The purpose of the study is to learn more about an experimental drug called ORC-13661 that may be helpful in treating hearing loss due to antibiotic use. The study is researching whether the drug is safe and tolerable, and trying to find out whether the drug may be able to mitigate or prevent hearing loss in patients being treated with intravenous (IV) amikacin. Participation in the study will consist of up to 10 visits over up to 129 days. The Day 1 visit (following the screening visit) will last up to 8 hours, while other visits will last up to 5 hours Participants will be randomly assigned to receive either ORC-13661at a higher dose or a lower dose or a placebo (a pill that looks the same as the study drug but has no real medicine in it), for up to 90 days to be taken along with IV amikacin. Participants will be asked to have a number of tests and procedures, which include questionnaires about family, medical, and hearing history, physical and hearing examination, and assessments of hearing.

The study will test an investigational drug known as 4D-710. An "investigational drug" is one that has not yet been approved for use by a Health Authority such as the United States Food and Drug Administration (FDA). 4D-710 is being studied as a potential treatment for cystic fibrosis lung disease. This is the first study to test 4D-710 in humans. The purpose of this study is to see if 4D-710 is safe for use in adults with cystic fibrosis and to see if 4D-710 can help lung function.