In this article we will discuss about the Drugs:- 1. Collection and Preparation of Drugs 2. Organoleptic Studies of Drugs.
Collection and Preparation of Drugs:
Medicinal plants are sometimes cultivated and drugs are collected from cultivated plants. But very often drugs are collected from wild plants growing in different parts of the world in various ecological conditions.
Persons engaged in the collection of drugs should therefore be experts in their profession. Carelessness or ignorance on the part of the collector may result in gathering completely different material or mixed up articles.
The proper time of harvesting the cultivated medicinal plants or gathering the drug from wild plant is to be taken into consideration as the nature and quantity of the constituents vary greatly in some species in different seasons.
Drugs should therefore be collected when the active principle is at its highest in the plant. Different types of drugs, i.e. roots, leaves etc. should therefore be collected at different phases of the life of the plants and some general rules have been formulated for collection of the drugs.
The rules generally followed are given below:
1. Roots and rhizomes should be collected when the vegetative growth of the plant is almost over, if collected earlier the roots shrink after some time.
2. Barks are collected in spring before the starting of annual growth.
3. Leaves and flowering tops are to be collected when photosynthetic action is going on very actively.
4. Flowers are usually collected just when they are fully open but in some cases these are collected when half open or even in bud condition.
5. Fruits are collected when full grown but still unripe in some cases, whereas in other cases fruits are collected when fully ripe.
6. Seeds are collected from fully ripe fruits. An expert collector knows which material is to be collected at what stage of maturity.
The mode of harvesting also varies in case of different types of drugs. Some are collected by engaging manual labour but mechanical devices are applied wherever suitable being much economical. Mechanical methods cannot replace manual labour when selected parts of the plant are only to be collected.
Sometimes harvesting is therefore done by combined methods. For example plant materials required for distillation are harvested with a mower and hauled directly to dryers. When dry, the leaves are separated by hands.
In case of small fruits or seeds e.g. caraway, flax seed etc. the fruits or fruiting tops are gathered with a combination of mower and binder. The fruits and seeds are later separated by threshing. Barks are collected striping by hand. Roots and other under ground parts are collected by hand as well as by mechanical devices, e.g. plough, potato digger or shrubbery lifter.
Organoleptic Studies of Drugs:
Organoleptic studies refer to evaluation of a drug by means of different organs of the human body or by sense, such as appearance of the drug material, its odour and taste. The sound or the ‘snap’ of its fracture and the touch of the drug are also helpful in the evaluation.
Macroscopic characteristics are of 5 types, viz.
(i) Shape and size of the material,
(2) Colour and external markings,
(3) Fracture and internal colour
(4) Odour and
(5) Taste.
Crude drugs are available in markets in various farms. Leaves, flowers, fruits, seeds and some roots and rhizomes are brought as entire material. Wood, bark and some root and rhizome may come in cut, broken or sliced form.
Sometimes they are matted together or in bales, may be pressed together or in powder. Often these are given different shapes. Sometimes roots, rhizomes and barks come to the market after removal of the periderm.
Drugs derived from the underground parts, e.g. rhizomes, roots, bulbs, corms and tubers are found in the market:
(1) As entire
(2) In longitudinal slices
(3) In oblique or transverse slices
(4) Cut in small cubical pieces or
(5) Broken into pieces.
The shape may be cylindrical or sub cylindrical, conical, fusiform, ovoid, terete or disc-shaped. The material may be simple or branched, straight or curved or twisted, the base and apex of the article are also to be determined i.e. the direction of growth is an important character.
The size of the material is given in terms of length and diameter. If the material is conical in shape the diameter of the broader end as well as of the narrower end is to be noted.
The external colour of the material is to be given, and in case of bark material the colour of the outer surface and also of the inner surface should be noted. External markings are also noted. Such markings are classified as ridges and furrows, wrinkles, fissures, projection and scars.
The fracture or the nature of breaking may bed:
(1) Complete,
(2) Incomplete,
(3) Short,
(4) Fibrous,
(5) Splintery,
(6) Brittle,
(7) Tough and
(8) Weak.
The nature of the fractured surface is also to be considered and it may be:
(1) Even surface,
(2) Uneven surface,
(3) Granular surface,
(4) Hard surface,
(5) Horny surface.
(6) Mealy surface
(7) Resinous surface,
(8) Concoidal surface and
(9) Waxy surface.
The colour of the fractured surface is known as the internal colour. Exudates are products formed in the metabolic process of the plant or are pathologic products. They include gums, resins, mucilage’s, oleoresin, juices, latex, tar, extracts, etc. These occur in the form of tears, cylindrical pieces, rounded or flattened masses, angular masses and agglutinated masses.
Odour and taste of the drug material are also considered important. The odour may be distinct or indistinct. The material may have a distinct taste or may be tasteless imsipid. The taste is distinct, may be acid, saline, saccharine or turpentine, and the material is classified accordingly.