Drugs for Pain & HA.docx - Opioids Mu receptors activation...

Opioids
Mu receptors : activation includes analgesia, respiratory depression, euphoria and sedation
Kappa receptors : produces analgesia, sedation, and respiratory depression
Pure Opioid Agonists : activate Mu and Kappa receptors, product analgesia, euphoria, sedation,
respiratory depression, physical dependence, constipation
Two subgroups
Strong opioid agonists: morphine
Moderate to strong opioid agonist: codeine oxycodone, hydrocodone,
Agonist-Antagonist Opioids : when administered alone they produce analgesia, in combination with pure
opioid agonist they can antagonize analgesia caused by the pure agonist
Ex: Pentazocine (Talwin), butorphanol, buprenorphine
Pure Opioid Antagonist: acts as an antagonist to Mu and Kappa receptors, used for reversal of CNS
depression
Ex: Naloxone (Narcan)
Opioid Agonists
Morphine : pure opioid agonists, used for moderate to severe pain
Adverse Effects
 Respiratory depression
 Constipation
 Orthostatic Hypotension
 Urinary retention
 Emesis
 Euphoria and dysphoria
 Sedation
 Neurotoxicity
Precautions
 Give sparingly with pts with impaired pulmonary function (asthma, emphysema, kyphoscoliosis,
chronic cor pulmonale, extreme obesity)
 With other respiratory depressant drugs
 Pt with inflammatory bowel disease can cause toxic megacolon or paralytic ileus
 Could be intensified in pts with liver impairment
 Pt with BPH could have urinary retention
 Infants and older adults are more prone to respiratory depression
 Pt with hypotension and reduced blood volume
Toxicity: coma, respiratory depression, pinpoint pupils

Fentanyl: (Duragesic) strong opioid agonist, 100x more potent than morphine
Routes:
 parental
 transdermal: change patch q72h, do not exposure to heat, not to be used for post-op pain
 transmucosal: approved only for breakthrough pain in pts with CA at least 18 yeas old who
already take opioids around the clock and have tolerance
 intranasal
Adverse effects: same as morphine, but greatest concern is respiratory depression
-levels can be increased by CYP34A inhibitors (ritonavir & ketoconazole)
Hydromorphone : (diladid) strong opioid agonist
-less N/V than morphine
Routes
 IR, ER, Oral Suppositories
Oxymorphone : (Opana) strong opioid agonist, can cause less N/V than morphine
Routes
 IR, 2mg q4-6h
 ER
 Oral
 Suppositories
Codeine : moderate to strong opioid agonist, also used as a cough suppressant, acts on Mu receptors
-schedule II alone but schedule III when combined with other drugs
-only available in tablets
Hydrocodone: Equivalent to codeine, indicated for moderate to severe pain and cough suppression
-Schedule 2 drug, can be reversed with naloxone.
- IR 5mg tablet, can be combined with Acetaminophen or Ibuprofen (Norco, Vicodin, Lortab). ER every
12-24hours.