Feasibility study of nonclinical safety assessments on homeopathic preparations using the example of protoanemonin in Pulsatilla pratensis L.

Homeopathy is a world-wide available form of complementary therapy, which has a tradition of 200years. Due to the long history of clinical use, i.e. reflected by the first edition of the Homeopathic Pharmacopoeia of the US of 1914, the conduct of toxicological studies is not required if the safety has been otherwise substantiated. The aim of this article is to establish a risk assessment procedure without full toxicological examination, using homeopathic preparations from Pulsatilla pratensis L. as an example. The literature review shows that protoanemonin is the most relevant constituent of these plants regarding potential toxicity. Based on structural alerts protoanemonin is classified as a Cramer class III compound with the threshold of toxicological concern (TTC) of 180µg/day in adults. Neither computer aided toxicology methods (Toxtree and Derek Nexus®) nor a literature search revealed any evidence of genotoxic, carcinogenic or teratogenic potential of protoanemonin. The protoanemonin exposure from a maximum daily dose of a typical homeopathic preparation of P. pratensis L. does not exceed the TTC. The presented method is transparent, reproducible and applicable to other homeopathic substances as a use-case scenario for computational toxicology in order to evaluate an approach for safety assessment of homeopathic medicinal products.

Historical blunders: how toxicology got the dose-response relationship half right.

Substantial evidence indicates that reliable examples of hormetic dose responses in the toxicological literature are common and generalizable across biological model, endpoint measured and chemical class. Further evaluation revealed that the hormetic dose response model is more common than the threshold dose response model in objective, head-to-head comparisons. Nonetheless, the field of toxicology made a profound error by rejecting the use of the hormetic dose response model in its teaching, research, risk assessment and regulatory activities over nearly the past century. This paper argues that the hormetic dose response model (formerly called the Arndt-Schulz Law) was rejected principally because of its close historical association with the medical practice of homeopathy as a result of the prolonged and bitter feud between traditional medicine and homeopathy. Opponents of the concept of hormesis, making use of strong appeals to authority, were successful in their misrepresentation of the scientific foundations of hormesis and in their unfair association of it with segments of the homeopathic movement with extreme and discreditable views. These misrepresentations became established and integrated within the pharmacology and toxicology communities as a result of their origins in and continuities with traditional medicine and subsequently profoundly impacted a broad range of governmental risk assessment activities further consolidating the rejection of hormesis. This error of judgment was reinforced by toxicological hazard assessment methods using only high and few doses that were unable to assess hormetic responses, statistical modeling processes that were constrained to deny the possibility of hormetic dose response relationships and by the modest nature of the hormetic stimulatory response itself, which required more rigorous study designs to evaluate possible hormetic responses.

Paradigm lost, paradigm found: the re-emergence of hormesis as a fundamental dose response model in the toxicological sciences.

This paper provides an assessment of the toxicological basis of the hormetic dose-response relationship including issues relating to its reproducibility, frequency, and generalizability across biological models, endpoints measured and chemical class/physical stressors and implications for risk assessment. The quantitative features of the hormetic dose response are described and placed within toxicological context that considers study design, temporal assessment, mechanism, and experimental model/population heterogeneity. Particular emphasis is placed on an historical evaluation of why the field of toxicology rejected hormesis in favor of dose response models such as the threshold model for assessing non-carcinogens and linear no threshold (LNT) models for assessing carcinogens. The paper argues that such decisions were principally based on complex historical factors that emerged from the intense and protracted conflict between what is now called traditional medicine and homeopathy and the overly dominating influence of regulatory agencies on the toxicological intellectual agenda. Such regulatory agency influence emphasized hazard/risk assessment goals such as the derivation of no observed adverse effect levels (NOAELs) and the lowest observed adverse effect levels (LOAELs) which were derived principally from high dose studies using few doses, a feature which restricted perceptions and distorted judgments of several generations of toxicologists concerning the nature of the dose-response continuum. Such historical and technical blind spots lead the field of toxicology to not only reject an established dose-response model (hormesis), but also the model that was more common and fundamental than those that the field accepted.

Hormesis and homeopathy: bridge over troubled waters.

Homeopathy is an empirical method of treatment. Hormesis, while stemming from within the rationalist tradition, has yet to be explained according to current pharmacological theory. Both share in common sub-threshold doses of toxic substances and an initial semi-toxicological insult followed by a greater compensatory (or healing) response. We question whether the differences between these fields may be amenable to scientific research. We identify five cardinal differences between homeopathy and hormesis: (1) Hormesis is a universal phenomenon, while homeopathy is highly specific; (2) Hormesis uses only measurable quantities of compounds, as opposed to homeopathy, which frequently administers medicines at dilutions far beyond the material range; (3) Preparation of hormetic solutions follows standard laboratory procedure, while homeopathy requires a sequential series of dilutions, each followed by vigorous shaking ('succussion'); (4) The effects of hormesis are moderate and temporary, while homeopathy claims curative and permanent responses and (5) Hormesis is a lab phenomenon observed primarily in healthy organisms, whereas homeopathy is a mode of treatment administered primarily to ailing individuals. We believe that all five of these differences are amenable to scientific investigation, and suggest comparing succussed to non-succussed diluted solutions as an optimal first evaluation. We conclude that while certain differences exist between hormesis and homeopathy, hormesis may in fact be a subset of homeopathy.

Evaluating homeopathic drugs within a biomedical framework.

The concept of hormesis can provide an evaluation framework for the assessment of homeopathic treatment preparations following a post-conditioning hormesis protocol based on the research of van Wijk and colleagues. This proposal would require that doses of administered drug conform to analytical chemistry requirements for quantification. This developmental framework can provide a scientific 'point of contact' between the homeopathic and biomedical communities, which has long been lacking.

Does homeopathy have anything to contribute to hormesis?

Homeopathy is the best known medical analogue of hormesis, others include hormoligosis and paradoxical pharmacology. Homeopathy is based on the concept Similia similibus curentur ('Let like be cured by like'); the exploitation of secondary effects of drugs, the body's reaction rather than the primary pharmacological action. The most controversial aspect of homeopathy is its use of 'ultramolecular' dilutions in which a single molecule of the starting substance is unlikely to be present. Classical pharmacological actions in vivo have been reported with dilutions as high as 10(-22)mol/L, but homeopathic medicines may be far more dilute than this. There is growing biological evidence including independent reproduction that in vivo effects may occur at such dilutions. In a systematic review, 73% of experiments showed an effect with ultramolecular dilutions including 68% of high-quality experiments. Physical and physico-chemical work suggests that homeopathic preparations contain stable ordered supramolecular structures, gas nanobubbles and dissolved silicates may be involved. Homeopathy may contribute to the generalizability and reproducibility of hormesis effects. It also raises the question of the threshold of hormesis effects.

Hormesis and its relationship with homeopathy.

Homeopathy is an ancient and complex therapeutic method that is rediscovering its scientific foundations. Hormesis is a frequently observed phenomenon that has been rigorously reported with precise dose-response curves. The therapeutic method based on the principle of 'like cures like' should not be confused with hormesis, which has several different implications from those of homeopathy. Yet, because both these approaches to nature and medicine are very broad in scope, they do end up having some points of contact. Thus, the well-established and consolidated field of hormesis can help cast light, through its ideas and research methods, on the possible mechanisms of action of remedies in ultra-low doses.

Miasmas, germs, homeopathy and hormesis: commentary on the relationship between homeopathy and hormesis.

Is hormesis related to homeopathy? Despite the superficial similarity of the low dose of the applied stimulus, there are compelling reasons for maintaining hormesis and homeopathy as unrelated. Homeopathy originated in the medical knowledge vacuum of the 19th century, prior to the acceptance of the germ/gene bases of disease. Homeopathy was never grounded on empirical scientific evidence. Hormesis, on the other hand, has always been an empirical science, involving properly controlled experiments. Hormesis is a concept in toxicology that involves biphasic dose responses in biological systems, wherein low doses of stressors can have beneficial effects and higher doses have harmful effects. Hormesis, as it applies to toxicology, is a necessary and useful concept describing adaptive organismic responses to applied stressors. Conversely, homeopathy is a medical doctrine based on the erroneous belief that substances which cause the symptoms of a disorder will cure the disorder when given to patients in small doses. To suggest that homeopathy is a form of post-exposure conditioning hormesis assumes that homeopathic practitioners employed the scientific method with measurable experimental end-points and proper controls, and that their 'provings' had actually determined the correct compound, at the correct dose, required to cure a disorder. Because many homeopathic preparations are diluted to a point where none of the starting solutes would likely remain, the idea of a beneficial or harmful hormetic dose becomes moot. Without supporting scientific evidence for the efficacy or purported mechanisms of homeopathy, the term hormesis should not be linked with it in any way.

Postconditioning hormesis and the homeopathic Similia principle: molecular aspects.

Postexposure conditioning, as a part of hormesis, involves the application of a low dose of stress following exposure to a severe stress condition. Depending on whether the low-dose stress is of the same type of stress or is different from the initial high-dose stress causing the diseased state, postconditioning can be classified as homologous or heterologous, respectively. In clinical homeopathy, the same distinction is found between isopathic and homeopathic application of low-dose substances. Homeopathy is unique for its Similia principle, which implies that substances causing symptoms in healthy biological systems can be used to treat similar symptoms in diseased biological systems. The evaluation of the Similia principle in an experimental set-up requires the analysis of a complex sequence of 'damage-disease-treatment-effect' events. The process of recovery from an insult is then monitored and a possible beneficial effect on this recovery process, upon application of a range of substances in low dose, can subsequently be analyzed using molecular and functional parameters. It is then possible to compare the effect of treatment with the degree of similarity between the diseased state and the effects caused by homologous and/or different heterologous substances. Beneficial effects of postconditioning mild stress conditions have been described in terms of an increase of the synthesis of stress proteins. In this commentary paper, we present additional information on this aspect. The experimental data suggest that the beneficial effect of the low-dose stress condition used as heterologous postconditioning is related to similarity in molecular stress response.

Testing the hormetic nature of homeopathic interventions through stress response pathways.

The scientific foundations of hormesis are now well established and include various biochemical and molecular criteria for testing the hormetic nature of chemicals and other modulators. In order to claim homeopathy as being hormetic, it is essential that, in addition to the hormetic biphasic dose response, homeopathic remedies should fulfill one or more molecular criteria. Since stress response pathways, such as heat shock response, antioxidative response, autophagic response and unfolded protein response, are integral components of the physiological hormesis, it is important that homeopathic drugs be tested for these pathways if these are to be considered as hormetins and to cause hormesis.

Um estudo dos textos clássicos do Ayurveda em perspectiva histórico-antropológica / A study of classical texts of Ayurveda in a historical and anthropological perspective

Nas últimas duas décadas a racionalidade médica ayurvédica tornou-se popular no ocidente e está se expandindo rapidamente. Esta expansão é conseqüência do renascimento do Ayurveda na Índia no século XX. Apesar do crescente interesse neste sistema antigo de medicina pouco se tem explorado, no nosso meio, da sua gênese Histórica e das pesquisas dos textos clássicos, riquíssimos em informações sobre esta antiga medicina e suas ferramentas de diagnóstico e terapêutica prevalentes no subcontinente indiano há milhares de anos. O renascimento do Ayurveda se intensificou após a libertação da Índia da dominação britânica em 1947. Na década de 50 vários esforços foram realizados para promover o ensino e desenvolvimento desta racionalidade médica pelo governo indiano...