Ethnopharmacological relevance: Theriac is considered the most popular cure-all multi-ingredient medicine and has been used for more than two millennia. It has also been used as one of the most important anti-epidemic drugs up to the 19th c., treated as an emergency medicine in case of e.g. bubonic plague.
Aim of the study: Until now, no reliable information regarding the pharmacological effect of the treacle was available, including its possible toxic or narcotic properties. In order to change the state of knowledge in this matter we have selected the Theriac recipe that had been actually used for producing the treacle in 1630, which was confirmed by the official municipal documents of the time.
Methods: The recipe was written in Latin, with the use of pre-Linnean nomenclature and then apothecary common names, which required translation into the modern scientific language in order to get reliable pharmacological conclusions. The information from historical sources has been compiled with the pharmacological data concerning the most potent compounds, which for the first time made it possible to calculate the amounts of active compounds in the doses taken by then patients.
Results: Only two species included in Theriac can be harmful in humans: poppy and sea squill, but in both cases the calculated quantity of morphine and cardiac glycosides, respectively, were below toxic level. There are no indications, both from the historical and pharmacological point of view, for Theriac being toxic or narcotic in patients, when used as prescribed.
Conclusions: As for now, the most probable is that the treacle owed its postulated efficacy in the main indications to the placebo effect. Still, the results should be further confirmed by reconstructing the actual Theriac and subjecting it to modern tests and analyses.
Keywords: Anti-epidemic drug; Herbal drugs; History of medicine; Plague; Theriac; Traditional medicine.
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