ABSTRACT
Carvedilol (CRV) is a non-selective blocker of α and ß adrenergic receptors, which has been extensively used for the treatment of hypertension and congestive heart failure. Owing to its poor biopharmaceutical properties, CRV has been incorporated into different types of drug delivery systems and this necessitates the importance of investigating their compatibility and stability. In this sense, we have investigated the applicability of several electroanalytical tools to assess CRV compatibility with lipid excipients. Voltammetric and electrochemical impedance spectroscopy techniques were used to evaluate the redox behavior of CRV and lipid excipients. Results showed that Plurol® isostearic, liquid excipient, and stearic acid presented the greatest anode peak potential variation, and these were considered suitable excipients for CRV formulation. CRV showed the highest stability at room temperature and at 50 °C when mixed with stearic acid (7% w/w). The results also provided evidence that electrochemical methods might be feasible to complement standard stability/compatibility studies related to redox reactions.
ABSTRACT
This work details the study of the redox behavior of the drugs cyclobenzaprine (CBP), amitriptyline (AMP) and nortriptyline (NOR) through voltammetric methods and computational chemistry. Results obtained in this study show that the amine moiety of each compound is more likely to undergo oxidation at 1a at Ep1a ≈ 0.69, 0.79, 0.93 V (vs. Ag/AgCl/KClsat) for CBP, AMP and NOR, respectively. Moreover, CBP presented a second peak, 2a at Ep2a ≈ 0.98 V (vs. Ag/AgCl/KClsat) at pH 7.0. Furthermore, the electronic structure calculation results corroborate the electrochemical assays regarding the HOMO energies of the lowest energy conformers of each molecule. The mechanism for each anodic process is proposed according to electroanalytical and computational chemistry findings, which show evidence that the methods herein employed may be a valuable alternative to study the redox behavior of structurally similar drugs.
ABSTRACT
Red fruits are rich sources of antioxidant compounds with recognized health benefits. Since they are perishable, dried extracts emerge as more durable products and their quality control must include antioxidant capacity assays. In this study, the redox behavior of commercial dried products obtained from camu-camu, açai, acerola and cranberry red fruits was evaluated by electroanalytical approaches. The antioxidant potential was determined by 2,2-diphenyl-1-picrylhydrazyl free radical assay and the electrochemical index concept. The total phenol content was estimated by using a laccase based biosensor. A significant correlation was found between all methods and literature data. The voltammetric profile (cyclic, differential and square wave) obtained for each type of dried extract showed distinguishable features that were correlated with their main major markers, being also useful for identification purposes. The electrochemical methods were cheaper and more practical for evaluation of antioxidant properties and total phenol content in dried powders obtained from different red fruits.
