Department of Anesthesiology, Kerman University of Medical Sciences, KERMAN-IRAN.
Background: Seizure is common after head trauma and neurosurgery. Phenytoin is the most common anti-convulsant drug used in epileptic patients and for prevention of seizure in patients with head trauma and stroke. This drug has unique pharmacokinetic and pharmacodynamic characteristics. Phenytoin administration along with enteral nutrition in ICU patients may be accompanied by decreased phenytoin absorption and inadequate therapeutic concentration. The present study was performed to assess the effect of enteral nutrition on the pharmacokinetic therapeutic parameters of phenytoin given to our patients. Materials and Methods: In a clinical trial, the study group was divided into two groups of 15 patients each. After obtaining steady-state phenytion serum concentration, two blood samples were obtained from each patient on 2 consecutive days and then analyzed. The mean was assessed on the basis of serum albumin level of the patient. Clearance and maximum metabolic capacity were also calculated. Results: Serum phenytoin level was below the therapeutic range (10- 20 mg/l) in 70% of patients in group 1 and was higher than the therapeutic range in 70% of patients in group 2 who received oral phenytoin (by dissolving in water) 2h after enteral nutrition. Mean phenytion concentration was 6.3±4mg/l and 24.7±9.4mg/l in group 1 and group 2, respectively. Conclusion: We found oral phenytoin administration with enteral nutrition (gavage solutions) to result in a significant decrease in absorption and blood concentration of phenytoin. We recommend administration of phenytoin with water only. In addition, monitoring of phenytoin serum concentration is necessary for assessment of therapeutic concentration and prevention of side effects. (Tanaffos 2008; 7(3): 59-62)