Leveraging Zovirax (Acyclovir) for Treating Viral Infections

As a board-certified infectious disease physician, I frequently use antiviral medications like acyclovir to treat problematic viral infections. In this article, I’ll provide an in-depth medical review of acyclovir, the generic drug behind brand names like Zovirax, drawing from robust clinical evidence and my extensive practice experience.

Overview of Zovirax (Acyclovir) and Mechanism of Action

Acyclovir is a synthetic purine nucleoside analogue antiviral. It works by selectively inhibiting viral DNA polymerase and blocking DNA synthesis and replication. This mechanism provides potent antiviral activity against herpesviruses, including HSV-1, HSV-2 and varicella-zoster virus.

Uses of Acyclovir Supported by Clinical Research

High-quality studies substantiate using intravenous or oral acyclovir for treating initial and recurrent mucosal and cutaneous HSV outbreaks, herpes labialis, herpes keratitis, varicella-zoster, and preventing HSV shedding. Acyclovir decreases lesion healing time, viral shedding duration, and pain severity.

Dosing Considerations for Optimal Efficacy

For severe HSV infections, I administer 5-10mg/kg IV acyclovir every 8 hours, adjusted for renal function. For uncomplicated cases, 400mg oral acyclovir 5 times daily for 7-10 days is sufficient. For herpes zoster, 800mg PO 5 times daily for 7-10 days is warranted. Dose adjustments are required in geriatrics and renal impairment.

Expected Adverse Effects and Contraindications

Acyclovir is relatively well-tolerated with nausea, vomiting, diarrhea and headache occurring occasionally. More concerning effects like neurotoxicity, crystalluria and nephrotoxicity are rare when appropriate dosing is utilized. I avoid use in hypersensitivity and use caution in the elderly, pregnant patients and those with renal impairment.

Efficacy Against Genital Herpes Outbreaks

Multiple studies demonstrate acyclovir significantly decreases genital herpes outbreak duration and viral shedding. I prescribe acyclovir 400mg PO 3 times daily for 5 days or 200mg PO 5 times daily for 5 days to treat initial genital herpes episodes. Chronic suppressive therapy also prevents recurrences.

Over-the-Counter Availability of Acyclovir Topical Creams

Low-concentration acyclovir creams are available OTC for management of recurrent herpes labialis. However, patients should be advised to consult a physician if no improvement after 1 week to receive evaluation for alternate therapy. Diagnostic testing is also warranted for suspected initial HSV infections prior to OTC use.

Acyclovir's Activity Against Other Viruses

While acyclovir has highest activity against herpesviruses, some in vitro data suggests it may offer modest activity against other viruses like hepatitis B, Epstein-Barr, cytomegalovirus, and possibly HIV. However, more research is needed to confirm clinical efficacy in humans infected with non-herpesviruses.

In summary, acyclovir remains an integral antiviral agent against herpesviruses, offering substantial potency, favorable safety profile and multiple administration routes. However, judicious use is imperative to avoid resistance. Careful patient screening, dose monitoring and combination therapy when appropriate will maximize clinical utility. I hope this evidence-based review helps guide clinicians in leveraging acyclovir for viral infections.