Among neglected tropical diseases, schistosomiasis is the second most important public health disease in the world, after malaria. Among the species capable of affecting humans, Schistosoma mansoni stands out for being one of the most prevalent etiological agents in tropical and subtropical regions, present in approximately 54 endemic countries (Brasil, 2014). These parasites inhabit the host's mesenteric veins and are responsible for the development of acute and chronic forms of the disease (Vitorino et al., 2012; Barbosa et al., 2016). In order to reduce the severe forms of mansonic schistosomiasis, therapeutic alternatives have been studied worldwide. In Brazil, chemotherapy has been used in order to reduce morbidity, prevalence and incidence (Silva et al., 2012; Brasil, 2014).

Currently, praziquantel (PZQ), or 2-cyclohexylcarbonyl-1,2,3,6,7,11b-hexahydro-4H-pyrazine(2,1-a)isoquinoline-4-one, is the most used drug, a pyrazinoisoquinoline derivative that has become the treatment of choice for being effective against all Schistosoma species. PZQ has a lower cost and lower toxicity compared to other schistosomicidal compounds previously used (Santiago et al., 2014; Cioli et al., 2014; Marques et al., 2018).

The exclusive use of PZQ in its treatment can cause the development of a possible resistance of Schistosoma mansoni worms to this drug (DOENHOFF, CIOLI, UTZINGER, 2008; CIOLI et al., 2014). Due to this problem, there is an urgent need to develop new schistosomicidal options that can be used as alternatives for the treatment of this parasitosis.

Thiosemicarbazones are compounds that, due to their structure, make it easy to synthesize new molecules by structural rearrangement and addition of radicals, which helps in the development of new compounds with pharmacological activity, thus expanding their applications, presenting themselves as new alternatives for treatment of some diseases (Figueirêdo, 2017). Therefore, new drug candidates derived from a thiosemicarbazone were discovered, including 2-(-5-bromo-1-h-indol-3-yl-methylene)-N-(naphthalene-1-yl_hydrazine-carbotiamide (LQIT/LT-50), used in the present study (Oliveira et al., 2015).

According to Almeida Júnior (2019), LQIT/LT-50, despite having good schistosomicidal activity in vitro, LQIT/LT-50 presents low solubility in water, which can hinder its pharmacological activity. This fact was also evidenced by other studies (JAIN, PATEL, LIN, 2014). In this premise, by increasing the solubility of a molecule, there may be an improvement in its pharmacological activity, in addition to its bioavailability (Silva et al., 2012; Huang et al., 2016).

the use of new technologies is an alternative to increase the solubility of a molecule, among them, solid dispersions have been widely used in recent years (schver et al., 2018; Marques et al., 2018; Park et al., 2018). In this type of pharmaceutical technology, a hydrophilic carrier with a hydrophobic drug is used. This combination can promote the modification of the physicochemical properties of the drug, which may allow to take advantage of the increased solubility in water of the amorphous form of the drug and, consequently, increase its bioavailability. The present study aimed to develop solid dispersions with LQIT/LT-50 and test their schistosomicidal activity in vitro.