Avicenna commends cannabis, but recognises opium as "the most powerful of stupefacients". The medical and recreational use of opiates has been popular since the dawn of civilisation. Combined use of opium and another ancient respiratory depressant, ethyl alcohol, can dull pain and sometimes extinguish consciousness, not always reversibly. Both natural and synthetic opioids are widely used in contemporary surgical medicine. But their depression of respiratory function is a drawback.
Refs and Further Reading
Anaesthesia and Anaesthetics