N-Acetyl-L-cysteine ethyl ester is an esterified form of N-acetyl-L-cysteine (NAC). N-Acetyl-L-cysteine ethyl ester exhibits enhanced cell permeability, and produce NAC and cysteine. N-Acetyl-L-cysteine ethyl ester increases circulating hydrogen sulfide (H2S) and can be used as an H2S producer. N-Acetyl-L-cysteine ethyl ester has the potential to substitute NAC as a mucolytic agent, and as a GSH-related antioxidant.In Vitro: N-Acetyl-L-cysteine ethyl ester is a an esterified form of N-acetyl-L-cysteine (NAC). N-Acetyl-L-cysteine ethyl ester exhibits enhanced cell permeability, and produce NAC and cysteine. N-Acetyl-L-cysteine ethyl ester increases circulating hydrogen sulfide (H2S) and can be used as an H2S producer. N-Acetyl-L-cysteine ethyl ester has the potential to substitute NAC as a mucolytic agent, and as a GSH-related antioxidant.