Cinacalcet

About Cinacalcet

Cinacalcet makes the calcium-sensing receptor on the parathyroid glands more sensitive to calcium, so the glands release less parathyroid hormone (PTH), and calcium and phosphorus in the blood fall. The label approves it for secondary hyperparathyroidism in adults with chronic kidney disease on dialysis, for hypercalcemia in adults with parathyroid carcinoma, and for hypercalcemia in adults with primary hyperparathyroidism who would need parathyroid surgery but cannot have it. It is not indicated for chronic kidney disease patients who are not on dialysis, because of the risk of low calcium. For dialysis patients the usual start is 30 mg once a day, raised no more often than every two to four weeks through 60, 90, 120 and 180 mg a day to reach the PTH target. For parathyroid carcinoma or primary hyperparathyroidism the start is 30 mg twice a day, raised as needed to a maximum of 90 mg three or four times a day. Every dose is taken with food or shortly after a meal, swallowed whole.

There is no boxed warning. Cinacalcet must not be started when the blood calcium is below the normal range. Its main risk is hypocalcemia, which can be life-threatening: tingling or numbness, muscle aches or cramps, muscle spasms and seizures are the warning signs, and low calcium can also prolong the QT interval and trigger an abnormal heart rhythm, so people with congenital long QT syndrome or other risk factors are watched closely. Low blood pressure, worsening heart failure and arrhythmias have been reported in people with impaired heart function, and the label warns of upper gastrointestinal bleeding, especially with gastritis, ulcers or severe vomiting. Nausea and vomiting are the most common side effects. Blood calcium is checked within a week of each start or dose change, then about monthly for dialysis patients and every two months for the other uses, and for dialysis patients PTH is measured one to four weeks after a change.

What is distinctive is the interaction profile. Cinacalcet is a strong inhibitor of the liver enzyme CYP2D6, so medicines cleared by that enzyme, including metoprolol, carvedilol, desipramine and other tricyclic antidepressants, and especially flecainide, may need a lower dose; strong CYP3A4 inhibitors such as ketoconazole and itraconazole raise cinacalcet levels, and MedlinePlus advises asking the prescriber about grapefruit. Human pregnancy data are too limited to assess risk; in rats, pup loss occurred alongside maternal hypocalcemia at exposures above the human dose. Cinacalcet is not a controlled substance.

Taking Cinacalcet

How to take it

Take it with food or shortly after a meal, swallowed whole; do not split, chew or crush the tablets. Take it at the same times each day and keep taking it even if you feel well.

If you miss a dose

Take it as soon as you remember, unless it is almost time for the next dose; then skip the missed dose. Do not take a double dose.

Storage

In the original tightly closed container at room temperature, away from heat and moisture (not in the bathroom), out of reach of children.

Interactions to know about

Cinacalcet raises the levels of medicines cleared by CYP2D6, including flecainide, desipramine and other tricyclic antidepressants, metoprolol and carvedilol. Ketoconazole, itraconazole and other strong CYP3A4 inhibitors raise cinacalcet levels. Ask about grapefruit, and tell the pharmacist about every medicine and supplement you take.

This summarizes the official prescribing information. Your prescriber’s and pharmacist’s instructions, and the leaflet that comes with your medicine, take priority.

Why the cash price for Cinacalcet differs from pharmacy to pharmacy

Cinacalcet is a specialist drug that not every pharmacy keeps on the shelf, so one may quote from stock while another orders it in. Quotes depend on which generic maker the pharmacy buys from, the bottle size it stocks, and whether the drug is on a flat-price generic list.

The dose is adjusted in steps over weeks and can reach several tablets a day for the cancer and primary hyperparathyroidism uses, so the monthly count, and the quote, change with the dose; a quote applies only to the strength and count written. Treatment is long term, so the dispensing fee on each fill adds up.

Ways to pay less for Cinacalcet without insurance

• If the prescription names Sensipar, expect a generic; ask the prescriber to allow substitution if it does not already.
• Ask the pharmacy to quote the exact strength and count on the prescription, since a change from 30 mg to 60 mg is a different product.
• Once your dose and calcium level are stable, ask the prescriber whether a ninety-day supply suits you, so you pay fewer dispensing fees.
• Compare more than one pharmacy, and ask whether yours stocks cinacalcet or needs a day or two to order it.
• Upload the prescription to Script Unlock so licensed pharmacies can quote their cash price. You pay the pharmacy directly.

Questions to ask your pharmacist about Cinacalcet

1. 1.Which of my other medicines, such as a beta blocker, an antidepressant or an antifungal, need a dose check while I take cinacalcet?
2. 2.What signs of low calcium should make me call my doctor right away?
3. 3.Should I take my cinacalcet with my main meal, and does it matter which one?
4. 4.When is my next calcium blood test due, and who orders it?

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