Topical application of sebacoyl dinalbuphine ester-loaded nanostructured lipid carriers alleviate pruritus in scratching mouse model.

Sebacoyl dinalbuphine ester (SDE) is a nalbuphine (NA) prodrug capable of biotransformation in vivo and prolong the duration of NA, maximize its effect in pain and pruritus management. However, the large molecular weight, low skin penetration, and stability concerns of SDE make it difficult to be used in local skin delivery. Nanostructured lipid carrier (NLC) is a lipid-based nanoparticulate system that has the potential for formulating SDE in order to promote drug delivery through the skin. The aim of this study was to develop SDE-loaded NLC formulations (SDE-NLC) with good stability, sustained release characteristics, and sufficient antipruritic effect. SDE was successfully encapsulated into NLC and the formulation increased the stability of SDE, enhanced skin penetration through hair follicles, and sustained SDE release during pruritus management. We also demonstrated that topical application of SDE-NLCs significantly reduced the number of scratches in pruritus-induced mice. Both NA and SDE were found in the skin strata, but only NA was detectable in the plasma, indicating rapid conversion of SDE into NA. All results demonstrated that SDE-NLC formulation protected SDE from degradation in vitro, while the released prodrug was converted into NA in vivo and extended antipruritic effect. The formulation has the potential of improving the life quality of patients with chronic pruritus.

Comparing efficacy and safety between Naldebain® and intravenous patient-controlled analgesia with fentanyl for pain management post-laparotomy: study protocol for a randomized controlled, non-inferior trial.

BACKGROUND: A long-acting prodrug of nalbuphine, nalbuphine sebacate, has been developed for meeting the unmet medical need of long-acting analgesics. Naldebain® (nalbuphine sebacate) has been developed as a new premedication for postoperative pain management. The primary objective of this study is to determine the efficacy and safety of a single dose of intramuscular Naldebain® in patients scheduled to undergo elective laparotomy. METHODS/DESIGN: A total of 110 patients will be recruited and randomized into two treatment groups. Group 1 receives a single dose of Naldebain® intramuscularly 24 ± 12 h prior to surgery. Group 2 receives intravenous patient-controlled analgesia (PCA) with fentanyl through 48 h postsurgery. Both groups will have follow-up observations until the final visit (day of discharge, day 6-30). The primary efficacy endpoint is to assess time-specific pain intensity calculated as the area under the curve (AUC) of a visual analog scale at individual time points and by using total AUC. Safety endpoints-including incidence of treatment, emergent adverse events, and percentage of abnormality from baseline to final visit-in vital signs, laboratory tests, and injection site evaluations will also be analyzed. Statistical analyses will be performed on the data to compare the two groups. DISCUSSION: Post-laparotomy pain can have a harmful effect on patient recovery; therefore, a slow-release formulation that can cover at least 7 days of analgesic effect is required. This study will demonstrate whether a single use of Naldebain® is not less efficacious than PCA with fentanyl for pain management as a non-inferior trial. TRIAL REGISTRATION: NCT03296488 .

Sebacoyl Dinalbuphine Ester Extended-release Injection for Long-acting Analgesia: A Multicenter, Randomized, Double-Blind, And Placebo-controlled Study in Hemorrhoidectomy Patients.

OBJECTIVES: This study was conducted to evaluate the safety and efficacy of single sebacoyl dinalbuphine ester (SDE) injection (150 mg/2 mL) when administered intramuscularly to patients who underwent hemorrhoidectomy for postoperative long-acting analgesia. METHODS: A total of 221 patients scheduled for hemorrhoidectomy from 6 centers in Taiwan were randomly divided into SDE group and placebo group, and received the treatment, vehicle or SDE, 1 day before the surgery. Visual analogue scale (VAS) was recorded up to 7 to 10 days. Pain intensity using VAS AUC through 48 hours after surgery was calculated as the primary efficacy endpoint. RESULTS: Area under the curve of VAS pain intensity scores (VAS AUC) through 48 hours after hemorrhoidectomy was significantly less in SDE group than those in placebo group (209.93 vs. 253.53). VAS AUC from the end of surgical procedure to day 7 was also significantly different between SDE and placebo group (630.79 vs. 749.94). SDE group consumed significantly less amount of other analgesics, such as PCA ketorolac and oral ketorolac. Median time from the end of surgery to the first use of pain relief medication was also shortened in the placebo group than in the SDE group. Most adverse events were assessed as mild and tolerable in both groups. DISCUSSION: SDE injection demonstrated an extended analgesia effect, with a statistically significant reduction in pain intensity through 48 hours and 7 days after hemorrhoidectomy.

Simultaneous determination of nalbuphine and its prodrug sebacoly dinalbuphine ester in human plasma by ultra-performance liquid chromatography-tandem mass spectrometry and its application to pharmacokinetic study in humans.

A rapid, simple, sensitive and selective ultraperformance liquid chromatography-tandem spectrometry (UPLC-MS/MS) method for the determination of nalbuphine and its prodrug sebacoly dinalbuphine ester (SDE) was developed and validated in human plasma. The sample pretreatment involves basification and iterative liquid-liquid extraction with ethyl-ether-dichloromethane (7:3, v/v) solution, followed by LC separation and positive electrospray ionization (ESI) API-3000 mass spectrometry detection. The chromatography was on a Waters Acquity UPLC BEH HILIC column (2.1 × 100 mm, 1.7 µm). The mobile phase was composed of acetonitrile and water (83:17, v/v) that contained 0.2% formic acid and 4 mm ammonium formate at a flow rate of 0.25 mL/min. Ethylmorphine and naloxine were selected as the SDE and nalbuphine internal standard (IS), respectively. The calibration curve for both was linear over the range from 0.05 to 20 ng/mL, with correlation coefficients ≥0.995. The lower limit of quantification was set at 0.05 ng/mL. The intra- and inter-day precision values for nalbuphine and SDE were acceptable as per FDA guidelines. The method was applied successfully to determine nalbuphine concentration in human plasma samples obtained from four Taiwanese volunteers receiving intramuscularly administration of sebacoyl dinalbuphine ester. The method is sensitive, selective and directly applicable to human pharmacokinetic studies involving nalbuphine.

Pharmacological properties of bivalent ligands containing butorphan linked to nalbuphine, naltrexone, and naloxone at mu, delta, and kappa opioid receptors.

Our investigation of bivalent ligands at mu, delta, and kappa opioid receptors is focused on the preparation of ligands containing kappa agonist and mu agonist/antagonist pharmacophores at one end joined by a chain containing the mu antagonist pharmacophores (naltrexone, naloxone, or nalbuphine) at the other end. These ligands were evaluated in vitro by their binding affinity at mu, delta, and kappa opioid receptors and their relative efficacy in the [35S]GTPgammaS assay.

The effects of electrically assisted methods on transdermal delivery of nalbuphine benzoate and sebacoyl dinalbuphine ester from solutions and hydrogels.

The aim of this study was to assess the effects of iontophoresis and electroporation on transdermal delivery of nalbuphine (NA) and its two novel prodrugs: nalbuphine benzoate (NAB) and sebacoyl dinalbuphine ester (SDN) from solutions as well as from hydrogels. Hydroxypropyl cellulose (HPC) and carboxymethyl cellulose (CMC) were used in hydrogel formulations to evaluate their feasibility for delivery of NA and its prodrugs. Application of iontophoresis or electroporation significantly enhanced the in vitro permeation of NA and its prodrugs. The enhancement effect was more pronounced after applying iontophoresis. The combination of two electrically assisted methods enhanced the delivery of NA; however, no such enhancement was observed for the permeation of NAB and SDN. Hydrogels containing low concentration HPC did not affect the passive as well as electrically assisted permeation of NA and its prodrugs. The increase of hydrogel concentration as well as molecular weight significantly decreased the electrically assisted permeation of NA, whereas the permeation of NAB and SDN remained unchanged. For the electrically assisted permeation from CMC-based hydrogels, the reduced permeation from higher percentage of CMC hydrogels may be attributed the viscosity effect as well as the ion competition effect. The above results demonstrated that lipophilicity and molecular size, as well as hydrogel compositions had significant effects on skin permeation of NA, NAB and SDN via passive diffusion or under the electric field.

In vitro and in vivo evaluation of the metabolism and pharmacokinetics of sebacoyl dinalbuphine.

A diester prodrug of nalbuphine, sebacoyl dinalbuphine (SDN), and its long-acting formulation are currently being developed to prolong the duration of nalbuphine. A comparative in vitro hydrolysis study was conducted for SDN in rat, rabbit, dog, and human blood. Both SDN and nalbuphine in blood or plasma were measured by high-performance liquid chromatography. The hydrolysis rates of SDN in blood were ranked as follows: rat > rabbit > human > dog. The rapid formation of nalbuphine in the blood accounted for almost 100% of the prodrug, which supported the contention that nalbuphine is the major metabolite after SDN hydrolysis. The hydrolysis profiles of SDN were similar both in plasma and in red blood cells when compared in the blood. In vitro release results of SDN long-acting formulation showed that the rate-limited step of SDN hydrolysis to nalbuphine in blood is the penetration of SDN from oil into the blood. After intravenous administration of SDN in sesame oil into rats, nalbuphine quickly appeared in plasma and, thereafter, exhibited monoexponential decay. Pharmaceutical dosage forms affecting the drug disposition kinetics were demonstrated after intravenous administration. The AUC of nalbuphine was significantly higher and clearance was significantly lower, without changes in the t(1/2) of nalbuphine after intravenous dosing of SDN in sesame oil when compared with that of intravenous dosing with nalbuphine HCl in rats. Overall, these results suggest that SDN fulfilled the original pro-soft drug design in which the prodrug can rapidly metabolize to nalbuphine, and no other unexpected compounds were apparent in the blood.

The antinociceptive effect of nalbuphine and its long-acting esters in rats.

A long-acting analgesic is particularly desirable in patients with long-lasting pain. In this study, we evaluated the antinociceptive effect and duration of action of three nalbuphine esters-nalbuphine propionate, enanthate, and decanoate-and observed whether these esters had a long-acting effect. Male Sprague-Dawley rats (n = 12 in each group) were used. Two studies were performed. In Study 1, we evaluated the antinociceptive effect of IM nalbuphine HCl with dosages of 0.25, 1.25, 2.5, 25, and 250 micro mol/kg. In Study 2, we evaluated the antinociceptive effects of IM nalbuphine base and esters with a dosage of 25 micro mol/kg. After 2.5, 25, and 250 micro mol/kg IM injections, we found that nalbuphine HCl produced a dose-related antinociceptive effect with durations of action of 1.5, 2, and 4 h, respectively. After a 25 micro mol/kg IM injection, the durations of action of the nalbuphine esters, nalbuphine propionate, enanthate, and decanoate were 5, 30, and 60 h, respectively. We conclude that, on an equimolar basis, nalbuphine esters produce relatively longer durations of action than nalbuphine HCl.

Biodegradable polymeric microspheres for nalbuphine prodrug controlled delivery: in vitro characterization and in vivo pharmacokinetic studies.

The objective of this work was to study the in vitro characteristics as well as in vivo pharmacokinetic performance of a series nalbuphine (NA) prodrug-loaded microspheres. An oil-in-water solvent evaporation method was used to incorporate the various NA prodrugs into poly(D,L-lactide-co-glycolide) (PLGA)-based microspheres. The morphology of microspheres under the scanning electron microscopy (SEM) revealed a spherical shape with smooth surface. Drug release rates for the microspheres were found to be a function of prodrug hydrophilicity, with higher drug release rates for microspheres loaded with more hydrophilic prodrugs. The release profiles fit well to the Baker and Lonsdale's spherical matrix model, suggesting the drug release from microspheres was consistent with a diffusion mechanism. The in vivo pharmacokinetic studies after s.c. injection of microspheres into rabbits showed sustained plasma NA-time profiles, with approximately 104.7, 67.2, and 41.0% relative bioavailability for microspheres loaded with nalbuphine propionate (NAP), nalbuphine pivalate (NPI), and nalbuphine decanoate (NDE), respectively. The in vitro release characteristics correlated well with the in vivo pharmacokinetic profiles. The results indicated that the prodrug hydrophilicity had significant effects on the in vitro as well as in vivo drug release kinetics. The present study demonstrates the feasibility of using biodegradable polymeric microspheres for controlled delivery of NA prodrugs.

The analgesic effect of nalbuphine and its long-acting prodrug, nalbuphine pivalate, in rats.

BACKGROUND: Nalbuphine is an opioid-analgesic with agonist-antagonist properties. Recently, we have synthesized a nalbuphine prodrug, nalbuphine pivalate. The aim of the present study was to evaluate the analgesic effect and the analgesic duration of this prodrug. METHODS: Forty-eight male Sprague-Dawley rats (4 groups, n = 12 in each group) were used. Rats in group 1 received nalbuphine HCl 25 mumol/kg (in saline) intramuscular injection; rats in group 2 received nalbuphine pivalate 25 mumol/kg (in sesame oil) intramuscular injection, whereas those in groups 3 and 4 received saline and sesame oil respectively. The analgesic effects of testing agents were evaluated using the cold ethanol tail-flick test (-30 degrees C). RESULTS: Both nalbuphine HCl and nalbuphine pivalate demonstrated significant analgesic effects. The analgesic duration of nalbuphine HCl was 2 h while that of nalbuphine pivalate was 30 h. CONCLUSIONS: Nalbuphine pivalate has a very long duration of analgesic action. This fascinating finding is worth further evaluation.

Transdermal delivery of nalbuphine and nalbuphine pivalate from hydrogels by passive diffusion and iontophoresis.

The objective of this study was to evaluate the in vitro transdermal permeation of nalbuphine hydrochloride (CAS 23277-43-2) (NA) and nalbuphine pivalate (NAP), a novel prodrug of NA, from different hydrogel formulations under passive diffusion as well as iontophoresis. Various concentrations of polymers, including polyvinylpyrrolidone (PVP) and hydroxypropyl cellulose (HPC) were used in the hydrogel formulations. The passive permeation rate of NA was affected by the polymer concentrations, which can be attributed to different viscosities of the hydrated formulations; whereas the passive permeation rate of NAP was not influenced by the various polymer concentrations. Iontophoresis significantly increased the permeation rates of NA and NAP from various hydrogel formulations through skin; the enhancement ratios were higher for NA in all the formulations studied. The iontophoretic permeation rates of NA were slightly decreased by the incorporation of polymers; however, the transdermal flux and membrane potential were independent of polymer concentrations for both NA and NAP, demonstrating that the polymer concentrations in the hydrogel formulations did not have significant effects on the iontophoretic permeation of NA and NAP.

High-performance liquid chromatographic method for the simultaneous determination of nalbuphine and its prodrug, sebacoyl dinalbuphine ester, in dog plasma and application to pharmacokinetic studies in dogs.

For the determination of nalbuphine and its long acting prodrug, sebacoyl dinalbuphine ester (SDN), in biological samples, a reversed-phase high-performance liquid chromatographic method using dual detectors was established. Ultraviolet and fluorescence detectors were connected in series for determining SDN and nalbuphine, respectively. The two analytes and internal standard were extracted from plasma by alkaline liquid-liquid extraction using n-hexane-isoamyl alcohol (9:1, v/v). The calibration curve for nalbuphine was linear over the range from 10 to 2,500 ng/ml, while the range was 25 to 2,500 ng/ml for SDN. The within- and between-day precision and accuracy were all within 10% for both nalbuphine and SDN over these concentrations. The method was applied successfully to a pharmacokinetic study of SDN administered at 20 mg/kg to two beagle dogs. Pharmacokinetic analysis revealed that SDN followed a linear one-compartment model with an elimination half-life of 74.7 min. Formation of nalbuphine after intravenous administration of SDN was observed in the first time point sample (5 min). These results indicate that SDN is rapidly metabolized to its active moiety, nalbuphine, in dogs and no other metabolites are detected in plasma.

Species variation in the disposition of nalbuphine and its acetylsalicylate ester analogue.

1. The disposition of (-)17-(cyclobutylmethyl)-4,5 alpha-epoxymorphinan-3,6 alpha, 14-triol (Nalbuphine, Nubain) and its 3-acetylsalicylate ester has been studied in rat and dog to determine whether this analogue can improve the oral bioavailability of nalbuphine. 2. In dog, administration of the acetylsalicylate analogue increased nalbuphine bioavailability 5-fold to 16% and this correlated with an increase in analgesic activity. 3. The disposition of the analogue in rat was characterized by low oral bioavailability and a short plasma half-life. 4. Although nalbuphine acetylsalicylate was rapidly hydrolysed to nalbuphine in rat, nalbuphine bioavailability was not increased in this species. 5. Other studies have shown that these conflicting results are due to species differences in nalbuphine metabolism. Conjugation at the 3-hydroxyl position is the major metabolic pathway for nalbuphine in dog but not rat. Consequently, 3-hydroxyl esters are ineffective prodrugs for nalbuphine in rat and probably man.