Lasix (furosemide) is a diuretic which is an anthranilic acid derivative. Lasix tablets for oral administration contain furosemide as the active ingredient and the following inactive ingredients: lactose monohydrate NF, magnesium stearate NF, starch NF, talc USP, and colloidal silicon dioxide NF. Chemically, it is 4chloro-N-furfuryl-5-sulfamoylanthranilic acid. Lasix (furosemide) is available as white tablets for oral administration in dosage strengths of 20, 40 and 80 mg. Furosemide is a white to off-white odorless crystalline powder. It is practically insoluble in water, sparingly soluble in alcohol, freely soluble in dilute alkali solutions and insoluble in dilute acids.