● The number of cases of Neonatal Abstinence Syndrome increased slightly from 810 in 2019 to 824 in 2020. 28 Opioids are classified according to their action at mu receptors as full agonists, mixed agonist-antagonists, or antagonists (Table 3). 29- 32 Most clinically prescribed opioids are full mu agonists. Buprenorphine has a reduced potential for respiratory depression and acts as an antagonist
at the kappa receptor, which is shown to reduce anxiety, depression, and the unpleasantness of opioid withdrawal. 5 Tapentadol and tramadol have dual modes of action as agonists at the mu receptor and SNRIs. 5 Considerations with dual- mechanism opioids include lowering of the seizure threshold in susceptible patients and the risk of serotonin syndrome. 33
Table 3. Opioid Analgesic Classifications
Type
Generic Name Codeine Dihydrocodeine Fentanyl Hydrocodone Hydromorphone Levorphanol Meperidine* Methadone Morphine Oxycodone Oxymorphone Propoxyphene
Notes/Cautions
Pure agonists
*Meperidine not recommended for long-term treatment or in patients with renal compromise due to toxicity risks
Partial agonist: Buprenorphine Mixed agonist-antagonists: Butorphanol Dezocine
Agonist-antagonists
May produce withdrawal with physical dependence
Nalbuphine Pentazocine Naloxone Naltrexone Tramadol Tapentadol
Pure antagonists
Administered to reverse opioid effects
Other
Dual action mu-agonist and serotonin–norepinephrine reuptake inhibitor Dual action mu-agonist and norepinephrine reuptake inhibitor be swallowed whole, never crushed, chewed, broken, cut, or dissolved, which may result in rapid release and absorption of a potentially fatal dose. 35,36 Transdermal systems and buccal films should not be cut, torn, or damaged before use nor chewed, swallowed, or patches exposed to heat, which may lead to fatal overdose. Possible opioid side effects include but are not limited to: 5,13 ● Lightheadedness
Formulations may be extended-release (ER) or immediate-release (IR), and delivery systems for outpatients include oral, transmucosal, and transdermal routes of administration. Combination products contain products such as acetaminophen (ACET) together with an opioid, necessitating careful tracking of daily dose limits so as not to incur risk for liver and GI toxic effects. 34 All transdermal and transmucosal fentanyl and hydromorphone ER products are for use only in opioid-tolerant patients and never for acute or short-term pain. 35 ER/LA opioids are primarily intended to be taken once or twice a day, are not indicated for acute pain, and are for use only in patients who are already tolerant to opioids. 13,35 The primary risk with opioids is respiratory depression leading to death. Some opioids (e.g., methadone) can prolong the QTc interval. ER/LA opioid tablets should
● Dizziness ● Sedation ● Nausea and vomiting ● Drowsiness ● Mental clouding ● Constipation
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Book Code: TN24CME
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