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University of California, Davis, researchers have developed a new, neuroplasticity-promoting drug closely related to LSD that harnesses the psychedelic’s therapeutic power with reduced hallucinogenic potential.

The research, published in PNAS, highlights the new drug’s potential as a treatment option for conditions like schizophrenia, where psychedelics are not prescribed for safety reasons. The compound also may be useful for treating other neuropsychiatric and neurodegenerative diseases characterised by synaptic loss and brain atrophy.

To design the drug, dubbed JRT, researchers flipped the position of just two atoms in LSD’s molecular structure. The chemical flip reduced JRT’s hallucinogenic potential while maintaining its neurotherapeutic properties, including its ability to spur neuronal growth and repair damaged neuronal connections that are often observed in the brains of those with neuropsychiatric and neurodegenerative diseases.

“Basically, what we did here is a tire rotation,” said corresponding author David E. Olson, director of the Institute for Psychedelics and Neurotherapeutics and a professor of chemistry, and biochemistry and molecular medicine at UC Davis. “By just transposing two atoms in LSD, we significantly improved JRT’s selectivity profile and reduced its hallucinogenic potential.”

JRT exhibited powerful neuroplastic effects and improved measures in mice relevant to the negative and cognitive symptoms of schizophrenia, without exacerbating behaviours and gene expression associated with psychosis.

“No one really wants to give a hallucinogenic molecule like LSD to a patient with schizophrenia,” said Olson, who is also co-founder and chief innovation officer of Delix Therapeutics, a company that aims to bring neuroplastogens to the market. “The development of JRT emphasises that we can use psychedelics like LSD as starting points to make better medicines. We may be able to create medications that can be used in patient populations where psychedelic use is precluded.”

Testing JRT’s potential

Olson said that it took his team nearly five years to complete the 12-step synthesis process to produce JRT. The molecule was named after Jeremy R. Tuck, a former graduate student in Olson’s laboratory, who was the first to synthesise it and is a co-first author of the study along with Lee E. Dunlap, another former graduate student in Olson’s laboratory.

Following JRT’s successful synthesis, the researchers conducted a battery of cellular and mouse assays that demonstrated the drug’s neuroplastic effects and improved safety profile relative to LSD.

Key findings included:

• JRT and LSD have the exact same molecular weight and overall shape, but distinct pharmacological properties.
• JRT is very potent and highly selective for binding to serotonin receptors, specifically 5-HT2A receptors, the activation of which are key to promoting cortical neuron growth.
• JRT promoted neuroplasticity, or growth between cellular connections in the brain, leading to a 46% increase in dendritic spine density and an 18% increase in synapse density in the prefrontal cortex.
• JRT did not produce hallucinogenic-like behaviors that are typically seen when mice are dosed with LSD.
• JRT did not promote gene expression associated with schizophrenia. Such gene expression is typically amplified with LSD use.
• JRT produced robust anti-depressant effects, with it being around 100-fold more potent than ketamine, the state-of-the-art fast-acting anti-depressant.
• JRT promoted cognitive flexibility, successfully addressing deficits in reversal learning that are associated with schizophrenia.

“JRT has extremely high therapeutic potential. Right now, we are testing it in other disease models, improving its synthesis, and creating new analogues of JRT that might be even better,” Olson said.

A more effective treatment for schizophrenia

Olson emphasised JRT’s potential for treating the negative and cognitive symptoms of schizophrenia, as most current treatments produce limited effects on anhedonia — the inability to feel pleasure — and cognitive function. Clozapine is the one exception, but it has side effects, and is not first-line drug of choice for people with severe schizophrenia.

Olson and his team are currently testing JRT’s potential against other neurodegenerative and neuropsychiatric diseases.

Source: University of California – Davis

Skin pigmentation may act as a “sponge” for some medications ranging from antibiotics to nicotine patches, potentially influencing the speed with which active drugs reach their intended targets, a pair of scientists report in a perspective article published in the journal Human Genomics.

There has been a growing awareness of genetic susceptibility or tolerance to medications. Redheads for example had been shown to need more inhalational anaesthetic than dark-haired individuals. The researchers argue that a sizable proportion of drugs and other compounds can bind to melanin pigments in the skin, leading to differences in how bioavailable and efficacious these drugs and other compounds are in people with varying skin tones.

“Our review paper concludes that melanin, the pigment responsible for skin colour, shows a surprising affinity for certain drug compounds,” said paper coauthor Simon Groen, an assistant professor of evolutionary systems biology at the University of California, Riverside. “Melanin’s implications for drug safety and dosing have been largely overlooked, raising alarming questions about the efficacy of standard dosing since people vary a lot in skin tones.”

According to Groen and coauthor Sophie Zaaijer, a consultant and researcher affiliated with UC Riverside who specialises in diversity, equity, and inclusion (DEI) in preclinical R&D and clinical trials, current FDA guidelines for toxicity testing fail to adequately address the impact of skin pigmentation on drug interactions.

“This oversight is particularly concerning given the push for more diverse clinical trials, as outlined in the agency’s Diversity Action Plan,” Zaaijer said. “But current early-stage drug development practices still primarily focus on drug testing in white populations of Northern European descent.”

In one example, the researchers found evidence of nicotine affinity for skin pigments, potentially affecting smoking habits across people with a variety of skin tones and raising questions about the efficacy of skin-adhered nicotine patches for smoking cessation.

“Are we inadvertently shortchanging smokers with darker skin tones if they turn to these patches in their attempts to quit?” Groen said.

Groen and Zaaijer propose utilising a new workflow involving human 3D skin models with varying pigmentation levels that could offer pharmaceutical companies an efficient method to assess drug binding properties across different skin types.

“Skin pigmentation should be considered as a factor in safety and dosing estimates,” Zaaijer said. “We stand on the brink of a transformative era in the biomedical industry, where embracing inclusivity is not just an option anymore but a necessity.” 

According to the researchers, skin pigmentation is just one example. Genetic variations among minority groups can lead to starkly different drug responses across races and ethnicities, affecting up to 20% of all medications, they said. 

“Yet, our molecular understanding of these differences remains very limited,” Zaaijer said.

For example, a study on acetaminophen – a drug that binds melanin – found no difference in total plasma levels of acetaminophen between individuals of African- and European-American ancestries. Oxidation clearance of acetaminophen did however show ancestry-based differences and was 37% lower in African–versus European-Americans, which could have been partially explained by polymorphisms in CYP2E1.

The researchers point out that a shift towards inclusive drug development is set to take place as instigated by a new law, the Food and Drug Omnibus Reform Act, enacted in 2022, which will mandate considering patient diversity in R&D and clinical trials. 

The researchers hope to activate the pharmaceutical industry and academia to start doing systematic experimental evaluations in preclinical research in relation to skin pigmentation and drug kinetics. They also encourage patients and advocacy groups to start asking about ancestry-related testing and efficacy of drugs.

Source: University of California – Riverside