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Intravenous administration of liposomal drugs can entail infusion reactions, also known as hypersensitivity reactions (HSRs), that can be severe and sometimes life-threatening in a small portion of patients. One empirical approach to prevent these reactions consists of lowering the infusion speed and extending the infusion time of the drug. However, different liposomal drugs have different levels of reactogenicity, which means that the optimal protocol for each liposomal drug may differ and should be identified and evaluated to make the treatment as safe and convenient as possible. The goal of the present study was to explore the use of pigs for the above purpose, using PEGylated liposomal prednisolone (PLP) as a model drug. We compared the reactogenicities of bolus versus infusion protocols involving 2-, 3- and 4-step dose escalations for a clinically relevant total dose, also varying the duration of infusions. The strength of HSRs was measured via continuous recording of hemodynamic parameters and blood thromboxane B2 levels. We showed that bolus administration or rapid infusion of PLP caused transient changes in systemic and pulmonary blood pressure and heart rate, most notably pulmonary hypertension with paralleling rises in plasma thromboxane B2. These adverse responses could be significantly reduced or eliminated by slow infusion of PLP, with the 3-h 3-step dose escalation protocol being the least reactogenic. These data suggest that the pig model enables the development of safe infusion protocols for reactogenic nanomedicines. Unlabelled Image [ABSTRACT FROM AUTHOR]

Human application of monoclonal antibodies (mAbs), enzymes, as well as contrast media and many other particulate drugs and agents referred to as "nanomedicines", can initiate pseudoallergic hypersensitivity reactions, also known as infusion reactions. These may in part be mediated by the activation of the complement system, a major humoral defense system of innate immunity. In this review, we provide a brief outline of complement activation-related pseudoallergy (CARPA) in general, and then focus on the reactions caused by mAb therapy. Because the alternative pathway of complement activation may amplify such adverse reactions, we highlight the potential use of complement factor H as an inhibitor of CARPA. [ABSTRACT FROM AUTHOR]

The unique magnetic properties of superparamagnetic iron oxide nanoparticles (SPIONs) have led to their increasing use in drug delivery and imaging applications. Some polymer-coated SPIONs, however, share with many other nanoparticles the potential of causing hypersensitivity reactions (HSRs) known as complement (C) activation-related pseudoallergy (CARPA). In order to explore the roles of iron core composition and particle surface coating in SPION-induced CARPA, we measured C activation by 6 different SPIONs in a human serum that is known to react to nanoparticles (NPs) with strong C activation. Remarkably, only the carboxymethyldextran-coated (ferucarbotran, Resosvist®) and dextran-coated (ferumoxtran-10, Sinerem®) SPIONs caused significant C activation, while the citric acid, phosphatidylcholine, starch and chitosan-coated SPIONs had no such effect. Focusing on Resovist and Sinerem, we found Sinerem to be a stronger activator of C than Resovist, although the individual variation in 15 different human sera was substantial. Further analysis of C activation by Sinerem indicated biphasic dose dependence and significant production of C split product Bb but not C4d, attesting to alternative pathway C activation only at low doses. Consistent with the strong C activation by Sinerem and previous reports of HSRs in man, injection of Sinerem in a pig led to dose-dependent CARPA, while Resovist was reaction-free. Using nanoparticle tracking analysis, it was further determined that Sinerem, more than Resovist, displayed multimodal size distribution and significant fraction of aggregates – factors which are known to promote C activation and CARPA. Taken together, our findings offer physicochemical insight into how key compositional factors and nanoparticle size distribution affect SPION-induced CARPA, a knowledge that could lead to the development of SPIONs with improved safety profiles. [ABSTRACT FROM AUTHOR]

Complement activation-related pseudoallergy (CARPA) is a hypersensitivity reaction occurring upon intravenous administration of numerous liposomal therapeutics, other nonbiological complex drugs and biologicals. It has a complex molecular and cellular mechanism that involves the production, actions and interactions of numerous vasoactive mediators in blood, including thromboxane A2 (TXA2). This short review focuses on the latter eicosanoid: its role in CARPA, effects underlying some of the symptoms and experimental evidence for its ratelimiting role in pulmonary hypertension in pigs. Animal experiments and recent clinical observations suggest that the cyclooxygenase blocker indomethacin may represent an effective new approach to prevent liposome-induced CARPA, lending clinical relevance to better understand the involvement of TXA2 and other eicosanoids in this adverse immune effect. [ABSTRACT FROM AUTHOR]