Valacyclovir 800mg Tablet Availability
No, there is no commercially available 800mg tablet of valacyclovir (Valtrex). Valacyclovir is only manufactured in 500mg and 1000mg (1 gram) tablet formulations 1.
Available Formulations
According to the FDA drug label, valacyclovir tablets come in only two strengths 1:
- 500mg tablets: Blue, film-coated, capsule-shaped tablets containing 556.2 mg of valacyclovir hydrochloride (equivalent to 500 mg free base)
- 1000mg (1 gram) tablets: Blue, film-coated, capsule-shaped tablets with partial scorebar on both sides, containing 1.112 grams of valacyclovir hydrochloride (equivalent to 1 gram free base)
Clinical Context
The confusion about an 800mg dose likely stems from acyclovir dosing, not valacyclovir. Acyclovir 800mg is a standard dose used for herpes zoster and recurrent genital herpes 2. The guidelines consistently reference acyclovir 800mg orally twice daily for episodic treatment of recurrent genital herpes 2.
Valacyclovir is the prodrug of acyclovir with enhanced bioavailability, allowing for less frequent dosing 2, 3. The bioavailability of acyclovir from valacyclovir is 54.5%, which is 3-5 times higher than oral acyclovir alone 1. This improved absorption is why valacyclovir uses different dosing (500mg or 1000mg) compared to acyclovir's 800mg dosing.
Practical Prescribing
If you need to prescribe valacyclovir for conditions typically requiring frequent acyclovir dosing:
- For herpes zoster: Use valacyclovir 1000mg three times daily (not 800mg) 2, 1
- For recurrent genital herpes: Use valacyclovir 500mg twice daily (not 800mg) 2, 1
- For suppressive therapy: Use valacyclovir 500mg to 1000mg once or twice daily depending on recurrence frequency 2, 1
The 1000mg tablet can be split along the scorebar if a 500mg dose is needed, but there is no mechanism to obtain an 800mg dose from commercially available tablets 1.