Trifluoperazine HCl (TFP) and isopropamide iodide (ISP) are commonly used as antipsychotic drugs. The stability of the two drugs was investigated against stress oxidation conditions and the effects of time and temperature on the degradation rate were studied. Separation was carried out on Agilent ZORBAX-CN column (150 X 4.6 mm id, 5µm particle size). The mobile phase composed of acetonitrile: 0.05 M phosphate buffer pH 3.5±0.1 containing 0.1% triethylamine adjusted with orthophosphoric acid 85 % 40:60 (v/v), pumped at flow rate 1 ml/min and UV detection was carried out at 220 nm.
The method had been validated as per the ICH guidelines and was successfully applied for the determination of the two drugs in their pharmaceutical dosage form in concentrations as low as 1 µg/ml. Human plasma were analyzed by including an early solid phase extraction step on a StrataTM -X-CW 33 µm weak polymeric cation exchanger prefilled tubes, conditions were optimized to maximize recovery of TFP and ISP and reduce noise in plasma samples.
Keywords: HPLC; Solid phase extraction; CN-column; Trifluoperazine Hydrochloride; Isopropamide Iodide.