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Medically reviewed by Militian Inessa Mesropovna, PharmD. Last updated on 04.04.2022
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Dosage Forms And Strengths
Sensipar tablets are formulated as light-green, film-coated, oval-shaped tablets marked with “AMG” on one side and “30” or “60” or “90” on the opposite side of the 30 mg, 60 mg, or 90 mg strengths, respectively.
Storage And Handling
Sensipar 30 mg tablets are formulated as light-green, film-coated, oval-shaped tablets marked with “AMG” on one side and “30” on the opposite side, packaged in bottles of 30 tablets. (NDC 55513-073-30)
Sensipar 60 mg tablets are formulated as light-green, film-coated, oval-shaped tablets marked with “AMG” on one side and “60” on the opposite side, packaged in bottles of 30 tablets. (NDC 55513-074-30)
Sensipar 90 mg tablets are formulated as light-green, film-coated, oval-shaped tablets marked with “AMG” on one side and “90” on the opposite side, packaged in bottles of 30 tablets. (NDC 55513-075-30)
Storage
Store at 25°C (77°F); excursions permitted from 15°C to 30°C (59°F to 86°F)..
Manufactured by: Amgen Inc. One Amgen Center Drive Thousand Oaks, California 91320-1799. Revised: March 2017
Secondary Hyperparathyroidism
Sensipar is indicated for the treatment of secondary hyperparathyroidism (HPT) in adult patients with chronic kidney disease (CKD) on dialysis.
Limitations Of Use
Sensipar is not indicated for use in adult patients with CKD who are not on dialysis because of an increased risk of hypocalcemia.
Parathyroid Carcinoma
Sensipar is indicated for the treatment of hypercalcemia in adult patients with Parathyroid Carcinoma.
Primary Hyperparathyroidism
Sensipar is indicated for the treatment of hypercalcemia in adult patients with primary HPT for whom parathyroidectomy would be indicated on the basis of serum calcium levels, but who are unable to undergo parathyroidectomy.
Sensipar tablets should be taken whole and should not be divided. Sensipar should be taken with food or shortly after a meal.
Dosage must be individualized.
Secondary Hyperparathyroidism In Adult Patients With Chronic Kidney Disease On Dialysis
The recommended starting oral dose of Sensipar is 30 mg once daily. Serum calcium and serum phosphorus should be measured within 1 week and intact parathyroid hormone (iPTH) should be measured 1 to 4 weeks after initiation or dose adjustment of Sensipar. Sensipar should be titrated no more frequently than every 2 to 4 weeks through sequential doses of 30, 60, 90, 120, and 180 mg once daily to target iPTH levels of 150 to 300 pg/mL. Serum iPTH levels should be assessed no earlier than 12 hours after dosing with Sensipar.
Sensipar can be used alone or in combination with vitamin D sterols and/or phosphate binders.
During dose titration, serum calcium levels should be monitored frequently and if levels decrease below the normal range, appropriate steps should be taken to increase serum calcium levels, such as by providing supplemental calcium, initiating or increasing the dose of calcium-based phosphate binder, initiating or increasing the dose of vitamin D sterols, or temporarily withholding treatment with Sensipar.
Parathyroid Carcinoma And Primary Hyperparathyroidism
The recommended starting oral dose of Sensipar is 30 mg twice daily.
The dose of Sensipar should be titrated every 2 to 4 weeks through sequential doses of 30 mg twice daily, 60 mg twice daily, and 90 mg twice daily, and 90 mg 3 or 4 times daily as necessary to normalize serum calcium levels. Serum calcium should be measured within 1 week after initiation or dose adjustment of Sensipar.
Monitoring For Hypocalcemia
Once the maintenance dose has been established, serum calcium should be measured approximately monthly for patients with secondary hyperparathyroidism with CKD on dialysis, and every 2 months for patients with parathyroid carcinoma or primary hyperparathyroidism.
For secondary hyperparathyroidism patients with CKD on dialysis, if serum calcium falls below 8.4 mg/dL but remains above 7.5 mg/dL, or if symptoms of hypocalcemia occur, calcium-containing phosphate binders and/or vitamin D sterols can be used to raise serum calcium. If serum calcium falls below 7.5 mg/dL, or if symptoms of hypocalcemia persist and the dose of vitamin D cannot be increased, withhold administration of Sensipar until serum calcium levels reach 8.0 mg/dL and/or symptoms of hypocalcemia have resolved. Treatment should be reinitiated using the next lowest dose of Sensipar.
Sensipar treatment initiation is contraindicated if serum calcium is less than the lower limit of the normal range.
WARNINGS
Included as part of the "PRECAUTIONS" Section
PRECAUTIONS
Hypocalcemia
Sensipar lowers serum calcium and, therefore, patients should be carefully monitored for the occurrence of hypocalcemia during treatment. Life threatening events and fatal outcomes associated with hypocalcemia have been reported in patients treated with Sensipar, including pediatric patients. Potential manifestations of hypocalcemia include paresthesias, myalgias, muscle cramping, tetany, and convulsions.
Sensipar is not indicated for patients with CKD not on dialysis. In patients with secondary HPT and CKD not on dialysis, the long-term safety and efficacy of Sensipar have not been established. Clinical studies indicate that Sensipar-treated patients with CKD not on dialysis have an increased risk for hypocalcemia compared with Sensipar-treated patients with CKD on dialysis, which may be due to lower baseline calcium levels. In a phase 3 study of 32 weeks duration and including 404 patients with CKD not on dialysis (302 cinacalcet, 102 placebo), in which the median dose for cinacalcet was 60 mg per day at the completion of the study, 80% of Sensipar-treated patients experienced at least one serum calcium value < 8.4 mg/dL compared with 5% of patients receiving placebo.
QT Prolongation
Decreases in serum calcium can also prolong the QT interval, potentially resulting in ventricular arrhythmia. Cases of QT prolongation and ventricular arrhythmia secondary to hypocalcemia have been reported in patients treated with Sensipar.
Seizures
In clinical studies, seizures (primarily generalized or tonic-clonic) were observed in 1.4% (43/3049) of Sensipar-treated patients and 0.7% (5/687) of placebo-treated patients. While the basis for the reported difference in seizure rate is not clear, the threshold for seizures is lowered by significant reductions in serum calcium levels. Therefore, serum calcium levels should be closely monitored in patients receiving Sensipar, particularly in patients with a history of a seizure disorder.
Hypotension And/Or Worsening Heart Failure
In postmarketing safety surveillance, isolated, idiosyncratic cases of hypotension, worsening heart failure, and/or arrhythmia have been reported in patients with impaired cardiac function, in which a causal relationship to Sensipar could not be completely excluded and which may be mediated by reductions in serum calcium levels.
Upper Gastrointestinal Bleeding
Cases of gastrointestinal bleeding, mostly upper gastrointestinal bleeding, have occurred in patients using calcimimetics, including Sensipar, from postmarketing and clinical trial sources. The exact cause of GI bleeding in these patients is unknown.
Patients with risk factors for upper GI bleeding (such as known gastritis, esophagitis, ulcers or severe vomiting) may be at increased risk for GI bleeding when receiving Sensipar treatment. Monitor patients for worsening of common GI adverse reactions of nausea and vomiting associated with Sensipar and for signs and symptoms of GI bleeding and ulcerations during Sensipar therapy. Promptly evaluate and treat any suspected GI bleeding.
Adynamic Bone Disease
Adynamic bone disease may develop if iPTH levels are suppressed below 100 pg/mL. One clinical study evaluated bone histomorphometry in patients treated with Sensipar for 1 year. Three patients with mild hyperparathyroid bone disease at the beginning of the study developed adynamic bone disease during treatment with Sensipar. Two of these patients had iPTH levels below 100 pg/mL at multiple time points during the study. In three 6-month, phase 3 studies conducted in patients with CKD on dialysis, 11% of patients treated with Sensipar had mean iPTH values below 100 pg/mL during the efficacy-assessment phase. If iPTH levels decrease below 150 pg/mL in patients treated with Sensipar, the dose of Sensipar and/or vitamin D sterols should be reduced or therapy discontinued.
Hepatic Impairment
Cinacalcet exposure, as defined by the Area Under the Plasma Drug Concentration Time Curve (AUC0-infinite), is increased by 2.4 and 4.2 fold in patients with moderate and severe hepatic impairment, respectively. These patients should be monitored throughout treatment with Sensipar.
Nonclinical Toxicology
Carcinogenesis, Mutagenesis, And Impairment Of Fertility
Carcinogenicity
Standard lifetime dietary carcinogenicity bioassays were conducted in mice and rats. Mice were given cinacalcet at dietary doses of 15, 50, and 125 mg/kg/day in males and 30, 70, and 200 mg/kg/day in females (exposures up to 2 times those resulting with a human oral dose of 180 mg/day based on AUC comparison). Rats were given dietary doses of 5, 15, and 35 mg/kg/day in males and 5, 20, and 35 mg/kg/day in females (exposures up to 2 times those resulting with a human oral dose of 180 mg/day based on AUC comparison). No increased incidence of tumors was observed following treatment with cinacalcet.
Mutagenicity
Cinacalcet was not genotoxic in the Ames bacterial mutagenicity assay, nor in the Chinese Hamster Ovary (CHO) cell HGPRT forward mutation assay and CHO cell chromosomal aberration assay, with and without metabolic activation, nor in the in vivo mouse micronucleus assay.
Impairment Of Fertility
Female rats were given oral gavage doses of 5, 25, and 75 mg/kg/day cinacalcet beginning 2 weeks before mating and continuing through gestation day 7. Male rats were given oral doses 4 weeks prior to mating, during mating (3 weeks) and 2 weeks postmating. No effects were observed in male or female fertility at 5 and 25 mg/kg/day (exposures up to 3 times those resulting with a human oral dose of 180 mg/day based on AUC comparison). At 75 mg/kg/day, there were slight adverse effects (slight decreases in body weight and food consumption) in males and females.
Use In Specific Populations
Pregnancy
Category C
In pregnant female rats given oral gavage doses of 2, 25, 50 mg/kg/day cinacalcet during gestation, no teratogenicity was observed at doses up to 50 mg/kg/day (exposure 4 times those resulting with a human oral dose of 180 mg/day based on Area Under the Curve [AUC] comparison). Decreased fetal body weights were observed at all doses (less than 1 to 4 times a human oral dose of 180 mg/day based on AUC comparison) in conjunction with maternal toxicity (decreased food consumption and body weight gain).
In pregnant female rabbits given oral gavage doses of 2, 12, 25 mg/kg/day cinacalcet during gestation, no adverse fetal effects were observed (exposures less than with a human oral dose of 180 mg/day based on AUC comparisons). Reductions in maternal food consumption and body weight gain were seen at doses of 12 and 25 mg/kg/day. Sensipar has been shown to cross the placental barrier in rabbits.
In pregnant rats given oral gavage doses of 5, 15, 25 mg/kg/day cinacalcet during gestation through lactation, no adverse fetal or pup (post-weaning) effects were observed at 5 mg/kg/day (exposures less than with a human therapeutic dose of 180 mg/day based on AUC comparisons). Higher doses of 15 and 25 mg/kg/day cinacalcet (exposures 2 to 3 times a human oral dose of 180 mg/day based on AUC comparisons) were accompanied by maternal signs of hypocalcemia (periparturient mortality and early postnatal pup loss), and reductions in postnatal maternal and pup body-weight gain.
There are no adequate and well-controlled studies of Sensipar in pregnant women. Sensipar should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Women who become pregnant during Sensipar treatment are encouraged to enroll in Amgen’s Pregnancy Surveillance Program. Patients or their physicians should call 1-800-77-AMGEN (1-800-772-6436) to enroll.
Nursing Mothers
Studies in rats have shown that Sensipar is excreted in the milk with a high milk-to-plasma ratio. It is not known whether this drug is excreted in human milk. Considering these data in rats, and because many drugs are excreted in human milk and there is a potential for clinically significant adverse reactions in infants who ingest Sensipar, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the lactating woman.
Women who choose to continue Sensipar treatment while nursing are encouraged to enroll in Amgen’s Lactation Surveillance Program. Patients or their physicians should call 1-800-77-AMGEN (1-800-772-6436) to enroll.
Pediatric Use
The safety and efficacy of Sensipar in pediatric patients have not been established. Sensipar is not indicated for use in pediatric patients. A fatal outcome was reported in a pediatric clinical trial patient with severe hypocalcemia.
Geriatric Use
Of the total number of subjects (n = 1136) in clinical studies of Sensipar, 26 percent were 65 and over, and 9 percent were 75 and over. No overall differences in the safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger subjects, but greater sensitivity of some older individuals cannot be ruled out.
Renal Impairment
No dosage adjustment is necessary for renal impairment.
Hepatic Impairment
Patients with moderate and severe hepatic impairment should have serum calcium, serum phosphorus, and iPTH levels monitored closely throughout treatment with Sensipar because cinacalcet exposure (AUC0-infinite) is increased by 2.4 and 4.2 fold, respectively, in these patients.
In vitro studies indicate that cinacalcet is a strong inhibitor of CYP2D6, but not an inhibitor of CYP1A2, CYP2C9, CYP2C19, and CYP3A4. In vitro induction studies indicate that cinacalcet is not an inducer of CYP450 enzymes. Tables 5 and 6 list the findings from in vivo drug-drug interaction studies.
Table 5. Effect of co-administered drugs on cinacalcet
| Co-administered drug and dosing regimen | Cinacalcet | ||
| Dose* | Mean change in AUC(0-inf) | Mean change in Cmax | |
| 200 mg ketoconazole twice daily for 7 days | 90 mg on day 5 | ↑127% | ↑116% |
| 1500 mg calcium carbonate, single dose | 100 mg | ↓6% | ↓5% |
| 80 mg pantoprazole daily for 3 days | 90 mg on day 3 | ↑1% | ↓3% |
| 2400 mg sevelamer HCl three times a day for 2 days | 90 mg on day 1 with first dose of sevelamer | ↓4% | ↓7% |
| *Single dose. |
Table 6. Effect of cinacalcet co-administration on other drugs
| Co-administered drug and dosing regimen | Co-administered drug | ||
| Name and Dose | Mean change in AUC(0-inf) | Mean change in Cmax | |
| 30 mg twice daily for 8 days | 25 mg warfarin* tablet† | ↑1 % for R-warfarin ↑1% S-warfarin |
↓10 % for R-warfarin ↓12 % for S-warfarin |
| 90 mg daily for 7 days to CYP2D6 extensive metabolizers | 50 mg desipramine† | ↑264% | ↑75% |
| 90 mg daily for 5 days | 2 mg midazolam† | ↑5% | ↑5% |
| 25 or 100 mg single dose to CYP2D6 extensive metabolizers | 50 mg amitriptyline single dose | ↑21-22% for amitriptyline ↑17-23% for nortriptyline‡ |
↑13-21% for amitriptyline ↑11-15% for nortriptyline‡ |
| *No significant change in prothrombin time. †Single dose on day 5. ‡Nortriptyline is an active metabolite of amitriptyline. |
Category C
In pregnant female rats given oral gavage doses of 2, 25, 50 mg/kg/day cinacalcet during gestation, no teratogenicity was observed at doses up to 50 mg/kg/day (exposure 4 times those resulting with a human oral dose of 180 mg/day based on Area Under the Curve [AUC] comparison). Decreased fetal body weights were observed at all doses (less than 1 to 4 times a human oral dose of 180 mg/day based on AUC comparison) in conjunction with maternal toxicity (decreased food consumption and body weight gain).
In pregnant female rabbits given oral gavage doses of 2, 12, 25 mg/kg/day cinacalcet during gestation, no adverse fetal effects were observed (exposures less than with a human oral dose of 180 mg/day based on AUC comparisons). Reductions in maternal food consumption and body weight gain were seen at doses of 12 and 25 mg/kg/day. Sensipar has been shown to cross the placental barrier in rabbits.
In pregnant rats given oral gavage doses of 5, 15, 25 mg/kg/day cinacalcet during gestation through lactation, no adverse fetal or pup (post-weaning) effects were observed at 5 mg/kg/day (exposures less than with a human therapeutic dose of 180 mg/day based on AUC comparisons). Higher doses of 15 and 25 mg/kg/day cinacalcet (exposures 2 to 3 times a human oral dose of 180 mg/day based on AUC comparisons) were accompanied by maternal signs of hypocalcemia (periparturient mortality and early postnatal pup loss), and reductions in postnatal maternal and pup body-weight gain.
There are no adequate and well-controlled studies of Sensipar in pregnant women. Sensipar should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Women who become pregnant during Sensipar treatment are encouraged to enroll in Amgen’s Pregnancy Surveillance Program. Patients or their physicians should call 1-800-77-AMGEN (1-800-772-6436) to enroll.
The following adverse reactions are discussed in greater detail in other sections of labeling:
- Hypocalcemia
- Upper Gastrointestinal Bleeding
- Adynamic Bone Disease
- Hepatic Impairment
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 with rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.
Secondary Hyperparathyroidism In Patients With Chronic Kidney Disease On Dialysis
In three double-blind, placebo-controlled clinical trials, 1126 patients with CKD on dialysis received study drug (656 Sensipar, 470 placebo) for up to 6 months. The most frequently reported adverse reactions are listed in Table 1.
Seizures were observed in 1.4% (13/910) of Sensipar-treated patients and 0.7% (5/641) of placebo-treated patients across all completed placebo-controlled trials.
Table 1. Adverse Reactions with Frequency ≥ 5% in Patients on Dialysis in Short-Term Studies for up to 6 Months
| Placebo (n = 470) |
Sensipar (n = 656) |
|
| Event*: | (%) | (%) |
| Nausea | 19 | 31 |
| Vomiting | 15 | 27 |
| Diarrhea | 20 | 21 |
| Myalgia | 14 | 15 |
| Dizziness | 8 | 10 |
| Hypertension | 5 | 7 |
| Asthenia | 4 | 7 |
| Anorexia | 4 | 6 |
| Pain Chest, Non-Cardiac | 4 | 6 |
| Dialysis Access Site Infection | 4 | 5 |
| *Included are events that were reported at a greater incidence in the Sensipar group than in the placebo group. |
In a randomized, double-blind placebo-controlled study of 3883 patients with secondary HPT and CKD receiving dialysis in which patients were treated for up to 64 months (mean duration of treatment was 21 months in the Sensipar group), the most frequently reported adverse reactions (incidence of ≥ 5% in the Sensipar group and a difference ≥ 1% compared to placebo) are listed in Table 2.
Table 2. Frequency of Adverse Reactions in Dialysis Patients Treated for up to 64 Months in a Long-Term Study1
| Placebo (n = 1923) | Sensipar (n = 1938) | |
| 3699 subject-years | 4044 subject-years | |
| Percent of subjects reporting Adverse Reactions (%) | 90.9 | 93.2 |
| Nausea | 15.5 | 29.1 |
| Vomiting | 13.7 | 25.6 |
| Diarrhea | 18.7 | 20.5 |
| Dyspnea | 11.5 | 13.4 |
| Cough | 9.8 | 11.7 |
| Hypotension | 10.5 | 11.6 |
| Headache | 9.6 | 11.5 |
| Hypocalcemia | 1.4 | 11.2 |
| Muscle spasms | 9.2 | 11.1 |
| Abdominal pain | 9.6 | 10.9 |
| Abdominal pain upper | 6.3 | 8.2 |
| Hyperkalemia | 6.1 | 8.1 |
| Upper respiratory tract infection | 6.3 | 7.6 |
| Dyspepsia | 4.6 | 7.4 |
| Dizziness | 4.7 | 7.3 |
| Decreased appetite | 3.5 | 5.9 |
| Asthenia | 3.8 | 5.4 |
| Constipation | 3.8 | 5.0 |
| 1 Adverse reactions that occurred in ≥ 5% Frequency in the Sensipar group and a difference ≥ 1% compared to the placebo group (Safety Analysis Set) Crude incidence rate = 100 * Total number of subjects with event/N n = Number of subjects receiving at least one dose of study drug |
Additional adverse reaction rates from the long-term, randomized, double-blind placebo-controlled study for Sensipar versus placebo are as follows: seizure (2.5%, 1.6%), rash (2.2%, 1.9%), hypersensitivity reactions (9.4%, 8.3%).
Parathyroid Carcinoma And Primary Hyperparathyroidism
The safety profile of Sensipar in these patient populations is generally consistent with that seen in patients with CKD on dialysis. Forty-six patients were treated with Sensipar in a single-arm study, 29 with Parathyroid Carcinoma and 17 with intractable pHPT. Nine (20%) of the patients withdrew from the study due to adverse events. The most frequent adverse reactions and the most frequent cause of withdrawal in these patient populations were nausea and vomiting. Severe or prolonged cases of nausea and vomiting can lead to dehydration and worsening hypercalcemia so careful monitoring of electrolytes is recommended in patients with these symptoms.
Eight patients died during treatment with Sensipar in this study, 7 with Parathyroid Carcinoma (24%) and 1 (6%) with intractable pHPT. Causes of death were cardiovascular (5 patients), multi-organ failure (1 patient), gastrointestinal hemorrhage (1 patient) and metastatic carcinoma (1 patient). Adverse events of hypocalcemia were reported in three patients (7%).
Seizures were observed in 0.7% (1/140) of cinacalcet-treated patients and 0.0% (0/46) of placebo-treated patients in all clinical studies.
Table 3. Adverse Reactions with Frequency ≥ 10% in a Single-Arm, Open-Label Study in Patients with Primary Hyperparathyroidism or Parathyroid Carcinoma
| Sensipar | |||
| Parathyroid Carcinoma (n = 29) |
Intractable pHPT (n = 17) |
Total (n = 46) |
|
| n (%) | n (%) | n (%) | |
| Number of Subjects Reporting Adverse Reactions | 28 (97) | 17 (100) | 45 (98) |
| Nausea | 19 (66) | 10 (59) | 29 (63) |
| Vomiting | 15 (52) | 6 (35) | 21 (46) |
| Paresthesia | 4 (14) | 5 (29) | 9 (20) |
| Fatigue | 6 (21) | 2 (12) | 8 (17) |
| Fracture | 6 (21) | 2 (12) | 8 (17) |
| Hypercalcemia | 6 (21) | 2 (12) | 8 (17) |
| Anorexia | 6 (21) | 1 (6) | 7 (15) |
| Asthenia | 5 (17) | 2 (12) | 7 (15) |
| Dehydration | 7 (24) | 0 (0) | 7 (15) |
| Anemia | 5 (17) | 1 (6) | 6 (13) |
| Arthralgiaq | 5 (17) | 1 (6) | 6 (13) |
| Constipation | 3 (10) | 3 (18) | 6 (13) |
| Depression | 3 (10) | 3 (18) | 6 (13) |
| Headache | 6 (21) | 0 (0) | 6 (13) |
| Infection Upper Respiratory | 3 (10) | 2 (12) | 5 (11) |
| Pain Limb | 3 (10) | 2 (12) | 5 (11) |
| n=Number of subjects receiving at least one dose of study drug. pHPT=primary hyperparathyroidism |
In a randomized double-blind, placebo-controlled study of 67 patients with primary hyperparathyroidism for whom parathyroidectomy would be indicated on the basis of serum calcium levels, but who are unable to undergo surgery, the most common adverse reactions are listed in Table 4.
Table 4. Adverse Reactions Occurring in ≥ 10% of Subjects in a Double-Blind, Placebo-Controlled Study in Patients with Primary Hyperparathyroidism
| Adverse Reaction | Placebo (n = 34) n (%) |
Cinacalcet (n = 33) n (%) |
| Nausea | 6 (18) | 10 (30) |
| Muscle spasms | 0 (0) | 6 (18) |
| Headache | 2 (6) | 4 (12) |
| Back pain | 2 (6) | 4 (12) |
| n = Number of subjects receiving at least one dose of study drug Coded using MedDRA version 16.0 |
Hypocalcemia
In 26-week studies of patients with secondary HPT and CKD on dialysis 66% of patients receiving Sensipar compared with 25% of patients receiving placebo developed at least one serum calcium value less than 8.4 mg/dL, whereas, 29% of patients receiving Sensipar compared with 11% of patients receiving placebo developed at least one serum calcium value less than 7.5 mg/dL. Less than 1% of patients in each group permanently discontinued study drug due to hypocalcemia.
In a randomized, double-blind, placebo-controlled study in patients with secondary HPT and CKD receiving dialysis in which patients were treated for up to 64 months (mean duration of treatment was 21 months in the cinacalcet group), 75% of patients receiving Sensipar compared with 29% of patients receiving placebo developed at least one serum calcium value less than 8.4 mg/dL and 33% of cinacalcet patients compared with 12% of patients receiving placebo had at least one serum calcium value less than 7.5 mg/dL. Most of the cases of severe hypocalcemia less than 7.5 mg/dL (21/33=64%) occurred during the first 6 months. In this trial, 1.1% of patients receiving Sensipar and 0.1% of patients receiving placebo permanently discontinued study drug due to hypocalcemia.
During a placebo-controlled part of a 52-week study in patients with primary HPT who met criteria for parathyroidectomy on the basis of corrected total serum calcium (> 11.3 mg/dL [2.82 mmol/L] and ≤ 12.5 mg/dL [3.12 mmol/L]), serum calcium less than 8.4 mg/dL was observed in 6.1% (2/33) of Sensipar-treated patients and 0% (0/34) of placebo-treated patients.
Postmarketing Experience
The following adverse reactions have been identified during postapproval use of Sensipar. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
- Rash and hypersensitivity reactions (including angioedema and urticaria), and myalgia
- Isolated, idiosyncratic cases of hypotension, worsening heart failure, and/or arrhythmia have been reported in patients with impaired cardiac function
- Gastrointestinal bleeding
Doses titrated up to 300 mg once daily have been safely administered to patients on dialysis. Overdosage of Sensipar may lead to hypocalcemia. In the event of overdosage, patients should be monitored for signs and symptoms of hypocalcemia and appropriate measures taken to correct serum calcium levels.
Since Sensipar is highly protein bound, hemodialysis is not an effective treatment for overdosage of Sensipar.
Reduction in iPTH levels correlated with the plasma cinacalcet concentrations in patients with CKD. The nadir in iPTH level occurs approximately 2 to 6 hours post dose, corresponding with the maximum plasma concentration (Cmax) of cinacalcet. After steady-state cinacalcet concentrations are reached (which occurs within 7 days of dose change), serum calcium concentrations remain constant over the dosing interval in patients with CKD.
Reductions in PTH are associated with a decrease in bone turnover and bone fibrosis in patients with CKD on dialysis and uncontrolled secondary HPT.
Absorption And Distribution
After oral administration of cinacalcet, Cmax is achieved in approximately 2 to 6 hours. Cinacalcet Cmax and AUC(0-infinite) were increased by 82% and 68%, respectively, following administration with a high-fat meal compared with fasting in healthy volunteers. The Cmax and AUC(0-infinite) of cinacalcet were increased by 65% and 50%, respectively, when cinacalcet was administered with a low-fat meal compared with fasting.
After absorption, cinacalcet concentrations decline in a biphasic fashion with a terminal half-life of 30 to 40 hours. Steady-state drug levels are achieved within 7 days, and the mean accumulation ratio is approximately 2 with once daily oral administration. The median accumulation ratio is approximately 2 to 5 with twice daily oral administration. The AUC and Cmax of cinacalcet increase proportionally over the dose range of 30 to 180 mg once daily. The pharmacokinetic profile of cinacalcet does not change over time with once daily dosing of 30 to 180 mg. The volume of distribution is approximately 1000 L, indicating extensive distribution. Cinacalcet is approximately 93% to 97% bound to plasma protein(s). The ratio of blood cinacalcet concentration to plasma cinacalcet concentration is 0.80 at a blood cinacalcet concentration of 10 ng/mL.
Metabolism And Excretion
Cinacalcet is metabolized by multiple enzymes, primarily CYP3A4, CYP2D6, and CYP1A2. After administration of a 75 mg radiolabeled dose to healthy volunteers, cinacalcet was metabolized via: 1) oxidative N-dealkylation to hydrocinnamic acid and hydroxy-hydrocinnamic acid, which are further metabolized via β-oxidation and glycine conjugation; the oxidative N-dealkylation process also generates metabolites that contain the naphthalene ring; and 2) oxidation of the naphthalene ring on the parent drug forming dihydrodiols, which are further conjugated with glucuronic acid. The plasma concentrations of the major circulating metabolites, including the cinnamic acid derivatives and glucuronidated dihydrodiols, markedly exceed the parent drug concentrations. The hydrocinnamic acid metabolite and glucuronide conjugates have minimal or no calcimimetic activity. Renal excretion of metabolites was the primary route of elimination of radioactivity. Approximately 80% of the dose was recovered in the urine and 15% in the feces.
