A rapid and sensitive reverse phase RP-HPLC method is proposed for the estimation of tamsulosin hydrochloride in tablets. Tamsulosin hydrochloride was chromatographed on a reverse phase C18 column with a mobile phase consisting of acetonitrile and water in the ratio of 50:50 v/v. The mobile phase was pumped at a flow rate of 1.5 ml/min. The eluents were monitored at 214 nm. The retention time of the drug was 1.7 min. With this method, linearity was observed between area under curve and concentration of tamsulosin hydrochloride in the injected solution, in the range of 5 to 100 μg/ml. The method was found to be applicable for analysis of the drug in tablets. The results were validated statistically.
The wide biological activity of 2-substituted 2-imidazolines has stimulated considerable synthetic work on this heterocycle. Phentolamine is well known drug of this family possessing antiallergic activity 1 and α-adrenergic activity. 2 Previous syntheses of this well known drug start with the cyanomethylation of the N-4-methylphenyl-N-3-acetoxyphenylamine with NaCN and formaldehyde requiring a closed vessel. 3 In other reported methods, the N-alkylation of N-4methylphenyl-N-3-hydroxyphenylamine with 2-chloromethyl-4,5-dihydro-1H-2-imidazole hydrochloride requires rather harsh conditions 3,4 (130-150 °C, closed vessel in some cases). Moreover the phentolamine obtained by this method requires a complicated purification. 3 Another logical route, the Nalkylation diphenylamines with ClCH 2 CN, has not yet been explored for the synthesis of the title compounds.The alkylation of diphenylamine 1a with ClCH 2 CN was undertaken first. As shown in Table 1, all our attempts to alkylate 1a with ClCH 2 CN in CH 3 CN, DMF, DMSO and THF as reaction medium were unsatisfactory. Although the alkylation of 1a with ClCH 2 CN and NaI in presence of KF, DMAP, Et( i Pr) 2 N in HMPA at 100°C afforded the corresponding N-alkylated nitrile 2a, the alkylation in absence of any base other than diphenylamine (substrate) itself in HMPA was most suitable. The structure of 2a was ascertained from its elemental and spectroscopic data. The IR spectrum of 2a displayed C-N str. at 2260 cm -1 for CN group and the 1 H-NMR spectrum displayed a two-proton singlet at δ H 4.4 (CH 2 -CN) thus confirming the alkylation of 1a with chloroacetonitrile. The yield of 2a exceeds 50% even though the N-alkylation of 1a is carried out in absence of any base other than diphenylamine (substrate) itself. This may be explained on the basis of formation of 1:1 complex 5 of A with HMPA and thus preventing the formation of equilibrium with another molecule of diphenylamine to give diphenylammonium iodide (Scheme 1). This standardised protocol was then utilised for the alkylation of other diphenylamine derivatives withThe alkylation of diphenylamines with chloroacetonitrile followed by annulation with ethylenediamine gave 2-imidazoline analogues of phentolamine.
Different N-benzyl anilines were N-alkylated with chloroacetonitrile to give the corresponding nitriles, which were subsequently condensed with ethylenediamine in the presence of thioacetamide to afford the corresponding title antazoline derivatives.
Two simple, precise and accurate visible spectrophotometric methods were developed for the estimation of Aceclofenac in bulk drug and in pharmaceutical formulations. The proposed methods were indirect and based on determination of aceclofenac after its reaction with either (p-dimethylaminocinnamaldehyde or 3-Methyl-2-benzothiazolinone hydrazine hydrochloride and measuring the chromogen at the λmax by 658 and 592, respectively. Beers law obeyed in the concentration range of 1-200 μg/ml for method A and 1-100 μg/ml for method B. The accuracy of the methods was determined by recovery studies. The methods showed good reproducibility and recovery with relative standard deviation (in %) less than 2. The methods were found to be simple, economical, accurate and reproducible and can be used for routine analysis of Aceclofenac in bulk drug and in pharmaceutical formulations.
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