The overall duration of the study for each participant will be up to approximately 48 days
This is a single center randomized parallel-group partially-blinded, 4-arm Phase 1 study to evaluate the phototoxic potential of two dose levels of SAR441566 treatment compared to placebo and the active comparator, ciprofloxacin, in healthy adults, 18 to 55 years of age.~There will be two parts:~Part I is a randomized placebo-controlled trial comparing sensitivity to ultraviolet (UV) light in participants treated with SAR441566 to those treated with placebo.~Part II is an open label arm consisting of participants treated with ciprofloxacin which induces mild phototoxicity and serves as a positive control.