Genetic Variants Associated with Opioid Use Disorder

State program enables the identification of factors associated with naloxone awareness, self-efficacy, and use for overdose reversal: A cross-sectional, observational study in an urban emergency department population

INTRODUCTION

To assist the state of Ohio in addressing the opioid epidemic, the Ohio Attorney General appointed experts in a variety of academic disciplines to the Scientific Committee on Opioid Prevention and Education (SCOPE). The focus of SCOPE is the application of scientific principles to the development of prevention and educational strategies for reducing substance use disorder and related harms (e.g., promoting naloxone awareness). Naloxone awareness is a step in the naloxone cascade, which is a useful model for understanding the sequential steps laypeople must take to prepare themselves to intervene using naloxone; other steps include training and previous administration experience. Prior work has explored correlates of these steps among individuals with risky substance use, but fewer studies have focused on broader populations containing potential bystanders (e.g., family and community members).

METHODS

This study was a secondary data analysis of patients from three urban emergency departments. Subsamples differed across five models (n = 479-1208) and included opioid-exposed and -naïve participants. Logistic regression characterized clinically useful sociodemographic predictors (e.g., race, ethnicity, education, employment, housing status) of naloxone awareness, self-efficacy (which relates to training), and previous-overdose administration. Two additional logistic regressions tested associations between risk factors for witnessing an opioid overdose and two cascade steps (awareness and self-efficacy).

RESULTS

Non-White race, Hispanic ethnicity, and lower education predicted not being aware of naloxone; non-White race also predicted lower naloxone self-efficacy, and older age predicted lack of previous-overdose administration. Having family members with risky opioid use was heavily associated with awareness, while personal substance-use behaviors and previous overdose witnessing were associated with both awareness and higher naloxone self-efficacy.

CONCLUSIONS

Characteristics associated with lower likelihood of completing each cascade step highlight opportunities for targeted interventions. Specifically, findings indicated the importance of expanding naloxone education and training programs to more diverse populations and to family members of individuals with risky opioid use. Further, these findings demonstrate how a state-funded program such as SCOPE can have a positive impact on identifying strategies that may assist in reducing mortality associated with opioid overdose.

Association of genetic variants in CYP3A5, DRD2 and NK1R with opioid overdose

In 2023, 3651 Ohioans died because of an opioid overdose. Of those opioid overdoses, 3579 (98%) of which were attributed to fentanyl. We evaluated the association between 180 candidate single nucleotide polymorphisms (SNPs) and self-reported, nonfatal opioid overdose history from a prospective sample of 1301 adult patients (≥18 years of age) seen in three urban emergency departments in Ohio. Candidate SNPs included 120 related to the dopamine reward pathway and 60 related to pharmacokinetics. Of the 821 patients who reported having been exposed to opioids in their lifetime, 95 (11.6%) also reported having experienced an opioid-related overdose. Logistic regression, adjusting for age and biologic sex, was used to characterize the association between each SNP and opioid overdose, correcting for multiple comparisons. Three SNPs, located in three different genes were associated with opioid overdose: increased odds with CYP3A5 (rs776746) and DRD2 (rs4436578), and decreased odds with NKIR (rs6715729). Homozygotic CYP3A5 (rs776746) had the highest adjusted odds ratio (OR) of 6.96 (95% CI [2.45, 29.23]) and homozygotic NK1R (rs6715729) had the lowest OR of 0.28 (95% CI [0.14, 0.54). Given that CYP3A5 (rs776746) has been associated with increased plasma concentrations of fentanyl, rs776746 could potentially be utilized as a prognostic risk indicator for the potential of an opioid overdose. NK1R regulates the expression of the neurokinin-1 receptor, a regulator of respiration and NK1R (rs6715729) represents a novel genetic marker for a decreased risk of opioid overdose risk.

Opioid use disorder risk alleles in self-reported assigned African American/Afro-Caribbean and European biogeographical genetic ancestry groups and in males and females

The influence of genetic variants related to opioid use disorder (OUD) was evaluated using multiple logistic regression analysis in self-reported assigned African American/Afro-Caribbean and European biogeographical ancestry groups (BGAGs) and by sex. From a sample size of 1301 adult patients (>18 years of age) seen in emergency departments of three medical centers in Ohio, six variants were found to be associated with OUD. Two of the variants, rs2740574 (CYP3A4) and rs324029 (DRD3), were included in the analysis having met criteria of at least five subjects for each BGAG, variant carrier status, and OUD status combinations. Variant carriers in the African/Afro-Caribbean BGAG had slightly lower predicted probabilities of OUD. Variant carriers in the European BGAG had slightly higher predicted probabilities of OUD. Relative to sex, all the six variants met evaluation criteria (five subjects for all sex, variant, and OUD status combinations). No statistically significant interactions were found between a given variant, BGAGs and sex. Findings suggest variant testing relative to OUD risk can be applied across BGAGs and sex, however, studies in larger populations are needed.

The dopamine 3 receptor as a candidate biomarker and therapeutic for opioid use disorder

Here, we present recent studies suggesting that specific DRD3 single nucleotide polymorphisms (SNPs, e.g. rs324029 and rs2654754) might serve as prognostic biomarkers for opioid use disorder (OUD). Additionally, preclinical studies with novel dopamine 3 receptor (D3R) partial agonists and antagonists have been evaluated as candidate OUD therapeutics and have shown a reduced risk of cardiovascular toxicity compared with the original D3R antagonist. From these findings, we argue that DRD3 SNPs could serve as a diagnostic tool for assessing OUD risk and that more research is warranted examining the D3R as a safe and effective therapeutic target for treating OUD.