Parsabiv

Etecalcetide.

Parsabiv 2.5 mg solution for injection: Each vial contains 2.5 mg of etelcalcetide (as hydrochloride) in 0.5 mL of solution. Each mL contains 5 mg etelcalcetide.
Parsabiv 5 mg solution for injection: Each vial contains 5 mg of etelcalcetide (as hydrochloride) in 1 mL of solution. Each mL contains 5 mg etelcalcetide.
Parsabiv 10 mg solution for injection: Each vial contains 10 mg of etelcalcetide (as hydrochloride) in 2 mL of solution. Each mL contains 5 mg etelcalcetide.
Excipients/Inactive Ingredients: Sodium chloride, succinic acid, water for injections, hydrochloric acid (for pH adjustment), and sodium hydroxide (for pH adjustment).

Pharmacotherapeutic group: Calcium homeostasis, anti-parathyroid agents. ATC Code: H05BX04.
Pharmacology: Pharmacodynamics: Mechanism of Action: The calcium-sensing receptor on the surface of the chief cell of the parathyroid gland is the principal regulator of PTH secretion. Etelcalcetide is a synthetic peptide calcimimetic agent which reduces PTH secretion through binding and activation of the calcium-sensing receptor. The reduction in PTH is associated with a concomitant decrease in serum calcium and phosphate levels.
Pharmacodynamic Effects: Following a single intravenous bolus administration of 5 mg etelcalcetide, PTH levels decreased rapidly within 30 minutes post-dose and were maximally decreased for 1 hour, before returning to baseline. The extent and duration of the reduction in PTH increased with increasing dose. Reduction in PTH levels correlated with plasma etelcalcetide concentrations in haemodialysis patients. The effect of reducing PTH levels was maintained throughout the 6-month dosing period when etelcalcetide was administered by intravenous bolus 3 times a week.
Clinical efficacy and safety: Placebo-controlled studies: Two 6-month, double-blind, placebo-controlled clinical studies were conducted in SHPT patients with CKD receiving haemodialysis 3 times per week (n = 1,023). Patients were administered Parsabiv or placebo at a starting dose of 5 mg 3 times per week at the end of haemodialysis and titrated every 4 weeks through week 17 to a maximum dose of 15 mg 3 times per week to achieve target PTH level ≤ 300 pg/mL. The median average weekly dose of Parsabiv during the efficacy assessment period (EAP) was 20.4 mg (6.8 mg per administration). Patients with lower screening PTH levels typically required lower doses (median average weekly doses of 15.0 mg, 21.4 mg, 27.1 mg, respectively, for patients with screening PTH levels < 600 pg/mL, 600 to ≤ 1,000 pg/mL, and > 1,000 pg/mL). Patients were maintained on dialysate calcium concentration ≥ 2.25 meq/L.
The primary endpoint in each study was the proportion of patients with > 30% reduction from baseline in PTH during the EAP (EAP, defined as weeks 20 to 27 inclusive). The secondary endpoints were the proportion of patients with a mean PTH ≤ 300 pg/mL during the EAP, and percent change from baseline during the EAP for PTH, serum cCa, phosphate and calcium phosphate product (Ca x P).
Demographic and baseline characteristics between the two groups in each study were similar. The mean age of patients across the 2 studies was 58.2 (range 21 to 93) years. Mean (SE) baseline PTH concentrations across the 2 studies were 846.9 (21.8) pg/mL, and 835.9 (21.0) pg/mL for the Parsabiv and placebo groups, respectively with approximately 21% of subjects enrolling across both studies having baseline PTH > 1,000 pg/mL. The average duration of haemodialysis prior to study entry was 5.4 years and 68% of patients were receiving vitamin D sterols at study entry, with 83% receiving phosphate binders.
Both studies demonstrated that Parsabiv reduced PTH, while lowering calcium, phosphate and Ca x P. Results of all primary and secondary endpoints were statistically significant and the results were consistent across both studies as shown in Table 1. (See Table 1.)

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Parsabiv decreased PTH regardless of baseline PTH, duration of dialysis, and whether or not patients were receiving vitamin D sterols. Patients with lower screening PTH levels were more likely to reach PTH ≤ 300 pg/mL during EAP.
Parsabiv was associated with reductions in bone metabolism markers (bone specific alkaline phosphatase and type I collagen c-telopeptide) and fibroblast growth factor 23 (exploratory endpoints) at the end of the study (week 27), compared with placebo.
Active-controlled study: A 6-month, double-blind, active-controlled study compared the efficacy and safety of Parsabiv with cinacalcet in 683 SHPT patients with CKD on haemodialysis. The dosing regimen for Parsabiv was similar to that in the placebo-controlled studies (starting dose of 5 mg titrated every 4 weeks with 2.5 mg to 5 mg increments to a maximum of 15 mg 3 times a week). The starting dose of cinacalcet was 30 mg daily, titrated every 4 weeks in 30 mg increments or 60 mg for the last uptitration to a maximum dose of 180 mg daily following the cinacalcet prescribing information. The median average weekly dose of Parsabiv during the EAP was 15.0 mg (5.0 mg per administration) and of cinacalcet was 360.0 mg (51.4 mg per administration). The primary endpoint was non-inferiority for the proportion of patients who achieved > 30% reduction from baseline in mean PTH during the EAP (weeks 20 to 27). Key secondary endpoints were the proportion of patients who achieved > 50% and > 30% reductions from baseline in mean PTH during the EAP and the mean number of days of vomiting or nausea per week in the first 8 weeks, sequentially tested for superiority. Mean (SE) baseline PTH concentrations were 1,092.12 (33.8) and 1,138.71 (38.2) pg/mL for the Parsabiv and cinacalcet groups respectively. Demographics and other baseline characteristics were similar to the placebo-controlled studies.
Parsabiv was non-inferior to cinacalcet for the primary endpoint, and was superior to cinacalcet for the secondary endpoints of proportion of patients achieving > 30% reduction from baseline in mean PTH during the EAP (68.2% Parsabiv versus 57.7% cinacalcet; p = 0.004); and proportion of patients achieving >50% reduction from baseline in mean PTH during the EAP (52.4% Parsabiv versus 40.2% cinacalcet; p = 0.001). No statistically significant difference between the two groups was observed for the secondary endpoint evaluating the mean number of days of vomiting or nausea per week in the first 8 weeks.
"Switch study": Results from a study which evaluated changes in corrected serum calcium levels when switching patients from cinacalcet to Parsabiv showed that treatment with Parsabiv, at a starting dose of 5 mg, could be safely initiated after a 7-day discontinuation of cinacalcet, provided that the corrected serum calcium was ≥ 8.3 mg/dL (2.08 mmol/L).
Open-label extension study: A 52-week, single arm extension study to the placebo-controlled and "switch" studies described above was conducted to characterise the long term safety and efficacy of Parsabiv in 891 SHPT patients with CKD on haemodialysis. All subjects received Parsabiv at a starting dose of 5 mg 3 times a week. The dose of Parsabiv could be titrated at weeks 5, 9, 17, 25, 33, 41, and 49 to a maximum dose of 15 mg to achieve target PTH levels ≤ 300 pg/mL while maintaining serum cCa concentrations.
At the end of 52 weeks, Parsabiv was not associated with any new safety findings and demonstrated maintenance of treatment effect as evidenced by a decrease in pre-dialysis PTH by > 30% from baseline in 2/3rd of patients. In addition, Parsabiv decreased pre-dialysis PTH to ≤ 300 pg/mL in more than 50% of patients and decreased mean PTH, cCa, cCa x P, and phosphate from baseline.
Paediatric population: The safety and efficacy of etelcalcetide in children and adolescents less than 18 years has not yet been established. No data are available.
Pharmacokinetics: Distribution: In the population pharmacokinetics model, volume of distribution at steady-state was approximately 796 L. Etelcalcetide is predominately bound to plasma albumin by reversible covalent binding. Non-covalent binding of etelcalcetide to plasma proteins is low with a fraction unbound ratio of 0.53. The ratio of blood-to-plasma [¹⁴C]-etelcalcetide concentrations is approximately 0.6.
Biotransformation: Etelcalcetide is not metabolised by CYP450 enzymes. Etelcalcetide is biotransformed in blood by reversible disulphide exchange with endogenous thiols to predominantly form conjugate with serum albumin. The plasma exposure of biotransformation products was approximately 5-fold higher than that of etelcalcetide and their concentration-time course parallels that of etelcalcetide. The predominant biotransformation product (albumin bound) was minimally active in vitro.
Elimination: Intravenous administration 3 times per week at the end of a haemodialysis session resulted in an effective half-life of 3 to 5 days. Etelcalcetide is rapidly cleared in subjects with normal renal function, whilst in CKD patients requiring haemodialysis, etelcalcetide was predominantly eliminated by haemodialysis. Etelcalcetide was efficiently removed with a haemodialysis clearance value of 7.66 L/hour. Following a single radiolabelled dose of etelcalcetide in CKD patients with secondary HPT receiving haemodialysis, approximately 60% of dosed [¹⁴C]-etelcalcetide was recovered in dialysate and approximately 7% recovered in urine and faeces combined over 175 days of collection period. The inter-subject variability of the system clearance in the patient population is approximately 70%.
Linearity/non-linearity: The pharmacokinetics of etelcalcetide is linear and does not change over time following single (5 to 60 mg) and multiple intravenous doses (2.5 to 20 mg) in CKD patients with secondary HPT receiving haemodialysis. Following 3 times a week intravenous dosing at the end of each 3 to 4 hour haemodialysis session in CKD patients, etelcalcetide plasma levels reached near steady-state 4 weeks after dosing with an observed accumulation ratio of 2- to 3-fold.
Renal impairment: No specific pharmacokinetic studies of etelcalcetide have been conducted in patients with mild to severe kidney impairment. The pharmacokinetics of etelcalcetide was characterised in CKD patients receiving haemodialysis. Etelcalcetide is intended for CKD patients receiving haemodialysis.
Hepatic impairment: No specific study in patients with hepatic impairment was performed.
Body weight, gender, age, race: No body weight, gender, age, or race-related pharmacokinetic differences have been observed in adult patients studied.
Toxicology: Preclinical safety data: The expected pharmacological effect of decreased PTH and calcium in blood were observed in animal studies at clinical exposure levels. Reductions in serum calcium associated with tremoring, convulsions and stress-related findings were observed at clinical exposure levels. All effects were reversible upon cessation of treatment.
Etelcalcetide was mutagenic in some strains of bacteria (Ames), however was not genotoxic in in vitro and in vivo mammalian genotoxicity assays and therefore is considered non-genotoxic in humans. In mouse and rat carcinogenicity studies, there were no etelcalcetide-related tumours up to exposure of 0.4-fold clinical exposure levels.
There was no effect on male or female fertility when etelcalcetide was administered to rats at exposure levels up to 1.8-fold higher than clinical exposures levels achieved in patients receiving etelcalcetide at 15 mg three times per week.
There were no effects on embryo-foetal development in rats and rabbits when exposed to up to 1.8 to 4.3 times clinical exposure levels during organogenesis. In a pre- and post-natal development study in rats there was a minimal increase in perinatal pup mortality, delay in parturition and transient reductions in post-natal growth associated with maternal toxicities of hypocalcaemia, tremoring, and reductions in body weight and food consumption at 1.8 times clinical exposure levels.
Studies in rats showed [¹⁴C]-etelcalcetide was excreted in the milk at concentrations similar to plasma.

Parsabiv is indicated for the treatment of secondary hyperparathyroidism (SHPT) in adult patients with chronic kidney disease (CKD) on haemodialysis therapy.

The recommended initial dose of etelcalcetide is 5 mg administered by bolus injection 3 times per week. Corrected serum calcium should be at or above the lower limit of the normal range prior to administration of first dose of Parsabiv, a dose increase, or reinitiation after a dose stop (see also dose adjustments based on serum calcium levels). Parsabiv should not be administered more frequently than 3 times per week.
Dose titration: Parsabiv should be titrated so that doses are individualised between 2.5 mg and 15 mg. The dose may be increased in 2.5 mg or 5 mg increments no more frequently than every 4 weeks to a maximum dose of 15 mg 3 times per week to achieve the desired parathyroid hormone (PTH) target.
Dose adjustments based on PTH levels: PTH should be measured after 4 weeks from initiation or dose adjustment of Parsabiv, and approximately every 1-3 months during maintenance. Dose adjustment may be necessary at any time during treatment including the maintenance phase.
If PTH is below 100 pg/mL (10.6 pmol/L), the dose should be reduced or temporarily stopped. If PTH does not return to > 100 pg/mL following dose reduction, the dose should be stopped. For patients in whom the dose is stopped, Parsabiv should be reinitiated at a lower dose once PTH returns to >150 pg/mL (15.9 pmol/L) and pre-dialysis serum corrected calcium (cCa) ≥ 8.3 mg/dL (2.08 mmol/L). If the patient's last administered dose was 2.5 mg, Parsabiv may be reinitiated at the 2.5 mg dose level if PTH is > 300 pg/mL (31.8 pmol/L), and the most recent pre-dialysis serum cCa ≥ 8.3 mg/dL (2.08 mmol/L).
Additional recommendations related to the management of low calcium are provided in the table below.
Parsabiv may be used as part of a therapeutic regimen including phosphate binders and/or vitamin D sterols, as appropriate (see Pharmacology: Pharmacodynamics under Actions).
Missed doses: If a regularly scheduled haemodialysis treatment is missed, do not administer any missed doses. Parsabiv should be administered at the next haemodialysis treatment at the same dose. If doses are missed for more than 2 weeks, then Parsabiv should be administered at 5 mg, (or 2.5 mg if that was the patient’s last administered dose), and titrated to achieve the desired PTH.
Dose adjustments based on serum calcium levels: Serum calcium should be measured within 1 week of initiation or dose adjustment of Parsabiv. Once the maintenance phase has been established for a patient, corrected serum calcium should be measured approximately every 4 weeks. In the studies total serum calcium was measured using Roche modular analysers. The lower limit of the normal range for corrected serum calcium was 8.3 mg/dL (2.08 mmol/L). Other laboratory assays may have different cut-offs for the lower limit of the normal range.
In the event that clinically meaningful decreases in corrected serum calcium levels below the lower limit of the normal range occur and/or symptoms of hypocalcaemia occur, the following management is recommended: see Table 2. (See Table 2.)

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Switch from cinacalcet to Parsabiv: Parsabiv should not be initiated in patients until 7 days after the last dose of cinacalcet and the corrected serum calcium is at or above the lower limit of the normal range (see Pharmacology: Pharmacodynamics under Actions).
Paediatric population: The safety and efficacy of etelcalcetide in children and adolescents less than 18 years has not yet been established. No data are available.
Elderly: Dosing recommendations for elderly patients are the same as for adult patients.
Method of administration: Parsabiv should not be diluted.
Parenteral medicinal products should be inspected visually for particulate matter and change in colour prior to administration.
Parsabiv is administered into the venous line of the dialysis circuit at the end of the haemodialysis treatment during rinse-back or intravenously after rinse-back. When given during rinse-back at least 150 mL of rinse-back volume should be administered after injection. If rinse-back is completed and Parsabiv was not administered, then it may be administered intravenously followed by at least 10 mL saline flush volume.

Overdose of etelcalcetide may lead to hypocalcaemia with or without clinical symptoms and may require treatment. In the event of overdose, serum calcium should be checked and patients should be monitored for symptoms of hypocalcaemia (see Precautions) and appropriate measures should be taken (see Dosage & Administration). Although Parsabiv is cleared by dialysis, haemodialysis has not been studied as a treatment for overdose. Single doses up to 60 mg and multiple doses up to 22.5 mg 3 times a week at the end of dialysis in patients receiving haemodialysis were safely administered in clinical trials.

Hypersensitivity to the active substance or to any of the excipients listed in Description.
Parsabiv should not be initiated if corrected serum calcium is less than the lower limit of the normal range (see Dosage & Administration and Precautions).

Parsabiv has not been studied in adult patients with parathyroid carcinoma, primary hyperparathyroidism, or with CKD who are not on hemodialysis and is not recommended for use in these populations.
Hypocalcaemia: Parsabiv treatment should not be initiated in patients if the corrected serum calcium is less than the lower limit of the normal range (see Contraindications).
Potential manifestations of hypocalcaemia include paraesthesias, myalgias, muscle spasm and seizures.
Since etelcalcetide lowers serum calcium, patients should be advised to seek medical attention if they experience symptoms of hypocalcaemia and should be monitored for the occurrence of hypocalcaemia (see Dosage & Administration). Serum calcium levels should be measured prior to initiating treatment, within 1 week of initiation or dose adjustment of Parsabiv and every 4 weeks during treatment. If clinically meaningful decreases in corrected serum calcium levels occur, steps should be taken to increase serum calcium levels (see Dosage & Administration).
Ventricular arrhythmia and QT prolongation secondary to hypocalcaemia: Decreases in serum calcium can prolong the QT interval, potentially resulting in ventricular arrhythmia (see Adverse Reactions). Serum calcium levels should be closely monitored in patients with congenital long QT syndrome, previous history of QT prolongation, family history of long QT syndrome or sudden cardiac death and other conditions that predispose to QT prolongation and ventricular arrhythmia while being treated with Parsabiv.
Convulsions: The threshold for seizures may be lowered by significant reductions in serum calcium levels. Serum calcium levels should be closely monitored in patients with a history of a convulsion disorder while being treated with Parsabiv.
Worsening heart failure: Decreased myocardial performance, hypotension, and congestive heart failure (CHF) may be associated with significant reductions in serum calcium levels. Serum calcium levels should be monitored in patients with a history of congestive heart failure while being treated with Parsabiv (see Dosage & Administration), which may be associated with reductions in serum calcium levels.
Co-administration with other medicinal products: Administer Parsabiv with caution in patients receiving any other medicinal products known to lower serum calcium. Closely monitor serum calcium (see Interactions).
Patients receiving Parsabiv should not be given cinacalcet. Concurrent administration may result in severe hypocalcaemia.
Adynamic bone: Adynamic bone may develop if PTH levels are chronically suppressed below 100 pg/mL. If PTH levels decrease below the recommended target range, the dose of vitamin D sterols and/or Parsabiv should be reduced or therapy discontinued. After discontinuation, therapy can be resumed at a lower dose to maintain PTH in the target range (see Dosage & Administration).
Immunogenicity: In clinical studies, 7.1% of patients with SHPT treated with Parsabiv for up to 6 months tested positive for binding antibodies. 80.3% of these had pre-existing antibodies. No evidence of altered pharmacokinetic profile, clinical response or safety profile was associated with pre-existing or developing anti-etelcalcetide antibodies. If formation of anti-etelcalcetide antibodies with a clinically significant effect is suspected, contact the Marketing Authorisation Holder to discuss antibody testing. Contact details are provided in section 6 of the package leaflet.
Excipient with known effect: Parsabiv contains less than 1 mmol sodium per vial, i.e. essentially sodium-free.
Effects on ability to drive and use machines: Parsabiv has no or negligible influence on the ability to drive and use machines. However, certain potential manifestations of hypocalcaemia may affect the ability to drive and use machines.
Impairment of Fertility: No data are available on the effect of etelcalcetide on human fertility. Animal studies do not indicate direct or indirect harmful effects with respect to fertility (see Pharmacology: Toxicology under Actions).

Pregnancy: There are no or limited amount of data from the use of etelcalcetide in pregnant women. Animal studies do not indicate direct or indirect harmful effects with respect to reproductive toxicity (see Pharmacology: Toxicology under Actions). As a precautionary measure, it is preferable to avoid the use of Parsabiv during pregnancy.
Breast-feeding: It is unknown whether etelcalcetide is present in human milk. Available data in rats have shown that etelcalcetide is excreted in milk (see Pharmacology: Toxicology under Actions).
A risk to breastfed newborns/infants cannot be excluded. A decision must be made whether to discontinue breast-feeding or discontinue/abstain from Parsabiv therapy taking into account the benefit of breast-feeding for the child and the benefit of therapy for the woman.

Summary of safety profile: Very common side effects with Parsabiv are blood calcium decreased, muscle spasms, diarrhoea, nausea, and vomiting. They were mild to moderate in severity and transient in nature in the majority of patients. Discontinuation of therapy as a result of undesirable effects was mainly due to low blood calcium, nausea, and vomiting.
Tabulated list of adverse reactions: Adverse reactions are listed as follows using the following convention: very common (≥ 1/10); common (≥ 1/100 to < 1/10); uncommon (≥ 1/1,000 to < 1/100); rare (≥ 1/10,000 to < 1/1,000); very rare (< 1/10,000). (See Table 3.)

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Description of selected adverse reactions: Hypocalcaemia: Most events of asymptomatic blood calcium decreased and symptomatic hypocalcaemia were mild or moderate in severity. In the combined placebo-controlled studies, a higher proportion of patients in the Parsabiv group compared with patients in the placebo group developed at least one serum cCa value < 7.0 mg/dL (1.75 mmol/L) (7.6% Parsabiv; 3.1% placebo), < 7.5 mg/dL (1.88 mmol/L) (27.1% Parsabiv; 5.5% placebo), and < 8.3 mg/dL (2.08 mmol/L) (78.6% Parsabiv; 19.4% placebo). In these studies 1% of patients in the Parsabiv group and 0% of patients in the placebo group discontinued treatment due to the adverse event of low serum calcium. For further information regarding potential manifestations of hypocalcaemia and serum calcium monitoring please see Precautions and Dosage & Administration, respectively.
QTc prolongation secondary to hypocalcaemia: In the combined placebo-controlled studies, a higher percentage of patients in the Parsabiv group compared with the placebo group had a maximum increase from baseline of > 60 msec in the QTcF interval (1.2% Parsabiv; 0% placebo). The patient incidence of maximum post-baseline pre-dialysis QTcF >500 msec in the Parsabiv and placebo groups was 4.8% and 1.9% respectively.
Worsening heart failure: In the combined placebo-controlled studies, the subject incidence of adjudicated CHF events requiring hospitalisation was 2.2% in the Parsabiv treatment group compared to 1.2% in the placebo group.

No interaction studies have been performed. There is no known risk of pharmacokinetic interaction with etelcalcetide.
In vitro, etelcalcetide did not inhibit or induce CYP450 enzymes and was itself not a substrate for metabolism by CYP450 enzymes. In vitro, etelcalcetide was not a substrate of efflux and uptake transporter proteins; and etelcalcetide was not an inhibitor of common transporter proteins.
Concurrent administration of other medicinal products known to reduce serum calcium and Parsabiv may result in an increased risk of hypocalcaemia (see Precautions). Patients receiving Parsabiv should not be given cinacalcet (see Precautions).

Special precautions for disposal and other handling: For single use only.
Any unused medicinal product or waste material should be disposed of in accordance with local requirements.
Incompatibilities: This medicinal product must not be mixed with other medicinal products.

Special precautions for storage: Store in a refrigerator (2°C-8°C).
Keep the vial in the outer carton in order to protect from light.
Shelf-Life: 3 years.
Once removed from the refrigerator: Parsabiv is stable for a maximum of 7 cumulative days if stored in the original carton. No special temperature storage requirements are needed.
If removed from the original carton Parsabiv is stable for a maximum of 4 hours if protected from direct sunlight.

Other Agents Affecting Metabolism

H05BX04 - etelcalcetide ; Belongs to the class of other anti-parathyroid agents. Used in the management of calcium homeostasis.

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