# Investigation of serum concentration and the type of opioid used in patients with opium poisoning

## TL;DR

This study examines opioid poisoning in Iran, finding methadone as the main cause and higher concentrations linked to severe symptoms.

## Contribution

The study identifies methadone as the leading cause of opioid poisoning and highlights the importance of serum concentration measurement for clinical management.

## Key findings

- Methadone caused 72% of opioid poisonings, with higher serum concentrations in men and rural residents.
- Higher opioid levels correlated with severe symptoms and increased intensive care needs.
- No in-hospital deaths occurred, and most patients recovered with medical treatment.

## Abstract

Opioid poisoning constitutes a major public health issue in Iran and worldwide, with increasing rates attributed to both traditional opiates and synthetic derivatives such as methadone. Reliable assessment of serum opioid concentrations is essential for clinical management and prognosis. Quantitative measurement of serum opioid concentrations determines local epidemiological patterns and identifies risk factors that guide future prevention and treatment strategies. This descriptive cross-sectional study was conducted at Imam Khomeini Hospital in Kermanshah, Iran, from March to June 2023. Fifty adult patients with confirmed opioid poisoning were clinically diagnosed based on the classic opioid toxidrome (decreased consciousness, miotic pupils, and respiratory depression) documented at emergency department admission. Clinical diagnosis was confirmed by positive response to naloxone administration. Demographic and clinical data, type and route of opioid use, clinical features, laboratory results, and patient outcomes were recorded. Serum concentrations of opioids were measured using gas chromatography–mass spectrometry (GC–MS) after administration of antidotes. Statistical analysis was performed with SPSS 26, using a significance threshold of p < 0.05. Among 50 patients (86 % male, mean age 33.5 ± 9.8 years), methadone was the most common cause of poisoning (72 %), followed by opium and heroin. The principal clinical findings included apnea (44 %), miosis (44 %), and weakness/lethargy (38 %), with severe symptoms observed primarily in methadone cases. Serum methadone concentrations were significantly higher in men than women (p = 0.007), and in rural residents compared to urban (p = 0.005). Higher opioid serum levels were associated with more severe clinical presentations and increased need for intensive care. Most patients recovered with medical management; no in-hospital deaths occurred. Methadone has become the leading cause of opioid poisoning in this region, with high serum concentrations predicting increased clinical severity. Measurement of serum opioid levels is a valuable tool for risk stratification and should be integrated into standard management protocols. Attention must be given to both preventive education and tighter regulation of methadone distribution, particularly among high-risk groups.