The present invention relates to sustained release pharmaceutical compositions of phosphodiesterase type 5 (PDE5) inhibitors or salts thereof for treatment of pulmonary arterial hypertension. The invention additionally relates to sustained release pharmaceutical compositions of phosphodiesterase type 5 (PDE5) inhibitors or salts thereof in combination with at least one of the prostacyclin analogues, endothelin receptor antagonists or soluble guanylate cyclase activators for treatment of pulmonary arterial hypertension.