Use of a compound of the formula (I) wherein R.sub.1 is selected from alkyl, alkoxy, aryloxy, alkylthio, arylthio, aryl, halogen, CN, NR.sub.7R.sub.8, NR.sub.6COR.sub.7, NR.sub.6CO.sub.2R.sub.9 and NR.sub.6SO.sub.2R.sub.9; R.sub.2 is selected from aryl attached via an unsaturated carbon; R.sub.3 and R.sub.4 are independently selected from H, alkyl, halogen, alkoxy, alkylthio, CN and NR.sub.7R.sub.8; R.sub.5 is selected from H, acyclic alkyl, COR.sub.6, CONR.sub.7R.sub.8, CONR.sub.6NR.sub.7R.sub.8, CO.sub.2R.sub.9 and SO.sub.2R.sub.9; R.sub.6, R.sub.7 and R.sub.8 are independently selected from H, alkyl and aryl or where R.sub.7 and R.sub.8 are in an NR.sub.7R.sub.8 group R.sub.7 and R.sub.8 may be linked to form a hererocyclic group, or where R.sub.6, R.sub.7 and R.sub.s are in a (CONR.sub.6NR.sub.7R.sub.s) group, R.sub.6 and R.sub.7 may be linked to form a hererocyclic group; and R.sub.9 is selected from alkyl and aryl, or a pharmaceutically acceptable salt thereof or prodrug thereof, in the manufacture of a medicament for 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 subect; compounds of formula (I) for use in therapy; and novel compounds of formula (I) per se.