Nuevos avances en el manejo de la hepatitis C / Current advances in hepatitis C treatment

La hepatitis por virus C constituye un problema de salud importante en México. El diagnóstico de poblaciones de alto riesgo es esencial dada la probabilidad de desarrollar enfermedad crónica, cirrosis, descompensación de la cirrosis y la consecuente necesidad de un trasplante hepático o de desarrollar carcinoma hepatocelular. Actualmente, el tratamiento de elección establecido (TEE) incluye interferón pegilado y ribavirina, los cuales han mostrado una tasa de respuesta de alrededor de 57 por ciento en el caso del genotipo 1, el más prevalente en México. Sabemos que entre 30 y 60 por ciento de la población no muestra una respuesta viral sostenida (RVS) o curación. Por lo tanto, en este artículo se revisan las estrategias terapéuticas existentes para optimizar el tratamiento, y se describen también las estrategias de tratamiento para el futuro. Eventualmente, será posible adicionar una o dos moléculas de los nuevos antivirales que actúan directamente (AAD) sobre áreas específicas del virus al TEE. Cada una de ellas cuenta con mecanismo de acción diferente y se está contemplando la posibilidad de una terapéutica libre de interferón después del año 2015.

Infection by hepatitis C virus constitutes an important health problem in Mexico. Diagnosis of high-risk population is essential given the probability of developing chronic disease, cirrhosis and cirrhosis decompensation, likely leading to the need of a liver transplant and/or the development of hepatocellular carcinoma. Currently, the standard of care (SOC) treatment includes pegylated interferon and ribavirin, which have shown an approximately 57 percent rate response in genotype 1, the most prevalent in Mexico. It is known that between 30 and 60 percent of the infected population does not show a sustained virological response or cure. Therefore, in this article, we review existing therapeutic strategies in order to optimize the treatment. Future treatment strategies are also described. Eventually, it will be possible to add one or two molecules of the new directly acting antiviral drugs, to the SOC treatment. Each of them has a different action mechanism, and we are envisioning the possibility of an interferon-free therapy after 2015.

Ergosterol biosynthesis and drug development for Chagas disease

This article presents an overview of the currently available drugs nifurtimox (NFX) and benznidazole (BZN) used against Trypanosoma cruzi, the aetiological agent of Chagas disease; herein we discuss their limitations along with potential alternatives with a focus on ergosterol biosynthesis inhibitors (EBI). These compounds are currently the most advanced candidates for new anti-T. cruzi agents given that they block de novo production of 24-alkyl-sterols, which are essential for parasite survival and cannot be replaced by a host's own cholesterol. Among these compounds, new triazole derivatives that inhibit the parasite's C14± sterol demethylase are the most promising, as they have been shown to have curative activity in murine models of acute and chronic Chagas disease and are active against NFX and BZN-resistant T. cruzi strains; among this class of compounds, posaconazole (Schering-Plough Research Institute) and ravuconazole (Eisai Company) are poised for clinical trials in Chagas disease patients in the short term. Other T. cruzi-specific EBI, with in vitro and in vivo potency, include squalene synthase, lanosterol synthase and squalene epoxidase-inhibitors as well as compounds with dual mechanisms of action (ergosterol biosynthesis inhibition and free radical generation), but they are less advanced in their development process. The main putative advantages of EBI over currently available therapies include their higher potency and selectivity in both acute and chronic infections, activity against NFX and BZN-resistant T. cruzi strains, and much better tolerability and safety profiles. Limitations may include complexity and cost of manufacture of the new compounds. As for any new drug, such compounds will require extensive clinical testing before being introduced for clinical use, and the complexity of such studies, particularly in chronic patients, will be compounded by the current limitations in the verification of true parasitological...

Antichagásicos potenciais: busca racional de compostos com ação seletiva pela cruzaína / Potential antichagasic agents: rational design of compounds with selective action in cruzain

A doença de Chagas, parasitose endêmica causada pelo Trypanosoma cruzi, se apresenta como grande causa de morbimortalidade, afetando cerca de 18 milhões de pessoas no continente americano e causando 21.000 mortes, a cada ano. Atualmente, estima-se que 100 milhões de pessoas estejam sob risco de contaminação nos 18 países da área endêmica da doença. A quimioterapia contra a tripanossomíase americana é constituída por apenas dois fármacos, nifurtimox e benznidazol, que não apresentam ação adequada na fase crônica da doença. Por estas razões, é premente a necessidade de novas e mais eficazes alternativas terapêuticas. A cruzaína, mais abundante cisteíno-protease do parasita, é enzima essencial em todos os estágios de modificação celular do parasita e está, também, presente no processo de invasão e modificação do sistema imune do hospedeiro. Além disso, apresenta diferenças em relação a enzimas dessa categoria no hospedeiro. Trata-se, pois, de excelente alvo bioquímico para a pesquisa de novos agentes contra o T. cruzi. Face ao exposto e tendo-se em vista a especificidade da cruzaína, considera-se de grande interesse a compreensão do mecanismo de interação de compostos com essa enzima com o intuito de planejar derivados com atividade antichagásica potencial. O presente trabalho teve o objetivo de elucidar a afinidade de diferentes classes de compostos pela enzima, na busca racional de novos tripanomicidas. Assim, pró-fármacos peptidicos recíprocos, derivados de primaquina(PQ) e de nitrofural(NF), anteriormente sintetizados, e pró-fármacos peptidicos duplos do hidroximetilnitrofural (NFOH) planejados, e cuja síntese foi estudada, foram submetidos a estudos de modelagem molecular e de docking...