This metabolic pathway leads to two major inactive metabolites (which each account for around 45% and 10% of an excreted dose at steady state), one minor metabolite, and several trace metabolites, none of which accounts for more than 1% of an excreted dose. Clearance of linezolid varies with age and gender; it is fastest in children (which accounts for the shorter half-life), and appears to be 20% lower in women than in men. There is a strong correlation between linezolid clearance and creatinine clearance. Chemistry
At physiological pH (7.4), linezolid exists in an uncharged state. It is moderately water-soluble (approximately 3 mg/mL), with a logP of 0.55. The oxazolidinone pharmacophore—the chemical "template" essential for antimicrobial activity—consists of a 1,3-oxazolidin-2-one moiety with an aryl group at position 3 and an S-methyl group, with another substituent attached to it, at position 5 (the R-enantiomers of all oxazolidinones are devoid of antibiotic properties). In addition to this essential core, linezolid also contains several structural characteristics that improve its effectiveness and safety. An acetamide substituent on the 5-methyl group is the best choice in terms of antibacterial efficacy, and is used in all of the more active oxazolidinones developed thus far; in fact, straying too far from an acetamide group at this position makes the drug lose its antimicrobial power, although weak to moderate activity is maintained when some isosteric groups are used.
Delayed pressure urticaria is known as one of the more painful subsets of physical urticaria due to formed hives being deep-seated and appearing after 4–6 hours. Causes
Due to the delayed appearance of wheals, plausible causes are hard to establish; the natural course and/or clinical pattern is variable and inconclusive. Treatment
It was noted that although antihistamines and anti-inflammatory drugs such as, colchicine, sulphasalazine, dapsone, and topical steroid are advocated for in the treatment of DPU, most if not all are unsatisfactory in relieving symptoms. Even a second generation antihistamine, ketotifen, was unable to efficiently and satisfactorily relieve symptoms of DPU


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