What is the earliest age at which anti‑parasitic medications can be safely given to infants/children, and which agents are appropriate?

Earliest Age for Anti-Parasitic Medications

Anti-parasitic medications can be safely administered from birth (neonatal period) for specific indications, with the exact minimum age varying by drug class and specific agent.

Age-Specific Guidelines by Drug Class

Antifungal Agents (for parasitic fungi like Candida)

Neonates (from birth):

• Micafungin can be initiated in infants <3 months at 25 mg/m²/day IV for prophylaxis, or 4-10 mg/kg/day IV for invasive candidiasis treatment, with no hepatic dose adjustment required 1, 2
• Amphotericin B deoxycholate 1 mg/kg/day IV is approved for neonates with invasive candidiasis from birth 1, 2
• Liposomal amphotericin B 2.5-7 mg/kg/day IV can be used in neonates, though not formally approved in infants <1 month 1
• Fluconazole 12 mg/kg/day IV (with 25 mg/kg loading dose) is appropriate for hemodynamically stable neonates without recent azole exposure 1, 2
• Nystatin suspension 100,000 units/mL (1 mL four times daily) is first-line for oral candidiasis from birth 3

Infants 3-12 months:

• Micafungin prophylaxis increases to 50 mg/m²/day IV 1, 2

Children ≥1 year:

• Caspofungin becomes available at ≥2 years: 50 mg/m² IV (loading 70 mg/m²) for children weighing <50 kg 1

Children ≥2 years:

• Voriconazole 8 mg/kg IV/PO twice daily (loading 9 mg/kg) with therapeutic drug monitoring required 1
• Itraconazole 2.5 mg/kg twice daily (oral suspension) with TDM 1

Adolescents ≥13 years:

• Posaconazole 300 mg daily (gastro-resistant tablet preferred) or 600 mg/day oral suspension in three divided doses with TDM 1

Antiprotozoal Agents

Infants ≥1 year:

• Nitazoxanide for Giardia lamblia or Cryptosporidium parvum: 100 mg (5 mL suspension) every 12 hours with food for 3 days in children 1-3 years 4

Children 4-11 years:

• Nitazoxanide dose increases to 200 mg (10 mL) every 12 hours 4

Children ≥12 years:

• Nitazoxanide 500 mg tablet every 12 hours with food 4

Infants ≥1 month:

• Dapsone 2 mg/kg daily (max 100 mg) or 4 mg/kg weekly (max 200 mg) for Pneumocystis prophylaxis 1

Metronidazole (for amebiasis):

• Can be used in children at 35-50 mg/kg/day divided doses, though specific minimum age not established in guidelines; 30 mg/kg/day documented in refugee populations 5, 6

Antihelminthic Agents

Infants as young as 5 months:

• Praziquantel has demonstrated safety and efficacy for Schistosoma infections in children 5 months to 7 years, with 99% egg reduction rate and 92% cure rate comparable to older children 7, 8

Children 1-5 years:

• Praziquantel treatment shows only 3.8% mild side effects (stomach ache, lethargy) within 24 hours, proving as safe as in 6-10 year olds 7

Children ≥6 years:

• Albendazole pharmacokinetics in children 6-13 years are similar to adults when given 10 mg/kg (200-300 mg) with fatty meals 9
• Albendazole should be administered with food (estimated 40g fat content) to enhance bioavailability up to 5-fold 9

Ivermectin:

• Age-appropriate for children in mass treatment programs, though specific minimum age not detailed in provided evidence 6

Critical Safety Considerations

Formulation Challenges in Young Infants

• Rapidly dissolving 2 mm mini-tablets can be used in preterm neonates; non-rapidly dissolving 2 mm mini-tablets from 6 months; uncoated 4 mm mini-tablets from 1 year 10
• Liquid suspensions remain preferred for infants unable to swallow tablets 3, 10

Drug-Specific Warnings

• Micafungin: EMA "black box" warning about hepatic tumors in rats should not preclude use in life-threatening invasive candidiasis, as no human safety signal exists 2
• Nystatin prophylaxis: Associated with potential increased risk of necrotizing enterocolitis in extremely low birth-weight infants 3
• Albendazole: Not detected in urine unchanged; primarily hepatic metabolism with biliary elimination 9

Therapeutic Drug Monitoring Requirements

• Mandatory TDM for voriconazole (target trough ≥1 mg/L), itraconazole (≥0.5 mg/L), and posaconazole suspension (≥0.7 mg/L) in children 1
• No TDM required for micafungin, amphotericin formulations, or echinocandins other than therapeutic monitoring 2

Common Pitfalls to Avoid

• Under-dosing neonates: FDA-approved micafungin 2 mg/kg/day is insufficient; use ESCMID-recommended 4-10 mg/kg/day range, especially when CNS involvement cannot be excluded 2
• Ignoring age-specific clearance: Young infants have markedly increased drug clearance (40-80 mL/h/kg in premature neonates vs. 10 mL/h/kg in adults), requiring higher weight-based dosing 2
• Treating oral thrush systemically: Reserve systemic antifungals for disseminated disease, immunocompromised children, or treatment failures; topical nystatin is first-line 3
• Simultaneous maternal treatment: For breastfeeding-associated oral candidiasis, treat both mother (miconazole cream to nipples) and infant concurrently 3
• Repeat praziquantel dosing: Cure rates decline significantly with multiple treatments (41.7% after 1-4 treatments vs. 77.6% in treatment-naïve children), suggesting potential resistance development 8