Common morphine-like drugs are classified in the following categories [1]:
| category | ingredients |
| Short-acting opioids | Ex: meperidine… etc |
| Mixed agonist-antagonist opioids | Ex: nalbuphine, butorphanol… etc |
| Antagonist opioids | Ex: naloxone… etc |
Most morphine analgesics are short-acting opioid drugs, which act on the central nervous system, although the analgesic effect is rapid, but they have high side effects and addiction, and need to be carefully evaluated by doctors for special groups such as mothers, lactating women, the elderly and children.
Nalbuphine is a semi-synthetic opioid analgesic, which belongs to the mixed opioid drug of protoxification and antagonism, mainly as an agonist of kappa receptor (kappa receptor agonist) and also a μ receptor antagonist of MU receptor, so it has both effective and antagonistic properties (mixed agonist–antagonist).
Nalbuphine is characterized by its analgesic effect from kappa receptors, so it has excellent analgesic effect but is not addictive; In addition, because most of the common side effects of opioid analgesics come from mu receptors, nalbuphine can partially antagonize mu receptors, and the use of the upper ceiling effect will not be aggravated by the increase of dose. The main side effect is sedation, but it is also helpful for children or injured people who are more easily agitated.
Safety of maternal use of morphine-based pain medications
- Considerations during delivery: the transfer of nalbuphine through the placenta is high and rapid, and the use of morphines during delivery may affect the respiratory function of the newborn, and in some cases naloxone has been shown to correct the side effects on the fetus. If it is used, it should be used under the strict guidance of medical personnel, and the effects on the newborn must be carefully observed.
- Relative safety: Nalbuphine’s kappa receptor agonism and MU receptor partial antagonism may reduce the risk of respiratory depression, making it a relatively safe choice in some contexts.
- Suppression of postoperative itching: Nalbuphine can effectively reduce the itching caused by opiate to neuraxial anesthesia, while not increasing drowsiness, and can reduce nausea and vomiting, and the anti-itching effect is better than diphenhydramine, naloxone, and propofol. [2]
- Reduced risk of addiction: Due to the pharmacological properties of nalbuphine, the potential risk of addiction is low, helping to reduce adverse effects on the future of the mother and fetus.
Safety of morphine-based analgesics in breastfeeding women
- There is limited data on the clinical significance of nalbuphine as a class B in the pregnancy drug classification, and there is no data showing that the average concentration in breast milk is only 42 lg/L, and the estimated RID is 0.59% [4].
Safety of morphine-based analgesics in older adults
- Physical function and risk of side effects: the metabolic function of the elderly is usually reduced, the ability to metabolize drugs is reduced, and morphine drugs may affect the urinary tract motility of patients, resulting in inability to urinate after surgery, and poor gastrointestinal peristalsis; The ceiling effect of nalbuphine can help reduce the cumulative effect of side effects such as constipation, respiratory depression, urinary retention, and more.
- Dosage: The dose of nalbuphine used in the elderly is calculated in the same way as that of adults, and no special adjustment is required.
- Abnormal liver and kidney function: Nalbuphine is eliminated by liver metabolism and kidney, and patients with abnormal liver and kidney function must be evaluated by medical staff to reduce the dose, but the products of nalbuphine in liver metabolism are inactive, and patients will not have metabolite accumulation to cause chronic toxicity.
Nalbuphine provides a safe and effective pain management option for special populations, such as maternity, nursing women, the elderly, and those with liver and kidney dysfunction, due to the ceiling effect of side effects. Because of its low addiction characteristics, it is classified as a non-controlled drug, which is relatively convenient for clinical prescription by physicians and drug management in medical institutions.
[1] Taiwan Association of Cancer Hospice and Palliative Medicine. Preface to the Seventh Edition of Pain Control. Chapter 3 Drug Treatment of Cancer Pain.
[2] February 2019, Issue 268. Taiwan Association of Obstetrics and Gynecology. “2018 Work Accident Relief Report”. A good anti-pain, anti-itch drug – Nalbuphine.
[3] Martin, E., Vickers, B., & Landau, R. Society of Breastfeeding Medicine Clinical Procedure #28: Analgesia and Anesthesia for Breastfeeding Mothers during Periparity.
[4] Jacqz-Aigrain E, Serreau R, Boissinot C, et al. Excretion of ketoprofen and nalbuphine in human milk during treatment of maternal pain after delivery. Ther Drug Monit 2007; 29: 815–818