An injectable solution of a compound useful as an anti-ulcer agent of the formula; ##STR1## wherein R.sup.1 represents hydrogen, methoxy or trifluoromethyl group; R.sup.2 and R.sup.3, being the same as or different from each other, represent hydrogen or methyl group; and R.sup.4 represents a fluorinated C.sub.2 to C.sub.5 lower alkyl group, is provided by dissolving the compound in at least one of ethanol, propylene glycol and polyethylene glycol; or by dissolving the freeze-dried material of an alkaline aqueous solution of the compound in a mixture of an acidic substance and at least one of the above solvents.