Recovery of phenytoin suspension after in vitro administration through percutaneous endoscopic gastrostomy Pezzer catheters

Various methods of administering phenytoin suspension through a percutaneous endoscopic gastrostomy (PEG) Pezzer catheter were evaluated in vitro to determine which method resulted in the most complete recovery of phenytoin. To determine the effect of temperature on phenytoin recovery, 12 mL of phenytoin suspension (Dilantin-125, 125 mg/5 mL) was administered through three separate 35.5-cm 20 French latex PEG Pezzer catheters under each of three temperature conditions (suspension 11.8°C and catheter 22°C, suspension and catheter 22°C, and suspension 22°C and catheter 37°C). To determine the effect of the administration method, 12-mL aliquots of phenytoin suspension were injected into the catheter by seven methods that varied with respect to catheter temperature, dilution of suspension, and irrigation of catheter. Each method was tested in triplicate, and samples were assayed by high-performance liquid chromatography. Varying the temperature of the catheter or suspension had little effect on the recovery of phenytoin. There was no appreciable loss of phenytoin when the suspension was undiluted, regardless of whether the catheter was irrigated. The greatest losses were seen when the suspension was diluted before administration. Irrigation also caused a decrease in recovery, but to a lesser extent than dilution. Until the effects of administering multiple doses of phenytoin through PEG Pezzer catheters are investigated, phenytoin suspension should not be diluted before administration because of decreased recovery and increased administration time.