The invention provides neuromuscular blockade agents of the non-depolarizing type with few if any circulatory effects. Compounds of the invention include bis(isoquinolylalkanol) diesters of fumaric, maleic, succinic, and acetylenedicarboxylic acids; compositions suitable for parenteral administration of these compounds as a surgical adjunct to anesthesia, and methods of preparation of the compounds. Compounds of the invention can produce neuromuscular blockade of short or intermediate duration, which for various compounds can be reversed by administration of a thiol compound such as L-cysteine, D-cysteine or glutathione. For various compounds of the invention, the neuromuscular blockade effect can be reversed quickly, efficiently, and without notable side-effects.