Novel Topical Anandamide Formulation for Alleviating Peripheral Neuropathic Pain

FAAH Modulators from Natural Sources: A Collection of New Potential Drugs

The endocannabinoid system (ECS) plays a crucial role in maintaining homeostasis by regulating immune response, energy metabolism, cognitive functions, and neuronal activity. It consists of endocannabinoids (eCBs), cannabinoid receptors (CBRs), and enzymes involved in eCB biosynthesis and degradation. Increasing evidence highlights the involvement of the ECS under several pathological conditions, making it a promising therapeutic target. Recent research efforts have focused on modulating endogenous eCB levels, particularly through the inhibition of fatty acid amide hydrolase (FAAH), the main catabolic enzyme of the major eCB anandamide. Natural substances, including plant extracts and purified compounds, can inhibit FAAH and represent a promising area of pharmacological research. Natural FAAH inhibitors are particularly attractive due to their potentially lower toxicity compared to synthetic compounds, making them safer candidates for therapeutic applications. Phytocannabinoids, flavonoids, and flavolignans have been shown to efficiently inhibit FAAH. The structural diversity and bioactivity of these natural substances provide a valuable alternative to synthetic inhibitors, and may open new avenues for developing innovative pharmacological tools.

Capsaicin nanocrystals burdened topical polymeric gel: An encouraging tactic for alleviation of paclitaxel-induced peripheral neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is triggered by clinically recommended chemotherapeutics. Topical capsaicin (CAP) is a US-FDA-approved therapeutic entity for the mitigation of CIPN. Besides good skin permeation efficiency, CAP concentration in a topical dermal dosage form must be controlled due to its dose-dependent therapeutic and adverse effects. Therefore, in the present investigation, capsaicin nanocrystals (CAP-NCs) were scaled up using the nanoprecipitation technique. CAP-NCs exhibited 145.4 ± 0.90 nm particle size, 0.254 ± 0.005 polydispersity index (PDI), -17.2 ± 0.80 mV surface charge (ζ), and markedly higher cumulative percentage drug release (85.68 ± 0.89 %) compared to pure CAP (12.56 ± 0.57 %) in 12 h. Later, capsaicin nanocrystals burdened polymeric gel (CAP-NCs-Gel) was characterized using analytical and spectral techniques. Furthermore, CAP-NCs-Gel depicted remarkable textural properties, and desirable viscosity along with ∼2.23-fold enhancement in permeability, ∼1.61-fold augmentation of CAP steady-state flux, and permeability coefficient. Additionally, the in vivo therapeutic efficacy assessment of CAP-NCs-Gel in the paclitaxel-induced peripheral neuropathy (PIPN) demonstrated remarkable improvements in mechanical hyperalgesia, heat hyperalgesia, cold allodynia, and locomotor behavior. Capsaicin nanocrystals burdened polymeric gel once-a-day (CAP-NCs-Gel-OD) and twice-a-day (CAP-NCs-Gel-TD) applications outstandingly diminished the levels of TNF-α (P < 0.0001) and IL-6 (P < 0.01) in the sciatic nerve homogenate in contrast to the positive control group and insignificant difference (P > 0.05) was noticed compared to the normal control group. Correspondingly, significant modulation of oxidative stress biomarkers, and noticeable regeneration of nerve fibers, a typical arrangement of the axon, with preserved intact myelin sheath integrity were professed in sciatic nerve; aimed at diminishing neuroinflammation, oxidative stress, and mitigating nerve damage in PIPN. In conclusion, CAP-NCs-Gel is a top-notch nanotherapeutic for translating into a clinically viable dosage form for treating CIPN.

Bioelectronic sensing platform emulating the human endocannabinoid system for assessing and modulating of cannabinoid activity

Cannabinoids are involved in physiological and neuromodulatory processes through their interactions with the human cannabinoid receptor-based endocannabinoid system. Their association with neurodegenerative diseases and brain reward pathways underscores the importance of evaluating and modulating cannabinoid activity for both understanding physiological mechanisms and developing therapeutic drugs. The use of agonists and antagonists could be strategic approaches for modulation. In this study, we introduce a bioelectronic sensor designed to monitor cannabinoid binding to receptors and assess their agonistic and antagonistic properties. We produced human cannabinoid receptor 1 (hCB1R) via an Escherichia coli expression system and incorporated it into nanodiscs (NDs). These hCB1R-NDs were then immobilized on a single-walled carbon nanotube field-effect transistor (swCNT-FET) to construct a bioelectronic sensing platform. This novel system can sensitively detect the cannabinoid ligand anandamide (AEA) at concentrations as low as 1 fM, demonstrating high selectivity and real-time response. It also successfully identified the hCB1R agonist Δ9-tetrahydrocannabinol and observed that the hCB1R antagonist rimonabant diminished the sensor signal upon AEA binding, indicating the antagonism-based modulation of ligand interaction. Consequently, our bioelectronic sensing platform holds potential for ligand detection and analysis of agonism and antagonism.

Anandamide-Mediated Modulation of Nociceptive Transmission at the Spinal Cord Level

Three decades ago, the first endocannabinoid, anandamide (AEA), was identified, and its analgesic effect was recognized in humans and preclinical models. However, clinical trial failures pointed out the complexity of the AEA-induced analgesia. The first synapses in the superficial laminae of the spinal cord dorsal horn represent an important modulatory site in nociceptive transmission and subsequent pain perception. The glutamatergic synaptic transmission at these synapses is strongly modulated by two primary AEA-activated receptors, cannabinoid receptor 1 (CB1) and transient receptor potential vanilloid 1 (TRPV1), both highly expressed on the presynaptic side formed by the endings of primary nociceptive neurons. Activation of these receptors can have predominantly inhibitory (CB1) and excitatory (TRPV1) effects that are further modulated under pathological conditions. In addition, dual AEA-mediated signaling and action may occur in primary sensory neurons and dorsal horn synapses. AEA application causes balanced inhibition and excitation of primary afferent synaptic input on superficial dorsal horn neurons in normal conditions, whereas peripheral inflammation promotes AEA-mediated inhibition. This review focuses mainly on the modulation of synaptic transmission at the spinal cord level and signaling in primary nociceptive neurons by AEA via CB1 and TRPV1 receptors. Furthermore, the spinal analgesic effect in preclinical studies and clinical aspects of AEA-mediated analgesia are considered.

Endocannabinoid Hydrolase Inhibitors: Potential Novel Anxiolytic Drugs

Over the past decade, the idea of targeting the endocannabinoid system to treat anxiety disorders has received increasing attention. Previous studies focused more on developing cannabinoid receptor agonists or supplementing exogenous cannabinoids, which are prone to various adverse effects due to their strong pharmacological activity and poor receptor selectivity, limiting their application in clinical research. Endocannabinoid hydrolase inhibitors are considered to be the most promising development strategies for the treatment of anxiety disorders. More recent efforts have emphasized that inhibition of two major endogenous cannabinoid hydrolases, monoacylglycerol lipase (MAGL) and fatty acid amide hydrolase (FAAH), indirectly activates cannabinoid receptors by increasing endogenous cannabinoid levels in the synaptic gap, circumventing receptor desensitization resulting from direct enhancement of endogenous cannabinoid signaling. In this review, we comprehensively summarize the anxiolytic effects of MAGL and FAAH inhibitors and their potential pharmacological mechanisms, highlight reported novel inhibitors or natural products, and provide an outlook on future directions in this field.

Mathematical modeling of transdermal delivery of topical drug formulations in a dynamic microfluidic diffusion chamber in health and disease

Mathematical models of epidermal and dermal transport are essential for optimization and development of products for percutaneous delivery both for local and systemic indication and for evaluation of dermal exposure to chemicals for assessing their toxicity. These models often help directly by providing information on the rate of drug penetration through the skin and thus on the dermal or systemic concentration of drugs which is the base of their pharmacological effect. The simulations are also helpful in analyzing experimental data, reducing the number of experiments and translating the in vitro investigations to an in-vivo setting. In this study skin penetration of topically administered caffeine cream was investigated in a skin-on-a-chip microfluidic diffusion chamber at room temperature and at 32°C. Also the transdermal penetration of caffeine in healthy and diseased conditions was compared in mouse skins from intact, psoriatic and allergic animals. In the last experimental setup dexamethasone, indomethacin, piroxicam and diclofenac were examined as a cream formulation for absorption across the dermal barrier. All the measured data were used for making mathematical simulation in a three-compartmental model. The calculated and measured results showed a good match, which findings indicate that our mathematical model might be applied for prediction of drug delivery through the skin under different circumstances and for various drugs in the novel, miniaturized diffusion chamber.