purple heart
noun
1
a capsule of phenobarbital (trade name Luminal™), a central nervous system depressant US, 1966.
2
a tablet of amphetamine Drinamyl™ used as a recreational drug. From the lilac colour of the pill; playing on the US military decoration awarded to any member of the armed forces wounded by the enemy. Also shortened to 'heart' or 'purple' US, 1962