<prompt> Bheka isigaba esingezansi bese uphendula umbuzo emva kwalokho ngolimi olufanayo nesigaba: Ukudlula: Ama-isomer anezakhiwo ezahlukene zokwelapha ajwayelekile; isibonelo, ukubekwa kwamaqembu e-methyl. Kuma-xanthines athathelwe indawo, i-theobromine, etholakala kushokoledi, i-vasodilator enemiphumela ethile efanayo ne-caffeine; kodwa, uma elinye lamaqembu amabili e-methyl lisuswa liye endaweni ehlukile enkabeni enezindandatho ezimbili, i-isomer yi-theophylline, enemiphumela ehlukahlukene, kufaka phakathi i-bronchodilation nesenzo sokulwa nokuvuvukala. Esinye isibonelo salokhu sitholakala emithini evuselelayo esekelwe ku-phenethylamine. I-Phentermine iyinhlanganisela engeyona i-chiral enomphumela obuthakathaka kunowama-amphetamine. Isetshenziswa njengomuthi wokunciphisa isifiso sokudla futhi inezakhiwo ezikhuthazayo ezincane noma engenazo nhlobo. Nokho, ukwakheka kwama-athomu okuhlukile kuveza i-dextromethamphetamine, okuyisikhuthazi esinamandla kune-amphetamine. Umbuzo: Yini etholakala kushokoledi enomphumela ovamile oshokoledi?  <response>: i-theobromine 