In vitro interaction studies of diltiazem with NSAID's using UV spectrophotometry and RP-HPLC techniques

Diltiazem [DTZ] is a well-known cardiovascular drug used clinically in the treatment of angina pectoris and hypertension. Present paper deals with the in vitro available studies of DTZ in presence of commonly used nonsteroidal anti-inflammatory drugs [NSAID's] like diclofenac sodium, flubiprofen, mefenamic acid and meloxicam. Simultaneous administration of both types of drugs may alter the antihypertensive effect of DTZ. These studies were carried out using BP 2005 dissolution test apparatus in simulated human body environments at body temperature and at elevated temperature in order to study the kinetics and energitics of these interactions. Both the drug in each case were analyzed either by measuring the absorbance of aliquots on a UV/VIS spectrophotometer, or by RP-HPLC method. Present study clearly indicated that most of the NSAID's studied bind to DTZ forming charge transfer complexes, evident from the high availability of DTZ. Hence, concurrent administration of NSAID's with DTZ is not recommended

validated method for the analysis of diltiazem in raw materials and pharmaceutical formulations by RP-HPLC

A simple, selective and rapid reversed phase high performance liquid chromatographic [HPLC] method for the analysis of diltiazem [DTZ] in bulk material and pharmaceutical formulations has been developed and validated. Sample was resolved on a Hypersil, ODS, C- 18 [1 50x4.6 mm, 5 micron] column. The mobile phase consisted of methanol- water [80:20 v/v, pH 3.1 adjusted with phosphoric acid] was delivered at a flow rate of 0.5 ml/min at ambient temperature and the retention time was about 2.6 minutes with symmetrical peaks. Studies were performed on an HPLC system equipped with a UV/ visible detector at 236nm. Flurbiprofen [FLR] was used as an internal standard. The developed method gave good resolution between diltiazem and internal standard. The method is specific to DTZ and able to resolve the drug peak from formulation excepients. The calibration curve was linear over the concentration range of 0.195-50 micro g/ml [R[2] = 0.999]. The proposed method is accurate [the accuracy results were 94.1-99.39 for diltiazem recoveries], precise [The intraday and interday precision CVs were 0.035-2.2%] and linear within the desired range. The lower limits of detection for DTZ was found to be 0.0 184 microg/ml and the quantitation limit was about 0.0564 micro g/ml and therefore could be employed as a more convenient and efficient option for the analysis of diltiazem and its related compounds in drug substance and formulations