Cristina S. Ortiz

Simultaneous spectrophotometric determination of phenilpropanolamine HCL, caffeine and diazepam in tablets

A rapid, reliable and specific UV spectrophotometric method was developed to determine Phenilpropanolamine Hydrochloride (I), Caffeine (II) and Diazepam (III) formulated in tablets. This method was validated and compared with a liquid chromatography (LC) procedure used for the simultaneous quantitative analysis of the drugs. The established linearity ranges by both methods for compounds I, II and III were 0.36-0.88, 0.012-0.028 and 0.036-0.084 mg/ml, respectively. The correlation coefficients by HPLC were r(I)(2)=0.997, r(II)(2)=0.999, r(III)(2)=0.999 and by the UV spectrophotometric method were r(I)(2)=0.998, r(II)(2)=0.996, r(III)(2)=0.999. LC and UV methods showed excellent precision and accuracy. As regards precision, LC showed CV values range of 0.2-0.9 and UV 0.15-0.72. On the other hand, accuracy was obtained with CV values range of 0.1-1.8 and 0.32-1.11 for LC and UV, respectively. The recoveries of I, II and III were >98.04% for both methods over the linear range. The UV and HPLC methods have been successfully used to determine the I, II and III content in tablets of different origin.

Analysis of multicomponent formulations containing phenylpropanolamine hydrochloride, caffeine and diazepam by using LC

A reverse phase high performance liquid chromatography assay was carried out for the simultaneous determination of three active principles present in tablets of different origin and wide commercial use in the Province of Córdoba (Argentina). Prescriptions, commercially available as appetite suppressants, very often include the active principles Phenylpropanolamine Hydrochloride (I), Caffeine (II) and Diazepam (III). Simultaneous determination of these three drugs: anorexic, central nervous stimulant and tranquilizer, respectively, in pharmaceutical dosage forms has not been reported. In this study these active principles are quantified. The only sample preparation necessary for the analysis was their dilution with acetonitrile. The resulting solution was filtered and analyzed on a column packed with Supelcosil LC-18 (5 microm) with acetonitrile:water (30:70 v/v) as initial mobile phase (0.4 ml min(-1)) and the detection was performed at 254 nm. Then a linear gradient up to 100% acetonitrile in 18 min (3.0 ml min(-1)) was applied. The procedure was simple and suitable for quality control. The calibration function was established in the ranges of 0.072-0.168 mg ml(-1) for I, 0.036-0.084 mg ml(-1) for II and 0.06-0.196 mg ml(-1) for III. The detection limits of these compounds were 12.8, 4.1 and 11.0 microg ml(-1), respectively with linear response. No chromatographic interference from the tablet excipients was found. The method described in this paper was validated following the analytical performance parameters required by the USP XXIV, and was successfully applied to the commercial tablets.

Physicochemical properties and photodynamic activity of novel derivatives of triarylmethane and thiazine

Triarylmethane and thiazine dyes have attracted attention as anticancer and antimicrobial agents, due to their structural features and selective localizations. Although these dyes have been initially explored in the context of photodynamic therapy, some of these such as New Fuchsin and Azure B have still not been extensively investigated. For this reason, we evaluated the chemical stability, aggregation effect, and lipophilicity, as well as the photodynamic activity against LM‐2 murine mammary carcinoma cells of five new brominated dyes of triarylmethane and thiazine. These cationic compounds were obtained at high purities and unequivocally characterized by conventional techniques. The introduction of bromine atoms into the chromophoric system of New Fuchsin and Azure B dyes gave rise to a moderate bathochromic shift and increased the lipophilicity, thereby improving their photophysical and photochemical properties for biomedical applications. Moreover, the in vitro photodynamic activity demonstrated that, as the degree of bromination increased, the phototoxicity remained unchanged or decreased. The lower efficiency to inactivate cultured tumor cells may be attributed to the formation of the colorless carbinol pseudobase and aggregation effects for triarylmethane and thiazine dyes, respectively. A promising strategy to reverse the biological activity decrease observed might be the design of third‐generation photosensitizers.

Thiazine dyes: Evaluation of monomeric and aggregate forms.

The aggregation phenomenon of Azure B, monobrominated Azure B, Thionine and Methylene Blue was studied by UV-Visible spectrophotometry in different media as a function of dye concentration and temperature variations. The tests carried out in organic solvents allowed the identification of monomeric species of these compounds, which have not been reported in literature and have been wrongly assigned for years. The results obtained in water allowed demonstrating that different kinds of aggregates are present in this medium. In addition, the aggregation tendency of these dyes in organic solvent and aqueous media was established. Several parameters such as lipophilicity, effect of bulky substituents and interactions with media were considered to interpret the aggregation behavior of thiazine dyes.

Photodynamic properties and photoinactivation of Candida albicans mediated by brominated derivatives of triarylmethane and phenothiazinium dyes

The photodynamic activity of brominated derivatives of New Fuchsin and Azure B was studied in solution and in cell suspensions of Candida albicans. The spectroscopic and photodynamic properties of these photosensitizers were compared with those of Crystal Violet and Azure B, which represent active photosensitizer related to each family of compounds. Triarylmethane derivatives absorb intensely with a band centered at ∼ 570 nm, while the phenothiazinium dyes at ∼ 650 nm. Photooxidation of 9,10-dimethylanthracene was observed using phenothiazinium compounds indicating the formation of singlet molecular oxygen, while it was not detected using triarylmethane agents. However, triarylmethane dyes were able to photooxidize l-tryptophan. In yeast cell suspensions, the photosensitized inactivation of C. albicans increases with photosensitizer concentration, causing a ∼ 5 log decrease of cell survival, when the cultures are treated with 20 μM of Crystal Violet and irradiated for 60 min. Under these conditions, the photodynamic activity of 50 μM Azure B induced a ∼ 3 log decrease of cell survival. Studies of photodynamic action mechanism indicated that photoinactivation of C. albicans cells induced by triarylmethane compounds involves mainly type I photoprocess. Although, phenothiazinium derivatives produce singlet molecular oxygen, a contribution of other reactive oxygen species cannot be discarded in the photoinactivation of C. albicans.

Novel oxazine and oxazone dyes: aggregation behavior and physicochemical properties

This research evaluated the synthesis and suitability of synthetic and commercial photosensitizers for use as potential photosensitizers in photodynamic therapy and photodynamic antimicrobial chemotherapy. Spectroscopic properties, experimental aggregation behavior in ethanol, N,N-dimethylformamide, water and water:polyethylene glycol 400, computational details, the ability to generate singlet oxygen, logPHPLC and theoretical logP were determined. All the compounds evaluated formed aggregates in different media. Novel brominated tested compounds exhibited higher lipophilicity and generation of singlet oxygen in comparison with the corresponding starting reagent. The studies showed that the tested oxazine and oxazone dyes satisfy the conditions of a potential drug in terms of physicochemical and photochemical properties.

Development and Validation of a Chromatographic Method for the Analysis of Multicompound Pharmaceutical Preparations

A reverse phase high performance liquid chromatographic assay was carried out for the simultaneous determination of two out of three active principles present in a pharmaceutical preparation. This method was developed to assess the quality of the product.

Development and validation of a reversed phase HPLC method for quantitative analysis of bis-isoxazolylnaphthoquinone

The goal of this study was to determine the kinetic parameters involved in the decomposition of 2-(5-methyl-4-isoxazolylamino)-N-(5-methyl-4-isoxazolyl)-1,4-naphthoquinone-4-imine (1) in aqueous solution and to identify the main degradation products. An isocratic HPLC assay was used to study the degradation rate of 1. The products of hydrolysis were identified by comparison of their retention times with those of authentic samples. The amount of 1 and the two degradation products resulting from storage of 1 in various buffer solutions was followed in function of time by a reversed-phase HPLC stability-indicating method. The observed degradation rates followed pseudo-first-order kinetics at constant pH, temperature and ionic strength. The logk-pH-profile was constructed at 35 degrees C from the first-order rate constants obtained from studies at pH values ranging from 0.88 to 10.80 (mu=0.5 M). Hydrolysis in the acidic and alkaline media resulted in the formation of two degradation products in each case. The pH-rate profile of 1 in buffer solution was adequately described using a four-term rate equation. The obtained pH-rate profile indicated specific acid-base catalysis with a region of maximum stability between pH 6.40 and 7.40 which can be adequate for formulations of 1.