Drug Guide
Cinacalcet Hydrochloride
Classification
Therapeutic: Calcimimetic agent for secondary hyperparathyroidism and parathyroid carcinoma
Pharmacological: Calcimimetic that increases the sensitivity of calcium-sensing receptors
FDA Approved Indications
- Secondary hyperparathyroidism in patients with chronic kidney disease on dialysis
- Parathyroid carcinoma in patients with hypercalcemia
Mechanism of Action
Cinacalcet increases the sensitivity of calcium-sensing receptors on parathyroid gland chief cells, leading to decreased parathyroid hormone (PTH) secretion and lowered serum calcium levels.
Dosage and Administration
Adult: Starting dose typically 30 mg once daily, titrated as needed up to a maximum of 180 mg daily based on response and tolerability.
Pediatric: Not approved for pediatric use.
Geriatric: No specific dose adjustments, but monitor more closely due to potential comorbidities.
Renal Impairment: Use with caution; dosing adjustments may be necessary, especially in severe impairment.
Hepatic Impairment: Use with caution; start at lower doses as hepatic metabolism may be affected.
Pharmacokinetics
Absorption: Well absorbed with oral administration.
Distribution: Widely distributed; approximately 85% protein-bound.
Metabolism: Primarily metabolized in the liver via CYP3A4 and CYP1A2.
Excretion: Excreted mainly in feces (as metabolites) and some in urine.
Half Life: Approximately 30-40 hours.
Contraindications
- Hypersensitivity to cinacalcet or any component of the formulation.
Precautions
- Patients with concomitant medications affecting CYP3A4 or CYP1A2; risk of drug interactions.
- Monitor serum calcium closely to prevent hypocalcemia.
- Use caution in patients with cardiovascular disease due to potential for hypocalcemia-induced arrhythmias.
Adverse Reactions - Common
- Nausea (Common)
- Vomiting (Common)
- Myalgia (Less common)
- Hypocalcemia (Common)
Adverse Reactions - Serious
- Seizures (Rare)
- QT prolongation (Rare)
- Severe hypocalcemia leading to cardiac arrhythmias (Rare)
Drug-Drug Interactions
- Digoxin Due to risk of hypocalcemia affecting its toxicity
- CYP3A4 inhibitors or inducers affecting cinacalcet metabolism
Drug-Food Interactions
- No significant food interactions reported
Drug-Herb Interactions
- Limited data; caution with herbs affecting CYP enzymes.
Nursing Implications
Assessment: Monitor serum calcium, phosphate, PTH, and related laboratory parameters regularly.
Diagnoses:
- Risk for electrolyte imbalance
- Risk for cardiac arrhythmias due to hypocalcemia
Implementation: Administer with food to reduce gastrointestinal irritation; titrate dose based on laboratory findings and clinical response.
Evaluation: Assess signs of hypocalcemia (e.g., tetany, paresthesias), monitor laboratory values, adjust dose accordingly.
Patient/Family Teaching
- Take medication exactly as prescribed, and do not adjust dose without healthcare provider approval.
- Report symptoms of hypocalcemia: muscle cramps, tingling, seizures, or irregular heartbeat.
- Keep regular follow-up appointments for blood tests.
- Avoid abrupt discontinuation or dose changes.
Special Considerations
Black Box Warnings:
- Severe hypocalcemia can occur, which may lead to seizures or cardiac arrhythmias.
Genetic Factors: Not specifically indicated.
Lab Test Interference: May alter serum calcium and PTH levels, requiring close monitoring.
Overdose Management
Signs/Symptoms: Severe hypocalcemia, seizures, arrhythmias.
Treatment: Discontinue cinacalcet, provide calcium supplementation intravenously if needed, and manage symptoms supportively.
Storage and Handling
Storage: Store at room temperature away from light and moisture.
Stability: Stable when stored properly for the duration of its shelf life.