Polyethylene glycol (PEG)-coated nanopharmaceuticals can cause mild to severe hypersensitivity reactions (HSRs), which can occasionally be life threatening or even lethal. The phenomenon represents an unsolved immune barrier to the use of these drugs, yet its mechanism is poorly understood. This study showed that a single i.v. injection in pigs of a low dose of PEGylated liposomes (Doxebo) induced a massive rise of anti-PEG IgM in blood, peaking at days 7–9 and declining over 6 weeks. Bolus injections of PEG-liposomes during seroconversion resulted in anaphylactoid shock (pseudo-anaphylaxis) within 2–3 min, although similar treatments of naı̈ve animals led to only mild hemodynamic disturbance. Parallel measurement of pulmonary arterial pressure (PAP) and sC5b-9 in blood, taken as measures of HSR and complement activation, respectively, showed a concordant rise of the two variables within 3 min and a decline within 15 min, suggesting a causal relationship between complement activation and pulmonary hypertension. We also observed a rapid decline of anti-PEG IgM in the blood within minutes, increased binding of PEGylated liposomes to IgM⁺ B cells in the spleen of immunized animals compared to control, and increased C3 conversion by PEGylated liposomes in the serum of immunized pigs. These observations taken together suggest rapid binding of anti-PEG IgM to PEGylated liposomes, leading to complement activation via the classical pathway, entailing anaphylactoid shock and accelerated blood clearance of liposome–IgM complexes. These data suggest that complement activation plays a causal role in severe HSRs to PEGylated nanomedicines and that pigs can be used as a hazard identification model to assess the risk of HSRs in preclinical safety studies.

The present study shows the advantages of liposome-based nano-drugs as a novel strategy of delivering active pharmaceutical ingredients for treatment of neurodegenerative diseases that involve neuroinflammation. We used the most common animal model for multiple sclerosis (MS), mice experimental autoimmune encephalomyelitis (EAE). The main challenges to overcome are the drugs’ unfavorable pharmacokinetics and biodistribution, which result in inadequate therapeutic efficacy and in drug toxicity (due to high and repeated dosage). We designed two different liposomal nano-drugs, i.e., nano sterically stabilized liposomes (NSSL), remote loaded with: (a) a “water-soluble” amphipathic weak acid glucocorticosteroid prodrug, methylprednisolone hemisuccinate (MPS) or (b) the amphipathic weak base nitroxide, Tempamine (TMN). For the NSSL-MPS we also compared the effect of passive targeting alone and of active targeting based on short peptide fragments of ApoE or of β-amyloid. Our results clearly show that for NSSL-MPS, active targeting is not superior to passive targeting. For the NSSL-MPS and the NSSL-TMN it was demonstrated that these nano-drugs ameliorate the clinical signs and the pathology of EAE. We have further investigated the MPS nano-drug’s therapeutic efficacy and its mechanism of action in both the acute and the adoptive transfer EAE models, as well as optimizing the perfomance of the TMN nano-drug. The highly efficacious anti-inflammatory therapeutic feature of these two nano-drugs meets the criteria of disease-modifying drugs and supports further development and evaluation of these nano-drugs as potential therapeutic agents for diseases with an inflammatory component.

Beta-casein (bCN) micelles were developed as a platform for improved oral bioavailability (BA) of poorly water-soluble drugs. Here we demonstrate a proof-of-concept using the NSAID celecoxib (Cx) loaded into bCN micelles (Cx/bCN). In a crossover pharmacokinetic (PK) study in pigs (n=4), dosed intraduodenally with either the commercial Cx formulation Celebra ^® or Cx/bCN, the C _max obtained after administration of Cx/bCN was 2.3-fold higher and the T _max was 1.57-fold faster, leading to a 1.76-fold increase in the BA of Cx, compared to the Celebra ^® formulation. It is suggested that this BA enhancement was caused by improvement of Cx solubility in intestinal fluids by bCN micelles, which maintained their Cx cargo in an amorphous state.

Mupirocin is an antibiotic having a unique mode of action, not shared by any other therapeutically available antibiotic. However, due to its rapid elimination following injection and high protein binding, current therapeutic use is limited to topical administration. Computational methods have identified mupirocin as a good candidate for delivery via long-circulating nano-liposomes. Formulating mupirocin in such liposomes to form Nano-mupirocin protects the drug in the circulation, enabling therapeutic efficacy. This was demonstrated using two different animal models that served as a proof of concept: the mice necrotizing fasciitis and rabbit endocarditis models. In both animal models, mupirocin administered intravenously (IV) lacked therapeutic efficacy, while the Nano-mupirocin administered IV was efficacious. In both mice and rabbits the pharmacokinetic (PK) profile following IV injection of Nano-mupirocin showed significantly greater AUC and elimination half-life of Nano-mupirocin compared to the free drug. In addition, in mice we also demonstrated significant drug distribution into the disease site. These PK profiles may explain Nano-mupirocin’s superior therapeutic efficacy. To the best of our knowledge, this is the first study demonstrating that systemic activity of mupirocin is feasible. Therefore, Nano-mupirocin can be considered a novel and unique parenteral antibiotic candidate drug.