Opiates are considered opium, morphine, pethidine, diamorphine, methadone, pentazocine, and dextropropoxyphene. These are able to sedate pain and result in drug dependence. Their production and sale are under strict control of the law. Overdose can be due to therapeutic excess, voluntary or negligent self-administration. In addition to the analgesic effect, these drugs have the ability to depress the entire central nervous system. The triad formed by coma, respiratory depression, and point myosis is diagnosed and often associated with cyanosis. Usually skeletal muscles are flaccid, and cardiovascular collapse is not severe.
Diagnosis and treatment
Circumstances usually lead to the diagnosis, and the sign of a recent injection is an important clue to look for in any case. Treatment is a true urgency and should never be postponed. To combat coma and respiratory depression, a specific antidote must be administered. Within a few minutes there is an improvement in breathing. In case there is no improvement one must opt for a different cause than opiate poisoning.
Source: Vadecum of poisoning therapy by Roy Goulding