Spectrophotometric Determination of Bisacodyl and Piribedil

ABSTRACT

Simple spectrophotometric methods are described for the assay of bisacodyl (BIS) and piribedil (PIR) based on charge‐transfer and ion‐pair complexation reactions. The first method is based on the reaction of the cited drugs with p‐chloranilic acid (p‐CA) in acetonitrile. The purple colored chromogen formed shows maximum absorbance at 518 nm. The second method is concerned with the reaction of the investigated drugs with picric acid (PA) and four sulphonphthalein acid dyes, namely; bromocresol green (BCG), bromocresol purple (BCP), bromophenol blue (BPB) and thymol blue (TB). The yellow ion‐pair complexes formed show absorption spectra with maxima within the range from 400 to 415 nm. The stoichiometric ratio was found to be 1:1, for all complexation reactions examined, as calculated by the continuous variations method. Beer's law validation, accuracy, precision, limits of detection, limits of quantification, and other aspects of analytical merit are presented in the text. The proposed methods were applied for the determination of the analytes in their pure forms and in pharmaceutical preparations. The results were in good agreement with those obtained by the official and reported methods.

Keywords:

• Bisacodyl
• Piribedil
• Spectrophotometry
• Charge‐transfer and ion pair complexation reactions

Notes

Note: S _y/x , standard error of estimates; S _a , standard deviation of intercept; S _b , standard deviation of slope; LOD, limit of detection; LOQ, limit of quantification.

Note: S _y/x , standard error of estimates; S _a , standard deviation of intercept; S _b , standard deviation of slope; LOD, limit of detection; LOQ, limit of quantification.

^a Mean ± standard deviation of five determinations.

^b Percentage relative standard deviation.

^c Percentage relative error.

^d The critical t value at 0.01 significance level = 4.604.

^a Mean ± standard deviation of five determinations.

^b Percentage relative standard deviation.

^c Percentage relative error.

^d The critical t value at 0.01 significance level = 4.604.

^a Mean ± standard deviation of five determinations.

^b Labeled to contain 10 mg BIS per tablet. It is manufactured by Pharco Pharmaceuticals Co., Alex., Egypt.

^c Ref.3.

^d Tabulated F‐value for P = 0.05 and f ₁ = 5, f ₂ = 24.

^e Labeled to contain 5 mg BIS per suppository. It is manufactured by Amriya Pharm. Ind., Alex., Egypt.

^f Labeled to contain 20 mg PIR per tablet. It is manufactured by Servier Egypt Ind. Ltd., 6th October City, Egypt under license of Les Laboratories Servier, France.

^g Ref.14.