Opioids Opioids in general cause respiratory depression, miotic pupils and some mild hypotensions and bradycardia when the patient is comatose. All opioids can cause varying degrees of histamine release. However, not all opioids are similiar, here are the unique toxicities of some various opioids - keep them in mind when you prescribe them: 1) Propoxyphene - seizures and TCA like effects, also not very effect analgesic 2) Meperidine - seizures, serotonergic (thus increased abuse potential) 3) Methadone - long half-life (30+hrs) and QT prolongation 4) Hydromorphone - rare seizures and most common opioid that causes iatrogenic overdose because of its potency. (Easy to write 2 mg of "Dilaudid" but that is equivalent to 14 mg of morphine!) 5) Tramadol - seizure (common) and serotonergic, this is only 20% opioid 6) Fentanyl - rigid chest syndrome with rapid IV administration causes intercostal muscle contraction - not good
