Famciclovir

About Famciclovir

Famciclovir is converted in the body to penciclovir, which stops herpes viruses from copying themselves; it can ease symptoms and help sores heal but does not cure the infection. In adults with a normal immune system, the label covers recurrent cold sores (a single 1,500 mg dose at the first sign, such as tingling, itching or burning), recurrent genital herpes outbreaks (1,000 mg twice in one day, started at the first sign), daily suppression of recurrent genital herpes (250 mg twice a day, with safety and effectiveness beyond one year not established), and shingles (500 mg every 8 hours for seven days, started as soon as it is diagnosed). Adults with HIV take 500 mg twice a day for seven days for recurrent cold sores or genital herpes. Its effectiveness has not been established when it is started more than 6 hours after genital symptoms or sores begin (48 hours in people with HIV) or more than 72 hours after a shingles rash appears, and its effectiveness and safety have not been established for a first episode of genital herpes, shingles of the eye, weakened immune systems other than in adults with HIV treated for repeat outbreaks, or Black and African American patients with recurrent genital herpes.

There is no boxed warning. It must not be taken by anyone allergic to famciclovir, its ingredients or penciclovir cream (Denavir). Acute kidney failure has occurred in people with kidney disease who were given doses too high for their kidney function, so the dose is lowered according to creatinine clearance, and people on hemodialysis take a dose after dialysis. Headache and nausea are the most common side effects; diarrhea, vomiting, tiredness and stomach pain also occur. Confusion, mostly in older people, seizures, low platelets, liver problems and serious allergic and skin reactions have been reported since approval, and anyone who feels dizzy, sleepy or confused should not drive. MedlinePlus says to call the doctor at once about pain, burning, numbness or tingling in the hands or feet.

Its effectiveness has not been established in children, and the label does not recommend it for infants or for adolescents with cold sores. The tablets contain lactose, which matters for people with galactose intolerance, severe lactase deficiency or glucose-galactose malabsorption. Reports gathered since approval have not identified a drug-related risk of major birth defects or miscarriage, and untreated herpes in pregnancy carries its own risks; there are no data on whether it passes into human breast milk. There are also no data on whether it prevents passing herpes to others, and the label advises safer sex.

Taking Famciclovir

How to take it

With or without food. Start at the earliest sign of a cold sore (tingling, itching or burning), at the first sign or symptom of a genital outbreak, or as soon as shingles is diagnosed: a single dose for cold sores, two doses about 12 hours apart on one day for a genital outbreak, every 8 hours for seven days for shingles, and twice a day for suppression.

If you miss a dose

Take it as soon as you remember, then space the remaining doses for the day evenly; if the next dose is almost due, skip the missed one. Do not take a double dose.

Storage

At room temperature in the original container, tightly closed, away from heat and moisture (not in the bathroom), out of reach of children. Use a take-back program for tablets you no longer need.

Interactions to know about

Probenecid and other medicines removed through the kidney tubules can raise penciclovir levels, so side effects are watched for. Raloxifene could reduce the conversion of famciclovir to penciclovir, although this has not been studied. Tell the prescriber about every medicine you take, kidney or liver disease, galactose intolerance, and any allergy to lactose, penciclovir cream or acyclovir.

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 Famciclovir differs from pharmacy to pharmacy

Famciclovir is a generic made by several companies, and the quantity on a prescription varies widely with its use: in 500 mg tablets, a cold sore dose is three tablets taken together, a genital outbreak four, and a shingles course twenty-one, while suppression is two 250 mg tablets a day. For a small fill, each pharmacy’s dispensing fee and any minimum charge make up much of the quote; for a month or more of suppression, the price per tablet matters more.

Each strength is priced separately, and a dose lowered for kidney function can change the strength and number of tablets; the label gives 125 mg doses only for reduced kidney function. Whether famciclovir is on a pharmacy’s flat-price generic list varies.

Ways to pay less for Famciclovir without insurance

• Ask whether famciclovir is on the pharmacy’s flat-price generic list, and compare more than one pharmacy.
• For daily suppression, ask the prescriber about a ninety-day supply once the plan is settled.
• Check that each quote is for the strength and number of tablets your dose needs.
• If it is quoted high, ask the prescriber whether valacyclovir or acyclovir, other generic herpes antivirals, would suit you.
• 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 Famciclovir

1. 1.How soon after symptoms start should I take my dose?
2. 2.Is my dose adjusted for my kidney function?
3. 3.Can I keep a dose at home so I can start at the first sign of an outbreak?
4. 4.Is it a problem that I am lactose intolerant?

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