This study was carried out to compare the rate and extent of absorption of a generic salbutamol in oral dosage form (Brethmol, 4 mg) with the proprietary equivalent product (Ventolin, 4 mg), in healthy adult subjects, under fasting conditions. The study was a single dose, randomized, two way crossover study with a four-week washout period. It involved 22 healthy volunteers who received a single dose (4 mg) of the test and the reference products after an overnight fast of at least 10 hours. Blood samples were collected at pre-dose and a serial of 14 samples were collected from each of the subject from 1 h until 48 h post-dose. Plasma concentrations of salbutamol were analyzed using GCMS method. The mean AUC(0-yen) values were 91.26 and 96.45 h.ng/ml for reference and test product, respectively. The mean C(max) values were 12.26 and 12.38 ng/ml and the mean t(max) values were 2.80 and 2.33 hours for reference and test product, respectively. Analysis of variance showed that the 90% confidence intervals on the relative difference of the ratio for the AUC(0-yen) and the C(max) for the test and reference products were contained within the bioequivalence limit (80 - 125%) (C(max): 89.8 - 110.5% and AUC(0-yen): 91.6 - 121.5%). There was no statistically significant difference for the t(max) between the test and reference formulations (p = 0.30). The test formulation was found to be bioequivalent to the reference formulation with regard to AUC(0-yen) and C(max). There was no statistically significant difference in Brethmol and Ventolin t(max). In conclusion, Brethmol and Ventolin are bioequivalent in healthy subjects.
An investigation was conducted on the usage of a single-step extraction procedure involving the retention of a phenylboronate-salbutamol complex on an end-capped C18 solid-phase sorbent to determine the level of salbutamol in human plasma samples. Propranolol, a beta-blocker, was chosen as the internal standard for this assay. In this solid-phase clean-up method, 50 mM sodium carbonate buffer, pH 9.60, was used for conditioning the column as well as washing the endogenous interference. Under the optimal conditions, the recovery of salbutamol from spiked plasma samples was found to be high and reproducible with mean recoveries (n = 3) of more than 90% after elution by using 50% 1 M trifluoroacetic acid in methanol. This sample clean-up step was effectively analyzed under reversed-phase high-performance liquid chromatography with fluorimetric detection. The method was successfully applied to the routine measurement of salbutamol in human plasma from the bioequivalence study on the different administration route of salbutamol. Quantification of salbutamol was convincingly reported with the correlation of coefficient of 0.9980 for the concentration range from 0 to 1000 ng ml(-1). An adequate precision was achieved with both between- and within-day precisions of less than 10% (n = 6) for 100 and 1000 ng ml(-1) and less than 15% (n = 6) for 10 ng ml(-1).
Salbutamol ¿2-(tert-butylamino)-1-[4-hydroxy-3- (hydroxymethyl)phenyl]ethanol¿, also known as albuterol, is clinically the most widely used beta 2-adrenoceptor agonist in the treatment of bronchial asthma. During this study, we evaluated liquid-liquid extraction (LLE) and solid-phase extraction (SPE) in order to develop a reliable extraction method followed by analysis using liquid chromatography and gas chromatography. An assay is described which involves SPE as the clean-up method followed by gas chromatography-mass spectrometry to determine salbutamol levels in human serum after oral administration. The SPE method requires the use of a hyper-cross-linked styrene-divinylbenzene bonded phase (ENV+) without involving any sample pre-treatment to obtain 60-65% recoveries for salbutamol and terbutaline as the internal standard. Distilled water and 1% trifluoroacetic acid in methanol were found to be the most suitable washing solvent and eluting solvent, respectively. A detection limit of 2 ng mL-1 was achieved by derivatization with N-methyl-N-trimethylsilyltrifluoroacetamide to form trimethylsilyl (TMS)-salbutamol (m/z 369) and TMS-terbutaline (m/z 356). The relationship between the ratio of the peak area of salbutamol to that of the internal standard and concentration was linear for the range tested (2-200 ng mL-1) and the correlation of coefficient was 0.9999 with a y-intercept not significantly different from zero. The inter-day relative standard deviation (RSD) was < 10% for all three concentrations. The intra-day RSD was 14% for 2 ng mL-1. This assay was then successfully applied to human serum samples obtained from clinical trials after oral administration of salbutamol.