Dose-response characteristics of cholesterol-lowering drug therapies: implications for treatment

To develop an optimal treatment strategy that reduces low-density lipoprotein (LDL) cholesterol levels and improves adherence to therapy by reviewing clinical trials that define the dose-response characteristics for 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins), bile acid sequestrants, and niacin.

Data were obtained from a MEDLINE search of the English-language literature published from 1975 through November 1995 and from an extensive bibliography review.

Controlled, clinical trials were reviewed if they evaluated 1) the effectiveness and toxicity of one LDL cholesterol-lowering agent (statins, bile acid sequestrants, or niacin, at two or more doses) or 2) monotherapy with two LDL cholesterol-lowering agents at defined doses used alone and in combination. Studies that had fewer than 10 patients in a treatment group or that selected patients on the basis of previous response to therapy were not included.

Trials were reviewed for overall methodology, inclusion and exclusion criteria, sources of bias, and outcomes.

Dose-response relations for bile acid sequestrants and statins are nonlinear, and most of their LDL cholesterol-lowering effects can be obtained with lower doses. The few dose-response studies of niacin that have been done suggest that most of niacin's high-density lipoprotein cholesterol-increasing effect can also be achieved with relatively low doses, but higher doses are needed to substantially reduce LDL cholesterol levels. If bile acid sequestrants or niacin are added to statin therapy, the effect of combined therapy on LDL cholesterol levels is additive.

The nonlinear dose-response relation of statins, bile acid sequestrants, and niacin and their additive LDL cholesterol-lowering effect when used together suggest a strategy for treating hypercholesterolemia that may optimize effectiveness while minimizing adverse effects and cost.