Biowaiver or Bioequivalence: Ambiguity in Sildenafil Citrate BCS Classification.

The aim of the present study is to contribute to the scientific characterization of sildenafil citrate according to the Biopharmaceutics Classification System, following the World Health Organization (WHO) guidelines for biowaivers. The solubility and intestinal permeability data of sildenafil citrate were collected from literature; however, the experimental solubility studies are inconclusive and its "high permeability" suggests an API in the borderline of BCS Class I and Class II. The pH-solubility profile was determined using the saturation shake-flask method over the pH range of 1.2-6.8 at a temperature of 37 °C in aqueous media. The intestinal permeability was determined in rat by a closed-loop in situ perfusion method (the Doluisio technique). The solubility of sildenafil citrate is pH-dependent and at pH 6.8 the dose/solubility ratio obtained does not meet the WHO criteria for "high solubility." The high permeability values obtained by in situ intestinal perfusion in rat reinforce the published permeability data for sildenafil citrate. The experimental results obtained and the data available in the literature suggest that sildenafil citrate is clearly a Class II of BCS, according to the current biopharmaceutics classification system and WHO guidance.

A genetic algorithm-based framework for wavelength selection on sample categorization.

In forensic and pharmaceutical scenarios, the application of chemometrics and optimization techniques has unveiled common and peculiar features of seized medicine and drug samples, helping investigative forces to track illegal operations. This paper proposes a novel framework aimed at identifying relevant subsets of attenuated total reflectance Fourier transform infrared (ATR-FTIR) wavelengths for classifying samples into two classes, for example authentic or forged categories in case of medicines, or salt or base form in cocaine analysis. In the first step of the framework, the ATR-FTIR spectra were partitioned into equidistant intervals and the k-nearest neighbour (KNN) classification technique was applied to each interval to insert samples into proper classes. In the next step, selected intervals were refined through the genetic algorithm (GA) by identifying a limited number of wavelengths from the intervals previously selected aimed at maximizing classification accuracy. When applied to Cialis®, Viagra®, and cocaine ATR-FTIR datasets, the proposed method substantially decreased the number of wavelengths needed to categorize, and increased the classification accuracy. From a practical perspective, the proposed method provides investigative forces with valuable information towards monitoring illegal production of drugs and medicines. In addition, focusing on a reduced subset of wavelengths allows the development of portable devices capable of testing the authenticity of samples during police checking events, avoiding the need for later laboratorial analyses and reducing equipment expenses. Theoretically, the proposed GA-based approach yields more refined solutions than the current methods relying on interval approaches, which tend to insert irrelevant wavelengths in the retained intervals. Copyright © 2016 John Wiley & Sons, Ltd.

Physical profile of counterfeit tablets Viagra® and Cialis®

The profile of tablets containing an active pharmacological ingredient can be obtained using different sets of properties, including physical and chemical aspects. The first measurements carried out on tablets are the physical characteristics also called post-tabletting batch (post-TB) characteristics. These data may be valuable to assist in the detection of pharmaceutical product forgery and may also be used in a forensic intelligence perspective when inserted into databases. This work is focused on the physical characteristics of Cialis® and Viagra® tablets seized by the Brazilian Federal Police in the Rio Grande do Sul state. Using the F-test (ANOVA), all samples of counterfeit Viagra® (n = 28) and Cialis® (n = 40) were well distinguished from authentic samples by the following post-TB characteristics: length (major and minor), thickness, and mass. Using the exploratory statistical technique of Hierarchical Cluster Analysis (HCA), tablets with similar physical profiles were grouped. This result may indicate a common illicit production. We observed the validity of using post-TB properties to generate - in a fast and reliable manner and with no sample preparation - a technological profile that joins itself to the other analytical methods assisting in routine forensic detection of counterfeit Viagra® and Cialis®.

Perfil para medicamentos na forma farmacêutica comprimidos contendo uma substância ativa pode ser obtido usando diferentes conjuntos de propriedades, incluindo aspectos físicos e químicos. As primeiras medições realizadas em comprimidos são de características físicas, também chamadas características pós-compressão. Tais dados podem ser valiosos para auxiliar na detecção de falsificações de medicamentos e ser utilizados em uma perspectiva de inteligência forense, quando inseridos em bancos de dados. Este trabalho está focado nas características físicas dos comprimidos de Cialis® e Viagra® apreendidos pela Polícia Federal no Estado brasileiro do Rio Grande do Sul. Com o emprego do Teste de Fisher (ANOVA), todas as amostras falsificadas de Viagra® (n = 28) e de Cialis® (n = 40) foram diferenciadas das amostras autênticas pelas seguintes características pós-compressão: comprimento (maior e menor), espessura e massa. Utilizando-se a Análise Hierárquica de Cluster (AHC), os comprimidos com perfis físicos semelhantes foram agrupados, o que pode indicar uma produção ilícita em comum. Observou-se a validade da utilização das características pós-compressão para gerar, de um modo rápido, confiável e sem preparo de amostra, um perfil tecnológico que se una aos demais métodos analíticos utilizados na rotina forense de detecção de falsificações de Cialis® e de Viagra®.