Novel peptoid hydrogels as long-acting injectable drug delivery systems

Long-acting injectable (LAI) nanosuspensions comprising water-insoluble drugs are already widely marketed for treatment of schizophrenia and are presently being evaluated in late-stage clinical studies as formulation strategies for pre-exposure prophylaxis (PrEP) against HIV infection. Alternative formulations are needed to overcome some of the disadvantages of nanosuspension injections, including the use of water-insoluble actives, the formation of amorphous drug during milling, and difficulties around large-scale manufacturing.

We will investigate the potential of novel peptoid hydrogels for long-acting subcutaneous drug administration. Peptoids are biocompatible molecules that mimic naturally occurring peptides. They form structured, tissue-like, hydrogel networks in aqueous environments and can offer sustained release of drugs. The formulations will comprise: a peptoid backbone capable of hydrogelation; a phosphate group to increase aqueous solubility and whose enzymatic removal triggers hydrogel formation in vivo; and a model antiretroviral molecule attached via a physiologically hydrolysable group. We will characterise antiretroviral-conjugated peptoids for their ability to form hydrogels, test the biocompatibility of peptoid hydrogels and evaluate sustained drug release properties.

Our findings could contribute to the development of alternative formulations for LAI drugs.