Griseofulvin Dosing for Ringworm in Pediatric Patients
For pediatric patients with ringworm (tinea corporis), griseofulvin should be dosed at approximately 3.3 mg per pound of body weight per day (equivalent to 15-20 mg/kg/day) for 2-4 weeks. 1
Dosage Recommendations by Weight
- Children weighing 35-60 pounds: 125 mg to 187.5 mg daily
- Children weighing over 60 pounds: 187.5 mg to 375 mg daily
- Children under 2 years: Dosage not established 1
Administration Guidelines
- Griseofulvin tablets may be swallowed whole or crushed and sprinkled onto 1 tablespoonful of applesauce and swallowed immediately without chewing
- Taking the drug with fatty food increases absorption and improves bioavailability 2
- Treatment must continue until the infecting organism is completely eradicated as indicated by appropriate clinical or laboratory examination 1
Treatment Duration Based on Infection Type
- Tinea corporis (ringworm of the body): 2-4 weeks
- Tinea capitis (scalp ringworm): 6-8 weeks (4-6 weeks according to FDA label)
- Tinea pedis (athlete's foot): 4-8 weeks 1
Organism-Specific Considerations
The choice of antifungal agent should be guided by the causative dermatophyte:
- Griseofulvin is more effective against Microsporum species (88.5% response rate)
- For Trichophyton species infections, terbinafine may be more effective (67.9% response rate with griseofulvin) 2
Monitoring and Follow-up
- Clinical improvement is typically expected within 1-2 weeks of starting treatment
- Treatment should continue for at least one week after clinical resolution
- The endpoint of treatment should be mycological cure, not just clinical improvement 3
- Consider follow-up mycological examination in resistant or recurrent cases 2
Potential Side Effects
- Griseofulvin is generally well-tolerated in children
- More common side effects include headaches, gastrointestinal reactions, and cutaneous eruptions 4
- Discontinuation due to adverse effects is rare (0.8%) 2
Contraindications
- Lupus erythematosus
- Porphyria
- Severe liver disease 2
Drug Interactions
- Plasma concentration is decreased by rifampicin
- Plasma concentration is increased by cimetidine
- May interact with oral contraceptives 4
Treatment Failure Considerations
If treatment fails, consider:
- Poor compliance
- Suboptimal absorption
- Relative insensitivity of the organism
- Reinfection 3
In cases of treatment failure, consider extending the treatment duration or switching to an alternative agent such as terbinafine (for Trichophyton species) or itraconazole as second-line therapy 2, 3.