Utility of Ion-associate Formation Reactions for the Spectrophotometric Determination of Sildenafil Citrate in Pure form and in Virecta Tablets

Eman Y.Z Frag,Hana M.S Alelaiwi,Gehad G Mohamed

doi:10.4172/2153-2435.1000131

Abstract

A simple, rapid and sensitive extractive spectrophotometric method has been developed for the assay of sildenafil citrate (SILC) in pure and pharmaceutical formulations (Virecta tablets). This method is based on the formation of chloroform soluble ion-pair of SILC with bromothymol blue (BTB) and methylene chloride soluble ion- pair of SILC with bromophenol blue (BPB) and eriochrome blue black R (EBBR) in borax buffer of pH 3 and volume 1mL for BTB while acetate buffer of pH 3 and volume 1mL for BPB and universal buffer of pH 2 and volume 1.5 mL for EBBR with absorption maximum at 415, 420 nm and 510 nm for BTB, BPB and EBBR reagents, respectively. Reaction conditions were optimized to obtain the maximum colour intensity. The absorbance was found to increase linearly with the increase in SILC concentration, which was corroborated by the calculated correlation coefficient values (0.9909, 0.9901 and 0.9917 for BTB, BPB and EBBR reagents, respectively). The systems obeyed Beer’s law over the concentration range of 1-40, 1-50 and 3-70 μg mL -1 for BTB, BPB and EBBR, respectively. Various analytical parameters have been evaluated and the results have been validated by statistical data. No interference was observed from common excipients present in pharmaceutical formulations.

Highlights

Slidenafil,(5-[2-ethoxy-5-(4-methylpiperazin-1-ylsulfonyl) phenyl]-1-methyl-3 propyl-1, 6-dihydro-7H-pyrazolo [4, 3-d]pyrimidin-7-one), Figure 1 [1], is a potent and competitive inhibitor of the type-V cGMP specific phosphodiesterase enzyme, the predominant isoenzyme in the human corpus cavernosum
The present communication describes an extractive spectrophotometric procedure for the assay of sildenafil citrate (SILC) in pure form and in its formulations, which are based on the formation of ion-pairs with bromothymol blue (BTB), bromophenol blue (BPB) and eriochrome blue black R (EBBR) in acidic buffer
It was observed that the anionic dyestuff reagents namely BTB, BPB and EBBR, form ion-pairs with the positively charged sildenafil drug

Summary

Introduction

Slidenafil,(5-[2-ethoxy-5-(4-methylpiperazin-1-ylsulfonyl) phenyl]-1-methyl-3 propyl-1, 6-dihydro-7H-pyrazolo [4, 3-d]pyrimidin-7-one), Figure 1 [1], is a potent and competitive inhibitor of the type-V cGMP specific phosphodiesterase enzyme, the predominant isoenzyme in the human corpus cavernosum. The present communication describes an extractive spectrophotometric procedure for the assay of SILC in pure form and in its formulations, which are based on the formation of ion-pairs with bromothymol blue (BTB), bromophenol blue (BPB) and eriochrome blue black R (EBBR) in acidic buffer. Using different concentrations of SILC with BTB, BPB and EBBR reagents which were prepared and the procedure was carried out as mentioned before.

Results

Conclusion