(Part I: A study of drugs)
Drugs may be arranged in several different ways, to suit the aim and convenience of the student. The prominent systems of classification in common use are as follows:
I. Therapeutical.—This system of classification is especially valuable to the student of medicine. Here the physiological action and therapeutical application are made most prominent.
II. Chemical.—Classification of organic drugs is not infrequently based upon the character of the constituents. In this way alkaloidal drugs, glucosidal drugs, drugs containing volatile oil, etc., form the subgroups. Other subgroups of chemical classification are:
Inorganic Chemicals.—To the pharmacist the chemical action, the crystalline form, the solubility, and other physical properties are of especial value. For mineral substances, therefore, he adopts the classification of the chemist. Some therapeutists, seeing a certain relation between therapeutical action and chemical constitution, adopt the same method of grouping also for these mineral substances.
Synthetical Remedies.—This class of remedial agents is most difficult to classify in a manner consistent with science, partly because our materia medica is becoming overloaded with proprietary combinations and mixtures of synthetic medicinal products with various adjuvants to modify their action. These latter have oftentimes certain unscientific names, which give little or no idea of their composition.
III. Physical.—According to this method, drugs having allied physical properties are brought together. Roots, leaves, flowers, fruits, and seeds form the principal divisions. Under this head two different arrangements are present in this volume: (a) Classification into subgroups based upon such prominent features as odor, taste, etc. By this means the aromatic, bitter, acrid, sweet, and mucilaginous drugs are brought together. (b) Classification into subgroups based upon structural characteristics. Here drugs having similar structure are found associated. In the table having this arrangement the official drugs only are found. Appended to each there is a physical description in the fewest possible terms-such prominent terms as are used in describing the physical and structural characteristics.
Each drug has a number, so that a ready reference to the same drug in the body of the work is made easy. Here a fuller description is found.
Instructors in pharmacognosy who use this book are recommended to employ this conspectus and to have the students use these numbers. When labeling the drug (or its container) for class work, these numbers should be employed. The experience of the author in teaching the subject under consideration has been most favorable to this method. By the use of the numbers at first, the student quickly grows to learn, not only the drug, but the place in the system to which it belongs. The subject grows in interest until he is able to recognize the drug and to properly classify it.
IV. Botanical.—By this arrangement drugs belonging to the same natural order are brought together. In subdividing these orders botanical relationship is emphasized to as large an extent as is practicable in dealing with drugs from a pharmaceutical standpoint. From the point of view of the scientist this is the ideal system. This method has been adopted in the body of this work.
Geographical.—Drugs are rarely classified according to the locality of their occurrence. It is, however, instructive to the student to refer individual, or classes of drugs, to their locality. Drugs of ancient times were obtained chiefly from Asia. Many of these have survived, and are official to-day; notably aloes, myrrh, etc. With the discovery of the new world many important drugs were made accessible. Geographical classification is therefore of interest from many points of view. The presentation of this subject is facilitated by outline maps with the drugs indicated in their natural localities. As an example of such a map, see Cinchona.
Alphabetical Arrangement.—In all the standard books of reference, such as the "Pharmacopoeia" and the "Dispensatories," a strictly alphabetical arrangement is followed, no attention being paid to systems of classification. The arrangement is made wholly subservient to quick and ready reference.
In the following order four classifications will be presented: I. A synopsis of therapeutical agents. 2. Chemical agents. 3. Classification of organic drugs, as indicated under (a) and (b). 4. Botanical arrangement, where drugs will be treated at some length.
A Manual of Organic Materia Medica and Pharmacognosy, 1917, was written by Lucius E. Sayre, B.S. Ph. M.