Effects of Diluents on Physical and Chemical Stability of Phenytoin and Phenytoin Sodium. Academic Article uri icon


  • The focus of the present work was to investigate compatibility between commonly used diluents and the drug (salt and acid form of the phenytoin). Lactose monohydrate (LMH), lactitol hydrate (LCT), and mannitol (MNT) were selected based on commercial products information of phenytoin sodium (PS) and phenytoin acid (PHT). Binary mixtures of the drug-diluent were stored at 60C and 40C/75% RH. Similarly, two commercial products, namely Product-A and Product-B, were also investigated in in-use stability. Color of PS-LMH changed from white to yellowish-brown and pH dropped by 3.4units after 4weeks exposure. FTIR, XRPD, and NIR chemical images indicated disproportionation in PS-LMH and PS-LCT mixtures stored at 40C/75% RH. Furthermore, PS-LMH also indicated chemical interactions as indicated by distortion of LMH peaks. PHT-diluent mixture did not exhibit any physical and chemical modifications. Product-A changed color, increased weight, dropped pH value, and exhibited disproportionation and chemical reactions. The dissolution of Product-A decreased from 83.31.4 to 7.14.4% on 8weeks exposure to 30C/75% RH. On the other hand, Product-B did not change; however, dissolution decreased by 15%. In conclusion, PS showed disproportionation and chemical reactions with LMH. Therefore, LMH should be avoided in PS formulations.

published proceedings

  • AAPS PharmSciTech

altmetric score

  • 0.5

author list (cited authors)

  • Rahman, Z., Dharani, S., Barakh Ali, S. F., Nutan, M., & Khan, M. A.

citation count

  • 4

complete list of authors

  • Rahman, Ziyaur||Dharani, Sathish||Barakh Ali, Sogra F||Nutan, Mohammad TH||Khan, Mansoor A

publication date

  • March 2020