**6.3 Other drugs**

Adenosine activates adenylate cyclase and stimulates the generation of cAMP. Adenosine is rapidly inactivated with a plasma half-life of less than 10 seconds. In a study performed on ten patients who received an infusion of low-dose adenosine (50 mg/Kg/min) after weaning from CPB a significant reduction in MPAP and PVR and an increase in CO were demonstrated without adverse side effects without any adverse side effects (Fullenrton et al., 1996).

Phosphodiesterase-5-inhibitors such as zaniprast, dipyridamole, and sildenafil have been studied in the field of PH. There have been reports of variable beneficial effects of these agents on PH after cardiac surgery in combination with NO (Ichinose et al., 2001).

Bosentan is an endothelin antagonist which does not act acutely but has shown promising results as a sole agent and as combination chronic therapy for PH (Channick et al., 2004).
