Gel-forming block copolymers were prepared comprising i) a central hydrophilic block consisting essentially of a divalent poly(ethylene oxide) chain and ii) two peripheral monocarbonate or polycarbonate hydrophobic blocks linked to the central block by linking groups bearing one or more hydrogen bond forming *—N(H)—* groups. The hydrophobic blocks comprise one or more vitamin-bearing subunits. The gel-forming block copolymers can be used to prepare various biodegradable and/or biocompatible hydrogel and organogel drug compositions, in particular antimicrobial and/or anti-tumor drug compositions. The hydrogel compositions have utility in depot injections for drug delivery. The hydrogen bonding *—N(H)—* group(s) provide longer in vivo lifetime of the hydrogel before degradation and a more prolonged and controlled release rate of a hydrophobic drug compared to similar hydrogels prepared from poly(ethylene glycol).