Infusum

INFUSUM, infusion (ФУII), one of the four forms of aqueous extracts from medicinal plant materials (decoctions, digests, macerates, and infusions). Infusions are prepared by pouring boiling distilled water over the plant substance and immediately immersing the vessel—after tightly closing it with a lid—in a steam bath for 5 minutes, after which the liquid is allowed to cool slowly (for at least 40 minutes). The cooled liquid is filtered through paper or strained through cloth; the residue is slightly squeezed. In urgent cases, it is permitted to let the prescribed substance stand on a steam bath for 10 minutes and to cool the infusion artificially. Infusions contain glycosides and volatile substances (essential oils) of the medicinal material, because the enzymes capable of acting destructively on glycosides are denatured by pouring boiling water over the material, and the preparation of infusions in closed vessels without prolonged boiling preserves the volatile substances in the medicine. - ФУП includes in the group 'infusions' also macerates, calling them 'Infusum frigide paratum' (cold infusion). This form is prepared by letting the substance stand on distilled water at room temperature for 4 hours; only substances rich in mucilage (marshmallow root) stand for 30 minutes. Soluble in cold water components of the material—sugar, mucilage, and proteins—pass into the cold infusion, while starch does not. Cold infusions should not be prescribed from plants containing easily decomposing glycosides. - Digests are an intermediate form between cold and hot infusions: they are prepared by extracting the material with hot water (30-50°), which is still incapable of coagulating proteins or causing the formation of a paste from starch. The aim of digests is a more complete extraction compared with the maceration method. All medicines prepared as infusions and especially macerates or digests are easily subject to fermentation, mold, etc., if antiseptics, for example benzoic acid, are not introduced into their composition. If a doctor does not specify the quantity of material in a prescription, the pharmacy takes one part for every 10 parts of infusion, with the exception of Bulbus Scillae, Herba Adonidis, Radix Colombo, Radix Senegae, Rhizoma Galangae, Rhizoma Valerianae, Rhizoma Zingiberis, Secale cornutum, which are taken in a ratio of 1:30, and strong-acting substances (Digitalis!) 1:400. Salts, extracts, tinctures, and other substances are added to the cooled and filtered infusions. All infusions, except I. Sen-nae compositum (Ph. VII), must be prepared when ordered (ex tempore); ФУП also permits the preparation of stock so-called 'concentrated infusions,' which are diluted with water at the time of dispensing in such a way that they correspond in the content of active principles to a freshly prepared infusion. By a special article (Ph. VII) concentrated infusion of ipecacuanha has been legalized. If a doctor prescribes I. without indicating the method of preparation, it is always (ФУП) necessary to prepare Infusum calide paratum. There are also dry concentrated infusions containing admixtures of substances that facilitate drying (dextrin, milk sugar, gum, etc.), but their use is not permitted in the USSR. The advantages of well-prepared concentrated forms are the standard content of active principles and the simplicity of preparing medicinal forms from them. According to the 1925 International Convention (§ 19), the substitution of infusions by simple dilution of the corresponding liquid extracts is not permitted. On the contrary, the Mexican Pharmacopoeia of 1925 excluded all aqueous extracts, replacing them with dilutions of liquid extracts devoid of foreign (insoluble in water) substances. Infusions are usually prescribed in a quantity of 180.0-200.0 and given with tablespoons, recommending that they not be taken on an empty stomach. Since plants always contain in large quantities a number of other substances (sugar, gums, pectin, salts, various colloidal substances, saponins, etc.) besides the active principles, the presence of these substances affects the rate of absorption of the active principles in the gastrointestinal tract, the strength of action, stability, etc. These circumstances determine, besides other properties of plants, the choice for the preparation of I. only of medicinal plants for which, in this form, one does not count on a rapid action, nor do they make demands for a fully precise dosage of the active principles, i.e., for the creation of certain concentrations of them in the blood after a certain period of time. The wide medical application of I. is explained not only by the simplicity of obtaining them, but also (in many cases) by medical observations that force a preference for I. in terms of the completeness of action over other medicinal forms or even over the active principles of the same plant isolated in pure form (for example, in foxglove, adonis, etc.). A frequent disadvantage of I. is their irritating action (especially with frequent intake of large doses) on the gastrointestinal tract. The presence of colloidal substances in I. does not allow the addition of metal compounds (formation of a gelatinous or curdy precipitate). It is also not recommended to add alcoholic or ether extracts and tinctures containing resinous components to I., as this results in milky, cloudy mixtures.