In vitro analysis of the effects of acetaminophen, ibuprofen and aspirin on motility of female adult Onchocerca volvulus worms

In view of the very ambitious global timelines for elimination of onchocerciasis in 2030, the search for alternative antifilarials cannot depend on drug development from scratch, and repurposed drugs offer cheaper and faster alternatives. Previous studies had demonstrated the presence and potential expression of amidase, an enzyme that can be targeted by repurposed analgesics, in Onchocerca volvulus worms. The aim of this study was to determine the effects of acetaminophen, ibuprofen and aspirin on the motility of adult O. volvulus worms. In total, thirty (30) female O. volvulus worms were exposed to acetaminophen, ibuprofen and aspirin in concentrations of either 5mg/ml, 2.5mg/ml, 1.25mg/ml or 0.63mg/ml control in duplicates. Worm motility was observed and recorded using the WormAssay software and a darkfield imaging apparatus starting on day 2 of incubation and ending on day 8. Acetaminophen, ibuprofen and aspirin inhibited O. volvulus motility by 2-fold compared to control in the first 24 hours of drug exposure. However, an extended exposure of the worms to these test drugs rather improved the motility of the worms. The study has demonstrated that a 24-hour exposure of O. volvulus worms to the analgesic drugs studied, results in significant inhibition in worm motility compared with the control group, but extended duration of exposure led to an enhancement in motility of the previously immobile worms. This finding supports the idea that aspirin and ibuprofen may have some longevity enhancing properties. Further research on the utility of these analgesics as possible anti-filarial drugs is thus warranted.