Phenytoin Crystallization in Intravenous Fluids

Abstract

Free phenytoin crystallization in various commercially available intravenous solutions was investigated. Phenytoin determinations were completed at various time periods, before and after filtration, by spectrophotometric analysis. Phenytoin was found to produce a more stable solution in normal saline and lactated Ringer's solutions than in 5 percent dextrose in normal saline or 5 percent dextrose in water. The pH differences between commercial phenytoin sodium for injection and the various intravenous fluids were felt to be the major factor responsible for free phenytoin crystallization. It was concluded that phenytoin sodium admixture to normal saline or lactated Ringer's solution can indeed be used clinically, with precautions. The variations in pH of available intravenous solutions make apparent the need for careful inspection of sodium phenytoin admixtures and for such infusions to be started immediately after admixture.