THE EFFECT OF SIMVASTATIN ON HDL CHOLESTEROL IN HYPERLIPIDEMIC PATIENTS - EVIDENCE OF A RELATIONSHIP WITH THE CHANGES IN SERUM TRIGLYCERIDELEVEL

The main effect of simvastatin is the decrease of serum cholesterol du e to the reduction of LDL. A decrease of serum triglycerides and an in crease of HDL-C are commonly observed during the treatment. The reduct ion of triglycerides is accounted for by the increased catabolism of a po B-containing lipoproteius whereas the mechanisms bringing about the increase of HDL-C are still unknown, We treated 318 patients with pri mary hyperlipidemia (277 with phenotype IIa and 91 with phenotype IIb) with simvastatin 10 mg a day and after 6 weeks we found a mean 3% inc rease in HDL-C. HDL-C increased only in about half of the patients and the patients in whom HDL-C increased had baseline higher serum trigly cerides and had a greater hypotriglyceridemic response than patients i n whom HDL-C did not increase. Accordingly, HDL-C increased in type II h patients who experienced a greater change in higlycerides than type IIa patients, in whom HDL-C did not increase significantly. Apo A-I le vels did not change and apo A-I/HDL-C ratio significantly decreased. A t a daily dose of 40 mg, administered to 51 treatment-resistant patien ts, simvastatin produced a marginally greater decrease in serum choles terol and LDL-C, but not in serum triglycerides and HDL-C, than at the daily dose of 10 mg, An increase in HDL-C was associated with a reduc tion in serum triglycerides. The decrease in apo A-I/HDL-C ratio sugge sts that the increase in HDL-C after simvastatin must be regarded as a n enrichment of the cholesterol core of HDL particles. The effect is l ikely to be due to the decrease of tile serum concentration of VLDL br inging about a reduction of cholesterol transfer from apo A-I- to apo B-containing lipoproteins.