Colestyramine (INN) or cholestyramine (USAN) (trade names Questran, Questran Light, Cholybar, Olestyr) is a bile acid sequestrant, which binds bile in the gastrointestinal tract to prevent its reabsorption. It is a strong ion exchange resin, which means it can exchange its chloride anions with anionic bile acids in the gastrointestinal tract and bind them strongly in the resin matrix. The functional group of the anion exchange resin is a quaternary ammonium group attached to an inert styrene-divinylbenzene copolymer. Colestyramine removes bile acids from the body by forming insoluble complexes with bile acids in the intestine, which are then excreted in the feces. As a result of this loss of bile acids, more plasma cholesterol is converted to bile acids in the liver to normalise levels. This conversion of cholesterol into bile acids lowers plasma cholesterol levels. Medical uses
Bile acid sequestrants such as colestyramine were first used to treat hypercholesterolemia, but since the introduction of statins, now have only a minor role for this indication. They can also be used to treat the pruritus, or itching, that often occurs during liver failure and other types of cholestasis where the ability to eliminate bile acids is reduced.Colestyramine is commonly used to treat diarrhea resulting from bile acid malabsorption. It was first used for this in Crohns disease patients who had undergone ileal resection. The terminal portion of the small bowel (ileum) is where bile acids are reabsorbed.
Naftifine hydrochloride (brand names include Exoderil and Naftin) is an allylamine antifungal drug for the topical treatment of tinea pedis, tinea cruris, and tinea corporis (topical fungal infections). Naftifine has triple action: antifungal, antibacterial, and anti-inflammatory. Its fungistatic activity is believed to be based on inhibition of the squalene-2,3-epoxidase enzyme, which in turn results in the shortage of ergosterol required for the formation of fungal cell membranes. With some fungal species, there is also fungicidal activity from a resulting accumulation of squalenes, leading to damage of the fungal cell membranes, including at the endoplasmatic reticulum. The half-life is approximately 2–3 days. The metabolites are excreted in the urine and feces.Naftifine was invented at the Sandoz Research Institute in Vienna, Austria. It was the first succesful antifungal medication of the allylamine class. Naftifine shows mostly fungicidal activity toward dematophytes and molds, and mostly fungistatic activity toward yeasts. It is also effective as an antibacterial agent in treating pyoderma. Naftifine is almost completely metabolized in the human body, with a half-life of 2–3 days. Its metabolytes do not have antifungal activity, and they are excreted with urine and bile. == References ==