Oxidation resistance of LDL in hypertriglyceridaemic patients treated with ciprofibrate.

The oxidative modification of low density lipoprotein (LDL) plays an important role in the pathogenesis of atherosclerosis. LDL of subjects with atherogenic lipoprotein phenotype (ALP) is known to be more susceptible to oxidation. We studied the effect of the hypolipidaemic drug ciprofibrate on the susceptibility of LDL to in vitro oxidation. Nine patients with primary hypertriglyceridaemia and hypoalphalipoproteinaemia (mean plasma triglycerides 3.76 mmol.l-1 and HDL-cholesterol 0.74 mmol.l-1) were treated with ciprofibrate for 12 weeks. The susceptibility of LDL to in vitro Cu(2+)-mediated oxidation was assessed by measuring conjugated diene formation at 234 nm. Ciprofibrate therapy significantly prolonged the lag time (93 +/- 7 min vs. 102 +/- 11 min, P = 0.02). The maximal rate of diene production was 11% lower, but the decrease was not significant. A significant positive correlation was observed between maximal rate and maximal amount of dienes formed. Thiobarbituric acid reacting substances (TBARS) and lipid hydroperoxides (LPO) in oxidatively-modified LDL, isolated from the plasma of patients before and after drug treatment, were unchanged. The results suggest that ciprofibrate therapy has a favourable effect by increasing the in vitro resistance of LDL against oxidation.