Fluconazole Dosing for a 15-Year-Old
For a 15-year-old patient, use adult fluconazole dosing, which is typically 400 mg (6 mg/kg) daily for invasive candidiasis or 200-400 mg daily for other indications, depending on the specific fungal infection being treated. 1
Age-Based Dosing Transition
- At age 15, patients should receive standard adult doses rather than pediatric weight-based dosing 1
- The ESCMID guidelines explicitly state that the "approved adult dose for patients 15 years and older" should be used 1
- For patients aged 12-14 years weighing >50 kg, adult dosing is also appropriate, but at exactly 15 years, adult dosing applies regardless of weight 1
Specific Dosing by Indication
For Invasive Candidiasis/Candidemia
- Loading dose: 800 mg (12 mg/kg) on day 1, then 400 mg (6 mg/kg) daily 1
- Continue for 2 weeks after documented clearance from bloodstream and resolution of symptoms 1
- This applies to both oral and intravenous administration 1
For Oropharyngeal Candidiasis
- Moderate to severe disease: 100-200 mg daily for 7-14 days 1
- For mild disease, topical agents may be preferred initially 1
For Esophageal Candidiasis
- 200-400 mg (3-6 mg/kg) daily for 14-21 days 1
- Intravenous administration at 400 mg (6 mg/kg) daily is an alternative if oral therapy cannot be tolerated 1
For Prophylaxis in High-Risk Settings
- 8-12 mg/kg daily (maximum 400 mg) for patients undergoing allogeneic HSCT or with acute leukemia 1
- Duration varies by clinical context: day 0 to day +75 post-transplant for HSCT, or after chemotherapy until neutrophil recovery for leukemia 1
Important Clinical Considerations
Maximum Dosing
- Total maximum daily dose of 1600 mg is recommended to avoid neurological toxicity 2
- Most common therapeutic doses range from 200-400 mg daily 2, 3
Renal Function Adjustment
- Fluconazole is primarily renally eliminated (approximately 60-70% unchanged in urine) 2, 3, 4
- Dosage reduction is required in patients with impaired renal function, following adult guidelines 3, 5
Route of Administration
- Oral and intravenous formulations are bioequivalent with >93% oral bioavailability 1, 2
- Food intake does not affect absorption 2, 4
- Can switch between routes based on clinical status 1
Common Pitfalls to Avoid
- Do not use pediatric weight-based dosing (8-12 mg/kg) without a maximum cap at age 15, as this would result in adult doses anyway 1
- Avoid fluconazole in patients with recent azole exposure when treating suspected invasive candidiasis, as resistance is more likely 1
- Do not use for empiric therapy if institutional rates of fluconazole-resistant Candida species (C. glabrata, C. krusei) are high 1
Drug Interactions
- Monitor patients on warfarin, oral hypoglycemics, phenytoin, and cyclosporine as fluconazole can affect their metabolism 3, 4
- Rifampin decreases fluconazole levels 3