Bilayer tablets. Quick + sustained release. Supports liver function. NAC sustain is a quick release/sustained release formulation of N-actyl-L-Cysteine (NAC), an antioxidant amino acid and a precursor to the antioxidant glutathione. Glutathione is important for dextoxification. NAC sustain is formulated with advanced bilayer sustain tablets that combine 1/3 Quick Release with 2/3 Sustained Release formats to release NAC over time.