Antiretroviral release from poly(DL-lactide-co-glycolide) nanoparticles in mice

Abstract

Objectives: Free ritonavir, lopinavir and efavirenz injected intraperitoneally were compared with antiretroviral (AR) nanoparticles (NPs).

Methods: This is a prospective study in BALB/c mice comparing the pharmacokinetics of free drugs with AR NPs. All animals received free drugs or AR NPs (20 mg/kg) in PBS. In vitro replication assays were used for determination of the anti-HIV efficacy of NP formulations. At specific times (free drugs 0.08, 0.125, 0.25, 0.33, 1, 2 and 3 days; AR NPs 0.125, 0.33, 1, 2, 4, 7, 14, 21, 28, 35 and 42 days) mice were euthanized and serum and organs were harvested for determination of AR concentrations by HPLC. Single treatment of monocyte-derived macrophages (MDMs) infected with HIV-1(ada) compared AR NPs (0.005-0.05 mg/mL) with free efavirenz or lopinavir/ritonavir (0.01-0.1 mg/mL), blank NPs and controls. Results are presented as means ± SEM.

Results: Serum free AR drug concentrations peaked 4 h post-injection (ritonavir 3.9 ± 3.05, lopinavir 3.4 ± 2.5 and efavirenz 1.8 ± 0.63 µg/mL) and were eliminated by 72 h. Poly(dl-lactide-co-glycolide) NP animals had detectable ritonavir, lopinavir and efavirenz concentrations in all tissues for 28 days. Treatment of MDMs with AR NPs resulted in sustained inhibition of HIV-1(ada) replication.

Conclusions: AR drug concentrations from NPs are sustained for 28 days in vivo and anti-HIV inhibition was comparable to that of free drugs in vitro and could be a sustained treatment for delivery of AR drugs.

Figure 1.

Serum and organ concentration versus time curves for AR drugs after 20 mg/kg intraperitoneal injection into mice. (a, c and e) Free drug injections. (b, d and f) AR NP injections. (a) Free ritonavir concentrations. (b) Ritonavir concentrations from NP formulation. (c) Free lopinavir concentrations. (d) Lopinavir concentrations from NP formulation. (e) Free efavirenz concentrations. (f) Efavirenz concentrations from NP formulation. Error bars represent SEM of three mice measurements by HPLC.

Figure 2.

AR NPs inhibit HIV-1 replication in MDMs in vitro. Virus replication was measured by the level of capsid protein (p24) released into the medium at the days indicated. Cells were treated as indicated for 4 h at 1 day post-infection. Control represents HIV-1-infected MDMs. (a) Data from an experiment in which free drugs were given at 0.01 mg/mL and AR NP was given at 0.005 mg/mL. (b) Data from an experiment in which MDMs were treated with 0.1 mg/mL free drugs or 0.05 mg/mL AR NPs. Error bars represent SEM. Data are representative of three independent experiments. **A significant difference between blank NPs or control MDMs and free AR drugs or AR NPs (P < 0.01). EFV, efavirenz; LPV/r, lopinavir/ritonavir.