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Plant-Derived Compounds as New Therapeutics for Substance Use Disorders
Published in Namrita Lall, Medicinal Plants for Cosmetics, Health and Diseases, 2022
Kevin S. Murnane, Mary Frances Vest
Administration of LSD directly into the hippocampus promotes learning (Romano et al., 2010). Administration of the novel psychedelic TCB-2 enhances the consolidation of object memory (Zhang et al., 2013). Ayahuasca enhances learned responses, as does the administration of TCB-2 into the basolateral amygdala (Clinard et al., 2015; Favaro et al., 2015). Viral-mediated induced re-expression of 5-HT2A receptors in mice genetically devoid of 5-HT2A receptors rescues learning and synaptic plasticity deficits (Barre et al., 2016). Microdosing of LSD has been reported to improve cognition in humans, and psilocybin microdosing improves attention in low-performing rats (Higgins et al., 2021; Hutten et al., 2020). As with cannabinoids, the fact that plant-based psychedelics may directly affect the dopamine reward system may improve cognition and behavioral flexibility and may have potential disease-modifying anti-inflammatory and antioxidant effects suggest that psychedelics may provide compelling medications for SUDs.
Translation of Radiopharmaceuticals
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Pedro Fragoso Costa, Latifa Rbah-Vidal, An Aerts, Fijs W.B. van Leeuwen, Margret Schottelius
Human microdosing studies can be considered for radiolabelled compounds. In this case, very low single doses of the tested compound are administered to very few human subjects (healthy volunteers or patients) to investigate target uptake (e.g. target receptor binding) or tissue distribution and/or to obtain pharmacokinetics parameters (such as volume of distribution, and clearance).
Radiochemistry for Preclinical Imaging Studies
Published in George C. Kagadis, Nancy L. Ford, Dimitrios N. Karnabatidis, George K. Loudos, Handbook of Small Animal Imaging, 2018
The PET method offers accurate tracer quantification with a sensitivity that is two orders of magnitudes higher compared to SPECT (Jones 1996). Arguably, translating small molecule PET radiotracer research into clinical diagnostics appears to be more straightforward compared to SPECT, in particular for small molecules and considering the radioisotopes fluorine-18 or carbon-11 compared to technetium-99m. In an ideal scenario for a targeted small molecule radiotracer, a potent drug molecule can be translated into its radioactively labeled counterpart that features an identical chemical structure. This is an expanding area especially in neurology covering brain receptors, transporters, enzymes, and other targets such as amyloid plaques or neurofibrillar tangles (Heiss and Herholz 2006; Zimmer and Luxen 2012). Figure 16.7 shows a simplified, exemplary scheme that illustrates the relationship between preclinical radiotracer research and drug development. Pharmacophores identified by pharma industry and academia can serve as basis for PET radiolabeling development programs. After a preclinical phase, the new drug candidate is evaluated in a small first-in-man (FiM) clinical trial using PET. Here, the microdosing concept can be applied to streamline extensive toxicological evaluations (Bergstr϶m and Långstr϶m 2005). In addition, a well-characterized PET tracer can serve as gold standard in human studies to evaluate the efficacy of new drugs. Both approaches can therefore help to reduce time and cost in drug development.
Modern approaches for the phenotyping of cytochrome P450 enzymes in children
Published in Expert Review of Clinical Pharmacology, 2020
In children, the administration of low- or microdosed probe drugs rather than therapeutic doses, in order to avoid any toxicity, may be considered for CYP450 phenotyping. Microdosing is generally defined as the administration of a dose substantially reduced (usually at least 100 times) compared to the therapeutic dose [8]. In order to replace the use of therapeutic doses of probe drugs with lower or microdoses, it is essential to first assess the linearity of the pharmacokinetic parameters between the two dosages [8]. For example, van Groen et al. showed recently that an intravenous [14 C]midazolam microdose (37.6 ng kg−1) can be an alternative to midazolam administered at therapeutic doses in children after having demonstrated linearity [9]. It is important to note that formulation of low- or microdosed probe drugs is often not available and may require specific and internal manufacturing or reconditioning unless a liquid formulation is already marketed for instance [8]. In addition, it requires a more sensitive quantification method than probe drugs used at therapeutic doses [8]. Despite these constraints, low-dose or microdosed probe drugs may offer a great opportunity to improve knowledge of CYP450 activity in children after clinical validation. However, even if it is technically feasible, it is still largely unexploited.
Psychedelic Microdosing: Prevalence and Subjective Effects
Published in Journal of Psychoactive Drugs, 2020
Lindsay P. Cameron, Angela Nazarian, David E. Olson
Of the various psychedelic compounds used for microdosing, LSD and psilocybin were the most common (48.58% and 26.18% respectively, NT = 317, Table 3). Individuals who selected “Other” (11.67%, n = 37, NT = 317) reported using marijuana, cocaine, or a combination of psychedelic compounds (i.e., LSD and psilocybin or LSD and ayahuasca). We did not collect information regarding dosing regimen because previous work has demonstrated that users largely estimate the dosage reported (Hutten et al. 2019; Winstock et al. 2018). Additionally, dosage can vary according to factors that cannot be controlled in survey studies, such as the compound used, the purity of the substance used, and the weight or body composition of the individual.
Psychedelic Microdosing: A Subreddit Analysis
Published in Journal of Psychoactive Drugs, 2020
Toby Lea, Nicole Amada, Henrik Jungaberle
In recent years, there has been growing awareness of “microdosing,” referring to people routinely self-administering very low doses of psychedelic drugs such as lysergic acid diethylamide (LSD) and psilocybin to enhance productivity and creativity at work, and improve mental health and wellbeing. This typically involves taking between 5–10% of a standard psychedelic dose on a fixed schedule for a period of time, without the intention of experiencing noticeable drug effects (Fadiman 2011). While there is no consensus about what range of LSD and psilocybin doses constitute microdoses (Kuypers et al. 2019), a randomized controlled trial recently reported subjective effects of LSD at 6.5, 13, or 26 mcg and concluded that 13 mcg would be a potentially safe threshold dose for repeated administration (Bershad et al. 2019).