Slow drug delivery decreased total body clearance and altered bioavailability of immediate- and controlled-release oxycodone formulations

Oxycodone alleviates mifepristone-stimulated human endometrial stromal cell injury by activating the Keap1/Nrf2/HO-1 signaling pathway

BACKGROUND

Endometrial injury is a common disease in women caused by intrauterine inflammation, infections, and endocrine disorders. Human endometrial stromal cells (hEndoSCs) can maintain endometrial homeostasis and play an important role in repairing endometrial injury. Mifepristone, a steroidal anti-progesterone drug, is widely used in the field of reproductive medicine worldwide. Mifepristone-induced hEndoSC injury has been used to study endometrial injury in vitro. At present, the pathogenesis and potential regulatory mechanisms of oxycodone in endometrial injury remain unknown.

AIMS

We aimed to evaluate the functions of oxycodone in mifepristone-stimulated hEndoSC injury and analyze its potential molecular mechanism.

MATERIALS & METHODS

hEndoSC viability, cytotoxicity, and apoptosis were analyzed using the methyl thiazolyl tetrazolium assay, the lactate dehydrogenase assay, and flow cytometry, respectively. Furthermore, the levels of cleaved-Caspase3, Keap1, Nrf2, HO-1, and NQO1 were assessed using reverse transcription quantitative polymerase chain reaction and western blot analysis, and the release of inflammatory cytokines was determined using the enzyme-linked immunosorbent assay.

RESULTS

We observed that oxycodone had no adverse effects on hEndoSCs; rather, it protected hEndoSCs against mifepristone-induced endometrial damage, as confirmed by the enhanced cell viability, reduced number of apoptotic cells, decreased Caspase3 activity and inflammatory cytokine secretion, and increased Keap1/Nrf2/HO-1 pathway-related protein expression. In addition, we found that the protective effects of oxycodone on mifepristone-induced hEndoSC injury were inhibited by ML385 (a Keap1/Nrf2/HO-1 inhibitor).

CONCLUSION

In summary, we confirmed that oxycodone alleviates mifepristone-induced hEndoSC injury by activating the Keap1/Nrf2/HO-1 signaling pathway.

Enhancing Atorvastatin In Vivo Oral Bioavailability in the Presence of Inflammatory Bowel Disease and Irritable Bowel Syndrome Using Supercritical Fluid Technology Guided by wbPBPK Modeling in Rat and Human

Inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) are common disorders that can change the body's physiology and drugs pharmacokinetics. Solid dispersion (SD) preparation using supercritical fluid technology (SFT) has many advantages. Our study aimed to explore the effect of IBS and IBD on atorvastatin (ATV) pharmacokinetics, enhance ATV oral bioavailability (BCS II drug) using SFT, and analyze drug-disease-formulation interaction using a whole-body physiologically based pharmacokinetic (wbPBPK) model in rat and human. A novel ATV formulation was prepared using SFT and characterized in vitro and in vivo in healthy, IBS, and IBD rats. The resulting ATV plasma levels were analyzed using a combination of conventional and wbPBPK approaches. The novel formulation increased ATV solubility by 20-fold and resulted in a zero-order release of up to 95%. Both IBS and IBD increased ATV exposure after oral and intravenous administration by more than 30%. The novel SFT formulation increased ATV bioavailability by 28, 14, and 18% in control, IBD, and IBD rat groups and resulted in more consistent exposure as compared to raw ATV solution. Higher improvements in ATV bioavailability of more than 2-fold upon receiving the novel SFT formulation were predicted by the human wbPBPK model as compared to receiving the conventional tablets. Finally, the established wbPBPK model could describe ATV ADME in the presence of IBS and IBD after oral administration of raw ATV and using the novel SFT formula and can help scale the optimized ATV dosing regimens in the presence of IBS and IBD from rats to humans.

Population Pharmacokinetics of Oxycodone and Metabolites in Patients with Cancer-Related Pain

Simple Summary

Patients with moderate to severe cancer-related pain are frequently treated with oxycodone, a strong-acting opioid. However, treatment with oxycodone does not always lead to sufficient analgesic action. In order to determine which factors affect treatment outcomes, we performed an observational study and developed a population pharmacokinetic model. The model described oxycodone, nor-oxycodone and nor-oxymorphone pharmacokinetics. The association between oxycodone or oxycodone metabolites’ exposure with pain scores and adverse events was not significant. The combined oxycodone, nor-oxycodone and nor-oxymorphone model is a good starting point for further unravelling the factors that affect the pharmacokinetic/pharmacodynamic relation of oxycodone and its metabolites.

Abstract

Oxycodone is frequently used for treating cancer-related pain, while not much is known about the factors that influence treatment outcomes in these patients. We aim to unravel these factors by developing a population-pharmacokinetic model to assess the pharmacokinetics of oxycodone and its metabolites in cancer patients, and to associate this with pain scores, and adverse events. Hospitalized patients with cancer-related pain, who were treated with oral oxycodone, could participate. Pharmacokinetic samples and patient-reported pain scores and occurrence and severity of nine adverse events were taken every 12 h. In 28 patients, 302 pharmacokinetic samples were collected. A one-compartment model for oxycodone and each metabolite best described oxycodone, nor-oxycodone, and nor-oxymorphone pharmacokinetics. Furthermore, oxycodone exposure was not associated with average and maximal pain scores, and oxycodone, nor-oxycodone, and nor-oxymorphone exposure were not associated with adverse events (all p > 0.05). This is the first model to describe the pharmacokinetics of oxycodone including the metabolites nor-oxycodone and nor-oxymorphone in hospitalized patients with cancer pain. Additional research, including more patients and a more timely collection of pharmacodynamic data, is needed to further elucidate oxycodone (metabolite) pharmacokinetic/pharmacodynamic relationships. This model is an important starting point for further studies to optimize oxycodone dosing regiments in patients with cancer-related pain.

Drug-Drug Interaction Between Oxycodone and Diazepam by a Combined in Silico Pharmacokinetic and Pharmacodynamic Modeling Approach

Opioids and benzodiazepines have complex drug-drug interactions (DDIs), which serve as an important source of adverse drug effects. In this work, we predicted the DDI between oxycodone (OXY) and diazepam (DZP) in the human body by applying in silico pharmacokinetic (PK) and pharmacodynamic (PD) modeling and simulation. First, we studied the PK interaction between OXY and DZP with a physiologically based pharmacokinetic (PBPK) model. Second, we applied molecular modeling techniques including molecular docking, molecular dynamics (MD) simulation, and the molecular mechanics/Poisson-Boltzmann surface area (MM-PBSA) free energy method to predict the PD-DDI between these two drugs. The PK interaction between OXY and DZP predicted by the PBPK model was not obvious. No significant interaction was observed between the two drugs at normal doses, though very high doses of DZP demonstrated a non-negligible inhibitory effect on OXY metabolism. On the contrary, the molecular modeling study shows that DZP has potential to compete with OXY at the same binding pocket of the active μ-opioid receptor (MOR) and κ-opioid receptor (KOR). MD simulation and MM-PBSA calculation results demonstrated that there is likely a synergetic effect between OXY and DZP binding to opioid receptors, as OXY is likely to target the active MOR while DZP selectively binds to the active KOR. Thus, pharmacokinetics contributes slightly to the DDI between OXY and DZP although an overdose of DZP has been brought to attention. Pharmacodynamics is likely to play a more important role than pharmacokinetics in revealing the mechanism of DDI between OXY and DZP.

Administration of melatonin improves testicular blood flow, circulating hormones, and semen quality in Shiba goats

Despite the role of melatonin in the regulation of the sleep-wake cycle and seasonal-reproduction, the present study investigated, for the first time, the potential role of melatonin on testicular blood flow (TBF) in goats. Twelve sexually mature male Shiba goats were exposed to a single s.c. injection of either melatonin suspended in one ml of corn oil (melatonin group; 36 mg/goat; n = 5) or one ml of corn oil (control group; n = 7). Monitoring the changes in TBF was done one week before (W-1), at the time of injection (W0), and once a week for 8 weeks after injection using color-pulsed Doppler ultrasonography. Concentrations of FSH, LH, inhibin, testosterone (T), estradiol (E2), and insulin-like growth factor-1 (IGF-1) in plasma were determined by radioimmunoassay. Melatonin and nitric oxide (NO) concentrations were measured using enzyme immunoassay kits. Moreover, semen collection and evaluation of some sperm parameters were performed once a week. Results revealed decreases (P < 0.05) in the Doppler indices (resistive index, pulsatility index) of the testicular arteries from W2 till W6 in the melatonin group. FSH, LH, and inhibin concentrations did not change between the two groups, while T, E2, IGF-1, NO, and melatonin concentrations increased (P < 0.05) in the melatonin group compared to the control. Estradiol and NO concentrations increased (P < 0.05), coinciding with decreases in the values of Doppler indices. Notable (P < 0.05) improvements in most parameters of semen quality were seen in the melatonin group. In conclusion, melatonin induced a stimulatory effect on TBF in Shiba goats and possibly, it could be a potential to improve male goats fertility.

Simultaneously predict pharmacokinetic interaction of rifampicin with oral versus intravenous substrates of cytochrome P450 3A/P‑glycoprotein to healthy human using a semi-physiologically based pharmacokinetic model involving both enzyme and transporter turnover

Several reports demonstrated that rifampicin affected pharmacokinetics of victim drugs following oral more than intravenous administration. We aimed to establish a semi-physiologically based pharmacokinetic (semi-PBPK) model involving both enzyme and transporter turnover to simultaneously predict pharmacokinetic interaction of rifampicin with oral versus intravenous substrates of cytochrome P450 (CYP) 3A4/P‑glycoprotein (P-GP) in human. Rifampicin was chosen as the CYP3A /P-GP inducer. Thirteen victim drugs including P-GP substrates (digoxin and talinolol), CYP3A substrates (alfentanil, midazolam, nifedipine, ondansetron and oxycodone), dual substrates of CYP3A/P-GP (quinidine, cyclosporine A, tacrolimus and verapamil) and complex substrates (S-ketamine and tramadol) were chosen to investigate drug-drug interactions (DDIs) with rifampicin. Corresponding parameters were cited from literatures. Before and after multi-dose of oral rifampicin, the pharmacokinetic profiles of victim drugs for oral or intravenous administration to human were predicted using the semi-PBPK model and compared with the observed values. Contribution of both CYP3A and P-GP induction in intestine and liver by rifampicin to pharmacokinetic profiles of victim drugs was investigated. The predicted pharmacokinetic profiles of drugs before and after rifampicin administration accorded with the observations. The predicted pharmacokinetic parameters and DDIs were successful, whose fold-errors were within 2. It was consistent with observations that the DDIs of rifampicin with oral victim drugs were larger than those with intravenous victim drugs. DDIs of rifampicin with CYP3A or P-GP substrates following oral versus intravenous administration to human were successfully predicted using the developed semi-PBPK model.

Absorption Study of Genistein Using Solid Lipid Microparticles and Nanoparticles: Control of Oral Bioavailability by Particle Sizes

In this study, the effect of particle size of genistein-loaded solid lipid particulate systems on drug dissolution behavior and oral bioavailability was investigated. Genistein-loaded solid lipid microparticles and nanoparticles were prepared with glyceryl palmitostearate. Except for the particle size, other properties of genistein-loaded solid lipid microparticles and nanoparticles such as particle composition and drug loading efficiency and amount were similarly controlled to mainly evaluate the effect of different particle sizes of the solid lipid particulate systems on drug dissolution behavior and oral bioavailability. The results showed that genistein-loaded solid lipid microparticles and nanoparticles exhibited a considerably increased drug dissolution rate compared to that of genistein bulk powder and suspension. The microparticles gradually released genistein as a function of time while the nanoparticles exhibited a biphasic drug release pattern, showing an initial burst drug release, followed by a sustained release. The oral bioavailability of genistein loaded in solid lipid microparticles and nanoparticles in rats was also significantly enhanced compared to that in bulk powders and the suspension. However, the bioavailability from the microparticles increased more than that from the nanoparticles mainly because the rapid drug dissolution rate and rapid absorption of genistein because of the large surface area of the genistein-solid lipid nanoparticles cleared the drug to a greater extent than the genistein-solid lipid microparticles did. Therefore, the findings of this study suggest that controlling the particle size of solid-lipid particulate systems at a micro-scale would be a promising strategy to increase the oral bioavailability of genistein.

Pharmacokinetics, safety and tolerability of a novel tocopheryl phosphate mixture/oxycodone transdermal patch system: a Phase I study

AIM

To characterize the pharmacokinetic profile and evaluate the safety and tolerability of a transdermal oxycodone patch containing tocopheryl phosphate mixture (TPM).

PATIENTS & METHODS

Eleven healthy subjects received a single application of three TPM/oxycodone patches applied to the torso for 72 h.

RESULTS

Oxycodone was detected 8.0 ± 2.7-h postpatch administration, reaching a mean maximum plasma concentration of 3.41 ± 1.34 ng/ml at 49.3 ± 21.2 h. The safety profile was consistent with the application method and known side-effect profile of oxycodone and naltrexone. No treatment-limiting skin irritation was observed.

CONCLUSION

A 3-day application of the TPM/oxycodone patch demonstrated an acceptable safety profile and was well tolerated by healthy subjects, with limited dermal irritation following application.

Pharmacokinetic and pharmacodynamic evaluation of oxycodone and naltrexone for the treatment of chronic lower back pain

INTRODUCTION

Chronic low back pain (CLBP) is a common and difficult illness to manage. Some individuals with CLBP have pain processing disorders and are also at risk for opioid abuse, misuse; addiction and diversion. Guidelines have been published to guide management; neuromodulation, exercise, mindfulness-based stress reduction and cognitive behavior therapies among other non-pharmacological reduce the pain of CLBP with minimal toxicity. Pharmacological management includes acetaminophen, NSAIDs and antidepressants, mainly duloxetine. Abuse-deterrent opioids have been developed which have been shown to reduce pain and opioid abuse risk. ALO-02 is a tamper-resistant sustained release opioid consisting of extended release oxycodone and sequestered naltrexone. Pivotal studies of ALO-02 have centered on patients with CLBP.

AREAS COVERED

This manuscript will review CLBP, the pivotal analgesic and clinical abuse potential studies of ALO-02. The opinion will cover whether opioids should be used for CLBP, when they should be used and opioid choices.

EXPERT OPINION

ALO-02 is one of several opioids which can be considered in the management of CLBP. The outcome to a trial of opioids should be function rather than analgesia. Most analgesic trials for CLBP have had analgesia as the primary outcome and function has not been vigorously studied as an outcome. Opioids should be considered as a trial only when other non-opioid analgesics have failed to improve analgesia and function. Universal precautions should be routinely part of phase III analgesic trial particularly for chronic non-malignant pain.

Slow drug delivery decreased total body clearance and altered bioavailability of immediate- and controlled-release oxycodone formulations

Oxycodone is a commonly used analgesic with a large body of pharmacokinetic data from various immediate-release or controlled-release formulations, under different administration routes, and in diverse populations. Longer terminal half-lives from extravascular administration as compared to IV administration have been attributed to flip-flop pharmacokinetics with the rate constant of absorption slower than elimination. However, PK parameters from the extravascular studies showed faster absorption than elimination. Sustained release formulations guided by the flip-flop concept produced mixed outcomes in formulation development and clinical studies. This research aims to develop a mechanistic knowledge of oxycodone ADME, and provide a consistent interpretation of diverging results and insight to guide further extended release development and optimize the clinical use of oxycodone. PK data of oxycodone in human studies were collected from literature and digitized. The PK data were analyzed using a new PK model with Weibull function to describe time-varying drug releases/ oral absorption, and elimination dependent upon drug input to the portal vein. The new and traditional PK models were coded in NONMEM. Sensitivity analyses were conducted to address the relationship between rates of drug release/absorption and PK profiles plus terminal half-lives. Traditional PK model could not be applied consistently to describe drug absorption and elimination of oxycodone. Errors were forced on absorption, elimination, or both parameters when IV and PO profiles were fitted separately. The new mechanistic PK model with Weibull function on absorption and slower total body clearance caused by slower absorption adequately describes the complex interplay between oxycodone absorption and elimination in vivo. Terminal phase of oxycodone PK profile was shown to reflect slower total body drug clearance due to slower drug release/absorption from oral formulations. Mechanistic PK models with Weibull absorption functions, and release rate-dependent saturable total body clearance well described the diverging oxycodone absorption and elimination kinetics in the literature. It showed no actual drug absorption during the terminal phase, but slower drug clearance caused by slower release/absorption producing the appearance of flip-flop and offered new insight for the development of modified release formulations and clinical use of oxycodone.