The efficacy of gemfibrozil therapy for raising high density lipoprotein levels

Thirty subjects, 5 normotriglyceridemic (NTG) with low HDL cholesterol (HDL-C < 35 mg/dl) and 25 hypertriglyceridemic (HTG) with low and high HDL-C (HDL-C > 35 mg/dl) were selected for this study. They were treated with gemfibrozil (600 mg BID) for 12 weeks. In both groups, gemfibrozil significantly reduced serum TG levels (p < 0.005), yet HDL-C increased significantly only in HTG patients (p < 0.005). The changes in HDL-C levels were highly variable (-40 to 50%) and appeared to be dependent on the levels of serum TG achieved during treatment. Based on post-treatment serum TG, the HTG patients were divided into 2 groups. Group 1 with serum TG of <100 mg/dL and Group 2 with serum TG levels >100 mg/dl. Significant post treatment increases in HDL-C were seen only in Group 1 (p < 0.005). The two groups had similar pretreatment serum TG and HDL-C levels but the LDL-C was significantly higher in Group 1 (p <0.025). Pretreatment serum LDL-C also correlated positively with the increases in HDL-C during treatment (r=0.51, p <0.01, n=25). Consequently, the patients were divided into three groups based on their initial serum LDL-C levels (Group 1: LDL-C < 130 mg/dl, Group 2: LDL-C, 130-159 mg/dl and Group 3: LDL-C>160 mg/dl). The HDL-C levels increased significantly upon treatment only in Group 3. Pretreatment levels of serum TG and HDL-C were not significantly different among the three groups. Initial body weight (r = -0.43 p <0.025, n=30) and percent change in body weight during treatment (r=-0.47, p < 0.025, n=30) correlated negatively with the percent reduction in serum TG. The change in body weight also showed significant negative correlation with the changes in HDL cholesterol (r=- 0.48, p<0.25, n=30). We conclude that gemfibrozil is most effective in reducing serum triglycerides, LDL-C and increasing serum HDL-cholesterol in HTG patients who also have comparatively high initial LDL cholesterol levels (Fredrickson's type IIb phenotype). For effective improvement of HDL- cholesterol in most HTG patients, serum TG levels need to be lowered below 100 mg/dl. Furthermore, the benefit of gemfibrozil therapy may be significantly enhanced by weight loss during treatment.