Abstract: A 3,3-diphenylpropylamine of the formula I, or its physiologically acceptable acid salt thereof: ##STR1## wherein R.sup.1 represents hydrogen or methyl, R.sup.2 and R.sup.3 independently represent hydrogen, methyl, methoxy, hydroxy, carbamoyl, sulphamoyl or halogen, and X represents a tertiary amino group of formula II ##STR2## wherein R.sup.4 and R.sup.5 independently represent a hydroxy substituted or unsubstituted non-aromatic hydrocarbyl group which can join together to form a ring and which together contain at least three carbon atoms, wherein at least one of R.sup.4 and R.sup.5 is hydroxy substituted, is useful in treating acetylcholine-mediated disorders such as urinary incontinence.