Medicine & USMLE


Neuro Drugs
  1. Levodopa, Carbidopa
  2. Levetiracetam
  3. Valproic Acid
  4. Anticholinergic Syndrome
  5. Cholinergic Crisis
  6. Benztropine / Trihexyphenidyl
  7. Lidocaine
  8. Pyridostigmine, Neostigmine, Edrophonium
  9. Naltrexone
  10. Pregabalin
  11. Scopolamine
  12. Phenytoin
  13. Ethosuximide
  14. Succinylcholine
  15. Opioids
  16. Memantine
  17. Halothane / Flurane
  18. Donepezil
  19. Propofol
  20. Ergotamine
  21. Triptans
  22. Selegiline / Rasagiline
  23. Entacapone / Tolcapone
  24. Gabapentin
  25. Lamotrigine
  26. Carbamazepine
  27. Ramelteon


Opioids are a large class of drugs typically used to treat moderate to severe pain. Important drug names to know include morphine and the related drug hydromorphone, codeine and the related drugs oxycodone and hydrocodone, tramadol, fentanyl, buprenorphine, and methadone. Opioids carry a risk of dependence and addiction, but they are considered safe when used as prescribed. The biggest adverse effect of opioids is respiratory depression, so it’s extremely important to monitor the patient’s respiratory rate throughout treatment. Other expected side effects include constipation, sedation, orthostatic hypotension, urinary retention, nausea and vomiting, as well as miosis. The antidote of an acute opioid intoxication is naloxone, which can be used to reverse the effects of opioids in the event of an overdose.

Key Points

  • Opioids
    • Key Drugs
      • Fentanyl
      • Morphine, Hydromorphone (Dilaudid)
        • Hydromorphone is approximately 6x more powerful than morphine
      • Codeine, Hydrocodone, Oxycodone
      • Methadone
        • May also be used as part of an addiction treatment regimen
      • Tramadol
      • Buprenorphine
    • Mechanism
      • Opioid analgesics / Opioid agonists
        • Primarily bind to the mu-opiate receptors to provide analgesia (pain relief)
        • Weak activation of the kappa-opiate receptors to also provide analgesic effect
        • Cause CNS depression
    • Clinical Use
      • Pain (analgesia)
        • Used only for moderate to severe pain
        • Pain is best controlled when opioid is given before the pain becomes unbearable
      • Cough suppression
        • Codeine has antitussive effects
    • Side Effects
      • Addiction/Dependence
        • Range between schedule I and schedule V controlled substance categories
        • Short-term use of narcotics for acute pain is considered safe and not likely to cause dependence or addiction.
        • Symptoms of withdrawal syndrome include irritability, nausea, vomiting, sweating, restlessness, tachycardia, and hypertension
      • Respiratory depression
        • Monitor respiratory rate frequently. Respiratory rate should be above 12 breaths per minute.
        • Use opioids with caution in people with these risk factors: elderly, underlying pulmonary disease, obesity, history of smoking, history of snoring, opiate naive, and post-surgery
      • Constipation
        • Patient will often be prescribed a mild laxative to be taken as needed
        • Increase fiber and fluid intake in diet
        • Tolerance does NOT develop to this side effect
        • Avoid in patients with paralytic ileus (e.g. post-op); use NSAIDs like ketorolac instead
      • Sedation
        • Do not take opioids with other CNS depressants (e.g. alcohol)
      • Orthostatic hypotension
        • Opioids dilate peripheral blood vessels and can cause hypotension that is most noticeable upon standing
        • Advise patient to rise slowly to avoid sudden drop in blood pressure
      • Miosis (pupil constriction)
        • Pinpoint pupils can indicate opioid overdose
        • Tolerance does NOT develop to this side effect
      • Urinary retention
        • Monitor intake and output
      • Nausea/Vomiting
        • Patients can take the drug with food to reduce GI irritation with orally-administered opioids
      • Pruritus (itching)
        • When giving via IV push, administer over 2-3 minutes to avoid pruritus, as well as nausea and flushing.
    • Antidote
      • Naloxone (Narcan)
        • Reverses the effects of opioid overdose (respiratory depression, sedation, hypotension)
        • Often multiple doses will be required. The nurse must carefully monitor respiratory rate to ensure the patient doesn’t fall back into respiratory depression.