Effectiveness of hyperbaric oxygen for experimental treatment of schistosomiasis mansoni using praziquantel-free and encapsulated into liposomes: Assay in adult worms and oviposition

- We tested the activity of PZQ and lip.PZQ in synergy with HBO on Schistosoma mansoni.
- Additional life expectancy and oviposition of worms were evaluated.
- lip.PZQ + HBO, 100 mg/kg, showed higher percentage of efficiency for both parameters.
- HBO improved the activity of lip.PZQ.

The treatment of schistosomiasis depends on a single drug: praziquantel (PZQ). However, this treatment presents limitations such as low and/or erratic bioavailability that can contribute to cases of tolerance. Improvements to the available drug are urgently needed and studies with a controlled system of drug release, like liposomes, have been gaining prominence. The present study evaluated the activity and synergy between liposomal-praziquantel (lip.PZQ) and hyperbaric oxygen therapy (HBO). Mice received doses of 60 or 100 mg/kg PZQ or lip.PZQ, 50 days post-infection, and after the treatment, were exposed to HBO (3 atmosphere absolute - ATA) for 1 h. The viability of adult worms and oviposition were analyzed, by necropsy and Kato-Katz examination performed after 15 days of treatment. A concentration of 100 mg/kg of lip.PZQ + HBO was more effective (48.0% reduction of worms, 83.3% reduction of eggs/gram of feces) and 100% of the mice had altered of oograms (indicating interruption of oviposition) compared to other treatments and to the Control group (infected and untreated). It is known that PZQ requires participation of the host immune system to complete its antischistosomal activity and that HBO is able to stimulate the immune system. The drug became more available in the body when incorporated into liposomes and, used with HBO, the HBO worked as an adjuvant. This explains the decreases of oviposition and worms recovered form hepatic portal system.

Activity of PZQ and lip.PZQ in synergy of HBO was tested on Schistosoma mansoni. Treatments done with PZQ + HBO and lip.PZQ + HBO showed higher activity than PZQ and lip.PZQ.