Abstract
A simple, sensitive and rapid spectrophotometric methods were developed and validated for the determination of two antihypertensive drugs namely, carvedilol and nebivolol hydrochloride in pure form and pharmaceutical formulations. Method (I) is based on the formation of a binary complex between the studied drugs and eosin Y in presence of tween 80 at (pH 3.0).The formed complex exhibited maximum absorption at 545 nm for carvedilol and 543 nm for nebivolol. The concentration plots were rectilinear over concentration range of 0.5-5 and 1-7 µg/mL with lower detection limits of 0.09 and 0.11µg/mL and lower quantitation limits of 0.28 and 0 .34 µg/mL for carvedilol and nebivolol respectively. Method (II) is based on the reaction of studied drugs through their secondary amino groups with 2, 4-dinitrofluorobenzene (DNFB) at pH 8 to form yellow colored reaction products peaking at 383 nm and 390 nm for carvedilol and nebivolol, respectively. The absorbance-concentration plots were rectilinear over the concentration ranges of 5-30 and 4-28 µg/ mLwith the lower detection limits of 0.48 and 0.51 µg/mL and the lower quantitation limits of 1.45 and 1.54 µg/mL for cavredilol and nebivolol respectively. The different experimental parameters affecting the development and stability of the formed complex and reaction products were carefully studied and optimized for both methods. Both methods were successfully applied for determination of the studied drugs in their dosage forms.
Highlights
Nebivolol HCl (NEB) is approximately 3.5 times more β1-adrenoceptor-selective than other β1adrenergicblockers in human myocardium and might be the most β1-adrenoceptor-selective antagonist available for clinical practice at the moment. It has a combined vasodilating β1-blocker activity with a vasodilatin effect mediated by the endothelial L-arginine nitric oxide pathway .Several analytical methods were developed for the assay of nebivolol [1]
NEB and CAR were found to react with DNFB in presence of borate buffer producing a yellow color peaking at 383 and 390 nm. (Figures. 2, 3)
To remove the interference of excess DNFB reagent on absorbance measurements of the reaction products, the excess reagent was acid hydrolyzed to colorless 2, 4- dinitrophenol by adding 0.2 mL of HCl
Summary
Nebivolol HCl (NEB) is approximately 3.5 times more β1-adrenoceptor-selective than other β1adrenergicblockers in human myocardium and might be the most β1-adrenoceptor-selective antagonist available for clinical practice at the moment It has a combined vasodilating β1-blocker activity with a vasodilatin effect mediated by the endothelial L-arginine nitric oxide pathway .Several analytical methods were developed for the assay of nebivolol [1]. Carvedilol (CAR) is a non-cardio selective beta blocker. It has vasodilating properties, which are attributed mainly to its blocking activity at alpha receptors at higher doses calciumchannel blocking activity may contribute. It is used to reduce mortality in patients with left ventricular dysfunction after myocardial infarction [1, 2]
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