Green’s Dictionary of Slang

amphetamines.

1965		H. Huncke ‘Frisky’ in Huncke’s Journal (1998) 34: There is one other beautiful child [...] who occasionally falls in, stays a while, maybe turns on a shot of amphets, and then disappears.
1980		(con. 1940s–60s) H. Huncke ‘Irving, In Part’ in Eve. Sun Turned Crimson (1998) 166: Ed said he would like just a small taste of the amphets.
2000		N. Griffiths Grits 231: Amphets’ll fuck yer pretty little head right up.