A new nanomedicine based on didanosine glycerolipidic prodrug enhances the long term accumulation of drug in a HIV sanctuary.

New nanomedicines could improve drug accumulation in HIV sanctuaries and ameliorate their antiretroviral efficiency. In this view, we propose herein a combined strategy based on a biomimetic prodrug of ddI and its formulation in well-characterized lipid nanoobjects. The glycerolipidic prodrug of ddI (ProddINP) has been synthesized and its bulk structure was characterized. An appropriate formulation of this prodrug has been designed using a rational approach combining different physicochemical techniques. The high incorporation ratio of the prodrug into dipalmitoylphosphatidylcholine (DPPC) bilayers was determined by DSC. Then two liposome preparation methods were compared, with respect to size, incorporation yield and molecular/supramolecular organization of vesicles. The best liposomal formulation of ProddINP has been checked to keep intact the anti-HIV activity of ddI. This formulation was finally compared to ddI after oral route in rat. The animal experiments evidenced the increase of ddI blood half life (3-fold) and its enhanced accumulation as prodrug form at 24h in numerous organs and especially intestine after administration of ProddINP in comparison with free drug. Finally, the tested liposomal formulation of ProddINP seems to be a promising approach to eradicate HIV infection from intestinal sanctuaries where the virus can concentrate.

Metabolism evaluation of biomimetic prodrugs by in vitro models and mass spectrometry.

Glycerolipidic prodrug is an interesting concept to enhance lymphatic absorption of polar drugs intended to oral delivery such as didanosine (ddI). In order to improve ddI bioavailability, two didanosine glycerolipidic prodrugs, the phosphorylated (ProddIP) and the non-phosphorylated derivatives (ProddINP) were synthesized to follow triglyceride metabolism. The biomimetism approach of these prodrugs has been studied in vitro at two steps. First, liposomal formulation of each prodrug was incubated with a lipolysis model based on pancreatin and analysed using liquid chromatography combined with tandem mass spectrometry (LC-MS/MS). These experiments evidenced that both didanosine prodrugs were recognized by the lipases; as expected, they were cleaved at both positions sn-1 and sn-3 of glycerol. ProddIP was metabolised twice more rapidly than ProddINP suggesting an implication of some phospholipases in ProddIP degradation. Secondly, the detection of dideoxyadenosine triphosphate (ddA-TP) into HIV-1 infected cells after their incubation with ProddINP loaded liposomes evidenced their ability to release ddI that could penetrate into the cells and be metabolised by intracellular kinases. These results confirmed that the synthesized glycerolipidic prodrugs of didanosine could be investigated for a biomimetic approach with final aiming of increasing the drug oral bioavailability by enhancing intestinal absorption.

Strategies to increase the oral bioavailability of nucleoside analogs.

Nucleoside analogs are first line chemotherapy in various severe diseases: AIDS (acquired immunodeficiency disease syndrome), cytomegalovirus infections, cancer etc. However, most of these compounds suffer from poor bioavailability via oral route. In order to get around this drawback, researchers have imagined many strategies including drug metabolism inhibitors, bio adhesive nanoparticles, amino ester prodrugs, as well as enhancing absorption by increasing drug lipophilicity. This paper illustrated these approaches by developing their application to some nucleoside analogs. Moreover, some of these strategies were very successful and some resulting compounds are now approved by FDA (Food and Drug Administration).

Synthesis and biological evaluation of two glycerolipidic prodrugs of didanosine for direct lymphatic delivery against HIV.

Novel glycerolipidic prodrugs of didanosine and didanosine monophosphate designed to by-pass the hepatic first pass metabolism were synthesized and tested for their cytotoxicity and anti-HIV-1 activity. Formulation as liposomes of dipalmitoylphosphatidylcholine was elaborated. A simple quantitative HPLC-UV method was developed and validated, and ESI-MS was used for qualitative purpose. These two prodrugs exhibited promising biological activities against HIV-1 in in vitro infected cell culture.