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Rafael Guimarães Dos Santos

13 papers in the library · 231 citations · publishing 0-2026

Papers

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Safety and tolerance of oral ketamine: A systematic review.

Psychiatry and Clinical Neurosciences May 30, 2026 Nathalia Novaretti, Rebeca Mendes P Pessoa, Jaime Eduardo Cecilio Hallak et al.

Oral ketamine has gained increasing interest beyond anesthesia, particularly for treatment-resistant depression, chronic pain, and pediatric procedural sedation. Despite expanding off-label use, there is no standardized pharmaceutical formulation, and long-term safety remains uncertain. A synthesis of evidence on safety and tolerability of the oral route is therefore needed to inform clinical...

Ayahuasca and Public Health III: Health Status of a Sample of Ayahuasca Ceremony Attenders in Portugal.

Journal of Psychoactive Drugs March 19, 2026 Pedro J. Teixeira, Jorge Encantado, Helena D Amaro et al.

Ayahuasca, a traditional Amazonian psychoactive brew, has gained increasing attention for its potential health benefits; however, no previous research has investigated its use in Portugal. This study aims to evaluate the health status, lifestyle behaviors, and psychosocial well-being of Portuguese ayahuasca users, comparing their self-reported health indicators with population norms. A...

Long-term ayahuasca use is associated with preserved global cognitive function and improved memory: a cross-sectional study with ritual users.

European Archives of Psychiatry and Clinical Neuroscience March 1, 2025 Arilton Martins Fonseca, Rafael Guimarães Dos Santos, Lívia Soman de Medeiros et al. 10 citations

Although several studies have been conducted to elucidate the relationship between psychedelic consumption and cognition, few have focused on understanding the long-term use influence of these substances on these variables, especially in ritualistic contexts. To verify the influence of ritualistic ayahuasca consumption on the cognition of experienced ayahuasca religious users (> 20 years) and...

Ayahuasca: pharmacology, safety, and therapeutic effects.

CNS Spectrums November 20, 2024 Rafael Guimarães Dos Santos, Jaime Eduardo Cecilio Hallak 13 citations

Ayahuasca is a botanical hallucinogen traditionally used for therapeutic and ritual purposes by indigenous groups from Northwestern Amazonian countries such as Brazil, Peru, Colombia, and Ecuador. Ayahuasca is made by the decoction of two plants, which are rich in the 5-HT1A/2A partial agonist dimethyltryptamine or DMT (from the leaves of the Psychotria viridis bush) and β-carbolines such as...

Ketamine-induced altered states of consciousness: a systematic review of implications for therapeutic outcomes in psychiatric practices.

European Archives of Psychiatry and Clinical Neuroscience October 28, 2024 Kaike Thiê da Costa Gonçalves, Vagner Deuel O de Tavares, Maria Luiza de Morais Barros et al. 5 citations

This systematic review aims to elucidate the nexus between ketamine's psychoactive properties and its efficacy in treating a broad spectrum of psychiatric disorders. We searched three databases and used citation tracking to include 29 studies. Predominantly, mood disorders, including bipolar disorder (BD) and major depressive disorder (MDD) (MDD + BD: + n = 25 studies), a large part of them...

Solvent-free parallel artificial liquid membrane extraction for drugs of abuse in plasma samples using LC-MS/MS.

Analytica Chimica Acta May 1, 2024 André Luis Fabris, Stig Pedersen-Bjergaard, Elisabeth Leere Øiestad et al. 9 citations

Parallel artificial liquid membrane extraction (PALME) is a 96-well plate setup variant of liquid-phase microextraction. Basic or acidic analytes are extracted in neutral form from the sample, through a supported liquid membrane (SLM), and into aqueous acceptor. PALME is already considered a green extraction technique, but in the current conceptual work, we sought to make it even greener by...

Santo Daime in the context of the new religious consciousness

April 8, 2016 Beatriz Caiuby Labate, Rafael Guimarães Dos Santos, Brian T Anderson et al. 2 citations

This chapter presents a series of reflections on the therapeutic potential of the ritual use of ayahuasca in the treatment and handling of substance dependence problems. It reviews anthropological and psychiatric data on the ritual use of ayahuasca for 'healing' dependence in psychotherapeutic centers as well as in ayahuasca religions. The chapter discusses methodological, ethical and political...

Immunological Effects of Ayahuasca in Humans

Journal of Psychoactive Drugs October 20, 2014 Rafael Guimarães Dos Santos 19 citations

Ayahuasca is a botanical hallucinogen traditionally used by indigenous groups of the northwest Amazon. In the last decade, the use of ayahuasca has spread from Brazil, Colombia, Ecuador, and Peru to the U.S., Europe, Asia, and Africa. Despite acute and long-term evidence of good tolerability and safety for ayahuasca administered in the laboratory or ritually consumed in religious contexts,...

A Critical Evaluation of Reports Associating Ayahuasca with Life-Threatening Adverse Reactions

Journal of Psychoactive Drugs April 1, 2013 Rafael Guimarães Dos Santos 47 citations

Ayahuasca is a botanical hallucinogenic preparation traditionally consumed by Northwestern Amazonian indigenous groups. Scientific evidence suggests good tolerability after acute administration of ayahuasca and also after years or even decades of its ritual consumption. Nevertheless, some scientific and media reports associate ayahuasca or some of its alkaloids with severe intoxications. The...

Safety and Side Effects of Ayahuasca in Humans—An Overview Focusing on Developmental Toxicology

Journal of Psychoactive Drugs 2013 Rafael Guimarães Dos Santos 87 citations

Despite being relatively well studied from a botanical, chemical, and (acute) pharmacological perspective, little is known about the possible toxic effects of ayahuasca (an hallucinogenic brew used for magico-ritual purposes) in pregnant women and in their children, and the potential toxicity of long-term ayahuasca consumption. It is the main objective of the present text to do an overview of...

Acute Psychological Adverse Reactions in First-Time Ritual Ayahuasca Users: A Prospective Case Series.

Journal of Clinical Psychopharmacology María Gómez-sousa, Daniel Jiménez‐garrido, Genís Ona et al. 24 citations

In recent decades, ritualistic use of ayahuasca has spread throughout the world. Retrospective studies have suggested a good psychological safety profile, but prospective studies involving ceremony ayahuasca-naive participants are lacking. We conducted the study using a subsample from a previous study, for which first-time ceremony ayahuasca participants were recruited. The subsample consisted...

Effects of a Single Dose of Ayahuasca in College Students With Harmful Alcohol Use: A Single-blind, Feasibility, Proof-of-Concept Trial.

Journal of Clinical Psychopharmacology Lucas Silva Rodrigues, José Augusto Silva Reis, Giordano Novak Rossi et al. 8 citations

Ayahuasca is a South American plant hallucinogen rich in the psychedelic N,N-dimethyltryptamine and β-carbolines (mainly harmine). Preclinical and observational studies suggest that ayahuasca exerts beneficial effects in substance use disorders, but these potentials were never assessed in a clinical trial. Single-center, single-blind, feasibility, proof-of-concept study, assessing the effects...