Identify where opioids act within the neurological pathway of pain transmission
- Opioids influence pain signals where peripheral nerve connects to the dorsal horn in the spine
- When activated opioid receptors generally create an inhibitory effect upon the neuron to which they are attached.
Acute pain
- 3-6 mos
- best treated with opioids
Chronic pain
- persist after normal healing process
- Fentanyl
Nociceptive pain
- Usually related to tissue damage, requires pain receptor activation
- normal opioid tx
Nociceptive pain: somatic
injury to body tissue, well localized
Nociceptive pain: Visceral
viscera mediated by stretch receptors
Neuropathic pain
- Abnormal neural activity secondary to disease, injury, or dysfunction of CNS.
- Tramadol
Cancer pain
-Best treated with opioids
List opioid drugs that are receptor agonist
Morphine
Hydromorphone
Codeine
Hydrocodone
Oxycodone
Meperidine (Demerol)
Fentanyl
Methadone
List opioid drugs that are receptor partial agonist
- Buprenophine
- Tramadol
List opioid drugs that are receptor antagonist
- Naloxone (Narcan)
- Naltrexone
- Methylnaltrexone
- Naloxegol
MC COD from opioid overdose
- Respiratory depression:
- Decreased sensitivity of chemoreceptors that sense high levels of CO2 in blood and decrease respiratory volume and rate
- Essentially brain stops realizing the pts need to breathe.
Mu receptors are found where
brainstem and medial thalamus
Kappa receptors are found where
limbic and other diencephalic areas.
Delta receptors are found where?
largely in the brain
PK of opioids
- PK properties determine their analgesic and side effects
- bioavailability is about 75-85%
- highly water soluble, rapid onset of action
- duration of action if related to their t 1/2
- flow dependent hepatic clearance
Max morphine dose in Washington state
120 mg PO per day
What actions need to betaken to exceed morphine dose?
- If above 120 pt required to consult a pain specialist
- Pain specialist can be considered a DO, MD, ARNP, pediatric physician
Key drugs used for opioid addiction treatment:
- Buprenorphine + Naloxone
- Methadone
Why is Buprenorphine + Naloxone used for opioid addiction tx?
- Natural ceiling effect of buprenorphine plus taper proofing of naloxone
- partial agonist at mu opioid receptor
- Once daily, easy to adhere to
Why is Methadone used for opioid addiction tx?
- Longer duration of action, can be given under medial supervision, not allowed to be “prescribed”.
- Less euphoria effect
Steps required for a Physician Assistant to qualify to prescribe medications for opioid addiction treatment?
- Need to apply for a separate DEA registration (X as first letter of DEA)
- Take and record no less than 24 hrs of certified training
- Apply for a DATA waiver from SAMSHA-skips CSAT approval stat.
Prescriptive limitations of a Physician Assistant compared to a MD or DO, in regards to prescribing for opioid addiction treatment
- PAs are allowed to care up to 30 pts for purposes of opioid addiction tx
VS MD OR DO:
- Initial limit: 30-100, petition for 275 pts.
List sedative/hypnotic drugs: benzodiazepine
- Alprazolam (Xanax)
- Chlordiazepoxide
- Clonazepam
- Diazepam
- Lorazepam (Ativan)
- Midazolam
- Triazolam
- Flumazenil—benzodiazepine overdose antidote
