NOVELTY - Process for the formulation of a pharmaceutical composition comprising zafirlukast comprises: brominating methyl 3-methoxy-4-methylbenzoate using a mixture of hydrogen bromide and a peroxide to afford methyl 3-methyloxy-4-bromomethylbenzoate; and condensing the methyl 3-methyloxy-4-bromomethylbenzoate with 1-methyl-5-nitro-1H-indole in the presence of a suitable catalyst to afford methyl 3-methoxy-4-(1-methyl-5-nitro-1H-indol-3-yl)methylbenzoate.    USE - The process is useful for formulating a pharmaceutical composition comprising zafirlukast. (I) is useful for analyzing zafirlukast or its related intermediates (claimed). The composition comprising zafirlukast is useful to treat asthma.    ADVANTAGE - The purified methyl-3-methoxy-4-(1-methyl-5-amino-1H-indol-3-yl)methylbenzoate has a purity of at least 99% by HPLC. The treated zafirlukast has a purity of at least 99% by HPLC. The process is simple, eco-friendly, cost-effective, robust, commercially viable and reproducible on an industrial scale.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a compound (I) including (3-(2-methoxy-4-(toluene-3-sulfonyl aminocarbonyl)-benzyl)-1-methyl-1H-indol-5-yl)-carbamic acid cyclopentyl ester, (3-(2-methoxy-4-(toluene-4-sulfonyl aminocarbonyl)-benzyl)-1-methyl-1H-indol-5-yl)-carbamic acid cyclopentyl ester, (3-(2-methoxy-4-methyl-benzyl)-1-methyl-1H-indol-5-yl)-carbamic acid methyl ester, (3-(2-methoxy-4-(toluene-2-sulfonyl aminocarbonyl)-benzyl)-1-methyl-1H-indol-5-yl)-carbamic acid methyl ester, 4-(5-cyclopentyloxycarbonylamino-1-methyl-1H-indol-3-yl-methyl)-3-methoxy-benzoic acid methyl ester, cyclopentyl N-(3-((5-(cyclopentoxycarbonylamino)-1-methyl-indol-3-yl)-(2-methoxy-4-(ortho-tolylsulfonylcarbamoyl)phenyl)methyl)-1-methyl-indol-5-yl)carbamate, (2,3-bis-(4-benzenesulfonylaminocarbonyl-2-methoxy-benzyl)-1-methyl-1H-indol-5-yl)-carbamic acid cyclopentyl ester or (3-(2-methoxy-4-(3-(2-methoxy-4-(toluene-2-sulfonylaminocarbonyl)-benzyl)-1-methyl-1H-indol-5-yl-carbamoyl)-benzyl)-1-methyl-1H-indol-5-yl)-carbamic acid cyclopentyl ester.