Effects of chlorhexidine on human taste perception.

Chlorhexidine, a bis-cationic biguanide antiseptic, greatly reduces the perceived intensity of the salty prototype sodium chloride and may prove to be an important probe of mechanisms that underlie the human salty taste quality. Chlorhexidine, which tastes bitter, also reduces quinine hydrochloride taste intensity, but neither sweet sucrose nor sour citric acid is affected. Perceptual intensity rating and quality identification were measured for human subjects before and for 30 min following treatment with 1.34 mM chlorhexidine gluconate. In one experiment, test stimuli were the taste-quality prototypes; in a second experiment, stimuli were series of sodium, halide and sulfate salts. Experiment 1 showed a single 3-min chlorhexidine treatment resulted in reductions in taste intensity that persisted for at least 30 min. Experiment 2 showed a single 2-min chlorhexidine treatment reduced perceptual intensities of halide and sulfate salts except those with divalent cations. Chlorhexidine impaired identification of the salty quality and produced a bitter quality in nonbitter salts and impaired identification of the bitter quality of quinine, but not bitter salts. The specific effect of chlorhexidine on the bitterness of quinine suggests it may bind to the same receptor as quinine. The ability of chlorhexidine to specifically disrupt saltiness of a wide range of salts is consistent with proposed peripheral transduction mechanisms for the salty quality that involve transepithelial ion transport.