Analytical study on determination of some drugs in pure form and in dosage form

Abstract

Several methods were developed for determination of omeprazole lansoprazole, mesalazine in pure forms and in pharmaceutical preparations. The first proposed method was spectrophotometric method, involves the oxidation of these drugs with potassium iodate in acidic medium with the liberation of iodine and subsequent extraction with cyclohexane followed by measuring the absorbance at λ = 520 nm under the optimized experimental conditions. Beer’s law is obeyed in the concentration range of 5-200 and 15-200 µgmL-1 with apparent molar absorptivities of 2.42x10-4 and 2.01x10-4 Lmol-1cm-1 for omeprazole and lansoprazole, respecivitiy. The second method was the potentiometric method involved the direct titration of the drugs with N-bromosuccinimide in acid medium and the end point is subsequently potentiometrically determined using platinum indicator electrode under the obtained optimum conditions. Omeprazole and lansoprazole could quantitatively be determined in the concentration range 25-100 and 15-100 mgml-1 with standard deviation of 0.007-0.042 and 0.005-0.034, and with relative standard deviation of 0.79-2.4 and 1.4-2.9. The third method TLC-densitometric method for drugs omeprazole using silica gel plates in simultaneous determination of omeprazole, tindazole and doxycyline in bulk powder; laboratory prepared mixture and combined dosage form. The technique adapted for quantification is coupled TLC-densitometry. The mobile phase used a mixture of methylene chloride : butanol : acetonitrile : Amonia (11:12:5:0.5 v/v/v/v). The detection of spots was carried