PURPOSE: Endothelin-1 is a potent vasoconstrictor and smooth-muscle mitogen. Many studies have shown that orally administered dual endothelin-receptor antagonist bosentan improves exercise capacity and cardiopulmonary hemodynamics in some patients with pulmonary arterial hypertension. These studies have not included patients with pulmonary hypertension secondary to diet pills or stimulants. The present study investigates the effect of bosentan on exercise capacity specifically in patients with pulmonary hypertension who have consumed diet pills or stimulants.
METHODS: Case control matched study comparing patients with pulmonary hypertension exposed to diet pills and/or stimulant (n=23) treated with bosentan to patients with pulmonary hypertension not exposed to anorexigens and/or stimulants (n=25) chosen from pulmonary hypertension database between 1995 and 2005. The primary end point is the change in exercise capacity before and after treatment with bosentan between these two groups.
RESULTS: Patients with pulmonary hypertension who were exposed to diet pills and/or stimulants had poor baseline exercise capacity compared to patients who were not exposed to diet pills and/or stimulants (P = 0.03). At week 12, patients with pulmonary hypertension associated with diet pills and/or stimulants treated with bosentan had an increase in 6-minute walking distance by 172 feet (SD ± 353) compared to patients not exposed to diet pills and/or stimulants with an increase by 31 feet (SD ± 197); P = 0.16.
CONCLUSION: There was a definitive positive effect on exercise capacity in patients with pulmonary hypertension treated with bosentan both exposed and not exposed to diet pills and/or stimulants. However, there was better response to bosentan in their exercise capacity in patients exposed to diet pills and/or stimulants, potentially because they were sicker at baseline and had a significant effect on treatment. More studies are required to understand their pathophysiology in treating these patients with bosentan.
CLINICAL IMPLICATIONS: Endothelin receptor antagonist may be considered for treatment of patients with pulmonary hypertension exposed to diet pills and/or stimulants.
DISCLOSURE: Uma Mohanasundaram, None.