Analgesics Flashcards
Nociceptive pain txvs Chronic neuropathic pain
nociceptive: treated with anti-inflammatory or analgesic medications
Chronic neuropathic pain: is treated with medications that act to influence neurotransmitters (i.e. antidepressants or antiepileptic drugs) in addition to anti- inflammatories and analgesics.
opiopeptins
include peptides such as the endorphins and the enkephalins.
opiate drugs work by binding to specific opioid receptors in order to produce effects that mimic the actions of opiopeptins.
5 areas of densest opiate receptors
brainstem, medial thalamus, spinal cord, hypothalamus and limbic system.
Also peripheral sensory nerves
5 Opiate receptor families
μ(mu), κ(kappa), σ(sigma), δ(delta) and ε(epsilon)
The analgesic properties of the opiates are
primarily mediated by the ??? receptors
mu
The enkephalins interact more selectively with the ???receptors in the periphery
delta
The ??? receptor appears to be less selective, interacting with drugs such as the hallucinogen, phencyclidine.
sigma
responsible for the hallucination sof opiates
which receptor only reacts to morphine?
mu3 opiate receptor.
Opiate analgesics MOA
nerve hyperpolarization
release of substance P from terminal and other pain mediators
Opiate/ Narcotic analgesics examples
- Morphine sulfate - MS Contin
- Meperidine - Demerol
- Hydromorphone - Dilaudid
- Fentanyl - Duragesic
- Oxycodone - Oxycontin, Percodan, Percocet
- Hydrocodone – Vicodin
- Codeine – T#3, T#4
- Tramadol/ Ultram
what shcedule are hydrocodone combination products (HCPs), which include opioids such as Vicodin, Lorcet, Lortab and Norco?
newly re-classified as schedule II and subject to tighter restrictions
HCPs are the most frequently-prescribed drugs in the U.S.
Morphine/ MS Contin
• Class: Opioid analgesic
• Indication: Pain relief
• MOA: Potent opioid agonist. High affinity for μreceptors. Morphine relieves pain both by raising the pain threshold at the brain stem, thalamic and spinal cord level as well as by altering the brain’s perception of pain. Patients treated with morphine may still be aware of the presence of pain but perception of the actual sensation of pain is blocked.
Morphine is also used in the setting of acute myocardial infarction. It can potentially provide pain relief, decrease anxiety and also acts as a peripheral vasodilator.
morphine char
Char: PO, PR, IM, IV. Duration of action varies by route. Significant first pass metabolism with oral route. Morphine is capable of producing a powerful sense of well being and euphoria. Highly addictive. Tolerance to dosing develops.
Morphine SE
Side effects:
• Morphine causes respiratory depression by reducing the sensitivity of respiratory center neurons to carbon dioxide.
Respiratory depression is the most common cause of death related to morphine.
• Miosis (pin point pupils) is due to enhanced parasympathetic stimulation to the occulomotor nerve.
• Itching is a common side effect due to the fact that the opiate drugs can stimulate histamine release.
• Morphine often causes nausea and vomiting due to stimulation of the chemoreceptor trigger (nausea center) in the brain.
• Constipation due to reduced G.I. smooth muscle motility. Paralytic ileus is possible.
• Morphine crosses the placenta, thus potentially creating physical dependence in infants exposed to the drug.
Fentanyl/ Duragesic
• Class: Opioid analgesic
• Indication: Pain relief, anesthesia
• MOA: Similar to morphine with 80x the
analgesic property of morphine. Used for
anesthesia and for intractable pain. • Char: I.V., transdermal patch, buccal
lozenge and film, sublingual spray and a “lollypop” form. Onset of action within minutes. Single I.M. doses have duration of action of 1-2 hours, single I.V. doses last 30 mins to 1 hour.
Patch delivers 25 – 100 mcg/ hour.
Fentanyl/ Duragesic SE
- Side effects: Respiratory depression with life threatening hypoventilation can occur.
- Patients using concomitant CYP 450 inhibitors may result in fatal blood levels of Fentanyl.
- Nausea/ vomiting.
- Constipation is a commonly occurring side effect and paralytic ileus can occur.
- Concurrent ethanol use may increase CNS depression.
- Highly addictive.
- Avoid concurrent intake of large quantities (>1 quart/day) of grapefruit juice and St Johnswort
schedule and category of Fentanyl/ Duragesic
Category CII
Pregnancy category C
other forms of Fentanyl/ Duragesic
• Transmucosal immediate-release Fentanyl products (i.e. sublingual tablets and spray, oral lozenges, buccal tablets and soluble film, nasal spray) are only available through the Transmucosal Immediate- Release Fentanyl (TIRF) ACCESS program.
Enrollment in the program is required for outpatients, prescribers for outpatient use, pharmacies (inpatient and outpatient), and distributors.
Codeine
• Class: Opioid analgesic
• Indication: Pain relief, antitussive
• MOA: Opioid agonist, is converted to
morphine in the body but mg per mg, codeine
is much weaker analgesic then morphine.
• Char: PO, IV, IM, SQ, - Lower abuse potential
than the more potent narcotic analgesics. Effective antitussive – codeine is able to suppress cough at doses which are lower then a typical analgesic dose.