Colforsin (NKH477) is a water-soluble forskolin derivative. NKH477, like forskolin, showed adenylate cyclase stimulant activity in guinea pig ventricular membrane but did not inhibit Na+, K(+)-ATPase or phosphodiesterase (PDE) activity. The compound was developed by a Japanese company Nippon Kayaku. Colforsin daropate, a prodrug of colforsin, is marketed in Japan for the treatment of acute heart failure under tradename Adehl.