Acyclovir
(Acycloguanosine)
Acyclovir (Zovirax)
Acycloguanosine (Zovirax)
Acyclovir
(ay- SYE-kloh-veer, ay- SYE-kloh- GWON-oh-seen)
Pregnancy Category: C Alti-Acyclovir Apo-Acyclovir Avirax Nu-Acyclovir Zovirax (Rx)

Classification: Antiviral anti-infective

See Also: See also Antiviral Drugs.

Action/Kinetics: A synthetic acyclic purine nucleoside analog converted by HSV-infected cells to acyclovir triphosphate, which interferes with HSV DNA polymerase, thereby inhibiting DNA replication. Systemic absorption is slow from the GI tract (although therapeutic levels are reached) and following topical administration. It is preferentially taken up and converted to the active triphosphate form by herpes virus-infected cells. Food does not affect absorption. Peak levels after PO: 1.5-2 hr. Widely distributed in tissues and body fluids. The half-life and total body clearance depend on renal function. t 1/2, PO, C _CR, greater than 80 mL/min/1.73 m ²: 2.5 hr. Metabolites and unchanged drug (up to 85%) are excreted through the kidney. Reduce dosage in clients with impaired renal function. Clients who take acyclovir (600-800 mg/day) with AZT had a significantly prolonged survival rate compared with clients taking only acyclovir.

Uses: PO. Initial and recurrent genital herpes in immunocompromised and nonimmunocompromised clients. Prophylaxis of frequently recurrent genital herpes infections in nonimmunocompromised clients. Treatment of chickenpox in children ranging from 2 to 18 years of age. Acute treatment of herpes zoster (shingles).
Parenteral. Initial therapy for severe genital herpes in clients who are not immunocompromised; initial and recurrent mucosal and cutaneous HSV-1 and HSV-2 infections in immunocompromised individuals. Varicella zoster infections (shingles) in immunocompromised clients. HSE in clients over 6 months of age. Neonatal herpes simplex infections.
Topical. To decrease healing time and duration of viral shedding in initial herpes genitalis. Limited non-life-threatening mucocutaneous HSV infections in immunocompromised clients. No beneficial effect in recurrent herpes genitalis or in herpes labialis in nonimmunocompromised clients.
Investigational: Cytomegalovirus and HSV infection following bone marrow or renal transplantation; herpes simplex ocular infections; herpes simplex proctitis; herpes simplex labialis; herpes simplex whitlow; herpes zoster encephalitis; disseminated primary eczema herpeticum; herpes simplex-associated erythema multiforme; infectious mononucleosis; and varicella pneumonia.

Contraindications: Hypersensitivity to formulation. Use in the eye. Use to prevent recurrent HSV infections.

Special Concerns: Use with caution during lactation or with concomitant intrathecal methotrexate or interferon. Safety and efficacy of PO form not established in children less than 2 years of age. Prolonged or repeated doses in immunocompromised clients may result in emergence of resistant viruses. Use of oral acyclovir does not eliminate latent HSV and is not a cure.

Side Effects: PO. S hort-term treatment of herpes simplex. GI: N&V;, diarrhea, anorexia, sore throat, taste of drug. CNS: Headache, dizziness, fatigue. Miscellaneous: Edema, skin rashes, leg pain, inguinal adenopathy.
Long-term treatment of herpes simplex. GI: Nausea, diarrhea. CNS: Headache. Other: Skin rash, asthenia, paresthesia.
Treatment of herpes zoster. GI: N&V;, diarrhea, constipation. CNS: Headache, malaise.
Treatment of chickenpox. GI: Vomiting, diarrhea, abdominal pain, flatulence. Dermatologic: Rash.
Parenteral (frequency greater than 1%). A t injection site: Phlebitis, inflammation. GI: N&V.; CNS: Encephalopathic changes, including lethargy, obtundation, tremors, agitation, confusion, hallucination, seizures, coma, jitters, headache. Miscellaneous: Skin rashes, urticaria, itching, transient elevation of serum creatinine or BUN (most often following rapid IV infusion), elevation of transaminases, fatal renal failure, fatal thrombotic thrombocytopenic purpura or hemolytic uremic syndrome in immunocompromised clients.
Topical. Transient burning, stinging, pain. Pruritus, rash, vulvitis, local edema. NOTE: All of these effects have also been reported with the use of a placebo preparation.

Overdose Management: Symptoms: Increased BUN and serum creatinine, renal failure following parenteral overdose. Treatment: Hemodialysis (peritoneal dialysis is less effective).

Drug Interactions: Probenecid / Bioavailability and half-life of acyclovir effect Zidovudine / Severe lethargy and drowsiness

How Supplied: Capsule: 200 mg; Injection: 5 mg/mL, 25 mg/mL, 50 mg/ml; Ointment: 5%; Powder for injection: 500 mg, 1000 mg; Suspension: 200 mg/5 mL; Tablet: 400 mg, 800 mg

Dosage
?Capsules, Suspension, Tablets Initial genital herpes.
200 mg q 4 hr, 5 times/day for 10 days.
Chronic genital herpes.
400 mg b.i.d., 200 mg t.i.d., or 200 mg 5 times/day for up to 12 months.
Intermittent therapy for genital herpes.
200 mg q 4 hr, 5 times/day for 5 days. Start therapy at the first symptom/sign of recurrence.
Herpes zoster, acute treatment.
800 mg q 4 hr, 5 times/day for 7-10 days.
Chickenpox.
20 mg/kg (of the suspension) q.i.d. for 5 days. A single dose should not exceed 800 mg. Begin therapy at the earliest sign/symptom.
?IV Infusion Mucosal and cutaneous herpes simplex in immunocompromised clients.
Adults: 5 mg/kg infused at a constant rate over 1 hr, q 8 hr (15 mg/kg/day) for 7 days. Children less than 12 years of age: 250 mg/m ² infused at a constant rate over 1 hr, q 8 hr for 7 days.
Varicella-zoster infections (shingles) in immunocompromised clients.
Adults: 10 mg/kg infused at a constant rate over 1 hr, q 8 hr for 7 days (not to exceed 500 mg/m ² q 8 hr). Children less than 12 years of age: 500 mg/m ² infused at a constant rate over at least 1 hr, q 8 hr for 7 days.
Herpes simplex encephalitis.
Adults: 10 mg/kg infused at a constant rate over at least 1 hr, q 8 hr for 10 days. Children less than 12 years of age and greater than 6 months of age: 500 mg/m ² infused at a constant rate over at least 1 hr, q 8 hr for 10 days.
?Topical (5% Ointment)
Adults and children: Lesion should be covered with sufficient amount of ointment (0.5-in. ribbon/4 in. ² of surface area) q 3 hr, 6 times/day for 7 days. Initiate treatment as soon as possible after onset of symptoms.