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

Breast Milk Excretion of Dinalbuphine Sebacate Injection Administered After Cesarean Section

Ensuring the safety of analgesics during lactation is crucial for women of childbearing potential. Available data regarding the transfer of nalbuphine for postoperative acute pain via breast milk are limited to the postmarketing experience. This lactation study aimed to assess nalbuphine and dinalbuphine sebacate concentrations in breast milk from lactating women with postoperative pain treated with dinalbuphine sebacate extended-release injection (150 mg dinalbuphine sebacate/2 mL Naldebain). Breast milk was collected throughout the 5-day posthospitalization interval from 20 mothers injected with one dose of extended-release dinalbuphine sebacate intramuscularly. Maternal safety was assessed during the study period. Nalbuphine was detectable in 71% of milk samples collected from all mothers, whereas dinalbuphine sebacate was undetectable or below the quantitation limit (0.1 ng/mL). The mean nalbuphine concentration in milk was approximately 10.55 ng/mL, with the peak concentration reaching up to 12.7 ng/mL. The mean relative infant dose was 0.39% (coefficient of variation, 65%). The mean pain intensity at rest was reduced to mild pain from Day 2 morning to discharge. Overall, the maternal safety profile was tolerable. The breast milk of women who receive one dose of dinalbuphine sebacate injection postpartum contains low nalbuphine concentration. In addition, dinalbuphine sebacate injection potentially reduces maternal pain intensity during the first postpartum week and offers low toxicity risk among breastfed infants.

A Validated UHPLC-MS/MS Method for Determination of Nalbuphine in Human Plasma and Application for Pharmacokinetic Study of Patients Undergoing General Anesthesia

Nalbuphine was a semisynthetic opioid analgesic widely used in the treatment of both acute and chronic pain. We developed and validated a rapid, simple and sensitive method by ultra-performance liquid chromatography-tandem mass spectrometry (MS/MS) for the simultaneous quantitation of nalbuphine in human plasma, and we reported the pharmacokinetic features of patients during general anesthesia for abdominal surgery. Sample separation was achieved on a Kinetex Phenyl-Hexyl column (50 × 2.1 mm, 1.7 μm) after simple protein precipitation with acetonitrile. The mobile phase was composed of acetonitrile and 3 mM of ammonium acetate aqueous solution with 0.1% formic acid. Gradient elution was used in 4.5 min with a flow rate of 0.5 mL/min at 40°C. MS detection using AB Sciex QTRAP 5500 mass spectrometer was characterized by electrospray ionization for positive ions in multiple reaction monitoring mode. Quantitative ion pairs were m/z 358.4 → 340.1 for nalbuphine and m/z 340.0 → 268.3 for nalmefene, which were used as the internal standard (IS). The calibration curves showed good linearity (r2>0.99) over concentration range of 0.1-500 ng/mL. The intra-and inter-batch precisions were within 10.67%, and accuracy ranged from 94.07 to 105.34%. The IS-normalized matrix factors were 1.02-1.03 with RSD% (≤5.82%). The recoveries ranged from 101.09 to 106.30%. In conclusion, a rapid, simple, sensitive and economical analytical method was developed and validated to detect the concentration in plasma samples obtained from patients receiving nalbuphine intravenous injection and was successfully applicated to human pharmacokinetic studies of nalbuphine.

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.

Pharmacokinetics of dinalbuphine sebacate and nalbuphine in human after intramuscular injection of dinalbuphine sebacate in an extended-release formulation

Nalbuphine is a semi-synthetic opioid indicated for the relief of moderate to severe pain. Its short half-life requires frequent injections in clinical practice, resulting in a greater incidence of adverse events. A prodrug of nalbuphine has been developed, dinalbuphine sebacate (DNS), dissolved in a simple oil-based injectable formulation, which could deliver and maintain an effective blood level of nalbuphine. An open-label, prospective, two-period study was performed in healthy volunteers to verify the extended blood concentration profile of nalbuphine. Twelve healthy Taiwanese were randomized to receive an intramuscular injection of 20 mg nalbuphine HCl and 150 mg DNS sequentially with a washout period of 5 days. To prevent DNS hydrolysis during sample analysis, the effect of four esterase inhibitors was evaluated in the quantitation of DNS in human whole blood and thenoyltrifluoroacetone was chosen. The bioavailability of nalbuphine from intramuscularly injected DNS relative to that from nalbuphine HCl was 85.4%. The mean absorption time of nalbuphine from DNS was 145.2 h. It took approximately 6 days for the complete release of DNS into the blood stream where DNS was rapidly hydrolysed to nalbuphine; suggesting a single injection of 150 mg DNS in our extended-release formulation could provide long-lasting pain relief.

Utility of Activated Glassy Carbon and Pencil Graphite Electrodes for Voltammetric Determination of Nalbuphine Hydrochloride in Pharmaceutical and Biological Fluids

This work compares voltammetric response of nalbuphine hydrochloride (NP·HCl) at both activated glassy carbon and pencil graphite electrodes. The electrochemical oxidation of the drug was studied using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV) techniques. For analytical purpose a well-resolved irreversible diffusion controlled voltammetric peak was established in Britton-Robinson (B-R) buffer solution of pH 6.00 using pencil graphite electrode (PGE). Using activated glassy carbon electrode (GCE) a well-resolved irreversible diffusion controlled voltammetric peak was obtained at pH 7.00 using the same buffer solution. According to the linear relationship between the peak current and NP·HCl concentration, DPV and SWV methods were developed for their quantitative determination in pharmaceutical and human biological fluids. The linear response was obtained in the range from1.6×10-5to1.5×10-4 mol L−1using PGE and from12.5×10-6to13.75×10-5 mol L−1using a GC electrode, respectively. Precision and accuracy of the developed method were checked by recovery studies.

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.

Applicability of bioanalysis of multiple analytes in drug discovery and development: review of select case studies including assay development considerations

The development of sound bioanalytical method(s) is of paramount importance during the process of drug discovery and development culminating in a marketing approval. Although the bioanalytical procedure(s) originally developed during the discovery stage may not necessarily be fit to support the drug development scenario, they may be suitably modified and validated, as deemed necessary. Several reviews have appeared over the years describing analytical approaches including various techniques, detection systems, automation tools that are available for an effective separation, enhanced selectivity and sensitivity for quantitation of many analytes. The intention of this review is to cover various key areas where analytical method development becomes necessary during different stages of drug discovery research and development process. The key areas covered in this article with relevant case studies include: (a) simultaneous assay for parent compound and metabolites that are purported to display pharmacological activity; (b) bioanalytical procedures for determination of multiple drugs in combating a disease; (c) analytical measurement of chirality aspects in the pharmacokinetics, metabolism and biotransformation investigations; (d) drug monitoring for therapeutic benefits and/or occupational hazard; (e) analysis of drugs from complex and/or less frequently used matrices; (f) analytical determination during in vitro experiments (metabolism and permeability related) and in situ intestinal perfusion experiments; (g) determination of a major metabolite as a surrogate for the parent molecule; (h) analytical approaches for universal determination of CYP450 probe substrates and metabolites; (i) analytical applicability to prodrug evaluations-simultaneous determination of prodrug, parent and metabolites; (j) quantitative determination of parent compound and/or phase II metabolite(s) via direct or indirect approaches; (k) applicability in analysis of multiple compounds in select disease areas and/or in clinically important drug-drug interaction studies. A tabular representation of select examples of analysis is provided covering areas of separation conditions, validation aspects and applicable conclusion. A limited discussion is provided on relevant aspects of the need for developing bioanalytical procedures for speedy drug discovery and development. Additionally, some key elements such as internal standard selection, likely issues of mass detection, matrix effect, chiral aspects etc. are provided for consideration during method development.

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.