PHARMACOLOGIC PROPERTIES OF CYCLIZINE HYDROCHLORIDE (MAREZINE)

In anesthetized cats cyclizine blocks the vagus response, relaxes the tone and rhythmic contractions of the ileum and blocks injected histamine at low doses (0.5 mgm./kgm.). Doses up to 8 mgm./kgm. have little or no effect on the pupil, or on injected acetylcholine, epinephrine or norepinephrine but block responses to serotonin. Cyclizine is effective in reducing the mortality in guinea pigs exposed to nebulized histamine. The local anesthetic effects of cyclizine are similar to procaine when compared by the guinea pig wheal method. Cyclizine does not appear to block the sympathetic system and does not produce neuromuscular block. It is suggested that cyclizine may specifically block the vagus nerve peripherally. That this block may also be central is indicated by the antiemetic properties of the compound.