YM 976

Relaxant effect of YM976, a novel phosphodiesterase 4 inhibitor, on bovine tracheal smooth muscle.[Pubmed:12787831]

Eur J Pharmacol. 2003 May 30;470(1-2):57-64.

Effects of 4-(3-chlorophenyl)-1,7-diethylpyrido[2,3-d]pyrimidin-2(1H)-one (YM976), a novel and selective phosphodiesterase type 4 inhibitor, on tension and adenosine 3',5'-cyclic monophosphate (cAMP) content of bovine tracheal smooth muscle were compared with those of rolipram and theophylline. YM976, rolipram and theophylline relaxed the tracheal preparations contracted with histamine in a concentration-dependent manner. The relaxant effects of YM976 and rolipram were more potent than those of theophylline. These phosphodiesterase inhibitors-induced relaxations were dramatically diminished when tracheal smooth muscle was contracted with methacholine instead of histamine. Pretreatment of the tracheal preparations with YM976 (10 microM) or rolipram (10 microM), but not with theophylline (1 mM), shifted the concentration-response curves for contractile responses to histamine; however, the same procedure failed to affect concentration-response relationships for methacholine-induced contractions. At 1 and 10 microM, both YM976 and rolipram increased the tissues cAMP content. These results suggest that YM976 relaxes tracheal smooth muscle, probably through the cAMP-dependent mechanism.

Studies on mechanisms of low emetogenicity of YM976, a novel phosphodiesterase type 4 inhibitor.[Pubmed:11504812]

J Pharmacol Exp Ther. 2001 Sep;298(3):1142-9.

YM976 is a novel and selective inhibitor of phosphodiesterase type 4 (PDE4) with a different chemical structure from rolipram. Orally administered YM976 showed anti-inflammatory activity (ED(50) = 2.8 mg/kg) similar to rolipram (3.5 mg/kg). On the other hand, the emetogenicity of YM976, one of the main adverse effects of PDE4 inhibitors, was lower (maximal non-emetic dose = 10 mg/kg) than that of rolipram (1 mg/kg). The reasons for this low emetogenicity of YM976 remain unclear, and the present study endeavored to elucidate the mechanisms. Candidates for the possible mechanisms included 1) PDE4 subtype selectivity, 2) binding affinity for HAR-conformation, and 3) brain penetration. YM976 exhibited affinity for high affinity for rolipram-conformation (HAR-conformation) (IC(50) = 2.6 nM) identical to that of rolipram (1.2 nM), and failed to show significant selectivity for the individual PDE4 subtype. These results suggested that neither subtype selectivity nor the affinity for HAR-conformation may be related to the low emetogenicity of YM976. YM976 showed a minor effect on reserpine-induced hypothermia, in contrast to rolipram. To estimate brain penetration, we then measured cAMP contents in peripheral tissues (peritoneal macrophages) and in the brain. YM976 increased the cAMP content of peritoneal macrophages, but caused no significant increase in brain cAMP levels, while rolipram elevated the cAMP content of both tissues at the same dose. In conclusion, YM976 shows an apparent dissociation between its anti-inflammatory effects and emetogenicity, perhaps because of the poor brain penetration.

A novel phosphodiesterase type 4 inhibitor, YM976 (4-(3-chlorophenyl)-1,7-diethylpyrido[2,3-d]pyrimidin-2(1H)-one), with little emetogenic activity.[Pubmed:10991987]

J Pharmacol Exp Ther. 2000 Oct;295(1):255-60.

We synthesized a novel phosphodiesterase type 4 (PDE4) inhibitor, YM976, that is structurally different from the other PDE4 inhibitors like rolipram. In the present study, the pharmacological profile of YM976 was investigated. YM976 exhibited a strong and competitive inhibition against PDE4 purified from human peripheral leukocytes with an IC(50) of 2.2 nM. IC(50) values of rolipram and RP73401 were 820 and 0.43 nM, respectively. Test compounds had no effects on the other PDE isozymes, PDE1, -2, -3, and -5. YM976 potentiated prostaglandin E(2)-induced cAMP accumulation in a human mononuclear cell line, U937, and inhibited tumor necrosis factor-alpha production from human peripheral blood mononuclear cells stimulated by lipopolysaccharide. Anti-inflammatory activities of PDE4 inhibitors were compared in rat carrageenan-induced pleurisy models. YM976, rolipram, and RP73401 inhibited the cell infiltration into the pleural cavity with oral ED(30) values of 9.1, 10, and 7.4 mg/kg, respectively. YM976 produced no emesis up to 10 mg/kg, whereas rolipram and RP73401 induced emesis at oral doses of 3 mg/kg. To evidence the dissociation of anti-inflammatory activity from emesis, the anti-inflammatory effect of YM976 was examined in ferrets. YM976 dose dependently reduced carrageenan-induced leukocyte infiltration at the doses of 1, 3, and 10 mg/kg, p.o. On the other hand, rolipram failed to show obvious inhibition at doses that do not induce emesis. In conclusion, YM976 is a novel and orally active PDE4 inhibitor and possesses a good separation of emetogenicity from anti-inflammatory activity.