Anti-histaminics of the formula ##SPC1## Wherein R.sub.1 is alkyl, alkenyl or phenalkyl, R.sub.2 and R.sub.3 are alkyl or alkenyl and R and R' are optional are prepared by alkylating or alkenylating a 1-substituted-2-monoalkyl- or alkenylamino-quinazolin-4(1H)-one with an alkyl or alkenyl halide.