What is the recommended treatment and dosage of praziquantel (PZQ) for paragonimiasis in pediatric patients, including children over 4 years old and infants under 4 years old?

Treatment of Paragonimiasis in Children

Praziquantel at 75 mg/kg/day divided into three doses for 2 consecutive days is the recommended treatment for paragonimiasis in children, based on the highest cure rates demonstrated in clinical trials. 1

Standard Treatment Regimen

Children Over 4 Years Old

The optimal dosing regimen is praziquantel 25 mg/kg three times daily (total 75 mg/kg/day) for 2 consecutive days, which achieves cure rates of 85.7-95.2%. 2

• A single-day treatment with 3 x 25 mg/kg achieved a 71.4% cure rate, which increased to 95.2% after retreatment 2
• Two consecutive days of treatment (3 x 25 mg/kg daily) resulted in an 85.7% initial cure rate, reaching 95.2% overall after retreatment of failures 2
• Three consecutive days of treatment (3 x 25 mg/kg daily) achieved 100% cure rates at 4-month follow-up 2

Infants and Children Under 4 Years Old

For children under 4 years, praziquantel 40 mg/kg as a single dose can be used, though this is based on schistosomiasis data as specific paragonimiasis dosing for this age group is not well-established. 3

• The WHO-recommended dose of 40 mg/kg for schistosomiasis in school-aged children has been endorsed for preschool-aged children (2-5 years) in the absence of treatment alternatives 3
• Praziquantel shows a flat dose-response and overall lower efficacy in preschool-aged children compared to school-aged children 3
• A pediatric formulation of praziquantel suitable for children as young as 3-6 months is under development but not yet available 4

Dosing Algorithm by Clinical Scenario

For Confirmed Paragonimiasis in Children ≥4 Years

1. First-line treatment: Praziquantel 25 mg/kg three times daily for 2 consecutive days (total daily dose 75 mg/kg) 2
2. Alternative regimen: Praziquantel 25 mg/kg three times daily for 3 consecutive days if higher certainty of cure is desired 2
3. Follow-up: Monthly examinations for up to 4 months post-treatment to confirm parasitological cure 2

For Children Under 4 Years

1. Recommended dose: Praziquantel 40 mg/kg as a single oral dose, extrapolated from schistosomiasis treatment data 3
2. Consideration: This dosing is based on limited data; close monitoring is essential 3, 4

Species-Specific Considerations

For Paragonimus uterobilateralis infections specifically, the recommended dose is 75 mg/kg/day for 2 days, which achieved cure rates of 85.4-100% depending on age group. 1

• With 75 mg/kg daily dose, reduction in egg counts ranged from 90.8-96.8% with a cure rate of 97.6% 1
• A 100% cure rate was recorded in 15-29 year old patients treated with 75 mg/kg daily dose 1
• Lower doses (45 mg/kg or 60 mg/kg daily) resulted in inferior cure rates of 71.1% and 85.4% respectively 1

Safety and Tolerability

Praziquantel is well-tolerated in children with predominantly mild and transient side effects. 2

• The most common adverse effects are mild headache and dizziness 2
• No significant difference in side effects between dosage groups 2
• Hematological, biochemical, and urinalysis parameters remain within normal limits after therapy 2
• In preschool-aged children, diarrhea (9%) and stomach ache (8%) were the most common adverse events 3 hours post-treatment 3
• No serious adverse events have been reported in pediatric trials 3, 2

Monitoring Treatment Response

Parasitological cure should be confirmed through monthly follow-up examinations for up to 4 months after treatment. 2

• Disappearance of eggs in sputum and feces indicates successful treatment 1, 2
• Immunoelectrophoresis showing disappearance of precipitating bands provides additional confirmation of cure 2
• Chest X-ray abnormalities should resolve following successful treatment 2
• If parasitological cure is not achieved, retreatment with the same or higher dose regimen is appropriate 2

Critical Clinical Pearls

• The pattern of egg count reduction is directly related to the quantity of praziquantel administered 1
• Treatment failures with lower doses can be successfully retreated with higher doses or longer duration 2
• For infants under 4 years, the lack of a specifically approved pediatric formulation represents a significant treatment gap that is being addressed through ongoing drug development 4
• Praziquantel should be administered as oral doses, ideally with food to improve tolerability 2