Dosing and uses of Zovirax (acyclovir)
Adult dosage forms and strengths
injectable solution
- 50mg/mL
oral suspension
- 200mg/5mL
powder for injection
- 500mg/vial
- 1g/vial
tablet
- 400mg
- 800mg
capsule
- 200mg
Genital Herpes
Initial treatment: 200 mg PO q4hr while awake (5 times daily) for 10 days or 400 mg PO q8hr for 7-10 days
Intermittent treatment for recurrence: 200 mg PO q4hr while awake (5 times daily) for 5 days; initiate at earliest sign or symptom of recurrence
Chronic suppression for recurrence: 400 mg PO q12hr for up to 12 months; alternatively, 200 mg 3-5 times daily
Herpes Simplex Virus Encephalitis
10-15 mg/kg IV q8hr for 10 days; up to 14-21 days reported
In obese patients, use IBW
Mucocutaneous Herpes Simplex Virus Infection
Treatment in immunocompromised patients
IV: 5 mg/kg q8hr for 7 days; dosing up to 14 days reported
In obese patients, use IBW
PO (off-label): 400 mg q4hr while awake (5 times daily) for 7 days
Herpes Zoster (Shingles)
Acute treatment: 800 mg PO q4hr while awake (5 times daily) for 7-10 days
Immunocompromised patients
- 10 mg/kg IV q8hr for 7 days
- In obese patients, use IBW
- CrCl 25-50 mL/min: Full recommended IV dose q12hr
- CrCl 10-25 mL/min: Full recommended IV dose once daily
- CrCl 0-10 mL/min: 50% of recommended IV dose once daily
Varicella Zoster (Chickenpox)
>40 kg (immunocompetent): 800 mg PO q6hr for 5 days
Immunocompromised patients: 10-15 mg/kg IV q8hr for 7-10 days
In obese patients, use IBW
Dosing Modifications
Dose adjustment based on renal clearance and normal dosage regimen
200 mg every 4 hr
- 0-10 mL/min/1.73 m²: 200 mg q12hr
- >10 mL/min/1.73 m²: 200 mg q4hr (five times daily)
400 mg every 12 hr
- 0-10 mL/min/1.73 m²: 200 mg q12hr
- >10 mL/min/1.73 m²: 400 mg q12hr
800 mg every 4 hr
- 0-10 mL/min/1.73 m²: 800 mg q12hr
- 10-25 mL/min/1.73 m²: 800 mg q8hr
- >25 mL/min/1.73 m²: 800 mg q4hr (five times daily)
Dose adjustment based on dosage form
Renal impairment (IV)
- CrCl 25-50 mL/min/1.73 m²: Give recommended dose q12hr
- CrCl 10-25 mL/min/1.73 m²: Give recommended dose q24hr
- CrCl <10 mL/min/1.73 m²: Give 50% of recommended dose q24hr
Renal impairment (PO)
- Normal dosage 200 mg q4hr or 400 mg q12hr and CrCl <10 mL/min/1.73 m²: Decrease to 200 mg q12hr
- Normal dosage 800 mg q4hr and CrCl 10-25 mL/min/1.73 m²: Decrease to 800 mg q8hr
- Normal dosage 800 mg q4hr and CrCl <10 mL/min/1.73 m²: Decrease to 800 mg q12hr
Herpetic Keratitis (Orphan)
Orphan designation for treatment of herpetic keratitis
Sponsor
- Cumulus Pharmaceuticals LLC; 1712 Pioneer Avenue, Suite 1377; Cheyenne, Wyoming 82001
Pediatric dosage forms and strengths
injectable solution
- 50mg/mL
oral suspension
- 200mg/5mL
powder for injection
- 500mg/vial
- 1g/vial
tablet
- 400mg
- 800mg
capsule
- 200mg
Neonatal Herpes Simplex Virus Infection
30 mg/kg/day IV divided q8hr for 14-21 days; alternatively, 20 mg/kg IV q8hr for 14-21 days
In obese patients, use IBW
Herpes Simplex Virus Encephalitis
3 months-12 years: 20 mg/kg IV q8hr for 10 days; up to 14-21 days reported
In obese patients, use IBW
>12 years: 10-15 mg/kg IV q8hr for 14-21 days
Mucocutaneous Herpes Simplex Virus Infection
Treatment in immunocompromised patients
<12 years: 10 mg/kg IV q8hr for 7 days
In obese patients, use IBW
>12 years: 5-10 mg/kg/day IV divided q8hr for 5-7 days; up to 14 days reported
Herpes Zoster (Shingles)
<12 years (immunocompromised): 20 mg/kg IV q8hr for 7 days
In obese patients, use IBW
>12 years (immunocompetent): 800 mg PO q4hr while awake (5 times daily) for 7-10 days
>12 years (immunocompromised): 30 mg/kg/day IV divided q8hr for 7-10 days
Varicella Zoster (Chickenpox)
≥2 years and <40 kg: 20 mg/kg/dose PO q6hr for 5 days; not to exceed 800 mg/dose
In obese patients, use IBW
>40 kg: 800 mg PO q6hr for 5 days
Immunocompromised patients
- <12 years: 20 mg/kg/dose IV q8hr for 7 days
- >12 years: 10 mg/kg/dose IV q8hr for 7 days
Zovirax (acyclovir) adverse (side) effects
>10%
OraL
- Malaise (≤12%)
1-10%
ParenteraL
- Inflammation or phlebitis at injection site (9%)
- Nausea (7%)
- Vomiting (7%)
- Rash or hives (2%)
- Elevated transaminase levels (1-2%)
OraL
- Nausea (2-5%)
- Vomiting (≤3%)
- Diarrhea (2-3%)
- Headache (2%)
<1%
Abdominal pain
Aggression/confusion
Agitation
Alopecia
Anaphylaxis
Anemia
Angioedema
Anorexia
Ataxia
Coma
Disseminated intravascular coagulation (DIC)
Dizziness
Fatigue
Warnings
Contraindications
Hypersensitivity
Cautions
Avoid rapid infusion because of risk of renal damage
Renal failure, resulting in death, has occurred
Use with caution in immunocompromised patients (potential risk of thrombotic thrombocytopenic purpura [TTP]/hemolytic uremic syndrome [HUS])
Use with caution in patients with renal impairment
Treatment should begin within 24 hours of appearance of rash
Use with caution in patients receiving nephrotoxic drugs
Maintain adequate hydration during PO or IV therapy
Thrombocytopenic purpura/hemolytic uremic syndrome reported
Pregnancy and lactation
Pregnancy category: B
Lactation: Drug enters breast milk; use with caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Zovirax (acyclovir)
Mechanism of action
Interferes with DNA polymerase to inhibit DNA replication via chain termination
Absorption
Absorption: PO, 15-30%
Peak serum time: 1.5-2 hr (PO); 1 hr (IV)
Distribution
Distributed widely (brain, kidney, lungs, liver, spleen, muscle, uterus, vagina, cerebrospinal fluid [CSF])
Protein bound: 9-33%
Vd: 0.8 L/kg (63.6 L)
Metabolism
Metabolized by liver (in small amounts)
Elimination
Half-life: 4 hr (Neonates); 2-3 hr (children 1-12 years); 3 hr (adults)
Excretion: Urine (62-90% as unchanged drug)
Administration
IV Incompatibilities
Blood products and protein-containing solutions
Additive: Dobutamine, dopamine, meropenem (?)
Syringe: Caffeine
Y-site: Amifostine, amsacrine, aztreonam, cefepime, dobutamine, dopamine, fludarabine, foscarnet, gemcitabine, idarubicin, levofloxacin, morphine sulfate (?), ondansetron, piperacillin-tazobactam, sargramostim, vinorelbine
IV Compatibilities
Additive: Fluconazole
Y-site (partial list): Allopurinol, ampicillin, cefazolin, cimetidine, diphenhydramine, fluconazole, heparin, linezolid, lorazepam, magnesium sulfate, potassium chloride, propofol, trimethoprim-sulfamethoxazole, vancomycin
IV Preparation
Reconstitution: Concentrations >10 mg/mL increase risk of phlebitis; usually recommended not to exceed 7 mg/mL in D5W
IV Administration
Maximum dosage: 20 mg/kg q8hr
For IV infusion only
Avoid rapid infusion; infuse over 1 hour at constant rate to prevent renal damage
Maintain adequate hydration
Check for phlebitis, and rotate infusion sites
Storage
Reconstituted solutions remain stable for 24 hours at room temperature
To prevent precipitation, avoid refrigerating reconstituted solutions
