Green’s Dictionary of Slang

1. drunk.

1630		J. Taylor ‘A Brood of Cormorants’ in Works (1869) III 5: For though he be as drunke as any Rat, / He hath but catcht a Foxe, or whipt the Cat. / Or some say hee’s bewitcht, or scratcht, or blinde, / (Which are the fittest termes that I can finde).
1640		‘Mary Tattle-well’ Womens sharpe revenge 175: The first Health is call’d a Whiffe, the second a Slash, the third a Hunch, the fourth Thrust, the fift is call’d Pot-shaken, the sixth is seeing the Lions, the seventh he is scratch’d, the eighth, his Nose is dirty, the ninth he hath whipt the Catt, the tenth, he is fox’d, the eleventh, he is Bewitch’d, the twelfth, he is Blinde, and the thirteenth, and last, he is drunke.
1866		J. Greenwood Little Ragamuffin 15: He’s like all the rest of ’em [...] — shows a bit of the devil when he’s scratched.

2. (Aus.) intoxicated by a (narcotic) drug.

1996

(con. 1964-65) B. Thorpe Sex and Thugs and Rock ’n’ Roll 146: [of heroin] Manny was scratched out of his brain.