Valacyclovir
L-valyl ester prodrug of acyclovir with substantially greater oral bioavailability (~55% of acyclovir equivalents vs ~20% for oral acyclovir) achieved via intestinal valacyclovirase conversion. Used for HSV, VZV, and CMV prophylaxis. Typical regimens: 500 mg BID suppressive HSV, 1000 mg TID for shingles.
Projected serum levels — 1k mg, twice daily
Maintenance schedule: 1k mg twice daily (oral).
Modeled steady state after ~1 days: peak ≈ 106 mg, trough ≈ 0.000 mg body load. Population-based estimate over 15 days for a 1k mg dose at a 70 kg reference body mass — the interactive app scales curves to your doses, timing, and body mass.
Key facts
- Category
- Antibiotic
- Route modeled
- Oral
- Model confidence
- inferred
- Half-life
- 3 h
- Common dose
- 1k mg
- Suggested maximum
- 3k mg/day
- Reference dose range
- 500–3k mg (single dose)
- Suggested cadence
- twice daily
- Validated against
- 1k mg oral — Cmax 5.7 mg/L at 1.5 h
Research behind this entry
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Valaciclovir compared with acyclovir for improved therapy for herpes zoster in immunocompetent adults
Landmark trial showing valacyclovir 1000 mg TID accelerated zoster-associated pain resolution vs acyclovir 800 mg 5x/day with comparable safety, establishing valacyclovir superiority in shingles.
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Valacyclovir for the suppression of recurrent genital herpes simplex virus infection
RCT of valacyclovir 500 mg once daily for genital HSV suppression showed significantly reduced recurrences vs placebo, establishing once-daily dosing utility.
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Valaciclovir: a review of its antiviral activity, pharmacokinetic properties, and therapeutic efficacy in herpesvirus infections
PK review characterizing valacyclovir's near-complete intestinal conversion to acyclovir, ~55% acyclovir bioavailability (3-5x oral acyclovir), and 2.5-3.3 hour acyclovir half-life.
3 published studies referenced in the app, each with a plain-language summary.