Analytical Quality by Design as an Important Tool to Determine the Best Analytical Conditions for Isoniazid and Its Respective Succinylated Prodrug.

BACKGROUND: Tuberculosis is a worldwide health concern and isoniazid is the most used and considered one of the most effective drugs for its treatment. The "quality" concept must be incorporated into the final pharmaceutical product, according to the quality by design (QbD) definition. Therefore, the determination of analytical test conditions is extremely important and the design of experiments (DoE) becomes a very useful tool. OBJECTIVE: This paper used the concept of QbD to assist the development of analytical conditions for isoniazid and its respective prodrug, applying HPLC. METHOD: HPLC analytical methodologies were developed for isoniazid and its succinylated derivative. The experimental design was carried out using three analytical parameters at three levels. Four chromatographic responses were studied. The impact of analytical parameters on chromatographic responses was assessed using a Pareto chart. Regression models were obtained using multiple regression analysis. DoE analysis was conducted using the Minitab® program and the experiments were performed sequentially, with varying factors. RESULTS: We identify three main risk parameters: mobile phase (high), flow rate (moderate), and pH of buffer (moderate). The ratio of mobile phase buffer (X2) and mobile phase pH (X3) had a major influence on the peak resolutions (Y3). The capacity factors for iso-suc (Y1) and isoniazid (Y2) peaks should be within 3-9 and 4-10, respectively. The peak resolutions between iso-suc and isoniazid (Y3) should be above two. CONCLUSIONS: We designed 27 experiments, obtaining 1.0 mL/min flow rate, 95% buffer in the mobile phase, and pH 7.0 as the optimal analytical conditions. HIGHLIGHTS: Analytical Quality by Design was used as an important tool to determine the best analytical test conditions for isoniazid and its respective prodrug - succinylated isoniazid.

Malaria and tuberculosis as diseases of neglected populations: state of the art in chemotherapy and advances in the search for new drugs.

Malaria and tuberculosis are no longer considered to be neglected diseases by the World Health Organization. However, both are huge challenges and public health problems in the world, which affect poor people, today referred to as neglected populations. In addition, malaria and tuberculosis present the same difficulties regarding the treatment, such as toxicity and the microbial resistance. The increase of Plasmodium resistance to the available drugs along with the insurgence of multidrug- and particularly tuberculosis drug-resistant strains are enough to justify efforts towards the development of novel medicines for both diseases. This literature review provides an overview of the state of the art of antimalarial and antituberculosis chemotherapies, emphasising novel drugs introduced in the pharmaceutical market and the advances in research of new candidates for these diseases, and including some aspects of their mechanism/sites of action.

Future and Perspectives of the Zika Virus: Drug Repurposing as a Powerful Tool for Treatment Insights.

The Zika virus (ZIKV) infection is a major public health concern in Brazil and worldwide, being a rapidly spreading disease with possible severe complications for pregnant women and neonates. There is currently no preventative therapy or specific treatment available. Within this context, drug repositioning is a very promising approach for the discovery of new treatment compounds, since old drugs may become new ones. Therefore, this paper aims to perform a literature mini-review to identify promising compounds to combat this virus. The mechanism of action at the molecular level and the structure-activity relationship of prototypes are discussed. Among the candidates identified, we highlight sofosbuvir, chloroquine and suramin, which present a greater quantity of experimental data to draw on for our discussion. The current treatment is palliative; therefore, this study is of paramount importance in identifying drug candidates useful for combating ZIKV.

Searching for drugs for Chagas disease, leishmaniasis and schistosomiasis: a review.

Chagas disease, leishmaniasis and schistosomiasis are neglected diseases (NDs) and are a considerable global challenge. Despite the huge number of people infected, NDs do not create interest from pharmaceutical companies because the associated revenue is generally low. Most of the research on these diseases has been conducted in academic institutions. The chemotherapeutic armamentarium for NDs is scarce and inefficient and better drugs are needed. Researchers have found some promising potential drug candidates using medicinal chemistry and computational approaches. Most of these compounds are synthetic but some are from natural sources or are semi-synthetic. Drug repurposing or repositioning has also been greatly stimulated for NDs. This review considers some potential drug candidates and provides details of their design, discovery and activity.