cinacalcet

(sin-a-kal-set) cinacalcet,

Sensipar

(trade name)

Classification

Therapeutic: hypocalcemics
Pharmacologic: calcimimetic agents
Pregnancy Category: C

Indications

Secondary hyperparathyroidism in patients with chronic kidney disease (CKD) on dialysis.Hypercalcemia caused by parathyroid carcinoma.Severe hypercalcemia in patients with primary hyperparathyroidism in patients who are unable to undergo parathyroidectomy.

Action

Increases sensitivity of calcium-sensing receptors located on the surface of chief cells of parathyroid gland to levels of extracellular calcium. This decreases parathyroid hormone production with resultant decrease in serum calcium.

Therapeutic effects

Decreased bone turnover and fibrosis.Decreased serum calcium.

Pharmacokinetics

Absorption: Well absorbed following oral administration, absorption is enhanced by food and further enhanced by a high fat meal.Distribution: Unknown.Protein Binding: 93–97%.Metabolism and Excretion: Highly metabolized by CYP3A4, CYP2D6, and CYP1A2 enzyme systems; 80% excreted in urine as metabolites, 15% in feces.Half-life: 30–40 hr.

Time/action profile (effect on PTH levels)

ROUTE	ONSET	PEAK	DURATION
PO	rapid	2–6 hr	6–12 hr

Contraindications/Precautions

Contraindicated in: Hypersensitivity;Hypocalcemia; Lactation: Discontinue drug or bottle-feed.Use Cautiously in: History of seizure disorder (↑ risk of seizures with hypocalcemia);Chronic kidney disease patients who are not being dialyzed (↑ risk of hypocalcemia);Intact parathyroid hormone (iPTH) level <150 pg/mL (dose ↓ or discontinuation may be warranted);Moderate to severe hepatic impairment; Obstetric: Use only if benefits justify risks to fetus; Pediatric: Safety not established.

Adverse Reactions/Side Effects

Central nervous system

seizures

Gastrointestinal

nausea (most frequent)
vomiting (most frequent)

Fluid and Electrolyte

hypocalcemia

Metabolic

adynamic bone disease

Interactions

Drug-Drug interaction

Inhibits CYP2D6 and may ↑ levels of flecainide, vinblastine, thioridazine, metoprolol, carvedilol, and most tricyclic antidepressants ; dose adjustments may be necessary.Blood levels are ↑ by strong CYP3A4 inhibitors including ketoconazole, itraconazole, and erythromycin ; monitoring and dose adjustment may be necessary.

Route/Dosage

Oral (Adults) Secondary hyperparathyroidism in CKD patients on dialysis—30 mg once daily; may ↑ dose every 2–4 wk (dose range 30–180 mg once daily) based on iPTH levels; Parathyroid carcinoma or primary hyperparathyroidism—30 mg twice daily; may titrate every 2–4 wk up to 90 mg 3–4 times daily based on serum calcium levels.

Availability

Tablets: 30 mg, 60 mg, 90 mg

Nursing implications

Nursing assessment

Monitor for signs and symptoms of hypocalcemia (paresthesias, myalgias, cramping, tetany, convulsions) during therapy. If calcium levels decrease to below normal, serum calcium may be increased by adjusting dose (see Lab Test Considerations) and providing supplemental serum calcium, initiating or increasing dose of calcium-based phosphate binder or vitamin D.
Lab Test Considerations: Monitor serum calcium and phosphorous levels within 1 wk after initiation of therapy or dose adjustment and monthly for patients with hyperparathyroidism or every 2 mo for patients with parathyroid carcinoma once maintenance dose has been established, especially in patients with a history of seizure disorder. Therapy should not be initiated in patients with serum calcium less than the lower limit of normal (8.4 mg/dL).
- If serum calcium ↓ below 8.4 mg/dL but remains above 7.5 mg/dL, or if symptoms of hypocalcemia occur, use calcium-containing phosphate binders and/or vitamin D sterols to ↑ serum calcium. If serum calcium ↓ below 7.5 mg/dL, or if symptoms of hypocalcemia persist and the dose of vitamin D cannot be ↑, withhold administration of cinacalcet until serum calcium levels reach 8.0 mg/dL, and/or symptoms of hypocalcemia resolve. Re-initiate therapy using next lowest dose of cinacalcet.
- Monitor serum iPTH levels 1 to 4 wk after initiation of therapy or dose adjustment, and every 1 to 3 mo after maintenance dose has been established. If iPTH levels ↓ below 150–300 pg/mL, reduce dose or discontinue cinacalcet.
- Monitor liver function tests in patients with moderate to severe hepatic impairment during therapy.

Potential Nursing Diagnoses

Deficient knowledge, related to medication regimen (Patient/Family Teaching)

Implementation

Cinacalcet may be used alone or in combination with vitamin D and/or phosphate binders.
Oral: Administer with food or shortly after a meal. Take tablets whole, do not crush, break or chew.

Patient/Family Teaching

Instruct patient to take cinacalcet as directed.
Advise patient to report signs and symptoms of hypocalcemia to health care professional promptly.
Emphasize the importance of follow-up lab tests to monitor safely and efficacy.

Evaluation/Desired Outcomes

Decreased serum calcium levels.