Drug derivatives are provided herein which are suitable for loading into liposomal nanoparticle carriers. In some preferred aspects, the derivatives comprise a poorly water-soluble drug derivatized with a weak-base moiety that facilitates active loading of the drug through a LN transmembrane pH or ion gradient into the aqueous interior of the LN. The weak-base moiety can optionally comprise a lipophilic domain that facilitates active loading of the drug to the inner monolayer of the liposomal membrane. Advantageously, LN formulations of the drug derivatives exhibit improved solubility, reduced toxicity, enhanced efficacy, and/or other benefits relative to the corresponding free drugs.