Disclosed is a 6-mercapto-cyclodextrin derivative having a general formula (I, ) wherein m is 0-7 and n is 1-8 and m+n=7 or 8; R is (C_1-6) alkylene, optionally substituted with 1-3 OH groups, or (CH₂)_o-phenylene-CH₂)_p—; o and p are independently 0-4; X is COOH, CONHR₃, NHCOR₂, SO₂OH, PO(OH)₂, O(CH₂—CH₂—O)_q—H, OH or tetrazol-5-yl: R₂ is H or (C_1-3)alkyl; R₂ is carboxyphenyl; q is 1-3; or pharmaceutically acceptable salts thereof. The 6-mercaptocyclodextrin derivative is highly suitable for use in the reversal of drug-induced neuromuscular block.