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Pharmacologic class: Acyclic purine nucleoside analogue
Therapeutic class: Antiviral
Pregnancy risk category B
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).
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
• Renal impairment
• Obesity (adult dosage based on ideal weight)
• Elderly patients
• Herpes zoster encephalitis
• CMV and HSV infection after bone marrow or kidney transplantation
• Infectious mononucleosis
• Varicella pneumonia
• Hypersensitivity to drug or valacyclovir
Use cautiously in:
• preexisting serious neurologic, hepatic, pulmonary, or fluid or electrolyte abnormalities
• renal impairment
• pregnant or breastfeeding patients.
• 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.
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
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
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
• 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.
• 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.