What we need to know about drug interactions in patients with pulmonary arterial hypertension

In the past years, the number of selective vasodilatory drugs available for the management of patients with pulmonary arterial hypertension (PAH) has increased remarkably. Concomitant chronic or temporary treatment with warfarin, oral contraceptives, some antibiotics, statins or other drugs can exert potential significant drug–drug interactions to some of the specific vasodilatory drugs by competition, induction or inhibition of metabolic pathways. These drug interactions can adversely affect treatment efficacy by changes of their plasma levels and can cause potential harm. An example of a significant drug interaction is given in a case report. Combination therapy with specific pulmonary vasodilatory drugs is more and more the focus of clinical studies, as many patients fail to respond to monotherapy. Each of the substances could add positive treatment effects but they can also interact to each other by their metabolic pathways and increase side-effects or add synergistic effectiveness.