Abstract: Pharmacologically valuable esters of isobutyric acid have the general formula ##STR1## in which R is biphenylyl, norbornyl or para-cyclohexylphenyl and R.sup.1 and R.sup.2 are each lower alkyl groups or R.sup.1 and R.sup.2 together with the nitrogen atom to which they are linked is a saturated heterocyclic group which may contain an additional hetero atom. The esters may be used in the form of their salts with pharmaceutically acceptable acids.The esters and their salts possess spasmolytic and vasodilatory activity and are useful in the treatment of arterial disorders.