The most complete pharmacokinetic work to date in defense of pharmacology has been done by Dr. Corbel (Corbel). He demonstrated the critical importance of depth mastery in the implementation of mesotherapy injections. The most important conclusions reached by Dr. Corbel in the field of pharmacokinetics can be summarized as follows: 1. The diffusion and biodistribution of drugs in the body is slower through the subcutaneous route than through the intravenous route. 2. The final distribution of the drug in the human organism is the same regardless of which of these two routes is used. 3.The final distribution through subcutaneous injection is the same, regardless of the site of injection. 4.The rate of drug distribution in the body is inversely proportional to the molecular weight of the injected drug. 5.The initial speed of drug diffusion is faster through superficial subcutaneous injection than deep subcutaneous injection. 6, Procaine intervenes in the biodistribution of the drug by different pathways depending on the physical-chemical characteristics of the injected drug. These above-mentioned findings are self-evident as a guide to practice. Drug selection criteria for the implementation of mesotherapy Although we do not have sufficient information to define precisely which drugs can and cannot be injected, we should ensure that any drug that will be used in mesotherapy meets a set of criteria for its use before using it: The drug used in mesotherapy will be selected according to its more or less indications. The drug must be dissolvable in water, allowing us to make it into an aliquot solution. The drug presented in the form of salt is soluble in water, while the drug presented in the form of base is soluble in oils and fats, exhibiting lipophilic properties. Ideally, when the drug is manufactured, its use for subcutaneous injection is already envisaged, but generally this is rather exceptional. Drugs with vasoconstrictive properties are contraindicated for use in mesotherapy because of the risk of local gangrene due to prolonged local ischemia if these drugs are used. There are drugs such as adrenocorticosteroids that have the potential to cause skin atrophy or even generalized tissue atrophy, so these drugs are also generally contraindicated, except in certain very specific cases (e.g., keloids). Some excipients and preservatives (it is worth noting that polyhydroxy compound excipients should be distinguished from drugs such as blastoestimulina and some AINES) may cause polyhydroxy thrombosis due to excessive density (caused by their long chemical chains), which in turn may lead to tissue necrosis, even more extensive than gangrene caused by the use of drugs with vasoconstrictive properties. more extensive. Therefore, we must always be aware of the mixability of these excipients with other drugs (as vectors). Also, look carefully at the syringe into the light, which should not show anything iridescent. Other excipients (e.g. sulfites, ethane-based alcohols, etc.), may also lead to the production of pathologies caused by the physician’s treatment. Also, it should be envisaged that when two or more drugs are combined, there is a possibility of physical or chemical incompatibility, of antagonistic reactions of different drugs (e.g. between procaine and sulfonamide), and of non-neutralization of pH between several drugs with very high and very low pH [e.g. tilatracol (triiodothyroid acetic acid) procaine]. Different pH values have the potential to give drug solutions an egg-white sheen and may even produce precipitates. However, in principle, the appearance of these phenomena does not affect the effectiveness of the solvent and may even contribute to the formation of mixed salts (during the slow release). Every effort should be made to avoid allergic reactions caused by the drug. Before performing any kind of mesotherapy, the doctor should ask the candidate carefully about it and perform a skin test. We should not rule out the possibility of cross-skin infection from different agents, nor should we rule out the possibility that despite a negative skin test result, there may still be some kind of allergy in the candidate. The injected agent should be able to be absorbed by the tissue in order for it to be effective. In the field of mesotherapy, it is very important to maintain close contact with the pharmacist or pharmacologist so that they can answer our questions. Tip: A skin test, short for skin (or intradermal) sensitivity test, is the most commonly used clinical test for specificity. Certain drugs are prone to allergic reactions during clinical use, such as penicillin, streptomycin, cytochrome C, etc. Common allergic reactions include rash, urticaria, dermatitis, fever, angioneurotic edema, asthma, anaphylaxis, etc., of which anaphylaxis is the most serious and can even lead to death.