What is the prescription for acyclovir (antiviral medication) oral suspension for a 1.5-year-old child weighing 11.5 kg with oral stomatitis after suspected exposure to herpes simplex virus?

Acyclovir Prescription for Oral Stomatitis in a 1.5-Year-Old Child

For this 11.5 kg child with oral stomatitis (herpes simplex gingivostomatitis), prescribe acyclovir oral suspension 230 mg (20 mg/kg) three times daily for 5-10 days, starting immediately if within 72 hours of symptom onset. 1, 2, 3

Dosing Calculation and Formulation

• Weight-based dose: 20 mg/kg × 11.5 kg = 230 mg per dose 1, 2
• Frequency: Three times daily (every 8 hours) 1, 3
• Maximum single dose: 400 mg (this child's dose is well below the maximum) 1, 4
• Formulation: Acyclovir oral suspension 200 mg/5 mL 5
• Volume per dose: 5.75 mL per dose (230 mg ÷ 200 mg × 5 mL)

Complete Prescription Details

Rx: Acyclovir oral suspension 200 mg/5 mL

• Dispense: 350 mL (sufficient for 10 days)
• Sig: Give 5.75 mL (230 mg) by mouth three times daily for 5-10 days
• Instructions: Start immediately; continue until oral lesions completely heal 1

Duration of Treatment

• Minimum duration: 5 days for mild symptomatic gingivostomatitis 1, 3
• Standard duration: 5-10 days based on severity 1, 2
• Treatment endpoint: Continue until lesions completely heal 1
• Critical timing: Treatment must be initiated within 72 hours of symptom onset for maximum efficacy 6, 5, 7

Severity Assessment and Route Selection

• Mild to moderate disease (appropriate for oral therapy): Child can maintain hydration, no severe pain preventing oral intake 1, 3
• Severe disease requiring IV therapy: Consider IV acyclovir 5-10 mg/kg three times daily if child has severe pain, dehydration, inability to tolerate oral medications, or membranous conjunctivitis 1, 3
• Transition strategy: If starting IV therapy, switch to oral acyclovir once lesions begin to regress 1, 3

Expected Clinical Response

• Improvement timeline: Clinical improvement expected within 48-72 hours of initiating therapy 3
• Oral lesions: Duration reduced from median 10 days (untreated) to 4 days with acyclovir 7
• Fever resolution: Reduced from 3 days to 1 day 7
• Eating/drinking difficulties: Improved from 6-7 days to 3-4 days 7
• Viral shedding: Reduced from 5 days to 1 day 7

Monitoring and Supportive Care

• Hydration: Ensure adequate fluid intake throughout treatment to prevent crystalluria and dehydration 2, 3, 6
• Renal function: Monitor if treatment extends beyond 5 days due to risk of renal toxicity 2
• Pain management: Consider acetaminophen or ibuprofen for pain control 6
• Nutritional support: Offer soft, cool foods; avoid acidic or spicy foods 6

Common Adverse Effects

• Gastrointestinal: Nausea, vomiting, diarrhea (most common) 2
• Renal: Crystalluria if inadequate hydration 2
• Hematologic: Neutropenia with prolonged use (rare in short courses) 2
• Dermatologic: Rash (uncommon) 2

Critical Pitfalls to Avoid

• Late initiation: Starting treatment after 72 hours significantly reduces efficacy 6, 5, 7
• Inadequate hydration: Increases risk of renal toxicity and crystalluria 2, 3
• Premature discontinuation: Must continue until lesions heal, not just symptom improvement 1
• Underdosing: Using adult fixed dosing instead of weight-based pediatric dosing 1, 4

Alternative Considerations

• Valacyclovir: Not recommended—no pediatric formulation exists and dosing data in children are limited 1, 2
• Famciclovir: Not recommended—no pediatric preparation available 1, 2
• Topical acyclovir: Not effective for oral stomatitis; systemic therapy required 5

When to Escalate Care

• No improvement in 48-72 hours: Consider acyclovir resistance (rare) or alternative diagnosis 3
• Worsening dehydration: Switch to IV acyclovir and provide IV hydration 1, 3
• Inability to tolerate oral medications: Transition to IV therapy 1
• Immunocompromised status: Consider higher doses or IV therapy from onset 1