Gastrointestinal tract mucosal metabolism

Cartwright [124] reported that miconazole was slightly absorbed from epithelial and mucosal surface. The drug is well absorbed from the gastrointestinal tract, but caused nausea and vomiting in some patients. The drug may be given intravenously but was associated phlebitis. Up to 90% of the active compound was bound to plasma protein. Distribution into other body compartments was poor. Metabolism was primarily in the liver, and only metabolites were excreted in the urine. At therapeutic levels, they were relatively nontoxic both locally and systematically, but occasionally produced disturbances on the central nervous system. 

Many corticosteroids undergo metabolism via CYP3A4 and are substrates of P-gp. They are used to suppress inflammation in the respiratory tract, reducing mucosal oedema and decreasing bronchial secretions. They are employed both to prevent acute exacerbations of chronic airways disease and to treat acute flare-ups. They may be subject to interactions when administered orally, but interactions with high-dose inhaled formulations are thought to occur due to steroid that is deposited in the oropharynx, swallowed and absorbed via the gastrointestinal tract. 

The microflora of the gastrointestinal tract, which develop shortly after birth, are found in the lumen, associated with remnants of food, on the mucosal surface, and in the cry pts- These microorganisms, including prokaryotic and eukaryotic species, lend not to use oxygen in their energy metabolism since they exist in an environment that is essentially anaerobic. Over of the bacterial cells are... 

Bile salts are extensively metabolized to secondary bile acids by intestinal microflora in the gut. Approximately 94% of the bile salts are reabsorbed at special mucosal receptor sites in the distal ileum and reused by the liver by the process of enterohe-patic circulation. In enterohepatic circulation, compounds secreted in bile are reabsorbed in the gastrointestinal tract and returned to the liver. On reaching the liver in the portal blood, almost all of the bile salts are taken up across the sinusoidal membranes of hepatocytes (predominantly in periportal... 

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