Heparins and low-molecular-weight heparins are among the indirect parenteral anticoagulants. Their effect is mediated by plasma co-factors, thus they do not have intrinsic anticoagulant activity.
Today, low-molecular-weight heparins are used predominantly in both prevention and treatment of thromboembolic disease, mainly because of their improved pharmacokinetic profile, predictability of action, and because their effects don't need, with some exceptions, be monitored.