Cannabis remains a Schedule I drug in the United States, defined by the Drug Enforcement Administration (DEA) as having no currently accepted medical use and a high potential for abuse. 3 Rigorous studies are lacking on the safety and efficacy of any specific cannabis product as a treatment for pain. 3 Expert views and systematic reviews 65,66 differ regarding the strength and quality of evidence for cannabis use, and the IASP does not endorse general use of cannabinoids for pain, citing lack of high- quality research. The evidence remains inconclusive to recommend the general use of cannabis for pain. Little is known about the safety, efficacy, dose, and routes of administration of available cannabis products. Epidiolex (cannabidiol) [CBD] oral solution has been approved for the treatment of seizures associated with two rare and severe forms of epilepsy, Lennox-Gastaut syndrome and Dravet syndrome, in patients age 2 and older. 67 (It is THC that has the primary psychoactive component of marijuana, not CBD). Importantly, the FDA has not approved cannabis for the treatment of chronic pain. 65 However, a number of
patients with pain appear to be replacing opioids with cannabis. Marijuana is legal for medical use in several states, and public interest in cannabis and cannabis- derived products for pain treatment is rising. 65 Adverse events reported with cannabis use include psychotomimetic effects, anxiety and psychosis, cognitive dysmotivational syndrome, and learning deficits in adolescents. 68 Cannabis can also have hyperemesis effects, can impair driving safety, and is linked to vascular events. 68 The topic of concurrent cannabis and opioid use will be covered later in this activity. Self-Assessment Question 4 Which medication is an example of a nonopioid option for pain?
a. Codeine. b. Fentanyl. c. Naproxen. d. Meperidine. e. Oxycodone.
OPIOIDS FOR PAIN
Opioid analgesic effects are principally achieved by the opioid binding to and activating mu, kappa, and delta receptors in the endogenous opioid system.
Drugs are classified according to their action at these receptors as full agonists, mixed agonist-antagonists, or antagonists (Table 2).
Table 2: Opioid Analgesic Classifications Type
Generic Name
Notes/Cautions
Pure agonists
• Codeine • Dihydrocodeine • Fentanyl • Hydrocodone • Hydromorphone • Levorphanol
• Meperidine* • Methadone • Morphine • Oxycodone • Oxymorphone • Propoxyphene Mixed agonist- antagonists: • Butorphanol • Dezocine • Nalbuphine • Pentazocine
*Meperidine not recommended for long- term treatment or in patients with renal compromise due to toxicity risks.
Agonist-antagonists Partial agonist: • Buprenorphine
May produce withdrawal if started while patient is receiving full opioid agonist.
Pure antagonists
Naloxone Naltrexone Tramadol Tapentadol
Administered to reverse opioid effects.
Other
Dual action mu-agonist and serotonin– norepinephrine reuptake inhibitor. Dual action mu-agonist and norepinephrine reuptake inhibitor.
Full mu-agonists bind selectively to the mu-opioid receptor. When an antagonist occupies the receptor, it displaces the agonist and causes opioid withdrawal. Partial agonists, such as buprenorphine, have high receptor occupancy, some antagonistic effects, and low intrinsic activity at the site. Kappa opioid receptor agonists (including levorphanol, pentazocine, and butorphanol) have been used clinically but are
associated with such side effects as dysphoria and hallucinations. Buprenorphine has a reduced potential for respiratory depression and is considered safer than full agonists such as morphine, hydrocodone, and oxycodone. 3 Buprenorphine also acts as an antagonist at the kappa receptor, which is shown to reduce anxiety, depression, and the unpleasantness of opioid withdrawal. 3 Tapentadol and tramadol have dual
Book Code: MDCO1025
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