G-418 (disulfate) is an aminoglycoside antibiotic similar in structure to gentamicin B1, which blocks polypeptide synthesis by inhibiting the elongation step in both prokaryotic and eukaryotic cells.

G418 is an inhibitor of many pro- and eukaryotes at concentrations from 1-300 microgram/mL. Resistance to G418 conferring by the neo gene from Tn5 encoding an aminoglycoside 3'-phosphotransferase, APT 3' II is commonly used in laboratory research to select genetically engineered cells. In general for bacteria and algae concentrations of 5 mg/L or less are used, for mammalian cells concentrations of approximately 400 mg/L are used for selection and 200 mg/L for maintenance. Resistant clones selection could require from 1 to up to 3 weeks.

G418 (40 and 80 mg/kg) for three consecutive days are sufficient to eliminate all nontransfected T. brucei brucei parasites from infected mice^[3].

H₂O : ≥ 30 mg/mL (43.31 mM)

* "≥" means soluble, but saturation unknown.