An anti-emetic drug that also decreases acid secretion due to its action on H1 receptors is :
Promethazine is a first-generation H1-antihistaminic drug. It is indicated for the treatment of allergic reactions. Because of its anticholinergic action and ability to cross the blood-brain barrier, it can be used as an antiemetic (particularly for prophylaxis of motion sickness) and as an anti-Parkinsonian drug (particularly in drug-induced Parkinsonism).
Acid secretion is reduced mainly by H2-blocking drugs like ranitidine but even H1-antihistaminics can also reduce acid secretion at high doses (due to lack of selectivity at such high dose).
Promethazine
Domperidone
Metoclopramide
Ondansetron