Use of a compound of formula (I): wherein R.sub.1 is selected from alkyl, alkoxy, aryloxy, alkylthio, arylthio, aryl, halogen, CN, NR.sub.6R.sub.7, NR.sub.5COR.sub.6, NR.sub.5CONR.sub.6R.sub.7, NR.sub.5CO.sub.2R.sub.8 and NR.sub.5SO.sub.2R.sub.8; R.sub.2 is selected from heteroaryl attached via an unsaturated carbon; R.sub.3 is selected from H, alkyl, halogen, OR.sub.5, SR.sub.5 and NR.sub.6R.sub.7; R.sub.4 is selected from H, acyclic alkyl, CONR.sub.6R.sub.7, CONR.sub.5NR.sub.6R.sub.7, COR.sub.6, CO.sub.2R.sub.8 and SO.sub.2R.sub.8; R.sub.5, R.sub.6 and R.sub.7 are independently selected from H, alkyl and aryl, or where R.sub.6 and R.sub.7 are in an NR.sub.6R.sub.7 group, R.sub.6 and R.sub.7 may be linked to form a heterocyclic group, or where R.sub.5, R.sub.6 and R.sub.7 may be linked to form a heterocyclic group, or where R.sub.5, R.sub.6 and R.sub.7 are in a (CONR.sub.5NR.sub.6R.sub.7) group, R.sub.5 and R.sub.6 may be linked to form a heterocyclic group; and R.sub.8 is selected from alkyl and aryl, or a pharmaceutically acceptable salt thereof or prodrug thereof, in the treatment or prevention of a disorder in which the blocking of purine receptors, particularly adenosine receptors and more particularly A.sub.2A receptors, may be beneficial, particularly wherein said disorder is a movement disorder such as Parkinson's disease or said disorder is depression, cognitive or memory impairment, acute or chronic pain, ADHD or narcolepsy, or for neuroprotection in a subject; compounds of formula (I) for use in therapy; and novel compounds of formula (I) per se.