Metronidazole intestinal absorption

Absorption from the intestinal tract is usually good. Food delays but does not reduce absorption. The drug is distributed in body fluids and has a half-Ufe of about 8 hours. High levels are found in plasma and cerebrospinal fluid (CSF). Less than 20% binds to plasma proteins. Metronidazole is metabolized by oxidation and glucuronide formation in the liver and is primarily... 

The coadministration of mycophenolate mofetil with antacids results in decreased absorption. The plasma MPA concentration is significantly reduced by cholestyramine due to binding of the cholestyramine to MPAG in the intestine and interfering with the enterohepatic recirculation of the drug. The bioavailability of mycophenolate mofetil is higher when administered with tacrolimus as opposed to cyclosporine. The bioavailability of MPA is reduced by antibiotics including fluoroquinolones and metronidazole. 

In an intervention study with schoolchildren 8—10 years old in Malawi, Furnee et al. (1997) examined the relationship of intestinal parasite treatment and oral iodized oil efficacy. Severely iodine-deficient schoolchildren with a single parasitic infestation, either A. lumbricoides (n = 44), hookworm (n = 42), or Entamoeba histolytica (n = 24), were randomly allocated to receive or not receive treatment before taking a 1ml oral supplement (490 mg Iodine) of iodized ethyl esters from poppyseed oil. After supplementation, urinary iodine concentrations were measured regularly, to define time intervals indicating moderate iodine deficiency before urinary iodine concentrations returned to 0.40 mmol/1. Treatment with metronidazole for E. histolytica increased the protection period from 2.0 to 21.0 weeks P < 0.05). For all untreated children, the duration effect was 9.2 weeks shorter P < 0.001) than for their treated peers (16.8 weeks). They concluded that, by interfering with absorption, intestinal parasitic infestations reduce the efficacy of oral supplementation with iodized ethyl esters (Table 52.8). 

The reduction of intestinal ammonia synthesis can also be achieved by the administration of non-absorbable disaccharides-like lactulose and lactitol or antibiotics like neomycin, paramomycin, metronidazole or rifaximin. Lactulose exerts several effects (1). acidification of the intestinal content resulting in a reduction of ammonia absorption and net movement of ammonia from the blood into the bowel and (2). reduced bacterial production of ammonia in the colonic lumen due to environmental changes with promotion of the growth of non-urease producing bacteria and (3). the cathartic effect. The daily dose of lactulose is between 30 and 60 g per day. The goal is to obtain 2-3 soft bowel movements per day. Recently lactulose has been proven to be effective even in patients with minimal HE (Prasad et al., 2007). 

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