acyclovir
[a-si´klo-vir]acyclovir
acyclovir sodium
Pharmacologic class: Acyclic purine nucleoside analogue
Therapeutic class: Antiviral
Pregnancy risk category B
Action
Inhibits viral DNA polymerase, thereby inhibiting replication of viral DNA. Specific for herpes simplex types 1 (HSV-1) and 2 (HSV-2), varicellazoster virus, Epstein-Barr virus, and cytomegalovirus (CMV).
Availability
Capsules: 200 mg
Cream: 5% in 2-g tube
Injection: 50 mg/ml
Ointment: 5% in 15-g tube
Powder for injection: 500 mg/vial, 1,000 mg/vial
Suspension: 200 mg/5 ml
Tablets: 400 mg, 800 mg
Indications and dosages
➣ Acute treatment of herpes zoster (shingles)
Adults: 800 mg P.O. q 4 hours while awake (five times/day) for 7 to 10 days
➣ Initial episode of genital herpes
Adults: 200 mg P.O. q 4 hours while awake (1,000 mg/day) for 10 days
➣ Chronic suppressive therapy for recurrent genital herpes episodes
Adults: 400 mg P.O. b.i.d., or 200 mg P.O. three to five times daily for up to 12 months
➣ Intermittent therapy for recurrent genital herpes episodes
Adults: 200 mg P.O. q 4 hours while awake (five times/day) for 5 days, initiated at first sign or symptom of recurrence
➣ Management of initial episodes of genital herpes and limited, non-life-threatening mucocutaneous herpes simplex virus infections in immunocompromised patients
Adults: Apply approximately ½″ ribbon of ointment per 4 square inches of surface area to sufficiently cover all lesions q 3 hours, six times daily for 7 days.
➣ Treatment of recurrent herpes labialis (cold sores)
Adults and adolescents ages 12 and older: Apply cream to infected area five times daily for 4 days.
➣ Varicella (chickenpox)
Adults and children weighing more than 40 kg (88 lb): 800 mg P.O. q.i.d. for 5 days
Children older than age 2: 20 mg/kg P.O. q.i.d. for 5 days
➣ Mucosal and cutaneous HSV-1 and HSV-2 in immunocompromised patients
Adults and children older than age 12: 5 mg/kg I.V. infusion over 1 hour given q 8 hours for 7 days
Children younger than age 12: 10 mg/kg I.V. infusion over 1 hour given q 8 hours for 7 days
➣ Herpes simplex encephalitis
Adults and children older than age 12: 10 mg/kg I.V. over 1 hour given q 8 hours for 10 days
Children ages 3 months to 12 years: 20 mg/kg I.V. over 1 hour given q 8 hours for 10 days
Children from birth to 3 months: 10 mg/kg I.V. over 1 hour given q 8 hours for 10 days
➣ Varicella zoster infections in immunocompromised patients
Adults and adolescents older than age 12: 10 mg/kg I.V. over 1 hour given q 8 hours for 7 days
Children younger than age 12: 20 mg/kg I.V. over 1 hour given q 8 hours for 7 days
Dosage adjustment
• Renal impairment
• Obesity (adult dosage based on ideal weight)
• Elderly patients
Off-label uses
• Herpes zoster encephalitis
• CMV and HSV infection after bone marrow or kidney transplantation
• Infectious mononucleosis
• Varicella pneumonia
Contraindications
• Hypersensitivity to drug or valacyclovir
Precautions
Use cautiously in:
• preexisting serious neurologic, hepatic, pulmonary, or fluid or electrolyte abnormalities
• renal impairment
• obesity
• pregnant or breastfeeding patients.
Administration
• Make sure patient is adequately hydrated before starting therapy.
• Give single I.V. dose by infusion over at least 1 hour to minimize renal damage.
• Don't give by I.V. bolus or by I.M. or subcutaneous route.
• Be aware that absorption of topical acyclovir is minimal.
Adverse reactions
CNS: aggressive behavior, dizziness, malaise, weakness, paresthesia, headache; with I.V. use-encephalopathic changes (lethargy, tremors, obtundation, confusion, hallucinations, agitation, seizures, coma)
CV: peripheral edema
EENT: vision abnormalities
GI: nausea, vomiting, diarrhea
GU: proteinuria, hematuria, crystalluria, vaginitis, candidiasis, changes in menses, vulvitis, oliguria, renal pain, renal failure, glomerulonephritis Hematologic: anemia, lymphadenopathy, thrombocytopenia, thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (in immunocompromised patients), disseminated intravascular coagulation, hemolysis, leukopenia, leukoclastic vasculitis
Hepatic: jaundice, hepatitis
Musculoskeletal: myalgia
Skin: photosensitivity rash, pruritus, angioedema, alopecia, urticaria, severe local inflammatory reactions (with I.V. extravasation), toxic epidermal necrolysis, erythema multiforme
Other: gingival hyperplasia, fever, excessive thirst, pain at injection site, anaphylaxis, Stevens-Johnson syndrome
Interactions
Drug-drug. Interferon: additive effect
Nephrotoxic drugs: increased risk of nephrotoxicity
Probenecid: increased acyclovir blood level
Zidovudine: increased CNS effects, especially drowsiness
Drug-diagnostic tests. Alanine aminotransferase, aspartate aminotransferase, bilirubin, blood urea nitrogen: increased levels
Patient monitoring
• Monitor fluid intake and output.
• Assess for signs and symptoms of encephalopathy.
• Evaluate patient frequently for adverse reactions, especially bleeding tendency.
• Monitor CBC with white cell differential and kidney function test results.
Patient teaching
• Instruct patient to keep taking drug exactly as prescribed, even after symptoms improve.
• Advise patient to drink enough fluids to ensure adequate urinary output.
• Tell patient to monitor urine output and report significant changes.
☞ Instruct patient to immediately report unusual bleeding or bruising.
• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.
• Advise patient to minimize GI upset by eating small, frequent servings of food and drinking plenty of fluids.
• Tell patient to use soft toothbrush and electric razor to avoid injury to gums and skin.
• Advise patient to avoid sexual intercourse when visible herpes lesions are present.
• Inform patient that he may need to undergo regular blood testing during therapy.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.
acyclovir
(ā-sī′klō-vîr, -klə-)Acyclovir
A nucleoside analogue used to manage viral infections in patients with bone marrow transplants, chemotherapy-induced or acquired immunosuppression—e.g., AIDS.Indications HSV-1, HSV-2, HVZ, and CMV. Acyclovir is considered safe for paediatric chickenpox (varicella-zoster) if begun in the first 24 hours of rash, although it is unclear if it reduces the rare serious complications of chickenpox or is more effective than vidarabine in reducing viral shedding by HSV-infected infants.
Adverse effects Upset stomach, headache, nausea; hair loss with chronic use.