Kinetic study of anti-HIV drugs by thermal decomposition analysis

Abstract

Kinetic study by thermal decomposition of antiretroviral drugs, Efavirenz (EFV) and Lamivudine (3TC), usually present in the HIV cocktail, can be done by individual adjustment of the solid decomposition models. However, in some cases unacceptable errors are found using this methodology. To circumvent this problem, here is proposed to use a multilayer perceptron neural network (MLP), with an appropriate algorithm, which constitutes a linearization of the network by setting weights between the input layer and the intermediate one and the use of Kinetic models as activation functions of neurons in the hidden layer. The interconnection weights between that intermediate layer and output layer determines the contribution of each model in the overall fit of the experimental data. Thus, the decomposition is assumed to be a phenomenon that can occur following different kinetic processes. In the investigated data, the kinetic thermal decomposition process was best described by R1 and D4 model for all temperatures to EFV and 3TC, respectively. The residual error adjustment over the network is on average 10 3 times lower for EFV and 10 2 times lower for 3TC compared to the best individual kinetic model that describes the process. These improvements in physical adjustment allow detailed study of the process and therefore a more accurate calculation of the kinetic parameters such as the activation energy and frequency factor. It was found E a = 75.230 kJ / mol and s -1 for EFV and E a = 103.25 kJ / mol and s -1 for 3TC.

Estudo Cinético De Decomposição Térmica De Espumas Rígidas De Poliuretano Por Rede Neural Artificial

“…3,4,6 Essas constantes são armazenadas na matriz W 1 , responsável pela linearização da rede. A matriz W 1 possui dimensão (n × 2), sendo n o número de modelos cinéticos considerados na rede.…”

“…29 Vale ressaltar que essa estrutura de rede não é rígida, sendo possível adicionar ou excluir modelos da camada intermediária, dependendo do sistema em estudo. [3][4]6 (5)…”

“…Os modelos podem ser representados por uma equação geral do tipo: 2 (1) em que α representa a fração de decomposição, t o tempo, k a constante de velocidade. Os parâmetros de ajuste p e q definem o modelo físico.Em alguns trabalhos já publicados pelo nosso grupo, como pode ser verificado na literatura, 3,4,6 foi construído um programa computacional baseado na teoria de redes neurais de múltiplas camadas para determinar o conjunto de modelos que melhor descrevem a cinética de decomposição térmica de sólidos. Nestes trabalhos foram estudados a cinética de decomposição do acetato de Ródio e os fármacos Lamivudina e Efavirenz, usados no coquetel anti-HIV.…”

Thermal decomposition kinetics of the antiparkinson drug “entacapone” under isothermal and non-isothermal conditions

“…where g(α) is the the conversion integral, p(x) the temperature integral, x = E/(R.T). The dependence on α is defined by the reaction model, f(α), which can take a variety of mathematical forms [48,32]. Experimentally the measured rate is adequate to the actual process kinetics only when the process variables (α, T, and ( )) are controlled accurately and precisely [32].…”

Kinetics of Lumefantrine Thermal Decomposition Employing Isoconversional Models and Artificial Neural Network

“…From this, for some specific conversion, the temperature of the event at these different curves is analyzed. 10 The isoconversinal approach has been used in research areas as environmental chemistry, 22 pharmaceutical industry 23,24 and materials chemistry. 16 Data for degradation processes need appropriate measurement according to ICTAC 21 and kinetic's committee recommendations.…”