Oxcarbazepine

About Oxcarbazepine

Oxcarbazepine, closely related in structure to carbamazepine, works mainly through an active breakdown product that is thought to block sodium channels and steady overexcited nerve cells. Trileptal tablets and suspension are labeled for partial-onset seizures in adults, alone or with other medicines, and in children, alone from age 4 or as an add-on from age 2; Oxtellar XR is labeled for partial-onset seizures from age 6. Adults usually start Trileptal at 300 mg twice a day and reach 1,200 mg a day, as an add-on in weekly steps of up to 600 mg or alone in steps of 300 mg every third day; people converting from another medicine may reach 2,400 mg a day. Children’s doses are set by weight. Oxtellar XR usually starts at 600 mg once a day in adults and rises weekly in 600 mg steps to 1,200 to 2,400 mg once a day. With a creatinine clearance below 30 mL/min, the starting dose is halved and raised slowly.

Oxcarbazepine can lower blood sodium enough to cause nausea, headache, lethargy, confusion or more frequent or severe seizures, so sodium checks are considered, especially with other medicines that lower sodium. Serious skin reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis, have been reported. Carriers of the HLA-B*1502 gene variant, found in some populations such as Han Chinese, may be at higher risk, so the label advises considering testing first in people with at-risk ancestry and avoiding it in carriers unless the benefits clearly outweigh the risks. It must not be taken by anyone allergic to oxcarbazepine or eslicarbazepine, and some people who have reacted to carbamazepine react to it too. Other warnings cover anaphylaxis and angioedema, a multi-organ allergic reaction (DRESS), suicidal thoughts, slowed thinking, sleepiness and poor coordination, rare blood disorders, and new or worse primary generalized seizures, especially in children. Dizziness, sleepiness, double vision, tiredness, nausea, vomiting and unsteadiness are the most common side effects.

It can make hormonal contraceptives less effective, so a nonhormonal method is advised. Levels of its active form can fall gradually during pregnancy, so patients are monitored carefully through pregnancy and after delivery. It is withdrawn gradually, because stopping suddenly can bring on more frequent seizures. The suspension, 300 mg per 5 mL, can replace the tablets at the same dose, but Oxtellar XR is not equivalent to the same total dose of the twice-daily forms, so a switch can need a higher dose and cannot be made at the counter.

Taking Oxcarbazepine

How to take it

Tablets and suspension twice a day, with or without food. Shake the suspension well, measure the dose with the oral syringe supplied, and take it straight from the syringe or mixed into a small glass of water just before taking it. Take Oxtellar XR once a day on an empty stomach, at least one hour before or two hours after a meal, swallowed whole and never cut, crushed or chewed.

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 and carry on as usual. Do not take a double dose, and do not stop it suddenly.

Storage

At room temperature, away from heat and moisture. Keep the suspension in its original container and throw away any left seven weeks after first opening.

Interactions to know about

Carbamazepine, phenytoin, phenobarbital and rifampin lower levels of its active form, and above 1,200 mg a day it can raise phenytoin levels. It can make hormonal contraceptives less effective and lowers felodipine levels. Alcohol and other sedating medicines can add to its side effects, and other medicines that lower sodium add to that risk.

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 Oxcarbazepine differs from pharmacy to pharmacy

The twice-daily tablets and the suspension come from many makers and cost pharmacies little, so a quote is mostly the dispensing fee and markup, although 1,200 mg or more a day means many tablets a month. The once-daily extended-release tablet has only a few generic makers, so quotes for it vary more, and a prescription that names Trileptal or Oxtellar XR without allowing substitution is filled at a brand price.

Ways to pay less for Oxcarbazepine without insurance

• Ask for generic substitution, and make sure the prescription names the form you are stable on.
• Ask for the strength that covers each dose in the fewest tablets, such as one 600 mg tablet rather than two 300 mg tablets.
• If the once-daily tablet is quoted high, ask the prescriber whether the twice-daily tablets would suit you; the doses differ, so the switch is theirs to make.
• Once stable, ask for a ninety-day supply so you never run short.
• 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 Oxcarbazepine

1. 1.When will my sodium be checked, and which symptoms of low sodium should I report?
2. 2.Should I be tested for HLA-B*1502 before starting?
3. 3.Does it affect my birth control or my other seizure medicines?
4. 4.How do I measure the suspension, and when must I throw out an opened bottle?

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