The effects of aging on the dissolution of phenytoin sodium capsule formulations

Joseph T. Rubino, Lisa M. Halterlein, James Blanchard

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


The effects of formulation and storage conditions on the dissolution of sodium phenytoin capsules have been evaluated. Capsule formulations were prepared containing lactose or CaSO4 · 2H2O as the excipient at a low (1:1) and high (3:1) excipient to drug ratio. The capsules were stored for 2 or 8 weeks at 11% and 67% relative humidity. The dissolution data were analyzed using a non-linear least-squares regression program and the Weibull function. An analysis of variance (ANOVA) performed on each of the Weibull function parameters revealed that the formulation and storage conditions had different effects on each of these parameters. A specific interaction between CaSO4 · 2H4O and phenytoin sodium was not evident from the data; however, significant effects on the deaggregation process could be detected from changes in the β parameter. Several interaction effects between storage conditions and formulation factors were also evident from the ANOVA results. This study illustrates the utility of the Weibull function analysis of dissolution data for detecting drug-excipient interactions and storage-related changes in solid dosage forms.

Original languageEnglish (US)
Pages (from-to)165-174
Number of pages10
JournalInternational Journal of Pharmaceutics
Issue number1-2
StatePublished - Sep 1985


  • Weibull function-excipient
  • aging
  • capsule
  • dissolution
  • phenytoin

ASJC Scopus subject areas

  • Pharmaceutical Science


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