Narcotics and Abuse Flashcards
Opioid mechanism of action
receptors in brain, spinal cord, and peripheral nerves, inhibit the release of substance P and its transmission from the dorsal horn
Opioid receptors and how opioids block signaling
GCPRs, the increase K+ efflux and inhibit Ca influx-> inhibits cAMP production
Op receptor subtypes, which is most targeted
Mu, delta, kappa: Mu is most targeted
Actions of Mu receptors
analgesia, decreased respiration, decrease GI motility, Increased appetite, sedation, decrease release of ACh and DA, miosis
Op tolerance
desensitization, receptor internalization
Bolus effect
effects could wear off before next dose because of its short half life, could make the patient appear to be drug seeking
Morphine
two major active metabolites, M6 is most active
Codeine
low receptor affinity, converted to morphine; because it is metabolized by CYP2D6, some caucasians may not be able to convert
Tramadol
synthetic codeine analog, less effective for severe pain but less constipation and less addicting
Fentanyl
very potent, long half life, patch for long term effect, be careful when changing dose
methadone
treat chronic pain and heroine users, very long half life and inexpensive
Oxycodone
very effective, oral agent, long acting, wide spread abuse and overdose
Meperidine
no longer recommended
Opioid antagonists
naloxone and nalmefene (opioid toxicity), naltrexone (alcoholism)
Caution with acetaminophen
most opioids are given in combination with acetaminophen, counsel patients
