Graduation Date

Spring 5-4-2019

Document Type


Degree Name

Doctor of Philosophy (PhD)


Pharmaceutical Sciences

First Advisor

Howard E Gendelman


Combination antiretroviral therapy (cART) for treatment of human immunodeficiency virus (HIV) infection demands life-long regimen adherence. Treatment interruptions lead to a lack of virologic control and the emergence of viral mutations and drug resistance. To address these, our laboratory developed long-acting (LA) parenteral administered nanoformulated abacavir prodrug (NMABC) by formulating myristoylated abacavir (MABC) with poloxamer 407 as stabilizer, which sustained ABC levels for up to 2 weeks with low levels of active drug metabolite (CBV-TP). To more significantly extend the apparent half-life of ABC and improve its antiretroviral activities, we developed second generation long-acting ABC prodrugs by ProTide technologies. This modification can deliver pre-activated nucleoside analog inside the target cells. The work proceeded in defined manner.

First, we synthesized then characterized traditional ProTides of ABC, AlaMe, with ProTide technology. The antiretroviral activity (EC50) of AlaMe was 7-fold lower then native ABC. Then, AlaMe loaded and lipid coated PLGA nanoparticle was prepared withna size of 250 nm by thin film hydration (NAlaMe). NAlaMe can be easily taken up and retained by monocyte-derived macrophages (MDM) for weeks and protect MDM against HIV infections. Male BALB/cJ mice were subcutaneously administered 54.3mg/kg ABC equivalents of NAlaMe and ABC. NAlaMe treated mice had higher CBV-TP levels than ABC at 24 and 72 h after administration. These results showed that ProTide technologies can be a useful strategy for the development of second-generation ABC LA.

Second, ProTide technology was combined with LA technology. Three ABC ProTides (AlaMe, PheMe and PheC22) were successfully synthesized. AlaMe and PheMe were traditional ProTides. PheC22 possessed a long-chain fatty alcohol moiety. All three ProTides demonstrated improved antiretroviral activities compared to ABC. Nanosuspensions of PheMe (NPheMe) and PheC22 (NPheC22) were formulated using P407 as stabilizer with sizes of 388 and 340 nm, respectively. Cell uptake, retention and antiretroviral activity of NAlaMe, NPheMe, NPheC22 were tested in MDM. NPheC22 had the highest uptake, retention and was able to protect MDM against HIV-1 infection up to 30 days. Combinatorial strategies thus show advantages for the development of second-generation ABC LA.ABC ProTides had long-chain fatty esters were specifically named ABC ProTides LA.

Third, we investigated the influence of different combination of amino acid and long-chain fatty alcohol on activities of ABC ProTides LA. Six ABC ProTides LA: AlaC14, AlaC18, AlaC22, PheC14, PheC18 and PheC22 were synthesized and characterized. The EC50 of ABC ProTides were up to 100- or 10-fold lower in MDM or CEM CD4+T cells against HIV infection compared to ABC. CBV-TP was increased by up to 45-fold of 8-fold in MDM or CEM CD4+T cells. Nanosuspension of all six ProTides were formulated using DSPG-mPEG2Kand Tween 80 as stabilizers. The six nanosuspension had sizes range from 220 - 300 nm. Nanosuspensions were taken up, retained and released by MDM and protected MDM against HIV-1 infection more than 28 days. PK studies in rats showed that ProTide nanosuspension provide CBV-TP over a longer time than ABC. NAlaC18 provided clinically relevant CBV-TP levels in rats up to 7 days following a single injection. In conclusion, ProTides and LA technologies were combinationally used to create second generation ABC LA. These works are a step forward in the development of long acting nucleoside reverse transcriptase inhibitors for human use.