mg kg daily orally or parenterally in single or two to four divided doses up to about 500 mg of a compound of formula i or a physiologically acceptable salt thereof is administered by incorporating in an oral dosage form such as tablets capsules or elixirs or in an injectable form in a sterile aqueous vehicle prepared according to conventional pharmaceutical practice the following examples are illustrative of the invention all temperatures are in degrees celsius additional variations are produced in the same manner by appropriate substitution in the starting material 10 08 g 60 mm of u03b1 mercaptophenylacetic acid and 6 6 g 60 mm of triethylamine are dissolved in 50 ml of tetrahydrofuran and 3 42 g 60 mm of methylisocyanate dissolved in 20 ml of tetrahydrofuran are added dropwise with stirring after stirring for 2 hours the solvent is drawn off in a vacuum and the oily residue is dissolved in water the mixture is then acidified with 2n hydrochloric acid and extracted three times each with 20 ml of ether after drying off the ether 10 5 g of white crystalline dl methylamino carbonyl thio phenylacetic acid are obtained which is recrystallized from ether petroleum ether m p 128 u00b0 129 u00b0 by substituting ethylisocyanate for.