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Long Term Effects of Transitioning from Sitaxsentan to Ambrisentan in Pulmonary Arterial Hypertension

Zeenat Safdar


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Conference: 2010 International PHA Conference and Scientific Sessions

Release Date: 06.24.2010

Presentation Type: Abstracts

Safdar Z, Frost A. 
Baylor College of Medicine, Houston, TX, USA

BACKGROUNDEndothelin receptor antagonists (ERA) are approved therapy to treat pulmonary arterial hypertension (PAH). Increased side effects or altered efficacy may develop when one ERA is transitioned to another. We report our 1 year long term experience in transition from sitaxsentan to ambrisentan in PAH patients (ETA receptor antagonists).

METHODS17 patients followed at Baylor PH Center in the open-label extension of the original sitaxentan trial (100 mg daily) were transitioned to ambrisentan (5 mg oral daily) (between July 2007 to September 2007) at trial closure. Each patient had pre-transition (PT) and 1 year post transition (1YR) assessments of BNP, six minute walk test, WHO functional class (WHO FC) and borg dyspnea score (BDS).

RESULTS15 females and 2 males with mean age of 52±14 (mean±SD) were transitioned. During the 1 year follow up, 1 patient died, 1 relocated and 1 underwent lung transplantation. 6MWD was 352±129 meters at PT and 407±121 meters at 1YR (374.6±125 days) (p=0.33). BNP was 141±192 pg/ml at PT and 205±224 pg/ ml at 1YR (p=0.53). The BDS was 2.4±1.2 (range 0 to 4) at PT and 3±1.0 (range 2 to 5) at 1 YR. Peripheral edema was present in 6/17 patients at PT and in 6/13 patients at 1 YR. 7/16 were in WHO FC III at PT and 6/14 at 1YR. None of the patients developed liver function abnormalities that required ERA interruption or cessation.

CONCLUSIONOur data suggests that ETA receptor antagonists can be switched from one to another with sustained exercise capacity, maintained WHO FC and with no worsening edema. Further studies are needed to confirm these findings.