Porphyrias are classified in two ways, by symptoms and by pathophysiology. Physiologically, porphyrias are classified as liver or erythropoietic based on the sites of accumulation of heme precursors, either in the liver or in the bone marrow and red blood cells.Deficiency in the enzymes of the porphyrin pathway leads to insufficient production of heme. Heme function plays a central role in cellular metabolism. This is not the main problem in the porphyrias; most heme synthesis enzymes—even dysfunctional enzymes—have enough residual activity to assist in heme biosynthesis. The principal problem in these deficiencies is the accumulation of porphyrins, the heme precursors, which are toxic to tissue in high concentrations. The chemical properties of these intermediates determine the location of accumulation, whether they induce photosensitivity, and whether the intermediate is excreted (in the urine or feces).There are eight enzymes in the heme biosynthetic pathway, four of which—the first one and the last three—are in the mitochondria, while the other four are in the cytosol. Defects in any of these can lead to some form of porphyria. The hepatic porphyrias are characterized by acute neurological attacks (seizures, psychosis, extreme back and abdominal pain, and an acute polyneuropathy), while the erythropoietic forms present with skin problems, usually a light-sensitive blistering rash and increased hair growth.Variegate porphyria (also porphyria variegata or mixed porphyria), which results from a partial deficiency in PROTO oxidase, manifests itself with skin lesions similar to those of porphyria cutanea tarda combined with acute neurologic attacks.
It is therefore reasonable to either also give thiamine supplements or to check blood thiamine levels in those being treated with chronic loop diuretics. Chemistry
Compared with other loop diuretics, torasemide has a more prolonged diuretic effect than equipotent doses of furosemide and relatively decreased potassium loss. Names
Torasemide is the recommended name of the drug (rINN) according to the (INN), which is the drug naming system coordinated by the World Health Organization. Torsemide is the official name of the drug according to the (USAN), which is the drug naming system coordinated by the USAN Council, which is co-sponsored by the American Medical Association (AMA), the United States Pharmacopeial Convention (USP), and the American Pharmacists Association (APhA). References
External links
"Torasemide". Drug Information Portal. U.S. National Library of Medicine.