Abstract

Spectrophotometric determination of some anti-tussive drugs and its applications to pharmaceutical formulations

Author(s): Ayman A.Gouda, Ragaa El-Shiekh, Alaa S.Amin

Four simple, sensitive and reproducible spectrophotometric methods for the determination of some Anti-tissuve drugs, pipazethate hydrochloride (PiCl), dextromethorphan hydrobromide (DEX) and butamirat citrate (BT) in bulk samples and in pharmaceutical formulations are described. The first and second methods, are based on the charge-transfer complex formation of DEX and BT as n-donors and 2,3-dichloro-5,6 dicyano-p-benzoquinone (DDQ) or p-chloranilic acid (p-CA) as -acceptors to give highly coloured species. The coloured products are measured spectrophotometrically at 465 and 462 for DEX and BT, respectively using DDQ (Method A) and at 530 and 525 nmfor DEX and BT nm, respectively using p-CA (Method B). The thirdmethod is based on the oxidation of the studied drugswith ammonium metavanadate in sulphuric acid medium resulting in the development of a greenish blue colour at 759, 765 and 766 nm for PiCl, DEX and BT, respectively (Method C). The fourth method is based on the formation of an ion-association complex with alizarin red S as chromogenic reagents in acidic medium, which is extracted into chloroform. The complexes have a maximumabsorbance at 425 and 428 nmfor DEX and (PiCl or BT), respectively (Method D). Regression analysis of Beer-Lambert plots showed a good correlation in the concentration ranges of 20-240g ml-1 for DDQ (MethodA), 30-360gmL-1 for p-CA(MethodB), 0.05-0.6mgmL-1 for ammonium metavanadate (Method C) and 2.0-24g mL-1 for alizarin red S (Method D). For more accurate analysis, Ringbom optimum concentration ranges were calculated. The molar absorptivity, Sandell sensitivity, detection and quantification limits were calculated. Applications of the procedures to the analysis of various pharmaceutical preparations gave reproducible and accurate results. Further, the validity of the procedures was confirmed by applying the standard addition technique.