vision
• indigestion
• lack or loss of strength
• large, flat, blue, or purplish patches in the skin
• leg cramps
• muscle pain or stiffness
• pain or tenderness around the eyes and cheekbones
• pain, swelling, or redness in the joints
• sensation of spinning
• sores on the skin
• stomach discomfort, upset, or pain
• stuffy nose

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Excessive administration of vitamin D compounds, including Zemplar capsules, can cause over suppression of PTH, hypercalcemia, hypercalciuria, hyperphosphatemia, and adynamic bone disease.

Hypercalcemia

Progressive hypercalcemia due to overdosage of vitamin D and its metabolites may be so severe as to require emergency attention [see Overdosage (10)]. Acute hypercalcemia may exacerbate tendencies for cardiac arrhythmias and seizures and may potentiate the action of digitalis. Chronic hypercalcemia can lead to generalized vascular calcification and other soft-tissue calcification. Concomitant administration of high doses of calcium-containing preparations or thiazide diuretics with Zemplar may increase the risk of hypercalcemia. High intake of calcium and phosphate concomitant with vitamin D compounds may lead to serum abnormalities requiring more frequent patient monitoring and individualized dose titration. Patients also should be informed about the symptoms of elevated calcium, which include feeling tired, difficulty thinking clearly, loss of appetite, nausea, vomiting, constipation, increased thirst, increased urination and weight loss.

Prescription-based doses of vitamin D and its derivatives should be withheld during Zemplar treatment to avoid hypercalcemia.

Digitalis Toxicity

Digitalis toxicity is potentiated by hypercalcemia of any cause. Use caution when Zemplar capsules are prescribed concomitantly with digitalis compounds.

Laboratory Tests

During the initial dosing or following any dose adjustment of medication, serum calcium, serum phosphorus, and serum or plasma iPTH should be monitored at least every two weeks for 3 months, then monthly for 3 months, and every 3 months thereafter.

In pre-dialysis patients, Zemplar capsules may increase serum creatinine and therefore decrease the estimated GFR (eGFR). Similar effects have also been seen with calcitriol.

Aluminum Overload and Toxicity

Aluminum-containing preparations (e.g., antacids, phosphate binders) should not be administered chronically with Zemplar, as increased blood levels of aluminum and aluminum bone toxicity may occur.

Excessive administration of Zemplar capsules can cause hypercalcemia, hypercalciuria, and hyperphosphatemia, and over suppression of PTH [see Warnings and Precautions (5.1)].

Treatment of Overdosage

The treatment of acute overdosage of Zemplar capsules should consist of general supportive measures. If drug ingestion is discovered within a relatively short time, induction of emesis or gastric lavage may be of benefit in preventing further absorption. If the drug has passed through the stomach, the administration of mineral oil may promote its fecal elimination. Serial serum electrolyte determinations (especially calcium), rate of urinary calcium excretion, and assessment of electrocardiographic abnormalities due to hypercalcemia should be obtained. Such monitoring is critical in patients receiving digitalis. Discontinuation of supplemental calcium and institution of a low-calcium diet are also indicated in accidental overdosage. Due to the relatively short duration of the pharmacological action of paricalcitol, further measures are probably unnecessary. If persistent and markedly elevated serum calcium levels occur, there are a variety of therapeutic alternatives that may be considered depending on the patient's underlying condition. These include the use of drugs such as phosphates and corticosteroids, as well as measures to induce an appropriate forced diuresis.

Paricalcitol is not significantly removed by dialysis.

Secondary hyperparathyroidism is characterized by an elevation in parathyroid hormone (PTH) associated with inadequate levels of active vitamin D hormone. The source of vitamin D in the body is from synthesis in the skin as vitamin D3 and from dietary intake as either vitamin D2 or D3. Both vitamin D2 and D3 require two sequential hydroxylations in the liver and the kidney to bind to and to activate the vitamin D receptor (VDR). The endogenous VDR activator, calcitriol [1,25(OH)2D3], is a hormone that binds to VDRs that are present in the parathyroid gland, intestine, kidney, and bone to maintain parathyroid function and calcium and phosphorus homeostasis, and to VDRs found in many other tissues, including prostate, endothelium and immune cells. VDR activation is essential for the proper formation and maintenance of normal bone. In the diseased kidney, the activation of vitamin D is diminished, resulting in a rise of PTH, subsequently leading to secondary hyperparathyroidism and disturbances in the calcium and phosphorus homeostasis. Decreased levels of 1,25(OH)2D3 have been observed in early stages of chronic kidney disease. The decreased levels of 1,25(OH)2D3 and resultant elevated PTH levels, both of which often precede abnormalities in serum calcium and phosphorus, affect bone turnover rate and may result in renal osteodystrophy.

Mechanism of Action

Paricalcitol is a synthetic, biologically active vitamin D2 analog of calcitriol. Preclinical and in vitro studies have demonstrated that paricalcitol's biological actions are mediated through binding of the VDR, which results in the selective activation of vitamin D responsive pathways. Vitamin D and paricalcitol have been shown to reduce parathyroid hormone levels by inhibiting PTH synthesis and secretion.

Pharmacodynamics

Paricalcitol decreases serum intact parathyroid hormone (iPTH) and increases serum calcium and serum phosphorous in both HD and PD patients. This observed relationship was quantified using a mathematical model for HD and PD patient populations separately. Computer-based simulations of 100 trials in HD or PD patients (N = 100) using these relationships predict slightly lower efficacy (at least two consecutive ≥ 30% reductions from baseline iPTH) with lower hypercalcemia rates (at least two consecutive serum calcium ≥ 10.5 mg/dL) for lower iPTH-based dosing regimens. Further lowering of hypercalcemia rates was predicted if the treatment with paricalcitol is initiated in patients with lower serum calcium levels at screening.

Based on these simulations, a dosing regimen of iPTH/80 with a screening serum calcium ≤ 9.5 mg/dL, approximately 76.5% (95% CI: 75.6% – 77.3%) of HD patients are predicted to achieve at least two consecutive weekly ≥ 30% reductions from baseline iPTH over a duration of 12 weeks. The predicted incidence of hypercalcemia is 0.8% (95% CI: 0.7% – 1.0%). In PD patients, with this dosing regimen, approximately 83.3% (95% CI: 82.6% – 84.0%) of patients are predicted to achieve at least two consecutive weekly ≥ 30% reductions from baseline iPTH. The predicted incidence of hypercalcemia is 12.4% (95% CI: 11.7% - 13.0%) [see Clinical Studies (14.2) and Dosage and Administration (2.2)].

Pharmacokinetics

Absorption

The mean absolute bioavailability of Zemplar capsules under low-fat fed condition ranged from 72% to 86% in healthy adult volunteers, CKD Stage 5 patients on HD, and CKD Stage 5 patients on PD. A food effect study in healthy adult volunteers indicated that the Cmax and AUC0-∞ were unchanged when paricalcitol was administered with a high fat meal compared to fasting. Food delayed Tmax by about 2 hours. The AUC0-∞ of paricalcitol increased proportionally over the dose range of 0.06 to 0.48 mcg/kg in healthy adult volunteers.

Distribution

Paricalcitol is extensively bound to plasma proteins (≥ 99.8%). The mean apparent volume of distribution following a 0.24 mcg/kg dose of paricalcitol in healthy adult volunteers was 34 L. The mean apparent volume of distribution following a 4 mcg dose of paricalcitol in CKD Stage 3 and a 3 mcg dose in CKD Stage 4 patients is between 44 and 46 L.

Metabolism

After oral administration of a 0.48 mcg/kg dose of 3H-paricalcitol, parent drug was extensively metabolized, with only about 2% of the dose eliminated unchanged in the feces, and no parent drug was found in the urine. Several metabolites were detected in both the urine and feces. Most of the systemic exposure was from the parent drug. Two minor metabolites, relative to paricalcitol, were detected in human plasma. One metabolite was identified as 24(R)-hydroxy paricalcitol, while the other metabolite was unidentified. The 24(R)-hydroxy paricalcitol is less active than paricalcitol in an in vivo rat model of PTH suppression.

In vitro data suggest that paricalcitol is metabolized by multiple hepatic and non-hepatic enzymes, including mitochondrial CYP24, as well as CYP3A4 and UGT1A4. The identified metabolites include the product of 24(R)-hydroxylation, 24,26- and 24,28-dihydroxylation and direct glucuronidation.

Elimination

Paricalcitol is eliminated primarily via hepatobiliary excretion; approximately 70% of the radiolabeled dose is recovered in the feces and 18% is recovered in the urine. While the mean elimination half-life of paricalcitol is 4 to 6 hours in healthy adult volunteers, the mean elimination half-life of paricalcitol in CKD Stages 3, 4, and 5 (on HD and PD) patients ranged from 14 to 20 hours.

Specific Populations

Geriatric

The pharmacokinetics of paricalcitol has not been investigated in geriatric patients greater than 65 years [see Use in Specific Populations (8.5)].

Pediatric

Paricalcitol Cmax, AUC, and t1/2 values were similar between Stage 3 and Stage 4 CKD pediatric patients 10 to 16 years of age. Population pharmacokinetic analysis shows that the pharmacokinetics of paricalcitol in Stage 5 CKD pediatric patients appear to be similar to those observed in Stage 3 and Stage 4 pediatric patients.

Gender

The pharmacokinetics of paricalcitol following single doses over the 0.06 to 0.48 mcg/kg dose range was gender independent.

Hepatic Impairment

The disposition of paricalcitol (0.24 mcg/kg) was compared in patients with mild (n = 5) and moderate (n = 5) hepatic impairment (as indicated by the Child-Pugh method) and subjects with normal hepatic function (n = 10). The pharmacokinetics of unbound paricalcitol was similar across the range of hepatic function evaluated in this study. No dose adjustment is required in patients with mild and moderate hepatic impairment. The influence of severe hepatic impairment on the pharmacokinetics of paricalcitol has not been evaluated.

Renal Impairment

Following administration of Zemplar capsules, the pharmacokinetic profile of paricalcitol for CKD Stage 5 on HD or PD was comparable to that in CKD 3 or 4 patients. Therefore, no special dose adjustments are required other than those recommended in the Dosage and Administration section [see Dosage and Administration (2)].

Drug Interactions

An in vitro study indicates that paricalcitol is neither an inhibitor of CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1 or CYP3A nor an inducer of CYP2B6, CYP2C9 or CYP3A. Hence, paricalcitol is neither expected to inhibit nor induce the clearance of drugs metabolized by these enzymes.

Omeprazole

The effect of omeprazole (40 mg capsule), a strong inhibitor of CYP2C19, on paricalcitol (four 4 mcg capsules) pharmacokinetics was investigated in a single dose, crossover study in healthy subjects. The pharmacokinetics of paricalcitol was not affected when omeprazole was administered approximately 2 hours prior to the paricalcitol dose.

Ketoconazole

The effect of multiple doses of ketoconazole, a strong inhibitor of CYP3A, administered as 200 mg BID for 5 days on the pharmacokinetics of paricalcitol (4 mcg capsule) has been studied in healthy subjects. The Cmax of paricalcitol was minimally affected, but AUC0-∞ approximately doubled in the presence of ketoconazole. The mean half-life of paricalcitol was 17.0 hours in the presence of ketoconazole as compared to 9.8 hours, when paricalcitol was administered alone [see Drug Interactions (7)].

Chronic Kidney Disease Stages 3 and 4

Adults

The safety and efficacy of Zemplar capsules were evaluated in three, 24-week, double blind, placebo-controlled, randomized, multicenter, Phase 3 clinical studies in CKD Stages 3 and 4 patients. Two studies used an identical three times a week dosing design, and one study used a daily dosing design. A total of 107 patients received Zemplar capsules and 113 patients received placebo. The mean age of the patients was 63 years, 68% were male, 71% were Caucasian, and 26% were African-American. The average baseline iPTH was 274 pg/mL (range: 145-856 pg/mL). The average duration of CKD prior to study entry was 5.7 years. At study entry 22% were receiving calcium based phosphate binders and/or calcium supplements. Baseline 25-hydroxyvitamin D levels were not measured.

The initial dose of Zemplar capsules was based on baseline iPTH. If iPTH was ≤ 500 pg/mL, Zemplar capsules were administered 1 mcg daily or 2 mcg three times a week, not more than every other day. If iPTH was > 500 pg/mL, Zemplar capsules were administered 2 mcg daily or 4 mcg three times a week, not more than every other day. The dose was increased by 1 mcg daily or 2 mcg three times a week every 2 to 4 weeks until iPTH levels were reduced by at least 30% from baseline. The overall average weekly dose of Zemplar capsules was 9.6 mcg/week in the daily regimen and 9.5 mcg/week in the three times a week regimen.

In the clinical studies, doses were titrated for any of the following reasons: if iPTH fell to < 60 pg/mL, or decreased > 60% from baseline, the dose was reduced or temporarily withheld; if iPTH decreased < 30% from baseline and serum calcium was ≤ 10.3 mg/dL and serum phosphorus was ≤ 5.5 mg/dL, the dose was increased; and if iPTH decreased between 30 to 60% from baseline and serum calcium and phosphorus were ≤ 10.3 mg/dL and ≤ 5.5 mg/dL, respectively, the dose was maintained. Additionally, if serum calcium was between 10.4 to 11.0 mg/dL, the dose was reduced irrespective of iPTH, and the dose was withheld if serum calcium was > 11.0 mg/dL. If serum phosphorus was > 5.5 mg/dL, dietary counseling was provided, and phosphate binders could have been initiated or increased. If the elevation persisted, the Zemplar capsules dose was decreased. Seventy-seven percent (77%) of the Zemplar capsules treated patients and 82% of the placebo treated patients completed the 24-week treatment. The primary efficacy endpoint of at least two consecutive ≥ 30% reductions from baseline iPTH was achieved by 91% of Zemplar capsules treated patients and 13% of the placebo treated patients (p < 0.001). The proportion of Zemplar capsules treated patients achieving two consecutive ≥ 30% reductions was similar between the daily and the three times a week regimens (daily: 30/33, 91%; three times a week: 62/68, 91%).

The incidence of hypercalcemia (defined as two consecutive serum calcium values > 10.5 mg/dL), and hyperphosphatemia in Zemplar capsules treated patients was similar to placebo. There were no treatment related adverse events associated with hypercalcemia or hyperphosphatemia in the Zemplar capsules group. No increases in urinary calcium or phosphorous were detected in Zemplar capsules treated patients compared to placebo.

The pattern of change in the mean values for serum iPTH during the studies is shown in Figure 1.

Figure 1. Mean Values for Serum iPTH Over Time in the Three Double-Blind, Placebo-Controlled, Phase 3, CKD Stages 3 and 4 Studies Combined

The mean changes from baseline to final treatment visit in serum iPTH, calcium, phosphorus, and bone-specific alkaline phosphatase are shown in Table 9.

Pediatric patients 10 to 16 years of age

The safety and efficacy of Zemplar capsules were evaluated in a 12-week, double-blind, placebo-controlled, randomized, multicenter study in pediatric patients ages 10 to 16 years with CKD Stages 3 and 4. A total of 18 patients received Zemplar capsules and 18 patients received placebo during the blinded phase of the study. The mean age of the patients was 13.6 years, 69% were male, 86% were Caucasian, and 8% were Asian.

The initial dose of Zemplar capsules was 1 mcg three times a week. Serum iPTH, calcium, and phosphorus levels were monitored every 2-4 weeks with a goal to maintain levels within target ranges: iPTH 35 to 70pg/mL for CKD stage 3, iPTH 70 to 100pg/mL for CKD stage 4, calcium < 10.2mg/dL, phosphorous < 5.8mg/dL. Starting at Treatment Week 4 and every 4 weeks thereafter, doses may have been increased in 1 mcg increments three times a week (e.g., increase from 1 mcg three times per week to 2 mcg three times per week) based upon safety observations and blood chemistry evaluations. Each administered dose could be decreased in 1 mcg increments three times a week, or held if the patient was receiving a 1 mcg dose, as appropriate at any time. The average cumulative weekly dose of Zemplar was 4mcg/week during the 12 week blinded treatment period.

The primary efficacy endpoint, the proportion of Stage 3 and 4 patients achieving two consecutive ≥ 30% reductions from baseline in iPTH levels, was statistically significant during the 12-week blinded phase. Results are shown in Table 10.

Chronic Kidney Disease Stage 5

Adults

The safety and efficacy of Zemplar capsules were evaluated in a Phase 3, 12-week, double blind, placebo-controlled, randomized, multicenter study in patients with CKD Stage 5 on HD or PD. The study used a three times a week dosing design. A total of 61 patients received Zemplar capsules and 27 patients received placebo. The mean age of the patients was 57 years, 67% were male, 50% were Caucasian, 45% were African- American, and 53% were diabetic. The average baseline serum iPTH was 701 pg/mL (range: 216-1933 pg/mL). The average time since first dialysis across all subjects was 3.3 years.

The initial dose of Zemplar capsules was based on baseline iPTH/60. Subsequent dose adjustments were based on iPTH/60 as well as primary chemistry results that were measured once a week. Starting at Treatment Week 2, study drug was maintained, increased or decreased weekly based on the results of the previous week’s calculation of iPTH/60. Zemplar capsules were administered three times a week, not more than every other day.

The proportion of patients achieving at least two consecutive weekly ≥ 30% reductions from baseline serum iPTH was 88% of Zemplar capsules treated patients and 13% of the placebo treated patients. The proportion of patients achieving at least two consecutive weekly ≥ 30% reductions from baseline iPTH was similar for HD and PD patients.

The incidence of hypercalcemia (defined as two consecutive serum calcium values > 10.5 mg/dL) in patients treated with Zemplar capsules was 6.6% as compared to 0% for patients given placebo. In PD patients the incidence of hypercalcemia in patients treated with Zemplar capsules was 21% as compared to 0% for patients given placebo. The patterns of change in the mean values for serum iPTH are shown in Figure 2. The rate of hypercalcemia with Zemplar capsules may be reduced with a lower dosing regimen based on the iPTH/80 formula as shown by computer simulations. The hypercalcemia rate can be further predicted to decrease, if the treatment is initiated in only those with baseline serum calcium ≤ 9.5 mg/dL [see Clinical Pharmacology (12.2) and Dosage and Administration (2.2)].

Figure 2. Mean Values for Serum iPTH Over Time in a Phase 3, Double-Blind, Placebo-Controlled CKD Stage 5 Study

Tell your doctor about all medicines you use, and those you start or stop using during your treatment with Zemplar, especially:

• conivaptan;

• digoxin;

• nefazodone;

• an antibiotic - clarithromycin, telithromycin;

• antifungal medicine - itraconazole, ketoconazole, posaconazole, voriconazole; or

• antiviral medicine to treat hepatitis C or HIV/AIDS - atazanavir, boceprevir, cobicistat, delavirdine, fosamprenavir, indinavir, lopinavir, nelfinavir, ritonavir, saquinavir, telaprevir.

This list is not complete. Other drugs may interact with paricalcitol, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.