[Determination of bromhexine in plasma by gas chromatography-electron capture detection and pharmacokinetic studies]

This paper reports a gas chromatography-electron capture detection(GC-ECD) method for the study of pharmacokinetics of bromhexine in healthy human body. A2 m x 3 mm i.d. silanized glass column packed with 5% SE-30 was used. The carrier gas was nitrogen. The internal standard was 5-chloro-2-amino-diphenyl ketone. After NaH2PO4-Na2HPO4 buffer (pH 6.0) being added, the plasma was extracted with n-hexane-dichloromethane (9:1, V/V). A good linearity was obtained from 1.0 microgram/L to 50.0 micrograms/L of bromhexine in human plasma, r = 0.9994. The detection limit of bromhexine in plasma was 0.5 microgram/L. The average recovery was 97.5%. The pharmacokinetics of bromhexine was determined by this method after a single oral dose of 8 mg bromhexine capsule given to each of 8 volunteers. The results showed that the plasma concentration-time courses conformed to one compartment model. The established GC-ECD method is a good method for the determination of bromhexine in human plasma. The method is rapid, simple, precise and sensitive.

Determination of bromhexine and ambroxol in pharmaceutical dosage forms, urine and blood serum

Data presented in this paper show that bromhexine and its pharmacologically active metabolite can easily be determined by capillary zone electrophoresis. The composition of the running buffer had a significant effect on the reproducibility of the migration time for which a carrier solution containing 30 mM phosphate buffer (pH 3.0), 5 M urea and 10% (v/v) acetonitrile was used. The method was validated with respect to its response linearity and reproducibility. The method is suitable for the determination of bromhexine and ambroxol in several samples such as pharmaceuticals, urine and serum. Photodiode-array detection permitted the rapid identification of both drugs in the sample analyzed.

Flow-injection extraction-spectrophotometric determination of bromhexine with orange IV

An automatic flow-injection photometric method for the determination of bromhexine is proposed. The drug was determined by formation of an ion-pair with orange IV, extraction into 1,2-dichloroethane and measurement of the absorbance at 412 nm of the organic phase. A linear calibration graph was obtained at concentrations of 5 x 10(-6)-1.6 x 10(-4) M of bromhexine. Up to 40 samples h-1 can be processed with an RSD of 0.32-0.88%. The method was applied to the determination of bromhexine in blood serum and a pharmaceutical preparation.

Characterization of bromhexine and ambroxol in equine urine: effect of furosemide on identification and confirmation

The purpose of this study was two-fold: (1) to develop a simple and sensitive screening procedure for identifying and confirming bromhexine and ambroxol and, (2) to determine the effect of furosemide on the detection of bromhexine, ambroxol, or their metabolites in urine. Female horses (450-550 kg) treated with bromhexine or ambroxol (1 g, p.o.) were used. Urine samples were collected up to 48 h post-drug administration and analysed. Blind samples were used in evaluating the sensitivity of these methods and reproducibility of the results. Bromhexine and ambroxol were extensively metabolized in the horse. These agents and their respective metabolites were identified and confirmed using thin-layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS), respectively. Hydroxy-bromhexine and desmethyl-bromhexine were major metabolites found to be unique to bromhexine-treated horses. These metabolites selectively absent from ambroxol-treated horse urine provide a chemical means to distinguish bromhexine from ambroxol administration in horses. These specific metabolites were similarly identified and confirmed in "blind" horse urine samples. The concomitant presence of furosemide (300 mg, i.v.) with bromhexine or ambroxol did not mask the presence of these agents or alter their metabolite profile. By application of the methods described in this study, bromhexine and ambroxol metabolites in horse urine can be easily identified and confirmed.

Determination of bromhexine in plasma by reversed-phase liquid chromatography. Interference of lipoproteins on extraction

Extraction of the hydrophobic tertiary amine bromhexine from plasma using cyclohexane-heptafluorobutanol (99.5:0.5, v/v) was studied at different pH values. The extraction yield from buffer solutions was quantitative at pH greater than 4.1, but from plasma the extraction yield decreased with increasing pH. Furthermore, at pH 8.4 the extraction yield varied greatly (56-99%) in different human plasma. The addition of lipoproteins to phosphate buffer, at pH 8.1, decreased the extraction yields considerably. Quantitative extraction from plasma was obtained by using a very long extraction time at pH 8.4 or by decreasing the pH to 5.4. The chromatographic system consisted of a reversed-phase column (Nucleosil C18, 5 microns) with an acidic mobile phase (methanol-phosphate buffer, pH 2) containing an aliphatic tertiary amine. UV detection at 308 or 254 nm was used. The limit of quantitation was 5 ng/ml using 3.00 ml of plasma and detection at 254 nm. The intra-assay precision for bromhexine was better than 3.6% at 5 ng/ml.

Lack of detectable N-nitroso-N-methyl-N-cyclohexylamine in humans after administration of bromhexine

The possible formation of N-nitroso-N-methyl-N-cyclohexylamine (NMCA) from the drug bromhexine (N-methyl-N-cyclohexyl-(2-amino-3,5-dibromobenzyl)-ammonium hydrochloride) and nitrite was investigated in humans using three different approaches: 1. analysis on metabolites of NMCA in human urine; 2. analysis on NMCA in human gastric juice; 3. in vitro incubation of human gastric juice with therapeutic bromhexine doses. Diet given to volunteers was varied during these investigations with respect to nitrate content. Experiments with a maximum load of 200 mg nitrate to stimulate nitrite formation were performed. Results of in vivo experiments did not indicate any formation of NMCA. In one out of 39 ex-vivo/in-vitro experiments (with a load of 100 mg nitrate in drinking water) 0.5 ng NMCA/ml gastric juice could be detected which is near the detection limit. Finally, this study showed that bromhexine is not secreted by saliva. This allows to conclude that nitrite and bromhexine do not reach the stomach simultaneously over a longer period of time. In consequence, medication with bromhexine is not regarded to represent a risk due to nitrosamine formation.

Bioavailability of bromhexine tablets and preliminary pharmacokinetics in humans

The absorption of bromhexine from Bromhexin tablets 8 mg, DAK has been compared with that from Bisolvon tablets 8 mg, Boehringer Ingelheim, in a two-way complete crossover study. Four tablets of each of the two bromhexine products, corresponding to a single dose of 32 mg of bromhexine hydrochloride (77.6 mumol), was administered to each of the 10 volunteers. The plasma concentration was followed over the 4-hour period following each administration. By means of Pratt's test for paired data no statistically significant difference (p greater than 0.10) between the two products was found with respect to maximum plasma concentration (89 and 84 nmol.1(-1), respectively), the times for their occurrence (1.3 and 1.0 h, respectively), and the area under the plasma concentration-time curves (140 and 132 nmol.1(-1).h, respectively). It is concluded that Bromhexin, DAK and Bisolvon are bioequivalent. Provisional pharmacokinetic data for bromhexine, after oral administration, in man were obtained. The first-pass effect and the biological half-life were estimated by combining plasma and 30 h urine data from four of the volunteers. The first-pass effect was estimated to be c. 75 per cent, the biological half-life to be c. 6 h, and c. 0.1 per cent of the dose was found as unmetabolized bromhexine in the urine. The data indicate that the pharmacokinetics of bromhexine may be described as a two-compartment open model.

Assay of bromhexine in human plasma by capillary gas--liquid chromatography with nitrogen-selective detection and selected ion monitoring

A specific, sensitive method for the determination of bromhexine in human plasma is described. It comprises a selective extraction procedure and a specific determination with capillary gas--liquid chromatography and nitrogen-selective flame ionization detection. The detection limit of the assay is about 0.5 ng/ml. The specificity of the assay was checked by gas chromatography--mass spectrometry. The method is applied to the pharmacokinetics of bromhexine in humans.

Electron-capture GLC determination of bromhexine in human plasma

A specific and sensitive GLC analysis of bromhexine in human plasma is described. After addition of the internal standard and an aqueous triethanolamine solution, bromhexine is extracted at alkaline pH into n-hexane, transferred to an acidic aqueous solution, and back-extracted into n-hexane after alkalinization. Both compounds are derivatized with trifluoroacetic anhydride and quantified by GLC using , 63Ni-electron-capture detector. The method has a sensitivity of approximately 1.0 ng/ml of plasma. Linearity of plasma working curves was good. The extraction recovery from spiked plasma was 90.1 +/- 5.68% (SD). The within-run and within-day precisions (CV) were 6.0% (4.3 ng/ml, n = 8) and 8.6% (11.0 ng/ml, n = 13), respectively. The procedure was applied successfully to measurement of the plasma concentration-time profile in a human volunteer after oral drug administration.

Determination of bromhexine as its trifluoroacetyl derivative by gas-liquid chromatography with electron-capture detection

A specific gas-liquid chromatographic method with electron-capture detection is described for the determination of bromhexine at the nanogram level. Structurally analogous internal standards were synthesized and their suitability was investigated, based on their chromatographic properties on different stationary liquid phases. The electron-capture activity of the compounds is increased by trifluoroacetylation. Reaction conditions for this derivatization were studied. Calibration graphs in the range 0-57 ng (in a total of 100 microliters of reaction mixture) showed good linearity.