Entecavir

About Entecavir

Entecavir is a nucleoside analog that blocks the enzyme the hepatitis B virus uses to copy itself. The label approves it for chronic hepatitis B in adults and children 2 and older who have evidence of active viral replication and either persistently raised liver enzymes (ALT or AST) or active disease on a liver biopsy. Adults and adolescents 16 and older who have not taken a nucleoside drug before and have compensated liver disease take 0.5 mg once a day; the dose is 1 mg once a day for people whose virus no longer responds to lamivudine or carries lamivudine or telbivudine resistance, and for people with decompensated liver disease. Children 2 and older who weigh at least 10 kg are dosed by weight, with the oral solution used up to 30 kg. Every dose is taken on an empty stomach, at least 2 hours after a meal and 2 hours before the next, and the dose is reduced, or the interval between doses lengthened, when creatinine clearance falls below 50 mL per minute, including for people on dialysis, who take it after the session.

The boxed warning has three parts: severe acute flares of hepatitis B have occurred in people who stopped anti-hepatitis B treatment, so liver function is followed closely for at least several months after stopping and treatment may need to be restarted; in someone with HIV that is not being treated, entecavir can select HIV that resists treatment, so an HIV test is offered before starting and entecavir is not recommended for people with both infections unless they are also on HIV treatment; and lactic acidosis and severe liver enlargement with fat, including deaths, have been reported with nucleoside analogs, so treatment is suspended if either is suspected. The label lists no contraindications. In adult trials the most common side effects were headache, tiredness, dizziness and nausea.

What is distinctive is that this is long-term, high-adherence treatment. The label says the optimal length of treatment is not known and that missed doses can let resistant virus emerge, so a steady daily supply matters. Entecavir leaves the body through the kidneys, so drugs that reduce kidney function or compete for the same route can raise levels of either drug and are watched; lamivudine, adefovir and tenofovir disoproxil showed no significant interaction. There is a pregnancy exposure registry, animal studies showed no developmental harm at exposures well above the human dose, and it is not known whether entecavir passes into breast milk. Tablets are dispensed in bottles of 30 with child-resistant caps and kept in the carton to protect from light; the oral solution is a ready-to-use orange-flavored liquid in a 210 mL fill with a dosing spoon, never diluted. Baraclude was first approved in March 2005. Entecavir is not a controlled substance.

Taking Entecavir

How to take it

Take one tablet by mouth once a day on an empty stomach, at least 2 hours after a meal and 2 hours before the next, at about the same time each day. Do not stop without talking to the prescriber, because hepatitis B can flare after the drug is stopped. The oral solution is measured with the spoon in the box, filled to the mark for the prescribed dose, and the spoon is rinsed with water after each dose.

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, and tell the prescriber if you miss doses often.

Storage

Tablets in the original bottle and carton, tightly closed, at room temperature, protected from light and away from heat and moisture (not in the bathroom), out of reach of children. The oral solution is kept in its carton at room temperature and used until the expiration date on the bottle.

Interactions to know about

Drugs that reduce kidney function or share the kidneys’ route of elimination can raise the level of entecavir or of the other drug, so tell the pharmacist about every medicine you take. Lamivudine, adefovir and tenofovir disoproxil showed no significant interaction in studies.

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 Entecavir differs from pharmacy to pharmacy

Generic tablets come from many makers, so quotes for a bottle of 30 vary with the maker the pharmacy buys from, with whether entecavir is on a flat-price generic list, and with the strength: the 1 mg tablet is a separate product from the 0.5 mg tablet. A prescription for Baraclude without substitution, or for the oral solution, is priced as a brand and costs far more.

Treatment runs for years, so the dispensing fee on every monthly fill adds up and a ninety-day fill spreads it. Some pharmacies order entecavir in rather than keep it in stock, and a pharmacy that stocks it can quote and fill the same day.

Ways to pay less for Entecavir without insurance

• Ask the prescriber to write entecavir generically and allow substitution, and confirm the strength, since the 0.5 mg and 1 mg tablets are priced separately.
• Once treatment is settled, ask the prescriber whether a ninety-day supply suits you, so you pay fewer dispensing fees and never run short, because missed doses can breed resistance and stopping can trigger a flare.
• Compare more than one pharmacy and ask whether entecavir is on a flat-price generic list and whether it is kept in stock.
• If the oral solution is prescribed for an adult who can swallow tablets, ask the prescriber whether tablets would suit you; do not change the form on your own.
• 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 Entecavir

1. 1.How do I fit my dose around meals so my stomach is empty, and what if I eat by mistake?
2. 2.What should I do if I run out of entecavir, given the warning about hepatitis flaring?
3. 3.Do any of my other medicines affect my kidneys or interact with entecavir?
4. 4.When are my liver and kidney blood tests due, and who orders them?

Related medications