2-heterocyclyloxymethyl and 2-heterocyclylthiomethyl-1,2,5-thiadiazolidin-3-one 1,1-dioxides and compositions and method of use thereof

A compound of the formula:

• ##STR36## wherein R.sup.1 is hydrogen, lower-alkyl, or phenyl-lower-alkyl;
• R.sup.2 is hydrogen, lower-alkyl, or phenyl-lower-alkyl;
• R.sup.3 is hydrogen, or lower-alkyl;
• or R.sup.2 and R.sup.3 together are --(CH.sub.2).sub.n -- wherein n is 3 or 4;
• X is O or S;
• and R.sup.4 is a heterocycle selected from the group consisting of tetrazolyl, pyrazolyl, imidazolyl, thiadiazolyl, thiazolyl, and triazolyl which is attached through any available carbon atom thereof to the --X-- group or said heterocycle substituted on any available carbon atom thereof by lower-alkyl, or trihalomethyl;
• and/or on any available nitrogen atom thereof by lower-alkyl, or phenyl;
• or a pharmaceutically acceptable acid-addition salt thereof;
• or where applicable, an enantiomer or a racemic mixture thereof.