Green’s Dictionary of Slang

(US drugs) methaqualone, or other depressant drugs; thus ludehead, a habitual user of the drug.

1978		Maclean’s (Toronto) 21 Aug. 22: Because ‘ludes,’ as the students call them, are so abused as a ‘fun’ drug, pharmacists are constantly on the watch for phoney prescriptions.
1985		N. Pileggi Wiseguy (2001) 219: I was snorting a lot of coke and eating ludes.
1992		G.P. Pelecanos Firing Offense 43: He unraveled his fist to reveal two orange hexagonal pills [...] ‘What is it?’ ‘Like a ‘lude, only not as heavy. [...] It’s just a painkiller’.
2002		(con. 1998–2000) J. Lerner You Got Nothing Coming 279: Later we’d drink and take ’Ludes to come down.
2004		Eble Campus Sl. Apr.
2015		L. Berney Long & Faraway Gone [ebook] Ludes made Genevieve feel gross and sluggish.
2024		J. Meades Empty Wigs (t/s) 301: I threw some ludes into my mouth.