Lucila Isabel Hinrichsen

Characterization of albendazole-randomly methylated-β-cyclodextrin inclusion complex and in vivo evaluation of its antihelmitic activity in a murine model of Trichinellosis.

Albendazole is a benzimidazole carbamate extensively used in oral chemotherapy against intestinal parasites, due to its broad spectrum activity, good tolerance and low cost. However, the drug has the disadvantage of poor bioavailability due to its very low solubility in water; as a consequence, a very active area of research focuses on the development of new pharmaceutical formulations to increase its solubility, dissolution rate, and bioavailability. The primary objective of this study was to prepare randomly methylated β-cyclodextrins inclusion complexes to increase albendazole dissolution rate, in order to enhance its antiparasitic activity. This formulation therapeutic efficacy was contrasted with that of the pure drug by treating Trichinella spiralis infected mice during the intestinal phase of the parasite cycle, on days five and six post-infection. This protocol significantly decreased muscle larval burden measured in the parenteral stage on day 30 post-infection, when compared with the untreated control. Thus, it could be demonstrated that the inclusion complexes improve the in vivo therapeutic activity of albendazole.

Novel albendazole formulations given during the intestinal phase of Trichinella spiralis infection reduce effectively parasitic muscle burden in mice

Trichinellosis is a zoonotic disease affecting people all over the world, for which there is no speedy and reliable treatment. Albendazole (ABZ), an inexpensive benzimidazole used in oral chemotherapy against helminthic diseases, has a broad spectrum activity and is well tolerated. However, the low absorption and variable bioavailability of the drug due to its low aqueous solubility are serious disadvantages for a successful therapy. In this study, we evaluated the in vivo antiparasitic activity of three novel solid microencapsulated formulations, designed to improve ABZ dissolution rate, in a murine model of trichinellosis. Both ABZ and the microparticulate formulations were administered during the intestinal phase of the parasite cycle, on days 5 and 6 post-infection. This protocol significantly decreased muscle larval burden measured in the parenteral phase, on day 30 post-infection, when compared with the untreated control. Moreover, two of the three microencapsulated formulations both strongly and consistently reduced worm burden.

Efficacy of albendazole:β-cyclodextrin citrate in the parenteral stage of Trichinella spiralis infection

Albendazole-β-cyclodextrin citrate (ABZ:C-β-CD) inclusion complex in vivo antiparasitic activity was evaluated in the parenteral phase of Trichinella spiralis infection in mice. An equimolar complex of ABZ:C-β-CD was prepared by spray-drying and tested in CBi-IGE male mice orally infected with L1 infective larvae. Infected animals were treated with 50 or 30mg/kg albendazole, (ABZ) equivalent amounts of the ABZ:C-β-CD complex and non treated (controls). Mice received a daily dose on days 28, 29 and 30 post-infection. A week later, larval burden and percentage of encysted dead larvae were assessed in the host by counting viable and non-viable larvae in the tongue. Complexation of ABZ with C-β-CD increased the drug dissolution efficiency nearly eightfold. At 37 days p-i, the reduction percentage in muscle larval load was 35% in mice treated with 50mg/kg/day ABZ and 68% in those given the complex. Treatment with the lower dose showed a similar decrease in parasite burden. Treated animals showed a high percentage of nonviable larvae, the proportion being significantly higher in mice receiving the complex than in control animals (72-88% vs. 11%, P=0.0032). These data indicate that ABZ:C-β-CD increases bioavailability and effectiveness of ABZ against encapsulated Trichinella larvae, thus allowing the use of small doses.

Phenotypic differences on the outcome of the host-parasite relationship: behavior of mice of the CBi stock in natural and experimental infections.

Investigation of defined animal models may help to elucidate the role of the host genetic background in the development and establishment of a parasitic infection. Four lines of mice obtained by disruptive selection for body conformation (CBi+, CBi-, CBi/C and CBi/L) and the unselected control line CBi were examined in their response to different parasites to assess whether these distinct genotypes showed differences in their resistance to natural and experimental parasitosis. Protozoans (Trichomonas muris and Spironucleus muris) and nemathelminths (Syphacia obvelata and Aspiculurus tetraptera) were found naturally parasitizing the mices intestines. CBi/C and CBi were the only genotypes in which T. muris was found. CBi- was least resistant to S. muris. The helminth parasitic burden showed differences between sexes within genotypes (males had a higher burden than females) and among genotypes (CBi/L males had the lowest burden). CBi/L animals were also most resistant to experimental challenge with Heligmosomoides polygyrus and Trypanosoma cruzi. Since all the animals examined shared a common habitat throughout the study and were equally exposed to infection, the phenotypic differences in the natural enteroparasitism herein described evince genetic differences among lines in the host-parasite relationship. This interpretation is further supported by the differences in the response to the experimental challenge to H. polygyrus and T. cruzi.

Combined calcitriol and menadione reduces experimental murine triple negative breast tumor

BACKGROUND Calcitriol (D) or 1,25(OH)2D3 inhibits the growth of several tumor cells including breast cancer cells, by activating cell death pathways. Menadione (MEN), a glutathione-depleting compound, may be used to potentiate the antiproliferative actions of D on cancer cells. We have previously shown in vitro that MEN improved D-induced growth arrest on breast cancer cell lines, inducing oxidative stress and DNA damage via ROS generation. Treatment with MEN+D resulted more effective than D or MEN alone. OBJECTIVE To study the in vivo effect of calcitriol, MEN or their combination on the development of murine transplantable triple negative breast tumor M-406 in its syngeneic host. METHODS Tumor M-406 was inoculated s.c., and when tumors reached the desired size, animals were randomly assigned to one of four groups receiving daily i.p. injections of either sterile saline solution (controls, C), MEN, D, or both (MEN+D). Body weight and tumor volume were recorded three times a week. Serum calcium was determined before and at the end of the treatment, at which time tumor samples were obtained for histological examination. RESULTS None of the drugs, alone or in combination, affected mice body weight in the period studied. The combined treatment reduced tumor growth rate (C vs. MEN+D, P<0.05) and the corresponding histological sections exhibited small remaining areas of viable tumor only in the periphery. A concomitant DNA fragmentation was observed in all treated groups and MEN potentiated the calcitriol effect on tumor growth. CONCLUSIONS As previously observed in vitro, treatment with MEN and D delayed tumor growth in vivo more efficiently than the individual drugs, with evident signals of apoptosis induction. Our results propose an alternative protocol to treat triple negative breast cancer, using GSH depleting drugs together with calcitriol, which would allow lower doses of the steroid to maintain the antitumor effect while diminishing its adverse pharmacological effects.