The first-pass effect of aspirin was measured in male Wistar rats by comparing the plasma concentration after intravenous, oral or intraportal administration (10 mg kg-1) of the drug. Approximately 88 and 86% of the dose was excreted mostly as salicylic acid and its conjugated forms, glucuronide and sulphate, in urine within 48 h of i.v. or oral administration, respectively. This suggests that the gastrointestinal absorption of aspirin was essentially complete in rats. On the average, the area under the plasma concentration-time curve for unchanged aspirin following oral dosing (AUCo) was 0.35 of that obtained following i.v. administration (AUCi.v.) and 0.53 of that following intraportal administration (AUCp). Therefore, orally administered aspirin is subject to first-pass metabolism both in the gut and in the liver of rats. The gastrointestinal first-pass effect is estimated to be relatively more important than the hepatic effect.

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Abstract：Aspartate aminotransferase (AST) is an enzyme used clinically as an indicator of cell injury in pathological conditions in which cytoplasmic enzymes are liberated into the extracellular fluid, increasing the AST concentrations in the serum. Elevated gingival crevicular fluid (GCF) levels of AST serve as a useful indicator of the disease activity of periodontitis. In this study, we measured the AST levels in GCF from chronic periodontitis patients before and after initial therapy or periodontal surgery (periodontal regeneration therapy using Emdogain ® gel) using a Periodontal Tissue Monitor (PTM) kit, and investigated the relationships among the AST levels (PTM values) and the probing pocket depth (PPD), clinical attachment level (CAL) and bleeding on probing (BOP). After the initial therapy, the PTM values improved at 22 out of 38 treatment sites. Among the 22 sites, PPD at 20 sites, CAL at 15 sites, and BOP at 21 sites either improved or showed no change. After periodontal surgery, the PTM values improved at 42 out of 56 treatment sites. Among the 42 sites, PPD at 39 sites, CAL at 32 sites improved, and BOP at 41 sites either improved or showed no change. Next, we explored the relationship between the PTM values and the mean PPD and CAL after periodontal surgery. In the 42 sites that showed improved PTM values, the mean PPD and CAL were significantly decreased. However, in the 14 sites that showed 390

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