Design of a magnesium-pridinolum complex for polylactide-drug conjugates formation.

Polylactide conjugates of the muscle contraction agent Pridinolum (PriOH = 1,1-diphenyl-3-(1-piperidinyl)-1-propanol) were prepared directly by ring-opening polymerization of L-lactide (L-LA) mediated by the pridinolum magnesium complex [Mg(μ,η(2)-OPri)(η(1)-OPri)](2). The ancillary O,N - bifunctional drug as a ligand stabilizes the magnesium species and initiates L-LA polymerization affording a polymer chain terminated by covalently attached drug molecules to the PLLA through ester linkers to form PriO-PLLA conjugate. Up to 80% of the pridinolum can be released from the conjugate by treatment with deuterated hydrochloric acid DCl at pH = 1.5 for 10 h at 37 °C.