Absorption of two antibacterial drugs, cephalexin and co-trimoxazole, in malabsorption syndromes.

Plasma concentrations and urinary excretion of cephalexin, trimethoprim and sulphamethoxazole (co-trimoxazole) were 
measured in normal subjects and in patients with coeliac disease, small 
bowel diverticulosis, Crohn's disease, cystic fibrosis (cephalexin only) and after administration 
of cholestyramine. The absorption of cephalexin was improved in coeliac disease 
diverticulosis and cystic fibrosis. In Crohn's disease the peak plasma level 
was reduced and delayed. The absorption of both trimethoprim and sulphamethoxazole 
was increased in all three conditions. However there was a disproportionate 
increase in the plasma level of trimethoprim in coeliac disease and 
diverticulosis when compared with that of sulphamethoxazole. In Crohn's disease there 
was a threefold increase in the peak plasma level of sulphamethoxazole. 
After cholestyramine administration there was malabsorption of all three drugs. 