This study aimed to analyze whether the enhancement of the biopharmaceutical efficiency of mebendazole, a poorly water-soluble anthelmintic drug, significantly improves its antiparasitic activity in a murine model of trichinellosis. Objectives: Two advanced oral formulations were developed, polyvinyl alcohol-derived nanoparticles (NP) and β-cyclodextrin citrate inclusion complexes (Comp), both employing mebendazole as an anthelmintic agent. The primary objective of this work is to treat trichinellosis, an infection with severe chronic effects. Methods: The physicochemical characteristics as well as the in vivo performance of the NP and Comp formulations were assessed. The in vivo studies involved the bioavailability analysis, comparing drug absorption between the pure drug and the novel formulations, as well as the in vitro anthelmintic activity and in vivo therapeutic efficacy against Trichinella spiralis encysted muscle larvae. The in vivo efficacy was evaluated during the parenteral stage of T. spiralis infection in male and female mice from two genetically distinct lines differing in mebendazole pharmacokinetic parameters and susceptibility to the parasite. Results: The formulations exhibited smaller particle sizes and improved dissolution properties compared to pure MBZ. The pharmacokinetics studies indicate that NP and Comp significantly improved MBZ bioavailability. Both NP and Comp significantly increased mebendazole’s anthelmintic activity against the encysted parasites, which would be attributed to the improved MBZ absorption. The formulations overcome the drug’s poor solubility and low bioavailability limitations, resulting in a higher plasma concentration of the active drug, even at low doses. Conclusions: These findings suggest that the newly designed mebendazole formulations are suitable for treating T. spiralis chronic infection and highlight a potential improvement in the pharmacological treatment of trichinellosis.