Pharmacokinetics of Dexamethasone Palmitate Injection

Five patients with rheumatoid arthritis (aged 50-80) took 1 tablet (equivalent to 2.5mg dexamethasone), and three healthy volunteers (aged 26-29) took 2 tablets (equivalent to 5.0mg dexamethasone). Figures 1 and 2 show the pharmacokinetics of rimethasone. Figure 1 Patients with Rheumatoid Arthritis 1 Changes of the plasma of this product and dexamethasone with time after intravenous injection of this product (each tablet is equivalent to 2.5mg dexamethasone) Figure 2 Changes of the plasma of this product and dexamethasone with time after intravenous injection of 2 tablets of this product (each tablet is equivalent to 5.0mg dexamethasone) in healthy men. The pharmacokinetic parameters measured by the above patients and healthy volunteers showed no significant difference between the two groups (the plasma half-lives of the two groups were 5.48 65438, respectively): dexamethasone Cmax:4.09±0.92 and 6.62 0.66 μ g/dl plasma and dexamethasone TMax:1.54 0.41and/kloc-. Except for the half-life of dexamethasone palmitate, it seems that the distribution, metabolism and excretion in animals are different: intravenous injection of this product in rats is equivalent to 0.05 mg/kg dexamethasone. In rats, the product was hydrolyzed by esterase to produce dexamethasone, a bioactive substance. The latter enters a slow excretion route to maintain a plasma half-life of about 2.7 hours, and most of them are distributed in reticular endothelial tissues such as liver, spleen, lung and myocardium. This product is gradually discharged from the above tissues, and only a small amount remains in the above tissues 48 hours after injection. This product is mainly metabolized in the liver and enters the enterohepatic circulation through bile. 48 hours after injection, about 60% of this product is excreted in urine and 40% in feces. The main metabolites in urine are dexamethasone, 1 1 ketodexamethasone, 6-β hydroxydexamethasone and 20 hydroxydexamethasone.