Available online at www.scholarsresearchlibrary.com Scholars Research Library Der Pharmacia Lettre, 2011: 3 (5) 173-178 (http://scholarsresearchlibrary.com/archive.html) ISSN 0974-248X USA CODEN: DPLEB4 173 Scholar Research Library Studies on physical /chemical compatibility between synthetic and herbal drugs with various pharmaceutical excipients Santanu Mallik,* 1 Mahendra D. Kshirsagar, 2 Vipin Saini 3 1 Mahatma Jyoti Rao Phoole University, Achrol, Rajasthan 2 Dept. of Pharmacy, P. Wadhwani College of Pharmacy Yavatmal, Maharashtra 3 MM College of Pharmacy, MM University, Mullana, Haryana _____________________________________________________________________________ ABSTRACT Stability of Pharmaceutical formulations are oftenly challenged by compatibility between drugs and excipients. The objective of the present study is to identify compatibility between drug:drug and drugs:excipient. Curcumin and Tretinoin were selected as model drug where Ethyl cellulose (EC) and Poly vinyl alcohol (PVA) as excipients. The study was done by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction study (XRD) and Thin layer chromatography (TLC). The spectrophotometric graphs revealed that there was no significant changes in position of functional groups of Curcumin, Tretinoin, EC and PVA (O-H, C=O, C-H str.) in pure drugs and excipients with respect to their physical mixtures. X-ray diffraction study reflects that the characteristic peaks of curcumin appeared at a diffraction angle of 2 at 7.95 0 , 8.80 0 , 12.28 0 , 17.29 0 showing that Curcumin and Tretinoin was present as a crystalline form as well. The R f values of the physical mixtures obtained from TLC study on the 0 th and 30 th day were approximately similar to the R f values of the pure Curcumin and Tretinoin. The above spectrophotometric data and retention factor clearly implies that the synthetic-herbal drug combinations with pharmaceutical excipients are compatible with each other and can be introduced for successful development of novel drug delivery system. Keywords: FTIR, Compatibility study, TLC, Curcumin, Tretinoin, XRD. _____________________________________________________________________________ INTRODUCTION Assessment of drug-drug-excipients compatibility is very important to identify product’s stability as well as its reproducibility with ensured therapeutic efficacy[1]. Although excipients selected for pharmaceutical formulations bears no pharmacological significance i.e. inert in nature[2]. But the excipients may participate in physical and chemical interaction and cause serious degradation of active pharmaceutical ingredients with poor dissolution rate and non-