Pharmacokinetics of Orally Applied Cannabinoids and Medical Marijuana Extracts in Mouse Nervous Tissue and Plasma: Relevance for Pain Treatment.

Cannabis sativa plants contain a multitude of bioactive substances, which show broad variability between different plant strains. Of the more than a hundred naturally occurring phytocannabinoids, Δ9-Tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD) have been the most extensively studied, but whether and how the lesser investigated compounds in plant extracts affect bioavailability or biological effects of Δ9-THC or CBD is not known. We therefore performed a first pilot study to assess THC concentrations in plasma, spinal cord and brain after oral administration of THC compared to medical marijuana extracts rich in THC or depleted of THC. Δ9-THC levels were higher in mice receiving the THC-rich extract. Surprisingly, only orally applied CBD but not THC alleviated mechanical hypersensitivity in the mouse spared nerve injury model, favoring CBD as an analgesic compound for which fewer unwanted psychoactive effects are to be expected.

Systemic inflammatory markers in patients with polyneuropathies.

Introduction: In patients with peripheral neuropathies (PNP), neuropathic pain is present in 50% of the cases, independent of the etiology. The pathophysiology of pain is poorly understood, and inflammatory processes have been found to be involved in neuro-degeneration, -regeneration and pain. While previous studies have found a local upregulation of inflammatory mediators in patients with PNP, there is a high variability described in the cytokines present systemically in sera and cerebrospinal fluid (CSF). We hypothesized that the development of PNP and neuropathic pain is associated with enhanced systemic inflammation. Methods: To test our hypothesis, we performed a comprehensive analysis of the protein, lipid and gene expression of different pro- and anti-inflammatory markers in blood and CSF from patients with PNP and controls. Results: While we found differences between PNP and controls in specific cytokines or lipids, such as CCL2 or oleoylcarnitine, PNP patients and controls did not present major differences in systemic inflammatory markers in general. IL-10 and CCL2 levels were related to measures of axonal damage and neuropathic pain. Lastly, we describe a strong interaction between inflammation and neurodegeneration at the nerve roots in a specific subgroup of PNP patients with blood-CSF barrier dysfunction. Conclusion: In patients with PNP systemic inflammatory, markers in blood or CSF do not differ from controls in general, but specific cytokines or lipids do. Our findings further highlight the importance of CSF analysis in patients with peripheral neuropathies.

Functional hydrophobin-coating of thermally hydrocarbonized porous silicon microparticles.

Porous silicon (PSi) particles have been widely used in modulating the dissolution rate of various types of drugs loaded within its mesopores. This material can be surface treated in order to vary its hydrophobicity and several other properties, such as drug loading degree and release rate. Hydrophobins are a family of self-assembling proteins of fungal origin which have the ability to form layers on hydrophobic materials. This type of protein layer can modify the characteristics and control the binding properties of the surface on which it assembles. In this study, we have developed a procedure to coat thermally hydrocarbonized-PSi microparticles with hydrophobin II (HFBII) in order to modify the particles' hydrophobicity and to improve their biocompatibility, while maintaining intact the advantageous drug releasing properties of the PSi. The HFBII content adsorbed onto the particles was successfully quantified by a protein assay. Drug dissolution and permeation across Caco-2 cell monolayers were also conducted, together with viability studies in AGS, Caco-2 and HT-29 cells. The characterization and coating stability assessment showed that the HFBII-coating desorbs partially from the particles' surface as the pH increases. The HFBII coating also improved the biocompatibility of the particles without compromising the enhanced drug permeation or release.