Effects of oxycodone and diazepam alone and in combination on operant nociception

Hydrocodone, Oxycodone, and Morphine Metabolism and Drug-Drug Interactions

Awareness of drug interactions involving opioids is critical for patient treatment as they are common therapeutics used in numerous care settings, including both chronic and disease-related pain. Not only do opioids have narrow therapeutic indexes and are extensively used, but they have the potential to cause severe toxicity. Opioids are the classical pain treatment for patients who suffer from moderate to severe pain. More importantly, opioids are often prescribed in combination with multiple other drugs, especially in patient populations who typically are prescribed a large drug regimen. This review focuses on the current knowledge of common opioid drug-drug interactions (DDIs), focusing specifically on hydrocodone, oxycodone, and morphine DDIs. The DDIs covered in this review include pharmacokinetic DDI arising from enzyme inhibition or induction, primarily due to inhibition of cytochrome p450 enzymes (CYPs). However, opioids such as morphine are metabolized by uridine-5'-diphosphoglucuronosyltransferases (UGTs), principally UGT2B7, and glucuronidation is another important pathway for opioid-drug interactions. This review also covers several pharmacodynamic DDI studies as well as the basics of CYP and UGT metabolism, including detailed opioid metabolism and the potential involvement of metabolizing enzyme gene variation in DDI. Based upon the current literature, further studies are needed to fully investigate and describe the DDI potential with opioids in pain and related disease settings to improve clinical outcomes for patients. SIGNIFICANCE STATEMENT: A review of the literature focusing on drug-drug interactions involving opioids is important because they can be toxic and potentially lethal, occurring through pharmacodynamic interactions as well as pharmacokinetic interactions occurring through inhibition or induction of drug metabolism.

Oxycodone: A Current Perspective on Its Pharmacology, Abuse, and Pharmacotherapeutic Developments

Oxycodone, a semisynthetic derivative of naturally occurring thebaine, an opioid alkaloid, has been available for more than 100 years. Although thebaine cannot be used therapeutically due to the occurrence of convulsions at higher doses, it has been converted to a number of other widely used compounds that include naloxone, naltrexone, buprenorphine, and oxycodone. Despite the early identification of oxycodone, it was not until the 1990s that clinical studies began to explore its analgesic efficacy. These studies were followed by the pursuit of several preclinical studies to examine the analgesic effects and abuse liability of oxycodone in laboratory animals and the subjective effects in human volunteers. For a number of years oxycodone was at the forefront of the opioid crisis, playing a significant role in contributing to opioid misuse and abuse, with suggestions that it led to transitioning to other opioids. Several concerns were expressed as early as the 1940s that oxycodone had significant abuse potential similar to heroin and morphine. Both animal and human abuse liability studies have confirmed, and in some cases amplified, these early warnings. Despite sharing a similar structure with morphine and pharmacological actions also mediated by the μ-opioid receptor, there are several differences in the pharmacology and neurobiology of oxycodone. The data that have emerged from the many efforts to analyze the pharmacological and molecular mechanism of oxycodone have generated considerable insight into its many actions, reviewed here, which, in turn, have provided new information on opioid receptor pharmacology. SIGNIFICANCE STATEMENT: Oxycodone, a μ-opioid receptor agonist, was synthesized in 1916 and introduced into clinical use in Germany in 1917. It has been studied extensively as a therapeutic analgesic for acute and chronic neuropathic pain as an alternative to morphine. Oxycodone emerged as a drug with widespread abuse. This article brings together an integrated, detailed review of the pharmacology of oxycodone, preclinical and clinical studies of pain and abuse, and recent advances to identify potential opioid analgesics without abuse liability.

GABAkines - Advances in the discovery, development, and commercialization of positive allosteric modulators of GABAA receptors

Positive allosteric modulators of γ-aminobutyric acid-A (GABA_A) receptors or GABAkines have been widely used medicines for over 70 years for anxiety, epilepsy, sleep, and other disorders. Traditional GABAkines like diazepam have safety and tolerability concerns that include sedation, motor-impairment, respiratory depression, tolerance and dependence. Multiple GABAkines have entered clinical development but the issue of side-effects has not been fully solved. The compounds that are presently being developed and commercialized include several neuroactive steroids (an allopregnanolone formulation (brexanolone), an allopregnanolone prodrug (LYT-300), Sage-324, zuranolone, and ganaxolone), the α2/3-preferring GABAkine, KRM-II-81, and the α2/3/5-preferring GABAkine PF-06372865 (darigabat). The neuroactive steroids are in clinical development for post-partum depression, intractable epilepsy, tremor, status epilepticus, and genetic epilepsy disorders. Darigabat is in development for epilepsy and anxiety. The imidazodiazepine, KRM-II-81 is efficacious in animal models for the treatment of epilepsy and post-traumatic epilepsy, acute and chronic pain, as well as anxiety and depression. The efficacy of KRM-II-81 in models of pharmacoresistant epilepsy, preventing the development of seizure sensitization, and in brain tissue of intractable epileptic patients bodes well for improved therapeutics. Medicinal chemistry efforts are also ongoing to identify novel and improved GABAkines. The data document gaps in our understanding of the molecular pharmacology of GABAkines that drive differential pharmacological profiles, but emphasize advancements in the ability to successfully utilize GABA_A receptor potentiation for therapeutic gain in neurology and psychiatry.

Engaging endogenous opioid circuits in pain affective processes

The pervasive use of opioid compounds for pain relief is rooted in their utility as one of the most effective therapeutic strategies for providing analgesia. While the detrimental side effects of these compounds have significantly contributed to the current opioid epidemic, opioids still provide millions of patients with reprieve from the relentless and agonizing experience of pain. The human experience of pain has long recognized the perceived unpleasantness entangled with a unique sensation that is immediate and identifiable from the first-person subjective vantage point as "painful." From this phenomenological perspective, how is it that opioids interfere with pain perception? Evidence from human lesion, neuroimaging, and preclinical functional neuroanatomy approaches is sculpting the view that opioids predominately alleviate the affective or inferential appraisal of nociceptive neural information. Thus, opioids weaken pain-associated unpleasantness rather than modulate perceived sensory qualities. Here, we discuss the historical theories of pain to demonstrate how modern neuroscience is revisiting these ideas to deconstruct the brain mechanisms driving the emergence of aversive pain perceptions. We further detail how targeting opioidergic signaling within affective or emotional brain circuits remains a strong avenue for developing targeted pharmacological and gene-therapy analgesic treatments that might reduce the dependence on current clinical opioid options.

Narcotic Refills and Patient Satisfaction With Pain Control After Total Joint Arthroplasty

BACKGROUND

Patient satisfaction has become an important metric for total joint arthroplasty (TJA) used to reimburse hospitals. Despite ubiquitous narcotic use for post-TJA pain control, there is little understanding regarding patient factors associated with obtaining opioid refills and associations with patient satisfaction.

METHODS

Using our state's mandatory opioid prescription monitoring program, we reviewed preoperative and postoperative narcotic prescriptions filled for 438 consecutive TJA patients. Subjects were divided into 3 groups based on the number of post-TJA narcotic refills obtained (0, 1, or >1), and logistic regression analysis was conducted comparing demographics, surgical factors, and satisfaction with pain control.

RESULTS

One hundred twenty-five patients (25.8%) did not consume preoperative opioids and received no postoperative refills. Total hip arthroplasty (THA) patients (P = .0004), subjects ≥65 years (P = .0057), and Medicare patients (P = .0058) had significantly higher rates of 0 postdischarge refills. THA recipients had 268% increased odds of not receiving a refill narcotic (adjusted odds ratio = 0.373; 95% confidence interval, 0.224- 0.622). Every 100-morphine milligram equivalent (MME) increase in presurgery use led to a 16% increase in odds of needing >1 opioid refill (adjusted odds ratio = 1.161; 95% confidence interval, 1.085-1.242). Subjects who noted higher satisfaction consumed less overall opioids when receiving a refill (436 vs 1119 MMEs, P = .021).

CONCLUSION

Subjects who received fewer narcotic prescriptions and overall MMEs demonstrated higher rates of satisfaction with early pain control. Our results are consistent with other studies in showing that increased preoperative narcotic use portends higher rates of postoperative refills. There appears to be a subset of THA patients >65 years of age who may be candidates for opioid-sparing analgesia.

Comparing the different oxycodone doses of prevent oxycodone for prevention of preventing fentanyl-induced cough during induction of general anaesthesia

BACKGROUND

Fentanyl-induced cough (FIC) usually occurs after the intravenous administration of fentanyl during general anaesthesia induction. It is a transient condition depending on the fentanyl administration dose and injection speed. Oxycodone can also prevent FIC because it has been proven to treat coughing. This study aimed to evaluate the efficacy of different oxycodone doses to prevent FIC during general anaesthesia induction.

METHODS

In a double-blind randomised controlled trial, 210 adult patients who were undergoing elective surgery, classified as American Society of Anaesthesiologists physical status I-II, and aged 20-65 years were randomly assigned into five equally sized groups: Sham group, Group Ⅰ, Group II, Group III and Group IV. Groups Ⅰ-IV were each intravenously injected with oxycodone 0.025, 0.05, 0.075 and 0.100 mg/kg, while an equal volume of normal saline was given instead of oxycodone in the Sham group. Five minutes later, fentanyl 3 μg/kg was intravenously injected within 5 seconds, then, 2 minutes later the other drugs were administered for general anaesthesia induction. The occurrence and severity of coughing were observed within 2 minutes of the fentanyl injection. Vital signs and intensities of coughing were recorded and analysed.

RESULTS

Coughing incidences were each 57.1, 50, 42.8, 33.3 and 21.4% in the Sham group and Groups Ⅰ-IV. Significant differences were found in the incidences of coughing between the Sham group and Groups III-IV. No significant differences in FIC incidences have been detected between the Sham group and Groups Ⅰ-II. However, no significant difference in FIC incidence existed between Group III and Group IV. Cough severities in Groups III and IV were significantly lower than in Groups Ⅰ and II (P < .05). No significant differences existed in the hypotension or severe bradycardia incidences during anaesthesia induction among the five groups (P > .05).

CONCLUSION

Oxycodone 0.075 mg/kg provided more effective FIC prevention during general anaesthesia induction.