Heroin Toxicity or Overdose
"The main toxic effect is decreased respiratory rate and depth, which can progress to apnea. Other complications (eg, pulmonary edema, which usually develops within minutes to a few hours after opioid overdose) and death result primarily from hypoxia. Pupils are miotic. Delirium, hypotension, bradycardia, decreased body temperature, and urinary retention may also occur.
"Normeperidine, a metabolite of meperidine, accumulates with repeated use (including therapeutic); it stimulates the CNS and may cause seizure activity."
"Opioids," The Merck Manual for Health Care Professionals, Special Subjects: Drug Use and Dependence, Opioids (Merck & Co. Inc., last revised July 2008), last accessed Feb. 16, 2013.