Selective inhibitor of phosphodiesterase type 4 (IC50 values are 1.9, > 100, > 100, > 100 and > 100 μM for human lung PDE4, lung PDE1, lung PDE2, heart PDE3 and platelet PDE-V respectively) that displays no significant PDE4 isozyme selectivity. Inhibits hydrolysis of cAMP in isolated human peripheral blood monocytes, eosinophils and T cells. Displays anti-inflammatory and bronchodilatory effects in vivo. Purity 99%. MW (observed): 316.39