## 2 Therapeutic Methodologies
### Pelotherapy
The clay minerals used in pharmaceutical formulations are smectite [(Na,Ca) 0.33(Al,Mg)2 (Si4O10)(OH)2 -nH2O], polygorskite [(Mg,Al)2 Si4O210(OH)4H2O], kaolinite [Al2 Si2O5(OH)4] and talc [Mg3 Si4O10(OH)2] [15]. The clay-drug interactions presented in most studies refer to the application of natural clays or synthetic and semi-synthetic derivatives to perform specific functions in new drug delivery systems, aimed to increase the stability of the drug and change the transmission pattern using clay minerals [14]. The use of kaolinite, talc and smectite in dermatological protectors is based on its absorbing capacity of skin's secretions, adhering to the skin and forming a film that mechanically protects it against external physical and chemical agents, resulting in a refreshing action by creating a large surface for its evaporation, and promoting an antiseptic action as it creates a low humidity surface for the development of bacteria. Palygorskite is not used in dermatological protectors due to some doubts regarding the carcinogenic effect if inhaled. In cosmetics, clays are recommended for inflammatory processes (e.g., boils, acne, ulcers) used in the form of creams, powders, emulsions, with talc and palygorskite being recommended only for liquid preparations [15]. Peloid, from the Greek pelos, was proposed by [PERSON], in 1933 and was definitively adopted by the International Society of Medical Hydrology in 1949 at the IV International Scientific Conference of Dax [7]. The most recent concept of peloid is defined by [PERSON] et al. (2013), and is designated as products formed by the spontaneous or artificial blending of natural mineral water, seawater or salt lake, with a solid component (organic or inorganic), resulting from geological or biological processes (or both) which, in the natural state or after preparation, are used topically for therapeutic purposes in the form of poultices or baths. In addition, the use of organic compounds has been shown to be associated with the biological metabolic activity [6]. The classification of therapeutic clays is usually made by the characteristics which distinguish them, namely by their composition, preparation, and use. Most studies associated with the use and effect of peloids are based on three criteria [16], (i) technical (preparation practices), (ii) physicochemical (intrinsic properties or composition) and (iii) clinical-biological (preponderant biological and therapeutic action). The International Society of Medical Hydrology has characterized some peloids, according to their solid component (inorganic or mineral), organic components and depending on the chemical nature of the liquid component [2]. In the formulation of thermal muds, the maturation time of the mixture of the liquid and solid phases, sun exposure, agitation of the mixture, temperature and the properties of its components are decisive in the characterization of the peloid [12]. Unlike pharmaceutical and cosmetic clays, peloids are not subject to any prior quality control or subject to any specific European regulation, as is the case of mineral waters for human consumption (Council Directive 98/83/EC of 3 November 1998). Regulation (EC) No. 1223/2009 of the European Parliament and of the Council of 30 November 2009, concerning cosmetic products, states that \"this regulation relates only to cosmetic products and not to medicinal products, medical devices or biocidal products\", considering that the \"delimitation follows in particular from the detailed definition of cosmetic products, which refers both to their areas of application and to the purposes of their use\". On the other hand, it states that to assess \"whether a product is a cosmetic product has to be made on the basis of case-by-case assessment, taking into account all characteristics of the product\". Directive 2001/83/EC of the European Parliament and of the Council, of 6 November 2001, defines \"Medicinal product: Any substance or combination of substances presented for treating or preventing disease in human beings.