We recently developed a series of nalfurafine analogs (TK10, TK33, and TK35) that may serve as non-addictive candidate analgesics. These compounds are mixed-action agonists at the kappa and delta opioid receptors (KOR and DOR, respectively) and produce antinociception in a mouse warm-water tail-immersion test while failing to produce typical mu opioid receptor (MOR)-mediated side effects. The warm-water tail-immersion test is an assay of pain-stimulated behavior vulnerable to false-positive analgesic-like effects by drugs that produce motor impairment. Accordingly, this study evaluated TK10, TK33, and TK35 in a recently validated assay of pain-related behavioral depression in mice that are less vulnerable to false-positive effects. For comparison, we also evaluated the effects of the MOR agonist/analgesic hydrocodone (positive control), the neurokinin 1 receptor (NK1R) antagonist aprepitant (negative control), nalfurafine as a selective KOR agonist, SNC80 as a selective DOR agonist, and a nalfurafine/SNC80 mixture. Intraperitoneal injection of dilute lactic acid (IP lactic acid) served as a noxious stimulus to depress vertical and horizontal locomotor activity in male and female ICR mice. IP lactic acid-induced locomotor depression was alleviated by hydrocodone but not by aprepitant, nalfurafine, SNC80, the nalfurafine/SNC80 mixture, or the KOR/DOR agonists. These results suggest that caution is warranted in advancing mixed-action KOR/DOR agonists as candidate analgesics.

Several commonly used opioid analgesics, such as fentanyl, sufentanil, alfentanil, and hydrocodone, are by report primarily metabolized by the CYP3A4 enzyme. The concurrent use of ritonavir, a potent CYP3A4 inhibitor, can lead to significant drug interactions. Using physiologically based pharmacokinetic (PBPK) modeling and simulation, this study examines the effects of different dosing regimens of ritonavir on the pharmacokinetics of these opioids. The findings reveal that co-administration of ritonavir significantly increases the exposure of fentanyl analogs, with over a 10-fold increase in the exposure of alfentanil and sufentanil when given with ritonavir. Conversely, the effect of ritonavir on fentanyl exposure is modest, likely due to additional metabolism pathways. Additionally, the study demonstrates that the steady-state exposure of hydrocodone and its active metabolite hydromorphone can be increased by up to 87% and 95%, respectively, with concurrent use of ritonavir. The extended-release formulation of hydrocodone is particularly affected. These insights from PBPK modeling provide valuable guidance for optimizing opioid dosing and minimizing the risk of toxicity when used in combination with ritonavir-containing prescriptions.

OBJECTIVE: To evaluate the impact of rescheduling hydrocodone combination products (HCPs) from schedule III of the Controlled Substances Act to the more restrictive schedule II on unintentional pediatric exposures (≤5 years old).
METHODS: Using U.S. data on outpatient retail pharmacy dispensing, emergency department (ED) visits, and poison center (PC) exposure cases, we assessed trends in prescriptions dispensed and unintentional pediatric exposure cases involving hydrocodone (rescheduled from III to II) compared to oxycodone (schedule II) and codeine (schedule III for combination products) using descriptive and interrupted time-series (ITS) analyses during the 16 quarters before and after the October 2014 rescheduling of HCPs.
RESULTS: Dispensing of hydrocodone products was declining before rescheduling but declined more steeply post-rescheduling. In ITS analyses, both hydrocodone and oxycodone had significant slope decreases in PC case rates in the post versus pre-period that was larger for hydrocodone, while codeine had a small but significant slope increase in PC case rates. An estimated 4202 ED visits for pediatric hydrocodone exposures occurred in the pre-period and 2090 visits occurred in the post-period, a significant decrease of 50.3%. Oxycodone exposures showed no significant decrease.
CONCLUSIONS: Pediatric hydrocodone unintentional exposure ED visits and PC cases decreased after HCP rescheduling more than would be expected had the pre-rescheduling trend continued; the acceleration in the decrease in hydrocodone PC cases was partially offset by a slowing in the decrease in codeine-involved cases. The trend changes were likely due to multiple factors, including changes in dispensing that followed the rescheduling. Unintentional pediatric medication exposures and poisonings remain a public health concern requiring ongoing, multifaceted mitigation efforts.

OBJECTIVE: Fatal drug overdoses often involve multiple co-intoxicants, including opioids. Hydrocodone, the most prescribed opioid for pain management, is metabolized to the active metabolite hydromorphone by hepatic CYP2D6. Inhibition of CYP2D6 by other compounds can disrupt the analgesic properties of hydrocodone and extend its half-life. Diphenhydramine is an over-the-counter cold medication and is known to inhibit CYP2D6 activity.
METHODS: A woman in her late 50s was prescribed hydrocodone/acetaminophen (Norco® 10/325). Days before her death, she began taking diphenhydramine for cold symptoms. A post-mortem toxicology report detected the following compounds by High Performance Liquid Chromatography/Time of Flight-Mass Spectrometry (LC/TOF-MS) analysis: acetaminophen (14 μg/mL), hydrocodone (410 ng/mL), dihydrocodeine (24 ng/mL), and diphenhydramine (150 ng/mL). Hydromorphone was not detected (<2 ng/mL). All compounds were detected in therapeutic concentrations, except for hydrocodone, which was present at lethal concentrations.
CONCLUSIONS: This case highlights a fatal drug-drug interaction between hydrocodone and diphenhydramine. The estimated total body burden of hydrocodone was 6- to 12-fold higher than acetaminophen, which is unexpected, as these two drugs were administered as a single formulation and have similar half-lives. Furthermore, hydromorphone was undetectable. Taken together, these findings are highly suggestive of a fatal opioid overdose precipitated by diphenhydramine.

The NC Office of the Chief Medical Examiner regularly assumes jurisdiction over deaths that are suspicious, unusual or unattended by a medical professional. In recent years, the presence of counterfeit pills is occasionally suggested by investigatory notes and/or scene findings that document reported consumption of prescription drugs, or prescription drugs on scene, which are not reflected in the final autopsy findings after toxicological analysis of the decedent\'s blood samples. Counterfeit pill consumption is a major public health hazard worthy of attention from the forensic toxicology community. Seventy-five cases from January 2020 to December 2022 serve as a convenience sample of cases where prescription pills including formulations of alprazolam, oxycodone and hydrocodone were specifically referenced during the death scene investigation as recently consumed, yet an unexpected substance was found during toxicological analysis rather than the expected pharmaceutical drug. Of note, novel benzodiazepines detected included flualprazolam, etizolam, clonazolam metabolite (8-aminoclonazolam), bromazolam, flubromazolam and desalkylflurazepam. Decedents\' ages ranged from 16 to 69, across 33 different NC counties. Case notes indicated that eight of the decedents obtained pills through direct personal relationships, six decedents obtained them from \"the street\" and one decedent likely purchased pills online. Pills were largely consumed orally or through insufflation. Seven case reports contained indication that decedents knew or suspected the counterfeit nature of their pills. This study describes the context and characteristics of 2020-2022 suspected counterfeit pill-involved deaths in NC to further the understanding of the forensic science community, law enforcement partners, public health stakeholders and those potentially at risk through the consumption of counterfeit pills.

BACKGROUND: Tramadol is increasingly used to treat acute postoperative pain among older adults following total hip and knee arthroplasty (THA/TKA). However, tramadol has a complex pharmacology and may be no safer than full opioid agonists. We compared the safety of tramadol, oxycodone, and hydrocodone among opioid-naïve older adults following elective THA/TKA.
METHODS: This retrospective cohort included Medicare Fee-for-Service beneficiaries ≥ 65 years with elective THA/TKA between January 1, 2010 and September 30, 2015, 12 months of continuous Parts A and B enrollment, 6 months of continuous Part D enrollment, and no opioid use in the 6 months prior to THA/TKA. Participants initiated single-opioid therapy with tramadol, oxycodone, or hydrocodone within 7 days of discharge from THA/TKA hospitalization, regardless of concurrently administered nonopioid analgesics. Outcomes of interest included all-cause hospitalizations or emergency department visits (serious adverse events (SAEs)) and a composite of 10 surgical- and opioid-related SAEs within 90-days of THA/TKA. The intention-to-treat (ITT) and per-protocol (PP) hazard ratios (HRs) for tramadol versus other opioids were estimated using inverse-probability-of-treatment-weighted pooled logistic regression models.
RESULTS: The study population included 2,697 tramadol, 11,407 oxycodone, and 14,665 hydrocodone initiators. Compared to oxycodone, tramadol increased the rate of all-cause SAEs in ITT analyses only (ITT HR 1.19, 95%CLs, 1.02, 1.41; PP HR 1.05, 95%CLs, 0.86, 1.29). Rates of composite SAEs were not significant across comparisons. Compared to hydrocodone, tramadol increased the rate of all-cause SAEs in the ITT and PP analyses (ITT HR 1.40, 95%CLs, 1.10, 1.76; PP HR 1.34, 95%CLs, 1.03, 1.75), but rates of composite SAEs were not significant across comparisons.
CONCLUSIONS: Postoperative tramadol was associated with increased rates of all-cause SAEs, but not composite SAEs, compared to oxycodone and hydrocodone. Tramadol does not appear to have a superior safety profile and should not be preferentially prescribed to opioid-naïve older adults following THA/TKA.

BACKGROUND: Septorhinoplasty is one the most common class of procedures performed worldwide, and opioids are frequently prescribed for post-operative pain [1].
OBJECTIVE: The objective of this study was to examine the rate of post-operative opioid prescription refills following septorhinoplasty.
METHODS: This study was a case-control study of patients who underwent septoplasty and other secondary concomitant procedures.
RESULTS: Of the 249 patients included in this study, the majority of patients (94.8%) were prescribed 12 tablets of hydrocodone-acetaminophen 5 mg - 325 mg and only 31 patients (13.3%) received refills. The presence of osteotomies and history of prior opioid use were associated with refills. Nasal valve repair type, open versus closed approach, and presence of autologous auricular cartilage graft harvest were not.
CONCLUSIONS: Our study highlights factors that surgeons should consider when prescribing opioids after septorhinoplasty. Twelve tablets of an opioid are likely sufficient for the majority of patients, but if osteotomies are performed or the patient has a history of prior opioid use, more may be indicated to avoid the need for refills. Additional narcotics are not necessary for an open approach or for patients in which auricular cartilage is needed.

OBJECTIVE: The abundance of opioids administered in the palliative care setting that was once considered a standard of care is at present necessitating that providers evaluate patients for unintentional and deleterious symptomology related to aberrant opioid use and addiction. Polypharmacy with opioids is dynamic in affecting patients neurologically, and increased amounts of prescriptions have had inimical effects, not only for the individual, but also for their families and healthcare providers. The purpose of this review is to widen the perspective of opioid consequences and bring awareness to the numerous neuropsychiatric effects associated with the most commonly prescribed opioids for patients receiving palliative care.
RESULTS: Numerous clinical and research studies have found evidence in support for increased incidence of opioid usage and abuse as well as undesirable neurological outcomes. The most common and concerning effects of opioid usage in this setting are delirium and problematic drug-related behavioral changes such as deceitful behavior towards family and physicians, anger outbursts, overtaking of medications, and early prescription refill requests. Other neuropsychiatric effects detailed by recent studies include drug-seeking behavior, tolerance, dependence, addictive disorder, anxiety, substance use disorder, emotional distress, continuation of opioids to avoid opioid withdrawal syndrome, depression, and suicidal ideation. Opioid usage has detrimental and confounding effects that have been overlooked for many years by palliative care providers and patients receiving palliative care. It is necessary, even lifesaving, to be cognizant of potential neuropsychiatric effects that opioids can have on an individual, especially for those under palliative care. By having an increased understanding and awareness of potential opioid neuropsychiatric effects, patient quality of life can be improved, healthcare system costs can be decreased, and patient outcomes can be met and exceeded.

Concurrent use of skeletal muscle relaxants (SMRs) and opioids has been linked to an increased risk of injury. However, it remains unclear whether the injury risks differ by specific SMR when combined with opioids. We conducted nine retrospective cohort studies within a US Medicaid population. Each cohort consisted exclusively of person-time exposed to both an SMR and one of the three most dispensed opioids-hydrocodone, oxycodone, and tramadol. Opioid users were further divided into three cohorts based on the initiation order of SMRs and opioids-synchronically triggered, opioid-triggered, and SMR-triggered. Within each cohort, we used Cox proportional hazard models to compare the injury rates for different SMRs compared to methocarbamol, adjusting for covariates. We identified 349,543, 139,458, and 218,967 concurrent users of SMRs with hydrocodone, oxycodone, and tramadol, respectively. In the oxycodone-SMR-triggered cohort, the adjusted hazard ratios (HRs) were 1.86 (95% CI, 1.23-2.82) for carisoprodol and 1.73 (1.09-2.73) for tizanidine. In the tramadol-synchronically triggered cohort, the adjusted HRs were 0.69 (0.49-0.97) for metaxalone and 0.62 (0.42-0.90) for tizanidine. In the tramadol-SMR-triggered cohort, the adjusted HRs were 1.51 (1.01-2.26) for baclofen and 1.48 (1.03-2.11) for cyclobenzaprine. All other HRs were statistically nonsignificant. In conclusion, the relative injury rate associated with different SMRs used concurrently with the three most dispensed opioids appears to vary depending on the specific opioid and the order of combination initiation. If confirmed by future studies, clinicians should consider the varying injury rates when prescribing SMRs to individuals using hydrocodone, oxycodone, and tramadol.

BACKGROUND: Emergency physicians play a critical role in mitigating the opioid epidemic in public health.
OBJECTIVE: To analyze the prescribing of emergency physicians for opioids among Medicare beneficiaries enrolled in the Part D program from 2013 to 2019.
METHODS: We conducted a retrospective, cross-sectional, descriptive analysis of Medicare Part D prescriber data, focusing on opioid claims between 2013 and 2019. The primary outcome variables evaluated included proportion of opioid claims, trends of the most prescribed opioids, cost of opioid claims, and days\' supply per claim.
RESULTS: A total of 63,586 emergency physicians were identified over the study period. Opioid prescription by emergency physicians decreased from 14.45% to 11.55%, and the cost spent on opioid drugs declined by 50%. The use of drugs such as hydrocodone-acetaminophen and oxycodone-acetaminophen declined substantially, whereas tramadol and acetaminophen-codeine prescription increased. The opioid prescribing rate and days\' supply also decreased.
CONCLUSIONS: The decline in traditional opioid agents such as hydrocodone-acetaminophen was partly offset by an increase in opioids like tramadol, which carry additional potential adverse events. Opioid prescribing rate, average days\' supply, and cost of opioid drugs significantly decreased from 2015 to 2019, after a spike in 2015. All regions observed a decrease in emergency physicians, but opioid prescribing rates varied across regions. These trends highlight successful opioid stewardship practices in some areas and the need for further development in others. This information can aid in designing tailored guidelines and policies for emergency physicians to promote effective opioid stewardship practices.