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Phenytoin absorption from tube feedings
G A Maynard1, K M Jones, J R Guidry
1Department of Medicine, Good Samaritan Medical Center, Phoenix, AZ 85006.
Archives of Internal Medicine
|October 1, 1987
Summary
Continuous enteral nutrition significantly reduces phenytoin absorption, potentially leading to undetectable drug levels. Higher doses may be required to achieve therapeutic phenytoin levels in patients receiving enteral feedings.
Area of Science:
- Pharmacology
- Gastroenterology
Background:
- Phenytoin is an antiepileptic drug often administered via feeding tubes.
- Continuous enteral nutrition is common in patients requiring long-term feeding support.
Observation:
- Phenytoin suspension administered through feeding tubes during continuous enteral nutrition shows poor absorption.
- Standard phenytoin doses (300-500 mg/day) can result in subtherapeutic serum levels.
Findings:
- A case study demonstrated that a patient required 1800 mg/day of phenytoin to achieve a serum level of 9 mcg/mL.
- Most enteral feeding products tested severely impaired phenytoin absorption.
- One enteral feeding product was identified that did not significantly hinder phenytoin absorption.
Implications:
- Clinicians must be aware of the potential for reduced phenytoin efficacy in patients receiving continuous enteral nutrition.
- Dosage adjustments or alternative administration methods may be necessary.
- Further research is needed to elucidate the mechanism of impaired absorption and identify suitable enteral feeding products.