Furosemide (also called frusemide (Lasix®)) is a sulfamoylanthranilic acid derivative, used for a long time as a diuretic in the treatment of edema associated with cardiac, renal and hepatic failure, and for the treatment of hypertension. The drug is qualified as a loop diuretic, acting on the thick ascending limb of the loop of Henle. It reduces tubular reabsorption of sodium and chloride in the kidney tubules, by inhibiting the sodium-chloride cotransport system. This effect results in an excessive excretion of water along with sodium, chloride, magnesium, and calcium. For decades, furosemide has been a pillar in the treatment of systolic heart failure, both in Europe and the US. The drug, first patented in 1959 and first approved in 1964, remains used today, although it is often replaced with other loop diuretics such as torsemide. Nevertheless, furosemide remains one of the most commonly prescribed medications, with about 45 million prescriptions/year in the US in the forms of tablets or oral solution. It can be administered also intravenously (iv furosemide is twice as potent as oral furosemide). The drug is strongly bound (>95%) to plasma proteins, mainly albumin; the unbound form is usually in the range of 2-4%. The drug is eliminated after hepatic and renal glucuronidation (50%, enterohepatic cycling) and by renal excretion (50%). The drug shows a poor water solubility and a low bioavailability after oral administration.
The drug is used mainly orally but when it is inhaled, furosemide can reduce the excessive secretion of the inflammatory cytokines IL-6 and TNFα, in patients with a viral infection. For this reason, the use of the drug has been suggested recently to reduce the “cytokine storm” frequently associated with the severe stage of Coronavirus disease 2019 (COVID-19).
The antique illustration “the water carrier” (soft engraving, intaglio) evokes the notion of fluid elimination. The drawing was made by the French painter and engraver Albert Marius Hippolyte Decaris (1901-1988), who has engraved many postal stamps in France. He is the author of many chisels and received the gold medal for engraving at the Olympic games in 1948.
