Unlocking Nanocarriers for the Programmed Release of Antimalarial Drugs

Efficient Treatment of Experimental Cerebral Malaria by an Artemisone-SMEDDS System: Impact of Application Route and Dosing Frequency

Artemisone (ART) has been successfully tested in vitro and in animal models against several diseases. However, its poor aqueous solubility and limited chemical stability are serious challenges. We developed a self-microemulsifying drug delivery system (SMEDDS) that overcomes these limitations. Here, we demonstrate the efficacy of this formulation against experimental cerebral malaria in mice and the impact of its administration using different routes (gavage, intranasal delivery, and parenteral injections) and frequency on the efficacy of the treatment. The minimal effective daily oral dose was 20 mg/kg. We found that splitting a dose of 20 mg/kg ART given every 24 h, by administering two doses of 10 mg/kg each every 12 h, was highly effective and gave far superior results compared to 20 mg/kg once daily. We obtained the best results with nasal treatment; oral treatment was ranked second, and the least effective route of administration was intraperitoneal injection. A complete cure of experimental cerebral malaria could be achieved through choosing the optimal route of application, dose, and dosing interval. Altogether, the developed formulation combines easy manufacturing with high stability and could be a successful and very versatile carrier for the delivery of ART in the treatment of human severe malaria.

Noninvasive characterization (EPR, μCT, NMR) of 3D PLA electrospun fiber sponges for controlled drug delivery

Highly porous 3D-scaffolds, made from cut, electrospun PLA fibers, are relatively new and promising systems for controlled drug-delivery applications. Because knowledge concerning fundamental processes of drug delivery from those scaffolds is limited, we noninvasively characterized drug-loading and drug-release mechanisms of these polymer-fiber sponges (PFS). We screened simplified PFS-implantation scenarios with EPR and μCT to quantify and 3D-visualize the absorption of model-biofluids and an oil, a possible drug-loading liquid. Saturation of PFS (6 × 8 mm, h x d) is governed by the high hydrophobicity of the material and air-entrapment. It required up to 45 weeks for phosphate-buffered saline and 11 weeks for a more physiological, surface-active protein-solution, indicating the slow fluid-uptake of PFS as an effective mechanism to substantially prolong the release of a drug incorporated within the scaffold. Medium-chain triglycerides, as a good wetting liquid, saturated PFS within seconds, suggesting PFS potential to serve as carrier-vessels for immobilizing hydrophobic drug-solutions to define a liquid's 3D-interface. Oil-retention under mechanical stress was therefore investigated. ¹H NMR permitted insights into PFS-oil interaction, confirming surface-relaxation and restricted diffusion; both did not influence drug release from oil-loaded PFS. Results facilitate better understanding of PFS and their potential use in drug delivery.

Electrospun Nimodipine-loaded fibers for nerve regeneration: Development and in vitro performance

Nimodipine is a 1,4-Dihydropyridine type calcium antagonist routinely used to control blood pressure and reduce the risk of secondary ischemia after aneurismal subarachnoid hemorrhage. Additionally, Nimodipine has unique neuroprotective properties. With respect to brain related applications, the full potential of the desired local effect can often not be realized after systemic administration due to systemic side effects. Therefore, it was our aim to develop a biodegradable drug delivery system for the local controlled release of the drug inside the brain. As a suitable and biodegradable system we successfully electrospun PLGA fibers containing 1 and 10% drug. The results of DSC and X-Ray diffractometry measurements indicate that Nimodipine was incorporated in the polymer matrix in the amorphous state. No drug recrystallization was detected for up to 6 months. Electron-beam sterilization was tried but reduced the drug content of the fiber mats considerably. A sustained drug release over 4-8 days was observed, highly depended on release conditions. The Nimodipine fiber mats exhibited no cell toxicity. In contrast, the electrospun fibers were able to significantly reduce cell death in in vitro cell models of oxidative, osmotic and heat-induced cell stress in Schwann cells, neuronal cells as well as immortalized and primary astrocytes. Therefore, electrospun Nimodipine loaded PLGA fibers represent a promising drug delivery system to realize the druǵs benefits for its intracranial use.

Exploration of Macroporous Polymeric Sponges As Drug Carriers

Achieving high drug loading capacity and controlling drug delivery are two main challenges related to drug carriers. In this study, polymeric macroporous sponges with very high pore volume and large porosity are introduced as a new-type of drug carrier. Due to the high pore volume (285 and 166 cm³/g for the sponges with densities of 3.5 and 6.0 mg/cm³, respectively), the sponges exhibit very high drug loading capacities with average values of 1870 ± 114 and 2697 ± 73 mg/g in the present study, which is much higher than the meso and microporous drug carriers (<1500 mg/g). In order to control the release profiles, an additional poly(p-xylylene) (PPX) coating was deposited by chemical vapor deposition on the drug loaded sponge. Consequently, Artemisone (ART) release in the aqueous medium could be retarded, depending on the density of the sponge and the thickness of the coating. In future, the new 3D polymeric sponges would be highly beneficial as drug carriers for the programmed release of drugs for treatment of chronic diseases.