Transition of PH patients from sildenafil to tadalafil: feasibility and practical considerations.
BACKGROUND
Sildenafil was the only phosphodiesterase-5 inhibitor available for the treatment of pulmonary arterial hypertension (PAH) until the approval and availability of once-daily tadalafil. Since no direct comparative study is likely to be performed between these agents, we sought to evaluate the feasibility of transitioning stable PAH patients from sildenafil to tadalafil.


METHODS
The primary end point was continuation on tadalafil without clinical deterioration. A functional outcome through an evaluation of serial change in the 6-min walk test distance (6MWD) was also performed.


RESULTS
Thirty-five patients on sildenafil qualified for the analysis, of which 85.7 % (30/35) were successfully transitioned. The remaining 14.3 % (5/30) (failure group) were switched back to sildenafil due to worsening symptoms. The mean pretransition 6MWD was 363 m, with an average change in the success group of +16.4 m (range = -64 to +140 m) compared to -45 m (range = -123 to +32 m) in the failure group at 1-3 months post switch (p = 0.02). All 30 patients in the success group remained on tadalafil, with an average improvement in the 6MWD of +37.04 m (range = -36.5 to +236.5 m) at 12 months post switch. The failure group had a higher daily sildenafil dose (180 vs. 115.5 mg; p = 0.06), with 42.8 % of patients at the highest sildenafil dose failing the transition.


CONCLUSIONS
The transition from sildenafil to tadalafil is safe and generally well tolerated. Patients with more severe disease and those on higher doses of sildenafil are more likely to fail the transition and should be monitored closely post switch.
Advanced Lung Disease and Lung Transplant Program, Inova Fairfax Hospital, 3300 Gallows Road, Falls Church, VA 22042, USA. oksana.shlobin@inova.org
Oksana A
OA
Shlobin
A Whitney
AW
Brown
Nargues
N
Weir
Shahzad
S
Ahmad
Merte
M
Lemma
Steven D
SD
Nathan
D000328:Adult; D000368:Aged; D002243:Carbolines / Q000627:therapeutic use*; D005080:Exercise Test / Q000187:drug effects; D065627:Familial Primary Pulmonary Hypertension; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000627:therapeutic use*; D011687:Purines / Q000627:therapeutic use; D012189:Retrospective Studies; D012720:Severity of Illness Index; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000627:therapeutic use*; D000068581:Tadalafil; D016896:Treatment Outcome; D014665:Vasodilator Agents / Q000627:therapeutic use*; D055815:Young Adult
D002243:Carbolines; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D014665:Vasodilator Agents; D000068581:Tadalafil; D000068677:Sildenafil Citrate