Cinacalcet (Sensipar)

A calcimimetic.

Increases sensitivity of Ca-sensing receptor in parathyroid cells to activation by extracellular calcium, downregulating PTH levels and consequently lowering serum Ca and phosphorus.

Oral agent with 20 to 25% bioavailability.

Bioavailability Increases if taken with food.

Protein binding 93 to 97%.

High fat meal increases both peak plasma concentration and AUC.

Peak plasma time of 2-6 hr.

Reduces parathyroid hormone levels in secondary hyperparathyroidism in patients on hemodialysis and decreases serum calcium and phosphorus disturbances.

Results in a 30% reduction in plasma parathyroid level in 60% of patients so treated.

In patients who respond reductions in serum calcium, phosphorus, bone-specific alkaline phosphatase and calcium-phosphorus product.

Rapidly reduces parathyroid hormone levels within 2-3 hours.

Hepatic metabolism-CYP3A4, CYP2D6 and CYP1A2 mediated.

Half-life of 30 to 40 hours.

Has 80% renal excretion and 15% fecal excretion.

A calcimimetic, mimicing the action of calcium on tissues by allosteric activation of the calcium-sensing receptor that is expressed in various human organ tissues.

The the principal regulator of parathyroid hormone secretion are the calcium-sensing receptors on the surface of the chief cell of the parathyroid gland.

The drug increases the sensitivity of calcium receptors on parathyroid cells to reduce parathyroid hormone levels and thus decrease serum calcium levels.

Lowers the threshold for activation of feedback on the parathyroid chief cells.

Used to treat secondary hyperparathyroidism, a consequence of end-stage renal disease.

Also indicated for the treatment of hypercalcemia in patients with parathyroid carcinoma.

Can also be used to treat severe hypercalcemia in patients with primary hyperparathyroidism who are unable to undergo parathyroidectomy.

Contraindicated in the presence of hypocalcemia.

Hypocalcemia symptoms include parathesias, myalgias, muscle cramping, tetany, and convulsions.

Common side effects include: Stomach upset, vomiting, diarrhea, nausea, dizziness, and chest pain.

Serious side effects include: Burning and tingling sensations, unusual feelings of the lips, tongue, fingers, or feet, cramps myalgias, tightening of muscles, and seizures,

A strong CYP2D6 inhibitor and is partially metabolized by CYP3A4 and CYP1A2.

Provided in three strengths 30 mg, 60 mg, and 90 mg.

Cinacalcet should be taken with food or after a meal for increased absorption of the medication, and should not be split, chewed, or crushed.

Intact parathyroid hormone levels are monitored, being measured 1 to 4 weeks after the initiation dose or dose adjustment, and every 1 to 3 months after the maintenance dose is established.

Serum calcium and phosphorus levels should be measured within 1 week after starting cinacalcet or after any dose adjustment, and monthly once the maintenance dose is established.

Category C in pregnancy and should only be used during pregnancy if the benefit outweighs the potential risk to the fetus.

Not known whether cinacalcet is excreted in human milk.

Indicated for secondary hyperparathyroidsm (HPT) in patients with chronic kidney disease on dialysis

Indicated for severe hypercalcemia in patients with primary HPT who are unable to undergo parathyroidectomy.

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