Aciclovir

Aciclovir is a nucleoside analogue antiviral medication specifically designed to manage infections caused by the herpes simplex virus (HSV) and varicella-zoster virus (VZV). As a first-line therapeutic agent, it inhibits viral DNA replication, thereby reducing the severity and duration of outbreaks. Clinically proven and widely prescribed, aciclovir is available in oral, topical, and intravenous formulations to suit varying patient needs and clinical scenarios. Its mechanism of action targets infected cells while sparing healthy ones, offering a favorable safety profile for both episodic treatment and long-term suppressive therapy.

Features

• Active ingredient: Aciclovir
• Available formulations: tablets, cream, intravenous injection, suspension
• Mechanism: selective inhibition of viral DNA polymerase
• Half-life: approximately 2–3 hours in adults with normal renal function
• Bioavailability: ~15–30% for oral administration; significantly higher with IV formulation
• Pregnancy category: B (systemic use)

Benefits

• Reduces healing time and pain associated with herpes outbreaks
• Decreases frequency of recurrent episodes with prophylactic use
• Low risk of systemic toxicity due to selective activation in infected cells
• Prevents viral shedding, reducing transmission risk
• Available in multiple formulations for flexible dosing and application
• Well-established safety profile with decades of clinical use

Common use

Aciclovir is primarily indicated for the treatment of initial and recurrent episodes of herpes simplex virus infections (genital herpes, cold sores, herpetic whitlow) and herpes zoster (shingles). It is also used for chickenpox in immunocompromised patients and for prophylaxis in immunocompromised individuals (such as transplant recipients or HIV patients) to prevent HSV reactivation. Off-label uses include prevention of herpes-related erythema multiforme and management of herpetic keratitis (in ophthalmic formulation).

Dosage and direction

Oral tablets:

• Genital herpes (initial): 200 mg 5 times daily for 10 days
• Genital herpes (recurrent): 200 mg 5 times daily for 5 days
• Suppressive therapy: 400 mg twice daily
• Herpes zoster: 800 mg 5 times daily for 7–10 days
• Chickenpox (immunocompetent adults/children >40 kg): 800 mg 4 times daily for 5 days

Topical cream:

• Apply to affected area 5 times daily at approximately 4-hour intervals for 4 days

Intravenous:

• 5–10 mg/kg every 8 hours (dose adjustment required for renal impairment)

Administration with food may minimize gastrointestinal discomfort. Maintain adequate hydration during treatment to prevent crystalluria.

Precautions

Use with caution in patients with renal impairment (dose adjustment necessary); monitor renal function during intravenous therapy. Ensure adequate hydration to reduce risk of crystalline nephropathy. Neurological symptoms (agitation, confusion) have been reported, particularly in elderly patients and those with renal insufficiency. Topical formulation is for external use only; avoid contact with eyes and mucous membranes. Not a cure for herpes infections; does not eliminate latent virus or prevent transmission to others.

Contraindications

Hypersensitivity to aciclovir, valaciclovir, or any component of the formulation. Intravenous administration is contraindicated in patients with known intolerance to intravenous formulations. Use with extreme caution in patients with pre-existing neurological abnormalities or severe renal impairment without appropriate dose adjustment.

Possible side effects

Common (≥1%):

• Nausea, vomiting, diarrhea
• Headache
• Mild skin reactions (topical formulation)

Less common:

• Elevated liver enzymes
• Rash, urticaria
• Fatigue, dizziness

Rare but serious:

• Acute renal failure (especially with IV administration)
• Neurological symptoms (confusion, hallucinations, seizures)
• Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome
• Anaphylaxis

Drug interaction

Probenecid may decrease renal clearance of aciclovir, increasing plasma concentrations. Concurrent use with other nephrotoxic drugs (aminoglycosides, cyclosporine, IV pentamidine) may increase risk of renal impairment. Zidovudine may potentiate fatigue and lethargy. No significant interactions with oral contraceptives or warfarin documented.

Missed dose

If a dose is missed, take it as soon as remembered unless it is nearly time for the next dose. Do not double the dose to make up for a missed one. Maintain regular dosing intervals for optimal antiviral efficacy.

Overdose

Symptoms may include agitation, coma, seizures, and renal impairment. Management includes supportive care and hemodialysis (significantly enhances aciclovir clearance). Maintain adequate urine output and monitor renal function closely.

Storage

Store at room temperature (15–30°C) in original container. Protect from moisture and light. Keep all medications out of reach of children. Do not use beyond expiration date. Intravenous solution should be used within 12 hours of reconstitution.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Always consult a healthcare professional for diagnosis and individualized treatment recommendations. Dosage and indications may vary based on patient-specific factors including age, renal function, and immunological status.

Reviews

Clinical studies demonstrate aciclovir reduces healing time by 1–2 days in recurrent herpes simplex infections and decreases pain duration in herpes zoster. Long-term suppressive therapy shows 70–80% reduction in recurrence frequency. Topical formulation shows modest efficacy compared to oral administration. Overall, aciclovir remains a cornerstone in antiviral therapy with well-documented efficacy and manageable side effect profile.