title: Turnover of low density lipoproteins during inhibition of cholesterol absorption by neomycin.
abstract: The mechanisms for the hypocholesterolemic actin of neomycin were examined in six patients with various levels of plasma total cholesterol and triglycerides. All patients were studied on a metabolic ward. The first period of 6 weeks was for control. Thereafter, neomycin (1.5 g/day) was started, and the patients were readmitted for another 6-week period after 2 to 3 months of treatment with the drug. Cholesterol balance studies showed that neomycin increased fecal excretion of neutral steroids by an average of 45%; the drug also inhibited absorption of exogenous cholesterol by an average of 44%. During treatment with neomycin, the plasma total cholesterol fell by an average of 20%, low density lipoproteins (LDL) fell by 25%, and high density lipoproteins, by 16%. Neomycin did not change plasma triglyceride levels. Turnover of the apoprotein of LDL (apoLDL) was measured following injection of 125I-apoLDL. Neomycin decreased synthesis of apoLDL by 28%. The decrease in plasma apoLDL level was correlated positively with the decrease in apoLDL synthetic rate. The effect of the drug on clearance of LDL was less constant; four of six patients had an increase in fractional clearance rates of apoLDL, but the change for the whole group was not statistically significant. These data suggest that a decrease in production of LDL is a major factor in the lowering of LDL following inhibition of cholesterol absorption; however, an increase in clearance rates may occur in some patients.
mesh_terms: D000042:Absorption; D000368:Aged; D001053:Apolipoproteins / Q000378:metabolism; D002784:Cholesterol / Q000097:blood / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008055:Lipids / Q000097:blood; D008077:Lipoproteins, LDL / Q000097:blood / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009355:Neomycin / Q000494:pharmacology*
chemical_list: D001053:Apolipoproteins; D008055:Lipids; D008077:Lipoproteins, LDL; D002784:Cholesterol; D009355:Neomycin