title: Compatibility studies of acyclovir and lactose in physical mixtures and commercial tablets.
abstract: This study documents drug-excipient incompatibility studies of acyclovir in physical mixtures with lactose and in different tablet brands. Differential scanning calorimetry (DSC) was initially used to assess compatibility of mixtures. The Fourier-transform infrared (FTIR) spectrum was also compared with the spectra of pure drug and excipient. Although DSC results indicated incompatibility with lactose, FTIR spectra were mostly unmodified due to overlapping peaks. Samples of isothermally stressed physical mixture were stored at 95 degrees C for 24 h. The residual drug was monitored using a validated high-performance liquid chromatography (HPLC) assay and data fitting to solid-state kinetic models was performed. The drug loss kinetics followed a diffusion model. The aqueous mixture of drug and excipient was heated in order to prepare an adduct mixture. HPLC analysis revealed one extra peak that was fractionated and subsequently injected into the liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) system. The MRM (Multiple Reaction Monitoring) chromatograms characterized the peak with molecular mass corresponding to an acyclovir-lactose Maillard reaction product. The presence of lactose in commercial tablets was checked using a new TLC method. Overall, the incompatibility of acyclovir with lactose was successfully evaluated using a combination of thermal methods and LC-MS/MS.
authors.affiliation: Department of Drug and Food Control, Tabriz University of Medical Sciences, Tabriz, Iran; Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Farnaz
authors.initials: F
authors.lastname: Monajjemzadeh
authors.forename: Davoud
authors.initials: D
authors.lastname: Hassanzadeh
authors.forename: Hadi
authors.initials: H
authors.lastname: Valizadeh
authors.forename: Mohammad R
authors.initials: MR
authors.lastname: Siahi-Shadbad
authors.forename: Javid Shahbazi
authors.initials: JS
authors.lastname: Mojarrad
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Robertson
authors.forename: Michael S
authors.initials: MS
authors.lastname: Roberts
mesh_terms: D000212:Acyclovir / Q000737:chemistry*; D000998:Antiviral Agents / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D002626:Chemistry, Pharmaceutical; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002855:Chromatography, Thin Layer / Q000379:methods; D004344:Drug Incompatibility; D005079:Excipients / Q000737:chemistry*; D006358:Hot Temperature; D007700:Kinetics; D007785:Lactose / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013607:Tablets; D053719:Tandem Mass Spectrometry
chemical_list: D000998:Antiviral Agents; D005079:Excipients; D013607:Tablets; D007785:Lactose; D000212:Acyclovir