valaciclovir hydrochloride: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
valaciclovir hydrochloride: clinical details
Prescribing considerations
- Assess renal function and account for age, hydration and concurrent nephrotoxic or renally secreted medicines.
- Ensure adequate hydration in patients at risk of dehydration.
- Monitor clinical response closely in immunocompromised shingles and ocular herpes; complicated, disseminated or visceral disease may require intravenous therapy.
- Valaciclovir reduces but does not eliminate genital-herpes transmission; advise avoidance of intercourse during symptoms and continued safer-sex practices.
- CMV prophylaxis is specialist care; renal and neurological toxicity require particular vigilance.
Contraindications and cautions
- Hypersensitivity to valaciclovir, aciclovir or a product excipient.
- Do not restart valaciclovir or aciclovir after valaciclovir-associated Stevens–Johnson syndrome, toxic epidermal necrolysis, DRESS or acute generalised exanthematous pustulosis.
Monitoring
- Renal function before and during treatment when impairment, older age, transplantation, high exposure or interacting medicines increase risk.
- Hydration status.
- New confusion, agitation, hallucinations, drowsiness, seizures or reduced consciousness.
- Skin and mucosal symptoms suggesting a severe cutaneous adverse reaction.
- Clinical progression in ophthalmic, complicated or immunocompromised infection.
Clinical pharmacology
Valaciclovir is the L-valine ester prodrug of aciclovir and is rapidly converted after oral administration. Activated aciclovir triphosphate selectively inhibits herpes-virus DNA polymerase and causes DNA-chain termination. Elimination is predominantly renal, and aciclovir exposure rises as renal function declines; neither valaciclovir nor aciclovir is metabolised by cytochrome P450 enzymes.
Formulation and product differences
- The selected product is a film-coated oral tablet supplied in PVC/aluminium blister packaging.
- Tablet appearance and excipients can differ between products; check product-specific information when allergy, swallowing or identification is relevant.
valaciclovir hydrochloride preparations and strengths
Tablet
Route: Oral
Strengths: 250 mg, 500 mg, 1000 mg
valaciclovir hydrochloride interactions
Check all prescribed, non-prescription and herbal products because kidney clearance is central to valaciclovir safety.
Nephrotoxic medicines, including aminoglycosides, platinum compounds, methotrexate, pentamidine, foscarnet, ciclosporin and tacrolimus
Combined use may increase the risk of kidney injury and warrants caution and renal-function monitoring, especially when kidney function is already impaired.
Iodinated contrast media
Concurrent exposure may add to kidney risk, so renal function and hydration require appropriate consideration.
Cimetidine or probenecid
These reduce renal clearance of aciclovir and increase systemic exposure, which may be important when exposure is already high or kidney function is reduced.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.