Fluconazole Dosing for a 10-Year-Old, 100-Pound Patient
For a 10-year-old child weighing 100 pounds (45.5 kg), the recommended fluconazole dose depends on the type and severity of fungal infection, ranging from 3-12 mg/kg/day, which translates to approximately 135-545 mg daily for this patient.
Weight-Based Dosing Framework
The patient weighs 100 pounds = 45.5 kg. Below are the specific dosing recommendations based on infection type:
Oropharyngeal Candidiasis (Thrush)
- Mild disease: Topical therapy with clotrimazole troches 10 mg five times daily for 7-14 days is preferred 1
- Moderate to severe disease: Oral fluconazole 100-200 mg daily (approximately 2.2-4.4 mg/kg for this patient) for 7-14 days 1
- This translates to 100-200 mg daily for this 45.5 kg patient 1
Esophageal Candidiasis
- Standard dosing: Fluconazole 200-400 mg daily (3-6 mg/kg) for 14-21 days 1
- For this patient: 135-270 mg daily based on the 3-6 mg/kg recommendation 1
- Practical dosing would be 200-300 mg daily 1
Candidemia and Invasive Candidiasis
- Loading dose: Fluconazole 800 mg (12 mg/kg) on day 1 1
- For this patient: approximately 545 mg loading dose 1
- Maintenance dose: Fluconazole 400 mg daily (6 mg/kg) 1
- For this patient: approximately 270 mg daily 1
- Continue for at least 2 weeks after blood culture clearance and symptom resolution 1
Urinary Tract Candidiasis
- Cystitis (fluconazole-susceptible): Fluconazole 200 mg daily (3 mg/kg) for 2 weeks 1
- For this patient: approximately 135 mg daily 1
- Pyelonephritis: Fluconazole 200-400 mg daily (3-6 mg/kg) for 2 weeks 1
- For this patient: 135-270 mg daily 1
CNS Candidiasis (Meningitis)
- Step-down therapy: Fluconazole 400-800 mg daily (6-12 mg/kg) after initial amphotericin B therapy 1
- For this patient: 270-545 mg daily 1
- Continue until all signs, symptoms, CSF, and radiological abnormalities resolve 1
Pediatric-Specific Considerations
Age-Appropriate Dosing
- Children 2-14 years: The standard pediatric dosing is weight-based (mg/kg) as outlined above 1
- Maximum doses: For children, oral doses typically do not exceed 400 mg daily for most indications, though higher doses (up to 800 mg) may be used for severe invasive infections 1
Pharmacokinetic Factors
- Children have higher clearance rates than adults, which is why mg/kg dosing in pediatrics often appears higher than adult dosing 2
- The volume of distribution in children is similar to adults (0.55-0.71 L/kg), supporting weight-based dosing 3
Critical Clinical Caveats
When NOT to Use Fluconazole
- Do not use for empirical therapy in patients who have received azole prophylaxis 1
- Avoid in suspected fluconazole-resistant species (C. krusei, some C. glabrata) - use an echinocandin instead 1
- Contraindicated with clopidogrel due to significant drug interaction reducing antiplatelet efficacy by 25-30% 4
Renal Dosing Adjustments
- For patients with impaired renal function, reduce the daily dose according to creatinine clearance 2
- Fluconazole is highly dialyzable; patients on continuous hemodiafiltration require significantly higher doses (500-600 mg every 12 hours) 3
Common Prescribing Errors to Avoid
- Underdosing invasive infections: Using 3 mg/kg instead of 6-12 mg/kg for serious infections leads to treatment failure 1, 5
- Inadequate duration: Stopping therapy before 2 weeks after blood culture clearance increases relapse risk 1
- Missing the loading dose: For invasive candidiasis, the 12 mg/kg loading dose on day 1 is critical for rapid therapeutic levels 1
Practical Dosing Summary for This Patient
For a 10-year-old, 45.5 kg (100 lb) patient:
- Oropharyngeal candidiasis: 100-200 mg daily 1
- Esophageal candidiasis: 200-300 mg daily 1
- Candidemia/invasive candidiasis: 400-600 mg loading dose, then 300 mg daily 1
- Urinary candidiasis: 150-200 mg daily 1
- Prophylaxis (high-risk settings): 400 mg daily (approximately 8-9 mg/kg) 1