Prepared from morphine by the action of hydrochloric acid. An active and certain emetic, which acts indirectly or through the vomiting centre in the medulla. It may therefore be given hypodermically if the patient be unable to swallow. In from five to twenty minutes it causes nausea and repeated vomiting.

If taken by the stomach it does not irritate, and leaves no ill after-effects. Very large doses cause prostration and paralysis of the voluntary muscles and depression of the respiratory centre.

Small doses are expectorant, but it is not much used in this way.

Average dose, expectorant, gr. 1/20-0.003 Gm.

Average dose, emetic, by mouth, gr. 1/6-0.01 Gm.

Average dose, emetic, by hypodermic, gr. 1/20-0.005 Gm.