Macrophage delivery of nanoformulated antiretroviral drug to the brain in a murine model of neuroAIDS.

Antiretroviral therapy (ART) shows variable blood-brain barrier penetration. This may affect the development of neurological complications of HIV infection. In attempts to attenuate viral growth for the nervous system, cell-based nanoformulations were developed with the focus on improving drug pharmacokinetics. We reasoned that ART carriage could be facilitated within blood-borne macrophages traveling across the blood-brain barrier. To test this idea, an HIV-1 encephalitis (HIVE) rodent model was used where HIV-1-infected human monocyte-derived macrophages were stereotactically injected into the subcortex of severe combined immunodeficient mice. ART was prepared using indinavir (IDV) nanoparticles (NP, nanoART) loaded into murine bone marrow macrophages (BMM, IDV-NP-BMM) after ex vivo cultivation. IDV-NP-BMM was administered i.v. to mice resulting in continuous IDV release for 14 days. Rhodamine-labeled IDV-NP was readily observed in areas of HIVE and specifically in brain subregions with active astrogliosis, microgliosis, and neuronal loss. IDV-NP-BMM treatment led to robust IDV levels and reduced HIV-1 replication in HIVE brain regions. We conclude that nanoART targeting to diseased brain through macrophage carriage is possible and can be considered in developmental therapeutics for HIV-associated neurological disease.

Suspensions for intravenous (IV) injection: a review of development, preclinical and clinical aspects.

There has been growing interest in nanoparticles as an approach to formulate poorly soluble drugs. Besides enhanced dissolution rates, and thereby, improved bioavailability, nanoparticles can also provide targeting capabilities when injected intravenously. The latter property has led to increased research and development activities for intravenous suspensions. The first intravenously administered nanoparticulate product, Abraxane (a reformulation of paclitaxel), was approved by the FDA in 2006. Additional clinical trials have been conducted or are ongoing for multiple other indications such as oncology, infective diseases, and restenosis. This article reviews various challenges associated with developing intravenous nanosuspension dosage forms. In addition, various formulation considerations specific to intravenous nanosuspensions as well as reported findings from various clinical studies have been discussed.

Itraconazole IV nanosuspension enhances efficacy through altered pharmacokinetics in the rat.

The goal of this research was to evaluate an intravenous itraconazole nanosuspension dosage form, relative to a solution formulation, in the rat. Itraconazole was formulated as a nanosuspension by a tandem process of microcrystallization followed by homogenization. Acute toxicity, pharmacokinetics, and distribution were studied in the rat, and compared with a solution formulation of itraconazole. Efficacy was studied in an immunocompromised rat model, challenged with a lethal dose of either itraconazole-sensitive or itraconazole-resistant C. albicans. Itraconazole nanosuspension was tolerated at significantly higher doses compared with a solution formulation. Pharmacokinetics of the nanosuspension were altered relative to the solution formulation. C(max) was reduced and t(1/2) was much prolonged. This occurred due to distribution of the nanosuspension to organs of the monocyte phagocytic system (MPS), followed by sustained release from this IV depot. The higher dosing of the drug, enabled in the case of the nanosuspension, led to higher kidney drug levels and reduced colony counts. Survival was also shown to be superior relative to the solution formulation. Thus, formulation of itraconazole as a nanosuspension enhances efficacy of this antifungal agent relative to a solution formulation, because of altered pharmacokinetics, leading to increased tolerability, permitting higher dosing and resultant tissue drug levels.

Itraconazole suspension for intravenous injection: determination of the real component of complete refractive index for particle sizing by static light scattering.

The purpose of this study is to assess the impact of real refractive indices, using different itraconazole suspensions, on the associated particle size distributions. Instrumental particle size measurement remains the practical option for determining the particle size distribution of a suspension. In this study, the suspension particle size distribution was measured by static light scattering, which requires knowledge of both the real and imaginary components of the complete refractive index. The real refractive indices of micronized itraconazole raw material, as well as vacuum-dried itraconazole suspension samples obtained from different formulations, polymorphs, manufacturing methods and particle size distributions, were determined using the Becke line method. Identical samples were analyzed by two contract laboratories in order to assess consistency. For the static light scattering equipment used in this study, the complete relative refractive index (RRI = n(particte) / n(dispersant) - ik) input required for software calculation is denoted by a refractive index kernel (RRI input) comprising a relative real component and an imaginary component. The reported real refractive indices for the itraconazole raw material as well as vacuum dried itraconazole suspension samples were different, ranging from 1.608 to 1.65 (selected kernel range of 120A010I to 124A010I). The imaginary component of itraconazole suspension was determined in a previous study to be 010I. The average real refractive index was calculated to be 1.62 (122A010I). The particle size distributions obtained using 120A010I and 124A010I were in good agreement with one generated using 122A010I. Therefore, itraconazole suspensions that were produced using different manufacturing methods/formulations or exhibited different particle size distributions/polymorphic forms may use 122A010I in determining particle size distribution. The particle size distributions determined using RRI input outside the range of 120A010I to 124A010I may not be reliable. However, it is recommended that similar investigations be conducted for other drug suspensions on a case-by-case basis.

Mechanism of 2-hydropropyl-beta-cyclodextrin in the stabilization of frozen formulations.

Freezing of commonly used parenteral products to increase pharmaceutical stability for cost-saving purposes is a common practice in patient care. However, frozen meropenem, a model drug, in saline has a shelf life of less than a month due to the low glass transition temperature (Tg'): below -40°C. When meropenem is formulated with the 2-hydroxypropyl-ß-cyclodextrin (HPBC) the shelf life (⩾90% potency) is extrapolated to be greater than one year at -25°C based on data for storage at 6months. The mechanisms that may explain meropenem-HPBC formulation frozen stability include vitrification and/or formation of an inclusion complex. Although NMR data indicated complexation of meropenem by HPBC in a ratio of 0.6:1, inclusion was unlikely to be the mechanism as stability was not extended to the thawed solutions. Therefore, vitrification is concluded to be the stabilization mechanism. The Tg' for meropenem-HPBC (13.3%) formulation at pH 7.9 was -17.75°C which was similar to that of a meropenem solution formulated with a known vitrifying agent, Dextran 40. This higher Tg' for HPBC was unexpected based on trends predicted by the Fox-Flory equation. Trial formulations containing either Dextran 1, Dextran 40, hydroxyethyl starch, or sulfobutyl-beta-cyclodextrin heptasodium (Captisol®) were also unable to stabilize meropenem as the Tg' values were below the frozen storage temperature. Upon 6-month storage, potency losses were -3.0% and -7.7% for meropenem frozen premix formulated in 13.3% HPBC (pH 7.9) at -25 and -20°C storage, respectively; versus -31.2% and -60.8% for controls. Frozen premixes with high ionic strength (containing NaCl or Captisol®) and/or at pH 7.3 were also found to be unstable.

Laboratory investigations for the morphologic, pharmacokinetic, and anti-retroviral properties of indinavir nanoparticles in human monocyte-derived macrophages.

The effectiveness of anti-retroviral therapies (ART) depends on its ultimate ability to clear reservoirs of continuous human immunodeficiency virus (HIV) infection. We reasoned that a principal vehicle for viral dissemination, the mononuclear phagocytes could also serve as an ART transporter and as such improve therapeutic indices. A nanoparticle-indinavir (NP-IDV) formulation was made and taken up into and released from vacuoles of human monocyte-derived macrophages (MDM). Following a single NP-IDV dose, drug levels within and outside MDM remained constant for 6 days without cytotoxicity. Administration of NP-IDV when compared to equal drug levels of free soluble IDV significantly blocked induction of multinucleated giant cells, production of reverse transcriptase activity in culture fluids and cell-associated HIV-1p24 antigens after HIV-1 infection. These data provide "proof of concept" for the use of macrophage-based NP delivery systems for human HIV-1 infections.

Development of a macrophage-based nanoparticle platform for antiretroviral drug delivery.

Complex dosing regimens, costs, side effects, biodistribution limitations, and variable drug pharmacokinetic patterns have affected the long-term efficacy of antiretroviral medicines. To address these problems, a nanoparticle indinavir (NP-IDV) formulation packaged into carrier bone marrow-derived macrophages (BMMs) was developed. Drug distribution and disease outcomes were assessed in immune-competent and human immunodeficiency virus type 1 (HIV-1)-infected humanized immune-deficient mice, respectively. In the former, NP-IDV formulation contained within BMMs was adoptively transferred. After a single administration, single-photon emission computed tomography, histology, and reverse-phase-high-performance liquid chromatography (RP-HPLC) demonstrated robust lung, liver, and spleen BMMs and drug distribution. Tissue and sera IDV levels were greater than or equal to 50 microM for 2 weeks. NP-IDV-BMMs administered to HIV-1-challenged humanized mice revealed reduced numbers of virus-infected cells in plasma, lymph nodes, spleen, liver, and lung, as well as, CD4(+) T-cell protection. We conclude that a single dose of NP-IDV, using BMMs as a carrier, is effective and warrants consideration for human testing.