Significant interest in long-acting parenteral (LAP) antiretroviral drugs (ARVs) has set a new bar for HIV/AIDS care. LAP ARVs are designed to improve treatment compliance and affect resistance patterns and drug toxicities. Cabotegravir (CAB), a potent viral integrase inhibitor, now in phase II clinical trials as an LAP (CAB-LAP) currently demonstrates sustained plasma drug levels in humans up to 52 weeks after single intramuscular dose. We sought that CAB LAP could be even further developed to reduce injection volumes and improve pharmacokinetic (PK) profiles that would make it even easier to administer. To this end a prodrug nanoformulation of CAB (called NMCAB) was made to improve drug half-life along with its antiretroviral activities. CAB was chemically conjugated to myristoyl chloride, transforming it into a more hydrophobic moiety. The prepared NMCAB particles were size reduced by high-pressure homogenization with poloxamer407. Uptake and retention were tested in human monocyte-derived macrophages (MDM). Antiretroviral activity was evaluated by reverse transcriptase (RT) activity and cell HIV-1p24 expression. NMCAB was efficiently taken up by cells with sustained release up to 10 days. Notably, the parent drug formulations were eliminated after a single day of treatment. MDM treated with NMCAB showed RT activity at or below the level of detection when infected at days 0, 2, 5 and 10 after drug particle treatment. HIV-1p24 was not detected in the NMCAB treated group at any of these time points. A PK evaluation is being monitored for 2 months after a single injection. We conclude that NMCAB shows improved uptake, retention and antiretroviral activity. Biodistribution, PK and pharmacodynamic studies are underway.