Lasix is a high-speed diuretic, which is a sulfonamide derivative. Lasix blocks the transport system of Na +, K +, Cl – ions in the thick segment of the ascending knee of the Henle loop, and therefore its saluretic effect depends on the drug delivery to the lumen of the renal tubules (due to the mechanism of anion transport). The diuretic effect of the drug Lasix is associated with the inhibition of the reabsorption of sodium chloride in this section of the Henle loop. Secondary effects on the increase in sodium excretion are: an increase in the amount of urine released (due to osmotically bound water) and an increase in potassium secretion in the distal part of the renal tubule. At the same time, the excretion of calcium and magnesium ions increases.
Synonyms: Lasix, Furantril, Afsamid, Arasemide, Diusemide, Diuzol, Dryptal, Edefrusex, Errolon, Franyl, Frugex, Frusemide, Frusolon, Furanthril, Furantral, Furfan, Furomex, Furosan, Furosemide, Fusid, Katlex, Kinex, Lasilix, Lasix, Nicorol, Profemin, Protargen, Rasisemid, Renex, Salix, Seguril, Trofurit, Uritol, Urosemid, and others.
According to the chemical structure (the presence of a chlorine atom and a sulfonamide group with a phenyl nucleus), it has similarities with dichlorothiazide and related compounds.
Pharmacology – Diuretics
Furosemide (Lasix) is a strong diuretic (saluretic) remedy. Effective for oral and parenteral use. The diuretic effect is associated with inhibition of the reabsorption of N and Cl ions, and this depression is observed not only in the proximal but also in the distal convoluted tubules, and in the region of the ascending section of the Henle loop. Reabsorption of potassium is also inhibited, but to a much lesser degree. There is no noticeable inhibition of carbonic anhydrase. The drug is equally effective in acidosis and alkalosis. Diuretic effect is most pronounced during the first 2 days of taking the drug, but does not disappear even with prolonged treatment.
The drug acts quickly. After intravenous injection, the diuretic effect begins in a few minutes, after ingestion – during the first hour. The duration of action after a single intravenous administration is 1, 5 – 3 hours after ingestion – 4 hours or more. A rapid effect with intravenous administration makes it possible to use furosemide in urgent cases (pulmonary edema, brain, etc.).
The effectiveness of furosemide in the treatment of patients with circulatory failure is associated not only with the diuretic effect, but also with a direct dilating effect on the peripheral vessels. The first (early) phase that develops within the first 30 minutes after the injection of the drug depends on its effect on the peripheral vessels, and the second (late) phase, developing 1 to 2 hours after the injection, is associated with diuretic action.
Furosemide also has an antihypertensive effect.
The drug is effective in various forms of hypertension, including in severe forms, in which other saluretics are ineffective. The mechanism of antihypertensive action is basically the same as with the use of thiazide diuretics.
Furosemide is also used for the relief of severe hypertensive crises.