CE as orthogonal technique to HPLC for alprazolam degradation product identification

Recent advances in capillary electrophoretic migration techniques for pharmaceutical analysis

Since the introduction about 30 years ago, CE techniques have gained a significant impact in pharmaceutical analysis. The present review covers recent advances and applications of CE for the analysis of pharmaceuticals. Both small molecules and biomolecules such as proteins are considered. The applications range from the determination of drug-related substances to the analysis of counterions and the determination of physicochemical parameters. Furthermore, general considerations of CE methods in pharmaceutical analysis are described.

Benzodiazepines: sample preparation and HPLC methods for their determination in biological samples

Benzodiazepines (BDZs) belong to a group of substances known for their sedative, antidepressive, muscle relaxant, tranquilizer, hypnotic and anticonvulsant properties. Their determination in biological fluids is essential in clinical assays as well as in forensics and toxicological studies. Researchers focus on the development of rapid, accurate, precise and sensitive methods for the determination of BDZs and their metabolites. A large number of analytical methods using different techniques have been reported, but none can be considered as the method of choice. BDZs are usually present at trace levels (microgram or nanogram per milliliter) in a complex biological matrix and the potentially interfering compounds must be isolated by various extraction techniques before analysis. An extended and comprehensive review is presented herein, focusing on sample preparation (pretreatment and extraction) and HPLC conditions applied by different authors. These methods enable bioanalysts to achieve detection limits down to 1-2 ng/ml using UV/diode array detection, readily available in most laboratories, and better than 1 ng/ml using electron capture detection, which is lower than that obtained using a nitrogen phosphorus detector. MS interfaced with electrospray ionization offered a similar sensitivity, while negative chemical ionization MS or sonic spray ionization MS provided sensitivity down to 0.1 ng/ml.

Analytical study proving alprazolam degradation to its main impurity triazolaminoquinoleine through Maillard reaction

Triazolaminoquinoleine is rapidly formed in formulations of alprazolam tablets in presence of excipients, and its generation is speeded up with increasing temperature and humidity. The present paper deals with detailed quantitative and qualitative studies into the nonactive constituents of the formulation in order to determine the excipient (or the mixture) responsible for the degradation. Our studies have demonstrated that reducing carbohydrate excipients play a fundamental role in the generation of triazolaminoquinoleine, with lactose as the main one responsible, through a Maillard reaction. In order to demonstrate the validity of the proposed degradation mechanism, p-nitrobenzaldehyde has been employed as a model of reaction of the nucleophylic attack of amino-opened structure of alprazolam to an aldehyde to generate the first intermediate involved in Maillard reaction, a Schiff base. This model enables the identification of all the intermediates by mass spectrometry and/or nuclear magnetic resonance techniques, with the outcome of this experiment leading to a full understanding of the generation pathway. Calcium carbonate has been proposed as a possible tablet diluent replacing lactose in the pharmaceutical formulation.

Isolation, identification and determination of the major degradation product in alprazolam tablets during their stability assay

The presence of a degradation product of alprazolam tablets that emerged throughout a short-stability assay has been determined and properly characterized. For this purpose an efficient methodology has been successfully applied, including SPE and HPLC methods for isolation and purification, respectively. LC/MS, MS/MS, 1H NMR, 13C NMR, UV and IR have been employed for structural elucidation confirming the identity of this impurity as 7-chloro-1-methyl-5-phenyl-[1,2,4]triazolo[4,3-a]quinolin-4-amine or triazolaminoquinoleine. The impurity, previously described as a long-term photodegradation product of alprazolam active pharmaceutical ingredient, was rapidly formed in the absence of light, but required the presence of excipients and its rate of formation increased with heat and humidity. In addition, a LC method has been developed and validated including triazolaminoquinoleine for the adequate determination of alprazolam and its mayor degradation product in tablets as pharmaceutical forms.