Barbiturates-barbiturates may be used to induce a coma in a patient with increased icp. this decreases cortical activity and cerebral metabolism, reduces cerebral blood volume, decreases cerebral edema, and reduces the brains need for glucose and oxygen. carbonic anhydrase inhibitors are used to decrease ocular pressure or to decrease the serum ph in a patient with metabolic alkalosis. anticholinergics have many uses including reducing gi spasms. histamine receptor blockers are used to decrease stomach acidity.