D-methionine
A RCT assessed the otoprotective effect of D-methionine in CiO in 27 patients receiving chemoradiotherapy for head and neck, genitourinary, and esophagus cancer. Radiotherapy was used on 37% of the patients, the delivered dose was not stated. While the placebo group showed significant hearing threshold decline from baseline to post-treatment at 10 kHz (-13.65 dB p =0.008), 11.2 kHz (-16.15dB p=0.008), and 12.5 kHz (-11.46dB p=0.03), the intervention group showed no significant hearing threshold shift. There was no difference in side effects between the groups (Campbell et al., 2022).