Drastic rhymes with:
bombastic, dynastic, ecclesiastic, elastic, enthusiastic, fantastic, fantastik, gymnastic, iconoclastic, inelastic, interscholastic, monastic, onomastic, plastic, sarcastic, scholastic, stochastic, thermoplastic, unenthusiastic
Drastic sounds like:
dershowitz, dershowitz's, detracts, directs, draughts, drought's, droughts, drozdowski, druggist's, druggists