Acyclovir pediatric dose
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Here is a comprehensive summary of pediatric acyclovir dosing from the Red Book 2021 (AAP Committee on Infectious Diseases), Table 4.10:
Acyclovir — Pediatric Dosing
1. Neonatal HSV Infection (Birth to 54 months)
| Route | Age | Dose |
|---|---|---|
| IV | Birth–54 mo | 60 mg/kg/day ÷ 3 doses × 14 days (SEM disease) or ≥21 days (CNS or disseminated disease); extend if CSF PCR remains positive |
| Oral (suppression) | 2 wk–8 mo | 300 mg/m²/dose TID × 6 months after completion of IV therapy; adjust monthly for growth |
2. HSV Encephalitis
| Route | Age | Dose |
|---|---|---|
| IV | >4 mo – 12 y | 30–45 mg/kg/day ÷ 3 doses × 14–21 days (Note: FDA-approved dose of 60 mg/kg/day is NOT recommended in this age range — AKI risk increases at doses >500 mg/m² or >15 mg/kg/dose) |
| IV | ≥12 y | 30 mg/kg/day ÷ 3 doses × 14–21 days |
3. Varicella (Chickenpox)
| Indication | Route | Age | Dose |
|---|---|---|---|
| Immunocompetent | Oral | ≥2 y, ≤40 kg | 80 mg/kg/day ÷ 4 doses × 5 days (max 3200 mg/day) |
| Immunocompetent | Oral | ≥2 y, >40 kg | 3200 mg/day ÷ 4 doses × 5 days |
| Requiring hospitalization | IV | >2 y | 30 mg/kg/day ÷ 3 doses × 7–10 days; OR 1500 mg/m²/day ÷ 3 doses |
| Immunocompromised | IV | <2 y | 30 mg/kg/day ÷ 3 doses × 7–10 days |
4. Herpes Zoster
| Indication | Route | Age | Dose |
|---|---|---|---|
| Immunocompetent | IV | ≥2 y | 1500 mg/m²/day ÷ 5 doses × 7–10 days; some experts use 30 mg/kg/day ÷ 3 doses |
| Requiring hospitalization | IV | All ages | Same as varicella immunocompromised dosing |
5. HSV Gingivostomatitis (Primary)
- Oral: 15 mg/kg/dose, 5 times daily × 7 days (suspension); start within 3 days of onset for best effect
- (Fitzpatrick's Dermatology)
Key Clinical Notes
- Renal dosing adjustment required — acyclovir is renally cleared; dose-reduce for creatinine clearance impairment.
- Neurotoxicity (agitation, myoclonus, delirium) can occur with high accumulated acyclovir levels, usually due to renal dysfunction without dose adjustment.
- Concomitant ceftriaxone may enhance nephrotoxicity risk.
- IV shortage: AAP recommends conserving IV acyclovir for neonatal HSV, HSV encephalitis, and VZV infections in immunocompromised hosts.
- Valacyclovir should NOT be used routinely for antiviral suppression in young infants (studied only up to 5 days in this age group).
— Red Book 2021, Table 4.10; Fitzpatrick's Dermatology
Acyclovir dose
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Here is a comprehensive acyclovir dosing reference covering all indications, ages, and routes:
Acyclovir — Complete Dosing Reference
Sources: Harriet Lane Handbook 23rd ed.; Red Book 2021 (AAP); Goldman-Cecil Medicine
Formulations
- Capsules: 200 mg
- Tablets: 400 mg, 800 mg
- Oral suspension: 200 mg/5 mL
- Injection: 50 mg/mL
- Ointment 5%, Cream 5%
- Ophthalmic ointment (Avaclyr) 3%
NEONATAL HSV (Birth–3 months)
| Situation | Route | Dose | Duration |
|---|---|---|---|
| HSV / HSV encephalitis (<34 wk postmenstrual age) | IV | 40 mg/kg/day ÷ Q12 hr | 14 days (SEM) or 21 days (CNS/disseminated) |
| HSV / HSV encephalitis (≥34 wk postmenstrual age) | IV | 60 mg/kg/day ÷ Q8 hr | 14 days (SEM) or 21 days (CNS/disseminated) |
| Post-IV oral suppression | PO | 300 mg/m²/dose Q8 hr | 6 months |
HSV ENCEPHALITIS (Immunocompetent)
| Age | Route | Dose | Duration |
|---|---|---|---|
| 3 mo – 12 yr | IV | 60 mg/kg/day ÷ Q8 hr | 14–21 days |
| ≥12 yr / Adult | IV | 30 mg/kg/day ÷ Q8 hr | 14–21 days |
⚠️ Red Book 2021 caution: For children >4 mo–12 yr, some experts prefer 30–45 mg/kg/day (NOT the full 60 mg/kg/day) due to AKI risk at doses >500 mg/m² or >15 mg/kg/dose; concomitant ceftriaxone increases nephrotoxicity risk.
MUCOCUTANEOUS / GENITAL HSV (≥12 yr)
| Indication | Route | Dose | Duration |
|---|---|---|---|
| Initial infection | IV | 15 mg/kg/day or 750 mg/m²/day ÷ Q8 hr | 5–7 days |
| Initial infection | PO | 200 mg 5×/day or 400 mg TID (1000–1200 mg/day ÷ 3–5 doses) | 7–10 days |
| Recurrence | PO | 200 mg 5×/day × 5 days; or 800 mg Q12 hr × 5 days; or 800 mg Q8 hr × 2 days | — |
| Chronic suppression | PO | 400–800 mg/day ÷ Q12 hr | Up to 1 year |
Pediatric oral HSV dosing: 40–80 mg/kg/day ÷ Q6–8 hr × 5–10 days (max 1000 mg/day)
HERPES LABIALIS / GINGIVOSTOMATITIS
| Indication | Route | Dose |
|---|---|---|
| Herpes labialis (≥12 yr) | Topical cream | Apply 5× daily × 4 days |
| Primary gingivostomatitis (children) | PO | 15 mg/kg/dose 5×/day × 7 days (suspension); start within 3 days of onset |
| Mucocutaneous HSV (immunocompromised) | Ointment | ½-inch ribbon per 4-inch² area, 6×/day × 7 days |
VARICELLA (Chickenpox)
| Indication | Route | Age | Dose | Duration |
|---|---|---|---|---|
| Immunocompetent | PO | ≥2 yr, ≤40 kg | 80 mg/kg/day ÷ 4 doses (max 3200 mg/day) | 5 days |
| Immunocompetent | PO | ≥2 yr, >40 kg / Adult | 3200 mg/day ÷ 4 doses | 5 days |
| Requiring hospitalization | IV | >2 yr | 30 mg/kg/day or 1500 mg/m²/day ÷ Q8 hr | 7–10 days |
| Immunocompromised | IV | <2 yr | 30 mg/kg/day ÷ Q8 hr | 7–10 days |
HERPES ZOSTER
| Indication | Route | Age | Dose | Duration |
|---|---|---|---|---|
| Immunocompetent | IV | ≥2 yr | 1500 mg/m²/day ÷ Q8 hr (or 30 mg/kg/day ÷ Q8 hr) | 7–10 days |
| Adult (outpatient) | PO | ≥12 yr | 800 mg 5×/day (4000 mg/day) | 5–7 days |
| Immunocompromised/hospitalized | IV | All ages | 30 mg/kg/day or 1500 mg/m²/day ÷ Q8 hr | 7–10 days |
IMMUNOCOMPROMISED HOST — HSV
| Indication | Route | Dose |
|---|---|---|
| Treatment | IV | 750–1500 mg/m²/day ÷ Q8 hr × 7–14 days |
| Treatment | PO | 1000 mg/day ÷ 3–5 doses × 7–14 days (peds max 80 mg/kg/day) |
| Prophylaxis | IV | 750 mg/m²/day ÷ Q8 hr during risk period |
| Prophylaxis | PO | 600–1000 mg/day ÷ 3–5 doses during risk period |
OPHTHALMIC
- HSV keratitis (≥2 yr): 1 cm ribbon into lower eyelid 5×/day until ulcer heals, then TID × 7 days
Renal Dose Adjustment
| CrCl (mL/min) | IV Adjustment | Oral Adjustment |
|---|---|---|
| 25–50 | 100% dose Q12 hr | No change |
| 10–25 | 100% dose Q24 hr | 800 mg Q12 hr |
| <10 | 50% dose Q24 hr | 200–400 mg Q12 hr |
Key Clinical Notes
- Oral bioavailability is poor (15–30%) — consider valacyclovir or famciclovir where better absorption is needed
- Hydrate adequately and infuse IV over ≥1 hour to prevent renal crystallization
- Use ideal body weight in obese patients
- Neurotoxicity (agitation, myoclonus, delirium) can occur with elevated acyclovir levels, typically from renal dysfunction without dose adjustment
- Resistant strains (HSV/VZV) occur in immunocompromised patients on prolonged therapy → use foscarnet
- IV shortage: Prioritize for neonatal HSV, HSV encephalitis, immunocompromised VZV/HSV
— Harriet Lane Handbook 23rd ed.; Red Book 2021 (AAP), Table 4.10
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