CaR/Ca receptor

AMG-073 orally administered to normal rats at doses of 1, 3, 10, and 30 mg/kg in 20% sulfobutyl ether β-cyclodextrin sodium causes a notable dose-dependent decrease in PTH levels that lasts for one to four hours. The 10- and 30-mg/kg doses of AMG-073 cause notable drops in PTH levels at 8 hours when compared to controls; these reductions disappear after 24 hours. After oral administration of AMG-073, 10, 30, and 40 mg/kg, respectively, there is a significant dose-dependent reduction in serum calcium levels at 4, 8, and 24 hours later. Only at the maximum dose of AMG-073 is a temporary drop in serum phosphorus levels seen. Furthermore, rats given 40 mg/kg of AMG-073 showed elevated calcitonin levels that correlated with PTH suppression. After oral administration of AMG-073, PTH and calcium levels rapidly decrease in five out of six nephrectomized rats, as they do in normal rats. Moreover, parathyroid weight is significantly decreased by oral AMG-073 at 5 and 10 mg/kg for 4 weeks when compared to controls.

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Administration of Cinacalcet HCl (5 or 10 mg/kg) significantly reduced the number of PCNA-positive cells and decreased parathyroid weight compared with vehicle-treated 5/6 nephrectomized rats. There was no difference in apoptosis from cinacalcet HCl-treated or vehicle-treated animals. Serum PTH and blood ionized calcium levels decreased in cinacalcet HCl-treated animals compared with vehicle-treated controls. Conclusion: The results confirm previous work demonstrating that calcimimetic agents attenuate the progression of parathyroid hyperplasia in subtotally nephrectomized rats, extending earlier observations to now include cinacalcet HCl. These results support a role for the CaR in regulating parathyroid cell proliferation. Therefore, cinacalcet HCl may represent a novel therapy for improving the management of secondary HPT [1].

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Calcimimetics, such as cinacalcet (Cin), increase the sensitivity of the CaR to Ca. The effects of Cin on UCa are complex and difficult to predict. We tested the hypothesis that Cin would alter urinary (U) Ca and supersaturation with respect to calcium hydrogen phosphate (CaHPO(4)) and calcium oxalate (CaOx). GHS or control rats were fed a normal Ca diet (0.6% Ca) for 28 days with Cin (30 mg/kg/24 h) added to the diet of half of each group for the last 14 days. The protocol was then repeated while the rats were fed a low Ca (0.02% Ca) diet. We found that Cin led to a marked reduction in circulating parathyroid hormone and a modest reduction in serum Ca. Cin did not alter UCa when the GHS rats were fed the normal Ca diet but lowered UCa when they were fed the low Ca diet. However, Cin did not alter U supersaturation with respect to either CaOx or CaHPO(4) on either diet. If these findings in GHS rats can be confirmed in man, it suggests that Cin would not be an effective agent in the treatment of human idiopathic hypercalciuria and resultant stone formation [2].

The compounds were evaluated in CHO cells transfected with the hCaSR and a 6×TRE luciferase reporter system.12 Compounds were tested in dose response, with increasing calcium concentration. The increasing concentration of a positive allosteric modulator induces a dose proportional leftward shift of the hCaSR calcium responses. The values indicated in this paper correspond to an EC50 at 2 mM of calcium. The most active compounds were then tested in vivo for their ability to decrease PTH levels in normal rats. Our two starting points, R-568 and Fendiline, were active at 80 and 1000 nM, respectively, and led to compound 46, active at 60 nM. Cinacalcet was found at 80 nM in this assay.[PMID: 23465611] https://pubmed.ncbi.nlm.nih.gov/23465611/

The Apoptag System measures nuclear DNA fragmentation in situ to identify apoptosis in parathyroid glands from 5/6 nephrectomized or sham rats treated with Cinacalcet HCl (10 mg/kg) or vehicle. In summary, after being treated with vehicle or cinacalcet HCl, parathyroid gland sections from the animals are digested using 20 μg/mL proteinase K in 0.1 mol/L PBS at room temperature for 15 minutes.To block endogenous peroxidase, the samples are then incubated with 3% hydrogen peroxide/methanol for 5 minutes. To label exposed 3′-OH DNA ends with digoxigenin-tagged nucleotides, sections are incubated with terminal deoxynucleotidyl transferase (TdT) for 1 hour at 37°C. The immunoperoxidase method finds DNA that has been labeled with digoxigenin. The nuclei of apoptotic cells are stained brown, and sections are created using 3,3′-diaminobenzidine (DAB). When TdT is replaced with distilled water, the specificity for apoptosis is confirmed using negative staining.

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\n\nCinacalcet HCl dosing for 4 weeks [1]
\nStarting 6 weeks postsurgery, 5/6 nephrectomized (N = 35) and sham (N = 18) animals received orally either vehicle (20% captisol in water) (mL/kg) or Cinacalcet HCl (1, 5, or 10 mg/kg) for 4 weeks. Sampling for the determination of serum PTH and serum chemistries after the initiation of cinacalcet HCl treatment began at the 8-week time point (see Figures 4 and 5 ).\n

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\n\nApoptosis [2]
\nTo identify apoptosis in parathyroid glands from 5/6 nephrectomized or sham rats treated with vehicle [phosphate-buffered saline (PBS)] or Cinacalcet HCl (10 mg/kg), nuclear DNA fragmentation was measured in situ using the Apoptag System. Briefly, parathyroid gland sections from animals treated with vehicle or cinacalcet HCl were digested with 20 μg/mL proteinase K in 0.1 mol/L PBS at room temperature for 15 minutes and incubated with 3% hydrogen peroxide/methanol for 5 minutes to block endogenous peroxidase. Sections were incubated for 1 hour at 37°C with terminal deoxynucleotidyl transferase (TdT) to label exposed 3′-OH DNA ends with digoxigenin-tagged nucleotides. Digoxigenin-labeled DNA was detected by the immunoperoxidase method. Sections were developed with 3,3′-diaminobenzidine (DAB), and the nuclei of apoptotic cells were stained brown. The specificity for apoptosis was verified by negative staining when distilled water was substituted for TdT. \n
\n\nFourteen 67th generation female GHS rats and 14 female Sprague–Dawley Ctl rats, initially weighing on average 238 g, were placed in metabolic cages. From days 1 to 14, each rat in each group was fed 13 g/day of a NCD (0.6% Ca and 0.65% P, Harlan Teklad, Madison, WI, USA). We have previously shown that rats of this size completely consume this amount of diet on a daily basis.15, 17, 18, 19, 20 During the last 5 days of this period (day 10–14), five successive 24-h urine collections were obtained. Three (first, second, fourth) were collected in concentrated HCl (0.5 ml) for all measurements except for pH, uric acid, and chloride and two collections (third and fifth) were collected in the presence of thymol for measurement of pH, uric acid, and chloride. All samples were refrigerated at 4°C until measurement and all measurements were completed within 2 weeks.
\n\nFrom days 15 to 28, half of each group (seven GHS and seven Ctl rats), chosen at random, was continued on NCD without modification and the other half (seven GHS and seven Ctl rats) was fed NCD supplemented with Cinacalcet (30 mg/kg/day) (Amgen Inc., Thousand Oaks, CA, USA). This dose has been shown to significantly inhibit PTH in normal rats.36 In humans, the terminal half-life of Cinacalcet is 30–40 h and steady-state drug levels are reached in 7 days.36, 37 During the last 5 days of this period (day 24–28), five successive 24-h urine collections were obtained as during days 10–14.
\n\nFrom days 29 to 42, all GHS and Ctl rats were fed 13 g/day of a LCD (0.02% Ca and 0.65% P). No rat received Cinacalcet. LCD was utilized to remove the contribution of appreciable intestinal Ca absorption to UCa excretion. During the last 5 days of this period (day 38–42), five successive 24-h urine collections were obtained as during days 10–14.\nFrom days 43 to 56, half of each group (seven GHS and seven Ctl rats) was continued on LCD without modification and the other half (the same seven GHS and seven Ctl rats that had previously received Cinacalcet) was fed LCD supplemented with Cinacalcet (30 mg/kg/day). During the last 5 days of this period (day 52–56), five successive 24-h urine collections were obtained as during days 10–14.

Absorption, Distribution and Excretion
Acutely absorbed after oral administration. Cinacalcet is primarily metabolized by multiple enzymes, including CYP3A4, CYP2D6, and CYP1A2. Renal excretion of metabolites is the main route of radioactive material clearance. 1000 L This study investigated the metabolism and distribution of the calcimimetic agent cinacalcet hydrochloride in mice, rats, monkeys, and human volunteers after a single oral dose. Cinacalcet was well absorbed in all tested animals, with oral bioavailability exceeding 74% in monkeys and humans. In rats, cinacalcet-derived radioactive materials were widely distributed in most tissues, with no significant sex difference. In all animal models, radioactive materials were rapidly excreted via the hepatobiliary and urinary routes. In humans, radioactive materials are primarily cleared via urine (80%), with 17% excreted via feces. Cinacalcet was not detected in human urine. ...
After absorption, cinacalcet concentration exhibits a biphasic decrease, with a terminal half-life of 30 to 40 hours. Renal excretion of metabolites is the primary route of radioactive material elimination. Approximately 80% of the dose is recovered in urine and 15% in feces.
Drug concentrations reach steady state within 7 days. The average accumulation ratio for once-daily oral administration is approximately 2. The median accumulation ratio for twice-daily oral administration is approximately 2 to 5. The AUC and Cmax of cinacalcet increase proportionally within the once-daily dose range of 30 to 180 mg. The pharmacokinetic characteristics of cinacalcet do not change over time with once-daily administration of 30 to 180 mg. A large volume of distribution (approximately 1000 L) indicates its wide distribution. Cinacalcet binds to plasma proteins at a rate of approximately 93% to 97%. At a plasma concentration of 10 ng/mL, the plasma concentration to plasma concentration ratio is 0.8. Following oral administration of cinacalcet, peak plasma concentration (Cmax) is reached approximately within 2 to 6 hours. A food effects study in healthy volunteers showed that, compared to fasting, cinacalcet administered with a high-fat meal increased Cmax and AUC by 82% and 68%, respectively; compared to fasting, cinacalcet administered with a low-fat meal increased Cmax and AUC by 65% and 50%, respectively. For more complete data on the absorption, distribution, and excretion of cinacalcet (6 types), please visit the HSDB record page. Metabolism/Metabolites: Primarily metabolized by various hepatic enzymes, including CYP3A4, CYP2D6, and CYP1A2. Following administration of a 75 mg radiolabeled dose of cinacalcet to healthy volunteers, the drug was rapidly and extensively metabolized via the following pathways: 1) oxidative dealkylation to hydrogenated cinnamic acid and hydroxyhydrocinnamic acid, the latter of which was further metabolized via β-oxidation and glycine conjugation; oxidative dealkylation also generates a naphthalene ring-containing metabolite; 2) oxidation of the naphthalene ring on the parent drug to dihydrodiol, which was further conjugated with glucuronic acid. The metabolism and in vivo distribution of the calcimimetic agent were investigated in mice, rats, monkeys, and human volunteers after a single oral administration of cinacalcet hydrochloride. The main metabolic pathways of cinacalcet were N-dealkylation to carboxylic acid derivatives (excreted in urine as glycine conjugates) and oxidation of the naphthalene ring to dihydrodiol (excreted in urine and bile as glucuronide conjugates). Radioactivity in animal and human plasma consisted primarily of carboxylic acid metabolites and dihydrodiol glucuronide, with less than 1% of circulating radioactivity being unmetabolized cinacalcet. Overall, the circulating and excretory metabolite profile of cinacalcet in humans is similar in nature to that observed in preclinical animal models. Cinacalcet is primarily metabolized by multiple cytochrome P-450 (CYP) isoenzymes, including CYP3A4, CYP2D6, and CYP1A2, and is a potent inhibitor of CYP2D6 in vitro. In the liver, cinacalcet is rapidly and extensively metabolized by multiple enzymes, primarily CYP3A4, CYP2D6, and CYP1A2. Initially, oxidative N-dealkylation yields hydrogenated cinnamic acid and hydroxylated cinnamic acid, the latter further metabolized via β-oxidation and glycine conjugation. Oxidative N-dealkylation also generates a naphthalene ring-containing metabolite; the naphthalene ring on the parent drug is oxidized to dihydrogen diol, which further conjugates with glucuronic acid. In cell-based calcium receptor activation assays, the hydrogenated cinnamic acid metabolite was inactive at concentrations up to 10 μM. The glucuronide conjugate formed after oxidation showed approximately 0.003 times the potency of cinacalcet in a cell-based calcium-sensitive receptor agonist response assay.
Biological half-life
The terminal half-life is 30 to 40 hours.
The mean half-life of cinacalcet is prolonged by 33% and 70% in patients with moderate and severe hepatic impairment, respectively.
The mean half-life of cinacalcet is prolonged by 33% and 70% in patients with moderate and severe hepatic impairment, respectively.
Terminal half-life: 30 to 40 hours

Effects During Pregnancy and Lactation
◉ Overview of Use During Lactation There is currently no information regarding the use of cinacalcet during lactation. However, some newborns with calcium metabolism disorders have been safely treated with cinacalcet. The concentration of cinacalcet in breast milk is unlikely to reach the doses used in these cases. If the mother needs to take cinacalcet, this is not a reason to stop breastfeeding. Until more data are available, breastfeeding women should use cinacalcet under close monitoring of their infants. ◉ Effects on Breastfed Infants As of the revision date, no relevant published information was found. ◉ Effects on Lactation and Breast Milk As of the revision date, no relevant published information was found. Protein Binding Approximately 93% to 97% is bound to plasma proteins. Interactions Potential pharmacokinetic interactions (increased plasma concentrations of the drug primarily metabolized by cytochrome P450 (CYP) isoenzyme 2D6). In patients taking 25 or 100 mg cinacalcet and 50 mg amitriptyline hydrochloride concurrently, exposure to amitriptyline and its active metabolite nortriptyline increased by 20%. Dosage adjustment may be necessary if cinacalcet is taken concurrently with drugs with a narrow therapeutic index that are primarily metabolized by CYP2D6 (e.g., flecainide, vincristine, thioridazine, and most tricyclic antidepressants). Pharmacokinetic interactions (increased plasma cinacalcet concentrations) may occur with potent CYP3A4 inhibitors (e.g., ketoconazole, erythromycin, itraconazole). A reported increase in cinacalcet exposure was approximately 2.3-fold after a single dose of 90 mg cinacalcet concurrently with ketoconazole (200 mg twice daily for 7 days). Dosage adjustment of cinacalcet may be necessary if starting or discontinuing a potent CYP3A4 inhibitor, with close monitoring of parathyroid hormone (PTH) and serum calcium levels.

[1]. Cinacalcet HCl attenuates parathyroid hyperplasia in a rat model of secondary hyperparathyroidism. Kidney Int. 2005 Feb;67(2):467-76.

[2]. Effect of cinacalcet on urine calcium excretion and supersaturation in genetic hypercalciuric stone-forming rats. Kidney Int. 2006 May;69(9):1586-92.

Therapeutic Uses

Cinacalcet is indicated for the treatment of hypercalcemia in patients with parathyroid carcinoma. /US product label includes/
Cinacalcet is indicated for the treatment of secondary hyperparathyroidism in patients with chronic kidney disease undergoing dialysis. /US product label includes/
Cinacalcet is indicated for the treatment of secondary hyperparathyroidism in patients with chronic kidney disease undergoing hemodialysis or peritoneal dialysis; its safety and efficacy in dialysis-naïve patients have not been established. Cinacalcet can be used alone or in combination with vitamin D analogs and/or phosphate binders.

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Drug Warnings
In three clinical studies of patients with chronic kidney disease (CKD) undergoing dialysis, 5% of patients in both the cinacalcet and placebo groups reported a history of epilepsy at baseline. During the trials, 1.4% of patients treated with cinacalcet experienced seizures (primarily generalized or tonic-clonic seizures), compared to 0.4% of patients treated with placebo. Of the nine patients treated with cinacalcet, five had a history of epilepsy, two of whom were taking antiepileptic drugs at the time of a seizure. Both of the two patients receiving placebo had a history of epilepsy and were taking antiepileptic drugs at the time of a seizure. While the reason for the reported difference in seizure rates is unclear, a significant decrease in serum calcium levels lowers the seizure threshold. Therefore, serum calcium levels in patients receiving cinacalcet should be closely monitored, especially those with a history of epilepsy. Rat studies have shown that cinacalcet is excreted into breast milk, with a high milk-to-plasma concentration ratio. It is currently unknown whether the drug is excreted into human breast milk. Considering the rat data, and the fact that many drugs are excreted into human breast milk and can have clinically significant adverse effects on infants, the importance of the drug to breastfeeding women should be weighed when deciding whether to discontinue breastfeeding or discontinue the medication. FDA Pregnancy Risk Classification: C/Risk cannot be ruled out. Currently, adequate, well-controlled human studies are lacking, and animal studies have not shown any risk to the fetus or lack relevant data. Taking this medication during pregnancy may harm the fetus; however, the potential benefits may outweigh the potential risks. Cinacalcet lowers serum calcium levels, therefore patients should be closely monitored for hypocalcemia. Cinacalcet should not be started if serum calcium levels are below the lower limit of normal (8.4 mg/dL). For more complete data on drug warnings for cinacalcet (10 in total), please visit the HSDB record page.

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Pharmacodynamics
Cinacalcet is a calcimimetic agent (i.e., it mimics the effects of calcium on tissues). Secondary hyperparathyroidism (HPT) in patients with chronic kidney disease (CKD) is a progressive disease associated with elevated parathyroid hormone (PTH) levels and disordered calcium and phosphorus metabolism. Elevated PTH stimulates osteoclast activity, leading to cortical bone resorption and myelofibrosis. The treatment goal for secondary hyperparathyroidism is to lower blood levels of PTH, calcium, and phosphorus to prevent progressive bone disease and systemic consequences of mineral metabolism disorders. In patients with chronic kidney disease undergoing dialysis and poorly controlled secondary hyperparathyroidism, lowering PTH levels can have beneficial effects on bone-specific alkaline phosphatase (BALP), bone turnover, and bone fibrosis. Cinacalcet lowers blood calcium levels by increasing the sensitivity of calcium-sensitive receptors to extracellular calcium.

C22H22F3N

357.41

357.17

C, 73.93; H, 6.20; F, 15.95; N, 3.92

226256-56-0

Cinacalcet hydrochloride; 364782-34-3; Cinacalcet-d3 hydrochloride; Cinacalcet-d3; 848608-66-2 [Cinacalcet (m2a-glu)]

156419

White to off-white solid powder

1.2±0.1 g/cm3

440.9±45.0 °C at 760 mmHg

220.5±28.7 °C

0.0±1.1 mmHg at 25°C

1.563

5.74

1

4

6

26

422

1

C[C@H](C1=CC=CC2=CC=CC=C21)NCCCC3=CC(=CC=C3)C(F)(F)F

VDHAWDNDOKGFTD-MRXNPFEDSA-N

InChI=1S/C22H22F3N/c1-16(20-13-5-10-18-9-2-3-12-21(18)20)26-14-6-8-17-7-4-11-19(15-17)22(23,24)25/h2-5,7,9-13,15-16,26H,6,8,14H2,1H3/t16-/m1/s1

N-[(1R)-1-naphthalen-1-ylethyl]-3-[3-(trifluoromethyl)phenyl]propan-1-amine

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 2.75 mg/mL (7.69 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 27.5 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.75 mg/mL (7.69 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 27.5 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.75 mg/mL (7.69 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 27.5 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 30% PEG400+0.5% Tween80+5% Propylene glycol : 30mg/mL

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 (Please use freshly prepared in vivo formulations for optimal results.)