Simultaneous determination of loratadine and pseudoephedrine sulfate in pharmaceutical formulation by RP-LC and derivative spectrophotometry.

Highly sensitive, simple and accurate reversed phase liquid chromatographic and first derivative spectrophotometric methods for determination of antihistaminic drug loratadine [I] and nasal decongestant drug pseudoephedrine sulfate [II] are described. The HPLC method involves separation of [I] and [II] on micro-BondaPak C18 column using mixture of (methanol:H(2)O:phosphoric acid:ammonium dihydrogen phosphate) (220:300:2:3 g) (V/V/V/W), 60 and 40% acetonitrile as mobile phase flowing at 2 ml/min with ultraviolet detection at 247 nm. The calibration graphs are linear from 5 to 100 microg/ml for [I] and from 120 to 1200 microg/ml for [II] the detection limits are 0.5 microg/ml for [I] and 60 microg/ml for [II]. The spectrophotometric method is based on recording the first derivative spectra for [I] and [II] at 307, 266 nm, respectively, of their solutions in 0.1 M hydrochloric acid using the acid as blank. The calibration graphs are linear in the range of 5-25 microg/ml for [I] and 240-720 microg/ml for [II]; the limits of detection are 0.16 microg/ml for [I] and 10 microg/ml for [II]. The mean percentage recoveries obtained for different synthetic mixtures by using this method are 97.6% with coefficient of variation 1.79 for [I] and 101.6% with coefficient of variation 1.95 for [II]. The two methods have been applied successfully for the determination of [I] in its combination with [II] Clarinase tablets and [I] alone in different pharmaceutical dosage forms.