The Composition Of Drugs

Drugs obtained from any source may be inorganic or organic in nature. Inorganic drugs have simple formula, whereas, organic drugs have complex one.

(A) Inorganic drugs: Acids, Bases and Salts.

(B) Organic drugs: Alkaloids, Glycosides, Oils, Tannins, Gums, Resins, Antibiotics, and Hormones.

In pharmacy curriculum drug composition and properties etc. are covered under pharmaceutical chemistry subjects. However, alkaloids and glycosides being the most, important, are mentioned briefly hereafter.

1. Alkaloids: These are naturally occurring complex basic nitrogenous compounds having physiological and therapeutic importance. They are of plant origin but some of them are of animal origin and the rest of synthetically prepared.

Chemically, they are nitrogenous bases with characteristics similar to substituted ammonia. Their formula has C, H, O and N. while a few alkaloids contain S & P also.

They are non-volatile, colorless, crystalline solids insoluble in water; but their salts are water-soluble.

Alkaloids are widely distributed in the plant kingdom, embedded in various parts of plants and trees. Quinine in cinchona bark, Emetine in some roots and morphine alkaloids in dried juice of unripe poppy capsules are common examples. Few are obtained from fungi, for example some from poisonous mushrooms and ergot alkaloids which are obtained from Claviceps Purpurea or grains.

2. Glycosides: these are complex plant principle of organic nature. They have different sub names (e.g. Galactoside) according to the sugar they contain. When they are made to combine with a non-sugar component, they are known as Aglycones or Genins. Their molecules have C, O, H and some glycosides also contain Sulphur and nitrogen.

Glycosides are generally water-soluble; colorless compounds some of them being optically active.

Glycosides of medicinal importance are Digoxin, Digitoxin and Gitoxin from the cardio tonic digitalis of the Anthracene group from Rhubarb and Aloin from Aloes, both being purgatives.

3. Oils: The term oil is applied to a large number of liquids, which are insoluble in water and highly viscous. Oils are of two kinds:

(a) Volatile oils are liquids that impart an aroma to a plant, and are volatilized by heat. They evaporate and leave no greasy stain. Because of their pleasant smell and taste they are frequently used as flavoring

(b) Fixed oils are the Glycerides of Oleic acid, Palmitic acid and Stearic acid. Fixed oils of vegetable origin include olive oil, castor oil, croton oil and peanut oil. Fixed oils do not exert marked pharmacological activity. Olive oil and cottonseed oil are used as food at high calorific value. Fats are fixed oils, which remain solid at ordinary temperature.

Waxes are composed of fatty acids combined with monohydric alcohol. They are firmer with a higher melting point and are mostly used as ointment bases. The term "lipids" includes fixed oils, fats and waxes. MINERAL OILS are mixture of hydrocarbons of the methane and related aliphatic series, obtained from petroleum by fractional distillation. They are produced in various consistencies- hard paraffin, soft paraffin and liquid paraffin. The first two are used as ointment bases, and liquid paraffin is used as a laxative.

4. Tannins: They are non-nitrogenous plant constituents, and have an astringent action. They are of two types: (a) Pyrogallol tannins, which are glycosides of glucose and occur in oak galls; (b) Pyrocatechol tannins, which are sugar, free derivatives of Catechol and occur in catechu and eucalyptus. Tannin is used for treating burns and diarrhea.

5. Gums: They are chemically polysaccharides, which on hydrolysis yield simple sugars. Upon addition of water some of them swell up and form adhesive mucilaginous masses; and some remain unchanged. In the gut they act as hydrophilic colloids and function as bulk laxatives. One gum in the form of an emulsion is used for chapped skin. Acacia is used as a suspending agent in making emulsions and mixtures like Bismuth-Kaolin mixture for diarrhea.

By Rolando Garcia -

Next page: Fatty Acid Formula

Bookmark/Share This Page:

Custom Search

Name:
Email:
Website URL:
Title / Subject:
	Hide my email
Comments:

Fatty Acid Composition Of Olive Oil News