Determination of Nalbuphine Hydrochloride in Pharmaceutical Formulations Using Diperiodatoargentate(III)-Rhodamine-B Chemiluminescence System by Flow Injection Analysis.

A novel method for the analysis of nalbuphine hydrochloride (NAL) is reported based on its enhancement effect on a diperiodatoargentate(III)-rhodamine-B (Ag(III) complex-Rh-B) chemiluminescence (CL) system in an aqueous sulfuric acid medium using flow-injection analysis (FIA). The optimal conditions of the CL reaction were: sulfuric acid, 10-2 M; Ag(III) complex, 2.0 × 10-4 M; Rh-B, 2.0 × 10-5 M; Brij-35, 0.01%; sample loop volume, 300 µL; and flow rate, 3.0 mL/min/stream. The limit of detection (LOD) and limit of quantification (LOQ) were 0.001 and 0.003 mg/L (S/N = 3 and 10); linear calibration range, 5 × 10-3 - 5.0 mg/L (R2 = 0.9999) and injection throughput, 150/h. The relative standard deviation (RSD) was from 0.8 - 3.2% over the range studied. The suggested technique was applied for the determination of NAL in pharmaceutical injections, compared with a reported spectrophotometric method, and obtained results were found to be satisfactory. Based on spectrophotometric studies, the most probable mechanism of the CL reaction has been briefly described and drawn schematically.

New spectrophotometric/chemometric assisted methods for the simultaneous determination of imatinib, gemifloxacin, nalbuphine and naproxen in pharmaceutical formulations and human urine.

In this paper, novel univariate and multivariate regression methods along with model-updating technique were developed and validated for the simultaneous determination of quaternary mixture of imatinib (IMB), gemifloxacin (GMI), nalbuphine (NLP) and naproxen (NAP). The univariate method is extended derivative ratio (EDR) which depends on measuring every drug in the quaternary mixture by using a ternary mixture of the other three drugs as divisor. Peak amplitudes were measured at 294nm, 250nm, 283nm and 239nm within linear concentration ranges of 4.0-17.0, 3.0-15.0, 4.0-80.0 and 1.0-6.0µgmL-1 for IMB, GMI, NLP and NAB, respectively. Multivariate methods adopted are partial least squares (PLS) in original and derivative mode. These models were constructed for simultaneous determination of the studied drugs in the ranges of 4.0-8.0, 3.0-11.0, 10.0-18.0 and 1.0-3.0µgmL-1 for IMB, GMI, NLP and NAB, respectively, by using eighteen mixtures as a calibration set and seven mixtures as a validation set. The root mean square error of predication (RMSEP) were 0.09 and 0.06 for IMB, 0.14 and 0.13 for GMI, 0.07 and 0.02 for NLP and 0.64 and 0.27 for NAP by PLS in original and derivative mode, respectively. Both models were successfully applied for analysis of IMB, GMI, NLP and NAP in their dosage forms. Updated PLS in derivative mode and EDR were applied for determination of the studied drugs in spiked human urine. The obtained results were statistically compared with those obtained by the reported methods giving a conclusion that there is no significant difference regarding accuracy and precision.

New spectrofluorimetric and spectrophotometric methods for the determination of the analgesic drug, nalbuphine in pharmaceutical and biological fluids.

We describe the first studies of a simple and sensitive spectrofluorimetric and spectrophotometric methods for the analysis of nalbuphine (NLB) in dosage form and biological fluids. The spectrofluorimetric method was based on the oxidation of NLB with Ce(IV) to produce Ce(III) and its fluorescence was monitored at 352 nm after excitation at 250 nm. The spectrophotometric method involves addition of a known excess of Ce(IV) to NLB in acid medium, followed by determination of residual Ce(IV) by reacting with a fixed amount of methyl orange and measuring absorbance at 510 nm. In both methods, the amount of Ce(IV) reacted corresponds to the amount of NLB and measured fluorescence or absorbance were found to increase linearly with the concentration of NLB, which are corroborated by correlation coefficients of 0.9997 and 0.9999 for spectrofluorimetric and spectrophotometric methods, respectively. Different variables affecting the reaction conditions such as concentrations of Ce(IV), type and concentration of acid medium, reaction time, temperature, and diluting solvents were carefully studied and optimized. The accuracy and precision of the methods were evaluated on intra-day and inter-day basis. The proposed methods were successfully applied for the determination of NLB in pharmaceutical formulation and biological samples with good recoveries.

Excretion of ketoprofen and nalbuphine in human milk during treatment of maternal pain after delivery.

Analgesics are required to prevent and treat postpartum pain, but breast-feeding may be contraindicated, because data on milk transfer are very limited. The present study was undertaken to quantify the transfer of ketoprofen and nalbuphine in milk. Eighteen patients gave their informed consent to participate and completed the study. Following delivery, they received ketoprofen (100 mg/12 hours) and nalbuphine (0.2 mg/kg/4 hours) as an intravenous bolus over 2 to 3 days for postpartum pain. Milk samples were collected during the 12 hours between the third and fourth ketoprofen administrations. Ketoprofen and nalbuphine concentrations were determined with high-performance liquid chromatography. The mean and maximum ketoprofen milk concentrations were 57+/-37 and 91+/-51 ng/mL, respectively. Assuming a milk volume of 150 mL/kg/day, the mean and maximum doses that a breast-fed neonate would ingest during one day are 8.5+/-5.5 and 13.6+/-7.6 microg/kg/day, respectively, and the relative infant dose is 0.31+/-0.17% of the weight-adjusted maternal daily dose. The mean and maximum nalbuphine milk concentrations were 42+/-26 and 61+/-26 ng/mL, respectively. Assuming a milk volume of 150 mL/kg/day, the mean and maximum doses that a breast-fed neonate would ingest during one day is 7.0+/-3.2 and 9.0+/-3.8 microg/kg/day, and the relative infant dose is 0.59+/-0.27% of the weight-adjusted maternal daily dose. Therefore, breast-feeding is permissible when ketoprofen and/or nalbuphine are administered to the mother to treat postpartum pain.

Hair analysis by LC-MS as evidence of nalbuphine abuse by a nurse.

Individuals in any profession can succumb to chemical abuse. Among the healthcare profession, nurses represent a specific group because of their ease of access to drugs, particularly narcotics. Opioids, potentially highly addictive agents, are usually their drug of choice. Nalbuphine, a synthetic opioid analgesic, is prescribed for moderate-to-severe acute pain, for chronic pain syndromes, and in obstetrics to decrease the adverse respiratory effect of opioid epidural administration. The case of a nurse who was suspected of drug misuse after the disappearance of two nalbuphine ampules in an obstetrics service is described. Because of discrepancies in the results of her blood and urine samples, a sample of head hair was subsequently collected from the nurse. A hair analysis of nalbuphine by liquid chromatography-mass spectrometry has not been previously described. Following decontamination and grinding, hair was mixed with a Söerensen buffer, then subjected to ultrasonic treatment (1 h), and extracted with ethyl acetate. A quantitative analysis was performed with two channels (30 and 45 V), and it is based on a m/z 358 for nalbuphine and a m/z 330 for methylclonazepam as an internal standard. The method was linear from 0.020 to 12 ng/mg of hair (R(2) = 0.972), and the limit of detection and limit of quantitation are 0.020 ng/mg. Accuracy (CV), assessed at 0.4 and 1.6 ng/mg of hair, was 6.18% and 5.77%, respectively, for intraday assays and 4.5% and 10.9% for interday assays. Recovery efficiency at 1.6 ng/mg and 8 ng/mg of hair was 100% and 97.4%, respectively. The hair specimen from the nurse (6 cm) was cut into three equal lengths. Nalbuphine, venlafaxine, and nordiazepam were detected. The concentration of nalbuphine was similar in the three hair locks: 5.07, 7.06, and 5.70 ng/mg of hair. A hair analysis revealed the repeated intake of nalbuphine by the nurse. This person was treated for depression for several months with Effexor (venlafaxine) and Nordaz (nordiazepam) prior to the investigation. Hair appears to be a unique matrix to provide evidence for chronic drug exposure by establishing a historic record that is not possible by blood or urine analysis.

High-performance liquid chromatography of nalbuphine, butorphanol and morphine in blood and brain microdialysate samples: application to pharmacokinetic/pharmacodynamic studies in rats.

A rapid and sensitive assay for quantification of nalbuphine, butorphanol and morphine in blood (50 microL) and brain microdialysate ( approximately 40 microL) samples was developed. Blood samples were extracted with ethyl acetate. Analysis was performed with high-performance liquid chromatography (HPLC) coupled to an electrochemical detector. The mobile phase was a mixture of 0.1 M sodium phosphate buffer, methanol and octane-sulfonic acid with ratio and pH depending on compound and matrix. The limits of quantification in blood samples were 25, 50 and 25 ng/mL for nalbuphine, butorphanol and morphine, respectively and 0.5 ng/mL for morphine in microdialysate samples. Based on sample volume, sensitivity and reproducibility, these assays are particularly suitable for pharmacokinetic/pharmacodynamic studies in rodents.

Role of drug testing as an early warning programme: the experience of the Republic of Korea.

Drug testing plays an important role in the provision of information to health authorities on trends in drug abuse. In the Republic of Korea, the testing of urine and postmortem specimens has been used as part of a programme to monitor and control the abuse of non-controlled drugs, i.e., substances that were not originally included in the lists of controlled substances in that country. Zipeprol, dextromethorphan, carisoprodol and nalbuphine are examples of such drugs, which are widely used as medicines. Increasing levels of abuse of these drugs, including abuse that resulted in fatalities, were confirmed in the Republic of Korea by the results of drug testing. Based on the accumulated data from postmortem specimens, the health authorities in the Republic of Korea subsequently introduced controls on these drugs. A significant drop in fatalities related to the abuse of these non-controlled drugs underlined the importance of timely action for improving community health. In the context of drug testing, the analysis of non-controlled and new drugs always presents a scientific challenge, because specific analytical methods for testing for those drugs are not available. In the Republic of Korea, as part of the drug abuse warning programme, it was necessary to establish methods for the detection and quantification in biological fluids of all four non-controlled drugs and their metabolites in order to monitor the trends in drug abuse. The present paper puts forward epidemiological and clinical data on abuse and fatalities associated with zipeprol, dextromethorphan, carisoprodol and nalbuphine, as well as details of the analytical methods developed.

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.

Investigation of 4,5-epoxymorphinan degradation during analysis by HPLC.

Compounds of the 4,5-epoxymorphinan series have been shown to degrade in solution to the corresponding 2,2'-dimers when stored in amber glass HPLC vials. A colorant in the glass has been shown to catalyze the degradation. Although amber glass is routinely used to protect solutions from light degradation, it should not be used without evaluating its effect on sample stability.

Delivery of nalbuphine and its prodrugs across skin by passive diffusion and iontophoresis.

The in vitro transport of nalbuphine (NA) and its prodrugs across various skins was investigated in order to assess the effects of prodrug lipophilicity on passive as well as iontophoretic permeation. The passive diffusion of NA and its prodrugs increased with the drug lipophilicity. Iontophoresis significantly increased the transport of NA and its prodrugs; the enhancement ratio was highest for NA and decreased as the drug lipophilicity increased. Measurements using intact and stratum corneum (SC)-stripped skins showed that the SC was the major skin diffusion barrier for the passive permeation of NA and nalbuphine pivalate (NAP). The iontophoretic permeation of NA and NAP across intact and SC-stripped skins indicated that the SC layer was not rate-limiting for the permeation of NA, but remained the rate-limiting barrier for transdermal permeation of NAP. Permeation studies using SC-stripped and delipidized skins suggested that the intercellular pathway was the predominant route for the passive permeation of NA and NAP as well as the iontophoretic permeation of NAP across the SC. The relative rates of passive and iontophoretic permeation across Wistar rat skins demonstrated that a significant amount of NA may permeate skin via the appendageal routes, whereas NAP permeated predominantly through the lipid matrix.

Derivatization methodology for the analysis of butorphanol by gas chromatography-mass spectrometry.

Butorphanol is an opioid used as analgesic in humans and other species. In horses, it can cause locomotor stimulation at low doses. This drug is not well chromatographed by GC and so, it is necessary to transform it into a more suitable compound, which can be done by derivatization. The derivatization of a drug is used to impart volatility, masking polar groups to improve the results in gas chromatographic analysis. We have evaluated N,O-bis(trimethylsilyl)- trifluoracetamide (BSTFA)+ 1% trimethylchlorsilane (TMCS) and N-methyl-N-trimethylsilil-trifluoroacetamide (MSTFA) as derivatizing reagents for butorphanol at 30, 60 and 80 degrees C during 15, 30 and 60 min. The effects of dilution of these reagents with toluene and the evaporation before the derivatization were tested. Both reagents can be used for butorphanol derivatization and analysis and the dilution and evaporation steps did not alter the final results. The best derivatization conditions were 15 min at 80 degrees C, although 60 degrees C, although 60 degrees C during 60 min were also suitable.

Determination of nalbuphine using high-performance liquid chromatography coupled to photodiode-array detection and gas chromatography coupled to mass spectrometry.

A procedure involving capillary column gas chromatography coupled to mass spectrometry and a method involving liquid chromatography coupled to a diode-array detector have been developed for the analysis of nalbuphine. The extraction step is the same for both techniques and involves extraction under alkaline conditions in chloroform-2-propanol-n-heptane (50:17:33, v/v/v) with levallorphan as the internal standard. After purification by acidic extraction and back alkaline extraction, drugs are derivatized with N,O-bis-(trimethylsilyl)trifluoroacetamide with 1% trimethylchlorosilane for gas chromatography-mass spectrometry and directly injected for high-performance liquid chromatography-diode-array detection. The limits of detection are 2.0 and 25.0 ng/mg, respectively.