In the 19th century, opiate-based preparations were legion. Patent medicines were taken as cure-alls in an age when cures were rare. The use and abuse of opiate-based remedies has been treated scornfully by medical historians. But taken sparingly and judiciously, they offered more effective pain-relief than is readily available over-the-counter today.
Opioids are used by anaesthetists in contemporary surgery as induction agents, as post-operative analgesics and as an ingredient in the maintenance of "balanced anaesthesia". In the pre-anaesthetic era, their use prior to surgery was erratic. The dose of opium and ethanol needed to induce stupor or insensibility may well kill one patient even if it merely knocks out another.
Refs and Further Reading
Anaesthesia and Anaesthetics