pethidine

see also opiates and opioids, pain, analgesia and analgesics

Pethidine is no longer recommended for primary care analgesia as:

• shorter acting opioid analgesic than morphine
• half-lives of pethidine & its active metabolite norpethidine, exceed duration of analgesia:
  • repeated doses to obtain satisfactory analgesia results in accumulation of norpethidine, increasing risk of toxicity, esp. if renal impairment:
    • excitation, twitching, tremor, agitation, convulsions
• widely considered to be associated with drug-seeking behaviour, esp. for recurring conditions such as migraine
• pethidine has no role in Mx of migraine, low back pain or chronic pain
• pethidine is no longer regarded as having a significant role in the management of ED patients, and thus, many ED's have decided to stop using it because of its tendency for substance abuse and that there are more effective options.
• indications for pethidine are very limited and usually restricted to:
  • maternity
  • oncology
  • palliative care
  • true type I hypersensitivity reactions to opiates (but anaphylaxis to opiates is actually quite rare)
  • certain rare conditions such as systemic mastocytosis which is associated with true anaphylaxis to NM blockers and opiates.
• pethidine is NOT the analgesic of choice for migraine, pancreatitis, biliary or renal colic.
• chronic pain patients should be considered for referral to a chronic pain service
• patients requesting pethidine should be considered for referral to an addiction medicine specialist.
• anaphylaxis to opiates is rare
• patients thought to have allergies to opiates should be referred to allergy testing to clarify this, either:
  • skin testing (eg. Dr Karl Bleasel, RMH Immunology, fax: 03 9349 3199) - may take 2-3 months to arrange
  • morphine RAST test (biochem serology blood tube) - takes 2-3 weeks for results.