A pharmaceutical composition comprising an ester of 4-(1-hydroxy-1-methylethyl)-2 propyl-1-[[2′-(1H-tetrazol-5-yl)[1,1′-biphenyl]-4-yl]methyl]-1H-imidazole-5-carboxylic acid characterized in that when exposed to 75% relative humidity at 40° in open dish for one month the total amount of related substances does not increase more than 1% is described.
