Conventional and first derivative synchronous spectrofluorimetric methods for the simultaneous determination of cisatracurium and nalbuphine in biological fluids.

Cisatracurium besylate has been determined by fast and highly sensitive spectrofluorimetric method based on measuring the fluorescence intensity of its methanolic solution at 312 nm after excitation at 230 nm (Method I). The linearity occurred over the concentration range of 10.0-130.0 ng/mL with detection limit of 1.07 ng/mL. The method was further extended for the determination of the studied drug in spiked human plasma with good percentage recoveries (97.43-103.50%). Cisatracurium is co-administered with nalbuphine during surgery. The simultaneous determination of both drugs was based on synchronous spectrofluorimetric technique. First derivative synchronous spectrofluorimetric amplitude was measured in methanol at Δ λ = 60 nm and each drug could be estimated at the zero crossing point of the other. Hence, cisatracurium could be measured at 284.6 nm while nalbuphine at 276.3 nm (Method II). The method was linear over the ranges of 50.0-750.0 ng/mL and 0.5-7.0 µg/mL with the detection limits of 2.16 ng/mL and 0.04 µg/mL for cisatracurium and nalbuphine, respectively. The method was further extended for the simultaneous determination of both drugs in spiked human urine with mean percentage recoveries of 99.99 ± 2.06 and 99.53 ± 6.17 for cisatracurium and nalbuphine, respectively. Both methods were validated in agreement with Guidelines adopted by International Council of Harmonization (ICH).

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.

Determination of nalbuphine in drug abusers' urine.

Nalbuphine, chemically derived from the oxymorphone, is a potent analgesic with narcotic antagonist activity. Because of the limited availability of methamphetamine, the abuse of nalbuphine as an alternative for methamphetamine began in late 1991 in Korea. In this study, the analysis of nalbuphine by gas chromatography (GC) was investigated. Using solid-phase extraction, we analyzed drug abusers' urine samples in order to quantitate nalbuphine by GC after trimethylsilyl derivatization with N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA), trimethylsilylimidazole (TSIM), and 1% trimethylchlorosilane (TMCS) (100:2:5). Nalbuphine and its two metabolites, nornalbuphine and 6-ketonalbuphine, were identified by gas chromatography-mass spectrometry. The ratio of total (i.e., nonconjugated and glucuronide) nalbuphine to nonconjugated nalbuphine ranged from 1.8 to 3.0 in the five drug abusers' urine. The urinary excretion of nalbuphine showed that 93% of nalbuphine was excreted in 6 h after intraperitoneal administration of 10 mg/kg nalbuphine to five rats. No nalbuphine was detected in the urine specimens of rats from 24 to 48 h.

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.

[Studies on the analysis of anileridine, levorphanol, nalbuphine and ethamivan in urine].

The method for the analysis of anileridine, levorphanol, nalbuphine and ethamivan in urine by means of GC/NPD and GC/MSD is described. TFAA and MSTFA-MBTFA have been used in this procedure for TFA and TMS derivatization. The parent forms and the metabolites of the four drugs can be found by GC/NPD screening and GC/MSD confirmation. The method is reliable, fast and sensitive.

Furosemide, Patella vulgata beta-glucuronidase and drug analysis: conditions for enhancement of the TLC detection of apomorphine, butorphanol, hydromorphone, nalbuphine, oxymorphone and pentazocine in equine urine.

We have investigated the action of five sources of beta-glucuronidase enzymes on the hydrolysis of glucuronides of apomorphine, butorphanol, hydromorphone, nalbuphine, oxymorphone and pentazocine in equine urine. For all glucuronides tested, Patella vulgata beta-glucuronidase yielded the largest thin layer chromatographic (TLC) spots. For oxymorphone, P. vulgata was the only treatment to yield detectable TLC spots under test parameters. For these six drugs, TLC spot size and chromatographic quality were compared between control horses and horses pretreated with furosemide four hours earlier. Furosemide pretreatment produced a statistically significant increase in spot size and was found to enhance chromatogram quality. These findings support previous suggestions that P. vulgata is a superior drug-glucuronide hydrolyzing enzyme. They also support earlier reports that administration of furosemide at four hours pre-race is unlikely to result in significant interference with routine drug testing procedures.