Direct oral anticoagulants in real practice: which doses for which patients. Limitations and bleeding risk compared to vitamin K antagonists

The new oral direct anticoagulants (DOACs) could represent a new frontier for management of thromboembolic diseases. However, the new drugs have limitations that need to be considered. Despite the fact that their efficacy and safety profile are at least not inferior to comparators, bleeding risk represents the most feared complication, as for all the antithrombotic drugs. Bleeding risk increases with conditions that interfere with pharmacokinetics, in addition to the risk strictly linked to patients or their co-morbidities. Since all DOACs are excreted from kidneys (even though at different percentages according to the different molecules), renal impairment represents one of the leading causes of DOACs accumulation and bleeding risk. Moderate renal failure is the main condition in which dose adjustment of DOACs could be required, while severe renal impairment represents an absolute contraindication for their use. Renal function must, therefore, be carefully monitored before prescription and during assumption. The older population is at higher bleeding risk, and dose adjustment of DOACs could be required. Although to a lesser degree than oral anticoagulant vitamin K antagonists, DOACs can have drug interactions, especially with P-glycoprotein and cytochrome P3A4 inducers or inhibitors, and these interactions must be taken into account in real practice to avoid accumulation or under dosage. The concomitant use of other drugs, especially antithrombotics, may expose the patients to bleeding risk by reducing the hemostatic properties.