Behavioural Effects and Naloxone Effectiveness With New Synthetic Opioids.

Area of Science:

• Pharmacology
• Toxicology
• Public Health

Background:

• Emergence of potent synthetic opioids, specifically nitazenes (benzimidazole derivatives), in the global drug market.
• Association of nitazenes with fatal and non-fatal overdose incidents.
• Need for updated information on novel synthetic opioids due to evolving drug trends.

Purpose of the Study:

• Synthesize current evidence on the pharmacological effects, potency, and naloxone responsiveness of new synthetic opioids.
• Focus on substances evaluated for international control since 2020.
• Inform understanding and harm reduction strategies for nitazenes.

Main Methods:

• Conducted a narrative review of critical reviews from the WHO Expert Committee on Drug Dependence.
• Included supplementary literature for comprehensive data.
• Extracted data on pharmacological profiles, behavioral effects, potency, and naloxone effectiveness.

Main Results:

• Examined thirteen synthetic opioids with potencies varying from morphine-like to exceeding fentanyl.
• Naloxone demonstrated efficacy in reversing overdose symptoms for most examined substances.
• Higher doses or infusions of naloxone were occasionally required for complete reversal.

Conclusions:

• Variability in nitazene potency and frequent unintended use necessitate education, broad naloxone access, and drug-checking.
• Challenges include detecting nitazenes in polydrug use and their presence in counterfeit medications.
• While naloxone can reverse acute nitazene poisonings, its effectiveness in treating opioid use disorder in nitazene-dependent individuals remains unstudied.