Background: Once a widely used analgesic in the United States (US), meperidine offered an alternative to other opioids as a pain reliever. However, within the last two decades, meperidine has gone from a drug to be utilized only when patients exhibit atypical reactions to opioids (e.g., morphine and hydromorphone) to being taken off the World Health Organization List of Essential Medications and receiving strong recommendations for the overall avoidance. The aim of this study was to identify changes in meperidine distribution in the US and regional disparities as reported to the Drug Enforcement Administration’s Automation of Reports and Consolidated Orders System (DEA ARCOS) and Medicaid. Methods: Data related to the meperidine distribution was obtained through ARCOS (2001 –2021) and Medicaid public use files (2016 –2021). Heat maps were used to visualize regional disparities in distribution by state. States outside a 95% confidence interval were statistically significant. Results: Meperidine distribution between 2001 and 2021 decreased by 97.4% (R=.-97, P < .0001). There was a 34-fold state-level difference in meperidine distribution between Arkansas (16.8 mg/10 persons) and Connecticut (0.5 mg/ 10 persons) in 2020. Meperidine distribution in 2020 was elevated in Arkansas, Mississippi, and Alabama. In 2021, Meperidine distribution was highest in Arkansas ( 1.67 /10 persons) and lowest in Connecticut (0.08 /10 persons). Total prescriptions of meperidine as reported by Medicaid decreased by 73.8% (R= -0.67, P = 0.045) between 2016 and 2021. Conclusion: We observed a decrease in the overall distribution of meperidine in the past two decades with similar recent declines in prescribing to Medicaid enrollees. The shortage of some parenteral formulations is an important contributor to these declines. This data may reflect plans to phase out the use of this opioid, especially in the many situations where preferred opioids are available.

The two-component compound formed by codeine and cyclopentobarbital was produced by grinding techniques and by evaporation from alcoholic solutions. The cocrystal nature of this phase was established unequivocally by single crystal X-ray structure determination. The asym-metric unit contains one formula unit. In the cyclopentobarbital molecule, the cyclopentenyl ring is disordered over two positions related by a rotation of approximately 180° about its C‒C bond to the pyrimidine ring. The two NH groups of the cyclopentobarbital molecule form N—H···N and N—H···O bonds to piperidine and hydroxyl groups, respectively, belonging to different codeine molecules. In addition, the hydroxyl and methoxy groups of neighboring codeine molecules are linked by O—H···O interactions, resulting H-bonded framework structure of codeine and cyclo-pentobarbital molecules. The cocrystal was also characterized by thermal analysis, X-ray powder diffraction and IR spectroscopy.

Buprenorphine, an analogue of thebaine, is a Schedule III opioid in the United States used for opioid-use disorder and as an analgesic. Research has shown drugs like buprenorphine have a complicated pharmacology with characteristics that challenge traditional definitions of terms like agonist, antagonist, and efficacy. Buprenorphine has a high affinity for the mu (MOR), delta (DOR), kappa (KOR), and intermediate for the nociceptin opioid receptors (NOR). Buprenorphine is generally described as a partial MOR agonist with limited activity and decreased response at the mu-receptor relative to full agonists. In opioid naïve patients, the drug’s analgesic efficacy is equivalent to a full MOR agonist, despite decreased receptor occupancy and the “ceiling effect” produced from larger doses. Some argue buprenorphine’s effects depend on the endpoint measured, as it functions as a partial agonist for respiratory depression, but a full-agonist for pain. Buprenorphine’s active metabolite, norbuprenorphine, attenuates buprenorphine's analgesic effects due to NOR binding and respiratory depressant effects. The method of administration impacts efficacy and tolerance when administered for analgesia. There have been eleven-thousand reports involving buprenorphine and minors (age < 19) to US poison control centers, the preponderance (89.2%) with children. The consequences of prenatal buprenorphine exposure in experimental animals and humans should continue to be carefully evaluated. In conclusion, buprenorphine’s characterization as only a partial mu-agonist is an oversimplification. Contemporary research shows the traditional explanation of the pharmacology of buprenorphine does not take into account changes to receptor theory, pharmacological terminology, route of administration, and biologically active major metabolites.