Carbamazepine

About Carbamazepine

Carbamazepine steadies overactive nerve firing by blocking sodium channels. It is labeled for partial seizures with complex symptoms, generalized tonic-clonic seizures and mixed seizure patterns, but not absence seizures, and for the pain of trigeminal neuralgia. Equetro is labeled for acute manic or mixed episodes of bipolar I disorder. Adults with epilepsy usually settle on 800 to 1200 mg a day, and the dose is built up gradually with blood tests.

It carries two boxed warnings. The first is for serious, sometimes fatal skin reactions (Stevens-Johnson syndrome and toxic epidermal necrolysis), far more common in carriers of the HLA-B*1502 gene variant, found mostly in people of Asian ancestry: patients from at-risk populations are tested before starting, and carriers should not take it unless the benefit clearly outweighs the risk. The second is for aplastic anemia and agranulocytosis: a blood count is taken before starting and watched, and fever, sore throat, mouth ulcers or unusual bruising should be reported at once. It can also lower blood sodium, cause the hypersensitivity reaction DRESS, raise the risk of suicidal thoughts and harm an unborn baby. It must not be taken with nefazodone, within 14 days of an MAO inhibitor, or after bone marrow depression.

The forms are not interchangeable at the counter. Immediate-release tablets, chewable tablets and the suspension are taken two to four times a day with meals; extended-release tablets (Tegretol XR and generics) twice a day, swallowed whole; extended-release capsules (Carbatrol, Equetro and generics) twice a day, whole or opened onto soft food. Moving between forms is the prescriber’s decision, and the prescription must name the form.

Taking Carbamazepine

How to take it

With meals, two to four times a day for regular tablets, chewables and the suspension, twice a day for extended-release forms. Swallow extended-release tablets whole; the empty shell may appear in the stool. Extended-release capsules can be opened and the beads sprinkled over a teaspoon of applesauce, without chewing. Shake the suspension and do not mix it with other liquid medicines. Do not stop it without talking to the prescriber.

If you miss a dose

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

Storage

At room temperature, tightly closed, away from light, heat and moisture; the suspension in a tight, light-resistant container, not above 86°F (30°C).

Interactions to know about

Erythromycin, clarithromycin, azole antifungals, cimetidine, diltiazem, verapamil, fluoxetine and grapefruit juice raise its levels; phenytoin, phenobarbital, rifampin and felbamate lower them. It speeds the breakdown of hormonal contraceptives, which can fail, and of warfarin, lamotrigine, corticosteroids, cyclosporine, methadone and many antidepressants and antipsychotics, so every new medicine is checked. Alcohol adds to drowsiness. Report rash, fever, mouth sores or bruising at once.

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 Carbamazepine differs from pharmacy to pharmacy

Immediate-release and extended-release tablets come from many makers, so their price is mostly fee and markup, though a daily dose of 800 to 1200 mg means many tablets. Extended-release capsules come from a few makers and the suspension from fewer, so those quotes vary more and may need ordering in. A brand named without substitution is priced as a brand, and the form on the prescription sets the price.

Ways to pay less for Carbamazepine without insurance

• Ask the prescriber to allow generic substitution and to name the form you are stable on.
• Ask for the strength that covers your dose in the fewest tablets, such as one 400 mg extended-release tablet rather than two 200 mg.
• Once stable, ask for a ninety-day supply so you never run out; it must not be stopped suddenly.
• 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 Carbamazepine

1. 1.Which form is this, and can it be substituted?
2. 2.Have I been tested for HLA-B*1502, and which symptoms mean I should stop and call?
3. 3.When are my blood count, sodium and drug level checks due?
4. 4.Does it affect my birth control or other medicines?
5. 5.Can I drink alcohol or grapefruit juice with it?

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