Green’s Dictionary of Slang

(drugs) any of the hypnotic drugs derived from barbituric acid.

1969		R.R. Lingeman Drugs from A to Z (1970).
1972		N.Y. Times 4 June 4:7: Barbs are cheaper than heroin [...] and not as detectable as marijuana.
1999		J. Cameron Brown Bread in Wengen [ebook] Yeah she was on the pills. Not likely she got any barbs so she probably had a jar of cheer-ups.
2001		‘Randy Everhard’ Tattoo of a Naked Lady 52: I offered her the barbies in my hand and told her they were bennies.
2023		(con. 1962) J. Ellroy Enchanters 356: She crossed ‘Norma Jean Baker’ off a barb vial in ’48.
2024		J. Meades Empty Wigs (t/s) 668: [H]e took from his canvas bag a litre of superior NAAFI brand gin and a bottle of 100 Secobarbital capsules [...] The barbs were astonishingly easy to swallow.