Acyclovir-Zovirax,Sitavig, Uses

- November 05, 2022

Acyclovir (Zovirax, Sitavig)

Acyclovir (Zovirax, Sitavig, Xerese) is one of the most commonly prescribed antiviral medications used to manage viral infections caused by the herpes family

– Generic Name: Acyclovir (ay-sye-kloe-veer)

Brand Names: Zovirax, Sitavig, Xerese
Drug Classification: Antiviral (Purine Analogue)
Pregnancy Category: B (oral, buccal, IV), C (topical)

Indications of Acyclovir

Oral (PO): Treatment of recurrent genital herpes, localized shingles (herpes zoster), and chickenpox (varicella).
Buccal (Sitavig): Recurrent herpes labialis (cold sores) in non-immunosuppressed patients.
Intravenous (IV): Severe primary genital herpes, herpes simplex encephalitis, or mucocutaneous herpes infections in immunocompromised patients.
Topical:
- Cream: Recurrent cold sores.
- Ointment: Limited herpes simplex skin infections in immunocompromised patients (systemic therapy preferred).

Mechanism of Action

Acyclovir interferes with viral DNA synthesis, preventing replication and spread of the virus.

Therapeutic Effects

Inhibits viral replication.
Decreases viral shedding.
Speeds up healing of lesions.

Pharmacokinetics

Absorption: Low (15–30%), but therapeutic levels are achieved.
Distribution: Widely distributed; cerebrospinal fluid (CSF) levels ~50% of plasma. Crosses placenta and appears in breast milk.
Protein Binding: ~30%.
Excretion: 90% excreted unchanged in urine; rest metabolized in liver.
Half-life:
- Neonates: 4 hr
- Children (1–12 years): 2–3 hr
- Adults: 2–3.5 hr (prolonged in renal failure)

Contraindications & Precautions

Contraindicated in:

Hypersensitivity to acyclovir or valacyclovir.
Hypersensitivity to milk protein concentrate (buccal).

Use with caution in:

Renal impairment (dose adjustment if creatinine clearance < 50 mL/min).
Elderly (reduced renal function).
Neurologic, hepatic, pulmonary, or fluid/electrolyte disorders.
Pregnant and breastfeeding women (safety not fully established).
Obese patients (dose based on ideal body weight).

Adverse Reactions & Side Effects

CNS: Seizures, dizziness, headache, hallucinations, tremors.
GI: Nausea, vomiting, diarrhea, abdominal pain, anorexia, elevated liver enzymes, hyperbilirubinemia.
GU: Renal failure, crystalluria, hematuria.
Dermatologic: Rash, hives, sweating, acne, Stevens-Johnson syndrome.
Hematologic: Thrombotic thrombocytopenic purpura / hemolytic uremic syndrome (rare, high doses).
Local: Pain or irritation at IV site.
Other: Joint pain, polyphlebitis, menstrual cycle changes.

Drug Interactions

Probenecid: ↑ Acyclovir levels.
Theophylline: ↑ Risk of toxicity (dose adjustment may be needed).
Valproic acid & Phenytoin: ↓ Effectiveness.
Other nephrotoxic drugs: ↑ Risk of renal toxicity.
Zidovudine & Methotrexate: ↑ CNS side effects.

Dosage & Administration

Initial Genital Herpes

Adults & Children (PO): 200 mg every 4 hr (5×/day) for 7–10 days, or 400 mg every 8 hr for 7–10 days.
- Children max: 80 mg/kg/day in 3–5 divided doses.

IV Therapy

Adults & Children: 5 mg/kg every 8 hr for 5–7 days.

Chronic Suppression (Recurrent Genital Herpes)

Adults: 400 mg twice daily or 200 mg 3–5×/day for up to 12 months.
Children: Max 80 mg/kg/day.

Intermittent Therapy (Recurrent Genital Herpes)

200 mg every 4 hr (5×/day), or 400 mg every 8 hr, or 800 mg every 12 hr for 5 days (start at first sign of outbreak).

Herpes Zoster (Shingles)

Adults (immunocompromised): 800 mg every 4 hr (5×/day) for 7–10 days.
Adults (immunocompetent): 4000 mg/day in 5 divided doses for 5–7 days.
Children: Max 80 mg/kg/day.

Nursing Implications

Assessment

Evaluate skin lesions before and daily during therapy.
Monitor recurrence frequency.
Check neurological status in patients with herpes encephalitis.
Labs: Monitor BUN, serum creatinine, and creatinine clearance (↑ levels may indicate renal failure).

Implementation

Start treatment as early as possible (within 24 hr of herpes zoster outbreak).
Oral: May be taken with or without food, with plenty of fluids.
Suspension: Shake well before use.
Buccal tablet: Place above upper gum (canine region), hold for 30 sec, let dissolve; do not crush, chew, or swallow.
IV: Ensure hydration (2000–3000 mL/day); monitor for phlebitis; dilute properly before infusion.
Topical: Apply thin layer to lesions 6×/day for 7 days; wash hands after use; avoid eye contact.

Patient & Family Teaching

Take full course of treatment as prescribed; do not double missed doses.
Acyclovir is not a cure; the virus remains dormant and may recur.
Avoid sexual contact during active outbreaks; use condoms to reduce transmission risk.
Do not use OTC creams/ointments with acyclovir, as they may delay healing.
Women with genital herpes should get annual Pap smears (increased cervical cancer risk).
Wear loose-fitting clothes to avoid irritation of lesions.
Report any unusual eye symptoms immediately (ocular herpes risk).
Stay hydrated to reduce risk of renal complications.

Desired Outcomes

Faster crusting and healing of herpes lesions.
Reduced frequency and severity of recurrences.
Shortened healing time and pain relief in shingles.
Decreased severity of chickenpox symptoms.

One1pharma