Analysis of cephalexin from canine skin biopsy by liquid chromatography with ultraviolet-visible photodiode-array detection

Quantitative analysis of cephalexin in solid dosage form by Raman spectroscopy and chemometric tools

OBJECTIVE

To use Raman Spectroscopy for qualitative and quantitative evaluation of pharmaceutical formulations of active pharmaceutical ingredient (API) of Cephalexin.

SIGNIFICANCE

Raman Spectroscopy is a noninvasive, nondestructive, reliable and rapid detection technique used for various pharmaceutical drugs quantification. The present study explores the potential of Raman Spectroscopy for quantitative analysis of pharmaceutical drugs.

METHOD

For qualitative and quantitative analysis of Cephalexin API, various standard samples containing less and more concentration of API than commercial tablet was prepared. To study spectral differences, the mean plot of all the samples was prepared. For qualitative analysis, Principal Component Analysis (PCA) and for quantitative analysis Partial Least Square Regression analysis (PLSR) was used. Both of these are Multivariate data analysis techniques and give reliable results as published in previous literature.

RESULTS

PCA model distinguished all the Raman Spectral data related to the various Cephalexin solid dosage formulations whereas the PLSR model was used to calculate the concentration of different unknown formulations. For the PLSR model, RMSEC and RMSEP were determined to be 3.3953 and 3.8972, respectively. The prediction efficiency of this built PLSR model was found to be very good with a goodness of the model value (R2) of 0.98. The PLSR model also predicted the concentrations of Cephalexin formulations in the blind or unknown sample.

CONCLUSION

These findings demonstrate that the Raman spectroscopy coupled to PLSR analysis could be regarded as a fast and effectively reliable tool for quantitative analysis of pharmaceutical drugs.

Simultaneous blood and brain sampling of cephalexin in the rat by microdialysis and microbore liquid chromatography: application to pharmacokinetics studies

To circumvent the need for laborious sample clean-up and multiple blood sampling, a system was developed consisting of on-line microdialysis coupled to microbore liquid chromatography and ultraviolet detection. The system was designed for the simultaneous and continuous monitoring of unbound blood and brain cephalexin in the rat following single bolus intravenous administrations (10 mg/kg, n = 6). Microdialysis probes were inserted into the jugular vein and brain striatum, respectively, for blood and brain sampling. Chromatographic conditions consisted of a mobile phase of methanol-100 mM monosodium phosphoric acid (20:80, v/v, pH 5.0) pumped through a microbore reversed-phase column at a flow-rate of 0.05 ml/min. Detection wavelength was set at 260 nm. The method was validated for response linearity as well as intra- and inter-day variabilities. Rapid appearance of cephalexin in the striatal dialysate suggested good blood-brain barrier penetration. This study provided pharmacokinetics information for cephalexin as well as demonstrated the applicability of this continuous sampling method for pharmacokinetics studies.

Determination of ceftazidime in dolphin serum by liquid chromatography with ultraviolet-visible detection and confirmation by thermospray liquid chromatography-mass spectrometry

A simple and sensitive liquid chromatographic method has been developed for the determination of therapeutic levels of ceftazidime in dolphin serum. The method involved an ultrafiltration of diluted serum with an equal amount of acetonitrile-ethanol-water (40:40:20, v/v/v) through a 10,000 daltons molecular mass cut-off filter. Separation of ceftazidime from the other serum components was performed by ion-paired (dodecanesulfonate) liquid chromatography using a reversed-phase column eluted with acetonitrile-water solution. The ultraviolet absorbance of the column effluent was monitored in the 200-340 nm range of a photodiode-array detector or at 258.8 nm on a variable-wavelength ultraviolet-visible detector. Recoveries of ceftazidime from dolphin serum spiked with 20 and 2 micrograms/ml were 92.9 and 91.1% with coefficients of variation of 5.5 and 5.7%, respectively. A correlation coefficient of 0.9994 occurred with ceftazidime in aqueous solutions (n = 6, in duplicates). The limit of detection for this antibiotic was estimated to be approximately 50 ppb (ng/ml). The unbound ceftazidime concentrations in dosed dolphin serum were determined to calculate the protein bindings of this antibiotic which yielded 32 +/- 2%. The ceftazidime peak identity in dosed dolphin serum was confirmed by thermospray liquid chromatography-mass spectrometry. The thermospray mass spectrum of ceftazidime exhibited only the fragment ions, involving the opening of the beta-lactam ring, at m/z 237, 255 and 315 when positive-ion detection mode was employed and the fragment ions at m/z 235, 253 and 313 when negative-ion detection mode was used.

Analysis of taurine in feline plasma and whole blood by liquid chromatography with fluorimetric detection and confirmation by thermospray mass spectrometry

A liquid chromatographic method with fluorimetric detection was developed to measure taurine (2-aminoethanesulfonic acid) in feline plasma and whole blood. Plasma or lysed whole blood was diluted with a mixture of acetonitrile-methanol-triethylamine-water (25:22:3:50, v/v), filtered through a 10,000 dalton exclusion filter and derivatized with dansyl chloride for 30 min at room temperature. Dansyl taurine was separated from other compounds by reversed-phase liquid chromatography using an octadecyl column and a methanol-acetic acid-triethylamine (30:0.5:0.025, v/v) aqueous mobile phase. The effluent was monitored fluorimetrically at an excitation wavelength of 329 nm and an emission wavelength of 530 nm. The presence of mono-dansylated taurine in feline plasma was confirmed by thermospray mass spectrometry. The limit of detection was 16 nmol/ml and the detector response was linear from 40 to 4000 nmol/ml taurine.

High-performance liquid chromatographic method for the simultaneous determination of enrofloxacin and its primary metabolite ciprofloxacin in canine serum and prostatic tissue

A simple and sensitive high-performance liquid chromatographic method was developed for the determination of enrofloxacin and ciprofloxacin in canine serum and prostatic tissue. Sample preparation consisted of mixing canine serum with a 1:1 dilution of acetonitrile and 0.1 M sodium hydroxide followed by ultrafiltration through a 10,000 molecular mass cut-off filter. Prostatic tissue was sonicated with the same solution prior to ultrafiltration. Separation of these two quinolones in the ultrafiltrate was accomplished by ion-paired liquid chromatography using a reversed-phase analytical column eluted with an acetonitrile-methanol-water solution. Enrofloxacin and ciprofloxacin were detected by a photometric ultraviolet-visible detector set at 278.6 nm and confirmed by a photodiode array detector operating from 230 to 360 nm. The limits of detection for enrofloxacin and ciprofloxacin were 4 and 2 ng/ml, respectively.

Development of an analytical method for penicillin G in bovine milk by liquid chromatography with ultraviolet-visible detection and confirmation by mass spectrometric detection

A liquid chromatographic (LC) method with ultraviolet-visible photodiode array (UV-VIS PDA) detection was developed to measure penicillin G in bovine milk. A liquid chromatographic-mass spectrometric (LC-MS) procedure was divised to confirm the LC method. The method involved diluting milk with a drug-releasing solvent consisting of acetonitrile-methanol-water and ultrafiltration through a 10,000 dalton cutoff filter. Penicillin G was separated from other components in the ultrafiltrate by ion-paired LC using a reversed-phase microbore column eluted with a 25% acetonitrile solution. The LC method was confirmed by thermospray LC-MS. The detection limit for penicillin G determination in milk was estimated to be 10 ppb for LC with UV-VIS PDA and 100 ppb for LC-MS.