8-Cyclopentyl-1,3-dipropylxanthine (DPCPX, PD-116,94 is a drug which acts as a potent and selective antagonist for the adenosine A1 receptor.[1][2] It has high selectivity for A1 over other adenosine receptor subtypes, but as with other xanthine derivatives DPCPX also acts as a phosphodiesterase inhibitor, and is almost as potent as rolipram at inhibiting PDE4.[3] It has been used to study the function of the adenosine A1 receptor in animals,[4][5] which has been found to be involved in several important functions such as regulation of breathing[6] and activity in various regions of the brain,[7][8] and DPCPX has also been shown to produce behavioural effects such as increasing the hallucinogen-appropriate responding produced by the 5-HT2A agonist DOI,[9] and the dopamine release induced by MDMA,[10] as well as having interactions with a range of anticonvulsant drugs.[11][12]

DPCPX has been shown to "supress head shakes induced by a serotonergic hallucinogen" meaning it can help one respond better to Tryptamines and MDMA...