Innovative pharmaceutical strategies for niclosamide repositioning / Estratégias farmacêuticas inovadoras para o reposicionamento da niclosamida

The antiparasitic niclosamide has shown promising anticancer activity in preclinical studies against several types of cancer, such as colorectal and prostate. Thus, the objective of this work was to develop innovative formulations for the repositioning of niclosamide as an anticancer agent. In chapter I, a critical review of the literature on the physicochemical properties of the drug was carried out, in addition the results of clinical studies against colorectal and prostate cancer. Besides, a review was carried out on studies that developed formulations containing this drug, as well as hypotheses to improve the biopharmaceutical performance of this molecule. In chapter II, the development of solid amorphous dispersion containing niclosamide was carried out. Drug/polymer solutions were acoustic levitated and characterized by synchrotron X-ray light. This set allowed fast, high quality measurements, as well as the identification of niclosamide recrystallization. Plasdone® and Soluplus® demonstrated better properties to form amorphous dispersions, with the latter showing superior solubility enhancement. The study showed that the developed formulation increased the apparent saturation solubility of niclosamide in water by two times. In chapter III the objective was the development, physicochemical characterization and in vitro anticancer activity of a niclosamide nanoemulsion, having HCT-116 cells as a cellular model. Preliminary results indicated Capmul® MCM C8 as the best liquid lipid for the system, but the first nanoemulsions containing this lipid were not stable to justify its usage. On the other hand, Miglyol® 812 indicated to be a suitable liquid lipid for the system. The niclosamide nanoemulsion (~200 nm) with Miglyol® 812 and poloxamer 188 was stable for 56 days, with a monomodal particle size distribution. Cell viability assay against HCT-116 cells demonstrated that niclosamide cytotoxicity is time and concentration dependent. Results herein obtained encourage further research to understand and optimize niclosamide performance as an anticancer drug substance

O antiparasitário niclosamida tem apresentado promissora atividade anticâncer em estudos pré- clínicos contra diversos tipos de câncer, como coloretal e próstata. Assim, o objetivo deste trabalho foi desenvolver formulações inovadoras para o reposicionamento da niclosamida como agente anticâncer. No capítulo I foi realizada revisão crítica da literatura sobre as propriedades físico-químicas do fármaco, além de resultados de estudos clínicos da niclosamida contra câncer de coloretal e de próstata. Além disso, foi feita revisão sobre estudos que desenvolveram formulações contendo esse fármaco, bem como hipóteses para melhorar o desempenho biofarmacêutico dessa molécula. No capítulo II foi realizado o desenvolvimento de dispersão solida amorfa contendo niclosamida. Soluções de fármaco/polímero foram levitadas em levitador acústico e caracterizadas por raios-X de luz síncrotron. Este conjunto permitiu medições rápidas e de alta qualidade, bem como identificação de recristalização da niclosamida. Plasdone® e Soluplus® demonstraram melhores propriedades para formar as dispersões amorfas, com o último apresentando aumento de solubilidade superior. O estudo mostrou que a formulação desenvolvida aumentou em duas vezes a solubilidade aparente de saturação da niclosamida em água. No capítulo III o objetivo foi o desenvolvimento, a caracterização físicoquímica e atividade anticâncer in vitro de uma nanoemulsão de niclosamida, tendo células HCT-116 como modelo celular. Resultados preliminares indicaram o Capmul® MCM C8 como o melhor lipídio líquido para o sistema, mas as primeiras nanoemulsões contendo este lipídio não foram estáveis para justificar seu uso. Por outro lado, Miglyol® 812 indicou ser um lipídio líquido adequado para o sistema. A nanoemulsão de niclosamida (~200 nm) com Miglyol® 812 e poloxâmero 188 foi estável por 56 dias, com distribuição monomodal do tamanho de partícula. O ensaio de viabilidade celular contra células HCT-116 demonstrou que a citoxicidade da niclosamida é dependente do tempo e da concentração. Os resultados aqui obtidos encorajam mais pesquisas para entender e otimizar o desempenho da niclosamida como uma substância anticancerígena

Bioensaio de atividade moluscicida adaptado para a avaliação de extratos de plantas medicinais / Bioensayo de actividad moluscicida adaptado para evaluación de extractos de plantas medicinales / Bioassay of molluscicidal activity adapted for the evaluation of medicinal plant extracts

Nesta nota é apresentada detalhadamente a metodologia (preparação dos extratos, adaptação dos caramujos, ensaio de atividade, destino dos caramujos) usada para a avaliação da atividade moluscicida de extratos de plantas frente a caramujos da espécie Biomphalaria glabrata. A adaptação desta metodologia tem o propósito de avaliar extratos naturais para a busca de produtos alternativos mais baratos, biodegradáveis, seguros e disponíveis localmente, para o controle das populações de caramujos.

The methodology (extract preparation, adaptation of the snails, activity test, destiny of the snails) used for the evaluation of the molluscicidal activity of plant extracts in relation to snails from the Biomphalaria glabrata species appears in detail in this note. The adaptation of this methodology has the purpose of evaluating natural extracts in order to find cheaper, biodegradable, safe and easily available alternative products for the control of the populations of snails.

En este apunte se presenta detalladamente la metodología (preparación de los extractos, adaptación de los caracoles, ensayo de actividad, destino de los caracoles) utilizada para la evaluación de la actividad moluscicida de extractos de plantas frente a caracoles de la especie Biomphalaria glabrata. La adaptación de esta metodología tiene el propósito de evaluar extractos naturales para la búsqueda de productos alternativos más baratos, biodegradables, seguros y disponibles localmente, para el control de las poblaciones de caracoles.

Effects of bayluscide WP 70 on the survival and water-leaving behaviour of Biomphalaria straminea, snail host of schistosomiasis in northeast Brazil

The toxic and behavioural effects of niclosamide (Bayluscide WP 70) on Biomphalaria straminea from a highly endemic area of schistosomiasis in northeastern Brazil were investigated through laboratory bioassays. The LD50 and LD90 were 0.114 mg/l and 0.212 mg/l, respectively. Water-leaving behaviour occured among 14 per cent to 30 per cent of snails in the presence of sublethal doses of niclosamide and among 16 per cent of the controls. It was concluded that both relatively low susceptibility to niclosamide and water-leaving behaviour of local B. straminea may be responsable for the recolonization of transmission foci after mollusciciding. It was suggested that recently improved measures of snail control, such as controlled-release formulations of niclosamide and plant molluscicides should be considered in areas where snail control is recommended.

Evaluation of the molluscicidal properties of Euphorbia splendens var. hislopii (N.E.B.) Latex: experimental test in an endemic area in the state of Minas Gerais, Brazil

Following the positive results obtained regarding the molluscicidal properties of the latex of Euphorbia splendens that were corroborated in laboratory and field tests restrited conditions, a field study was conducted in experimental streams located in an endemic area. After recording the average annual fluctuation of vectors in three streams, a solution of E. splendens latex at ppm was applied in stream A, a solution of niclosamide at 3 ppm that applied in stream B and a third stream (C) remained untreated for negative control. Applications of E. splendens and niclosamide resulted in a mortality of 100 per cent among the snails collected in the streams A and B. No dead snails were found in the negative control stream. A monthly follow-up survey conducted during three consecutive months confirmed the return of vectors to both experimental streams treated with latex and niclosamide. This fact has called for a need to repeat application in order to reach the snails that remained buried in the mud substrate or escaped to the water edge, as well as, newly hatched snails that did not respond to the concentration of these molluscicides. Adults snails collected a month following treatment led us to believe that they had migrate from untreated areas of the streams to those previously treated.

Efficacy of niclosamide as a potential antipenetrant (TAP) against cercariae of Schistosoma mansoni monkeys

A 1% (W/V) formulation of Niclosamide (2', 5-Dichloro-4-nitrosalicylanilide) (TAP) was tested on Cebus apella monkeys as a topical prophylatic against schistosomiasis mansoni. Two experiments were conducted using the same formulation. In the first experiment, the TAP provided complete protection against schistosomiasis for 3 days. Of the 4 monkeys treated with TAP 7 days before exposure to Schistosoma mansoni cercariae, 2 were completely protected. The remaining 2 monkeys of the 7 day treatment group had a 78% or greater reduction in adult worm buderns when compared to the placebo treated monkeys. The second experiment was designed determine the time between day 3 and 7 when the TAP no longer provided complete protection. However, all of the TAP treated monkeys in this experiment were completely protected, even the monkeys treated 7 days earlier. In both experiments, all monkeys used as infection controls and those receiving only the placebo became infected and showed typical experimental schistosomiasis. These results demonstrate that the TAP could provide fast acting, short-term protection to people who must enter cercariae infested water

Studies on the comparative efficacy of mebendazole, flubendazole and niclosamide against human tapeworm infections.

The efficacy of Mebendazole and Niclosamide was studied in two groups of 24 and 38 cases, respectively of patients suffering from taeniasis. Mebendazole with dose schedule of 200 and 300 mg twice daily for 3 consecutive days showed a cure rate of 71.42% and 92.30%, whereas Niclosamide at the dose rate of 200mg per patient was 94.76% effective. Flubendazole showed a cure rate of 66.66% only. Mebendazole and Niclosamide possess high taeniacidal activity, ability to reduce the clinical symptoms of taeniasis without any side effects. Niclosamide with high activity and excellent tolerance, is a drug of choice for the treatment of taeniasis in single dose treatment while for hymenolepsiasis it needs extended course.