Category Archives: Quality control of crude drugs
Evaluation of drug means confirmation of its identity and determination of its quality and purity and detection of nature of adulteration.
IDENTITY: refer to exact authentic biological source of the drug can be established by actual collection of the drug from a plant or animal which has been identified or comparing a representative unknown sample with a published description of the drug with authentic drug sample.
QUALITY: refer to the intrinsic value of drug i.e. the concentration or amount of medicinal principles or active constituents present. These constituents are classified as non-living cell inclusion and have been studied under the heading, the chemical classification. This includes fixed oils, carbohydrates, glycoside, alkaloids, resin, fats or waxes, volatile oil, tannins, vitamins, alergens, etc. A high grade of quality in a drug is of prime importance. An effort should be made to obtain mainly this high quality.
The high grade quality of the drug be accomplished by:
1) Collection of the drug from the correct natural source at proper time and in the proper manner.
2) Preparation of the collected drug by proper cleaning, drying, garbling.
3) Proper preservation of the cleaned, dried pure drug against contamination through moisture, fungi, filth and insects.
PURITY: of the drug depends upon the absence of foreign matters whether organic or inorganic.
The crude drugs can be identified on the basis of their morphological, histological, chemical, physical, and biological studies.
The evaluation of crude drug is necessary because of three reason:
1. Biochemical variation in the drug
2. Deterioration due to treatment and storage
3. Substitution and adulteration, as a result of carelessness, ignorance or fraud
The different techniques involved in standardization of crude drugs are as follows:
· Organoleptic evaluation
· Microscopic evaluation
· Physical evaluation
· Biological evalution
Standardization of herbal drugs is not an easy task as numerous factors influence the bio efficacy and reproducible therapeutic effect. In order to obtain quality oriented herbal products, care should be taken right from the proper identification of plants, season and area of collection and their extraction and purification process and rationalizing the combination in case of polyherbal drugs.
Organoleptic (Lit. “Impression on the organs”) evaluation of crude drugs refers to the evaluation of a drug by colour, odour, taste, size and shape, occasionally the sound or snap of fracture and special fetures including touch, texture, etc..
Organoleptic evaluation is also called MORHOLOGICAL or MACROSCOPICAL evaluation.
It is a technique of qualitative evaluation based on study of morphological and sensory profiles of whole drugs. Organoleptic evaluation means conclusions drawn from studies resulted due to impression on organ of senses.
PARAMETERS used for this type of evaluation can be explained as follows.
The colour is used in indicating the general origin of drug. e.g. material derived from the aerial part of the plant is usually green and the underground plat material is usually devoid of green colour.
The length, width and thickess of the crude material are of great importance while evaluating a crude drug.
PROCEDURE: A graduated ruler in millimetres is adequate for the measurement of the length, width and thickness of crude maerials small seeds and fruits may be measured by aligning 10 of them on a sheet of calibrated paper, with 1mm spacing b/w lines and dividing the result by 10.
3) ODOUR AND TASTE
To an expert, odour and taste of crude material are extremely sensitive criteria based on individuals perception. Therefore, he description of this feature may sometime cause some difficulties.
* Mouldy or musty
PROCEDURE: If the material is expected to be innocuous, place a small portion of the sample in the palm of the hand or a beaker of suitable size, and slowly and repeatedly inhale the air over the material. If no odour is perceptible, crush the sample between the thumb and index finger or between the palms of the hands using gentle pressure. If the material is known to be dangerous, crush by mechanical means and then pure a small quantity of boiling water onto the crushed sample in a beaker. First determine the strebgth of the odour (none, weak, distinct, strong) and then the odour sensation (aromatic, fruity, musty, mouldy, rancid, etc.) A direct comparision of the odour with a defined substance is advisable (e.g. peppermint should have an odour similar t menthol, cloes an odour similar to eugenol)
Tastes are f tw types
· True taste
* Acid (S*ur)
* Saline (Salty)
* Saccharine (Sweet)
· False taste (Sensati*ns t* the t*ngue)
* Mucilagin*us (s*ft slimy feeling)
* *il (Bland sm**th feeling)
* Astringent (C*ntracti*n *f m*uth tissue)
* Pungent (Warm biting sensati*n)
* Acrid (Unpleasant, Irritating)
* Nause*us (Induce v*miting)
SURFACE CHARACTERSTICS, TEXTURE AND FRACTURE CHARACTERSTICS:
Examine the untreated sample. If necessary, a magnifying lens (6x to 10x) may be used. Wetting with water or reagents, as required, may be necessary to observed the characteristics of a cut surface. The texture is best examined by taking a small quantity of material and rubbing it between the thumb and forefinger, it is usually described as ‘smooth’, ‘rough’,’guity’. Touch the material to determine if it is soft or hard, bend and rupture it to obtain information on brittleness and the appearance f the fracture plane whether it is fibrous, smooth, rough, granular, etc.
All this characteristics aare valuable in Indicating the general type of material and the presence of more then one component.
For convenience te description of macroscopic characters may be divided into four headings as-
a) Shape and size
b) Colour and external marking
c) Fracture and internal colour
d) Odour and taste
In some official crude drugs monograhs the entire macroscopic description consists of an organoleptic evaluation and is only means of evaluation given macroscopy refers to visual appearance to baked eyes. The macroscopic study depends on the part of the plant from which the drug is obtained.
According to the plant part used all organized drugs can be classified into following groups.
A) Underground plant parts
E) Flower fruit
Adulteration is as practice of substituting original crude drug partially or wholly with other similar looking substances, but the later is either free from or inferior in chemical or therapeutic properties.
Adulteration involves different conditions such as deterioration, admixture, sophistication, substitution, inferiority, and spoilage.
DETERIORATION: is the impairment in the quality of a drug.
ADMIXTURE: is the addition of one article to another due to ignorance or carelessness, or by accident.
SOPHISTICATON: is the intentional or deliberate type of adulteration.
SUBSTITUTION: occurs when some totally different substance
is added in place of original drug.
INFERIORITY: refers to any sub-standard drug.
SPOILAGE: deterioration due to the attack of microorganisms.
TYPES OF ADULTERANTS:
Generally the drugs are adulterated by substitution with sub-standard commercial varieties, inferior drugs, or artificially manufactured commodities.
The following types of adulteration are common:
1. SUBSTITUTION WITH SUB-STANDARD COMMERCIAL VARIETIES:
The adulterants here may resemble the original crude drug
in morphological, chemical, or therapeutic characters, but are sub-standard in nature and hence are cheaper in cost. This is a rather most common practce of adulteration e.g.
Strychnous nux-blanda or S.potatorum in place of S.nux-vomica, Capsicum annuum in place of C.minimum, Indian senna is substituted with arabian senna or dog senna, medicinal ginger is substituted with inferior varieties of African , Japanese, or Cochin ginger.
2. SUBSTITUTION WITH SUPERFICIALLY SIMILAR INFERIOR DRUGS:
These inferior drugs used may or may not be having any chemical or therapeutic value as that of original drug.
Due to their morphological resemblance to the authentic drug, they are marketed as adulterants.
Belladonna leaves are substituted with Ailanthus leaves, Saffron is admixed with dried flowers of carthamus tinctorious, and bees wax is substituted with Japan wax.
3. SUBSTITUTION WITH ARTIFICIALLY MANUFACTURED SUBSTANCES:
It has been also observed that substances artificially prepared to resemble the original drug are used as substitutes. This prectice is followed for much costlier drugs.
Compressed Chicory in place of coffee, yellow coloured praffin wax for bees wax, properly cut and shaved baswood for nutmeg.
4. SUBSTITUTION WITH EXHAUSTED DRUG:
The same drug is admixed but is devoid of any medicnally active constituents as they are already extracted out. This
practice is more common in case of volatile oil containing
drugs like fennel, clove, coriander, caraway etc. Sometimes natural characters of exhausted drugs like colour, and taste are manipulated by adding other additives and then it
is substituted, e.g. exhausted gentian made bitter with aloes, artificial colouring of exhausted saffron, etc.
5. Besides these common practices, sometimes other methods are also employed like use of synthetic chemicals to enhance the natural characater as in case of addition of benzyl benzoate to balsam of peru, citral to citrus oils
like oil of lemon and orange oil, etc.
6. PRESENCE OF VEGETATIVE MATTER FROM THE SAME PLANT:
Sometimes, the other miniature plants grwoing along with medicinal plants are admixed with the authentic drug, due to their resembling colour, odour, and in some cases constituents. The lower plants like moss, liverworts,
and epiphytes growing on bark portion are mixed with cascara or cinchona, The stem portions are mixed alongwith leaf drugs like stramonium , lobelia, and senna.
7. HARMFUL ADULTERANTS:
Sometimes the waste from the market are collected and admixed with the authentic drug. This is particularly noticed for liquids or unorganized drugs. The examples
like pieces of amber coloured glass in colophony, limestones in asafoetida, lead shot in opium, white oil in coconut oil, cocoa butter mixed with stearin or paraffin .
The addition of rodent feacal matter to cardamom seed is a very harmful adulteration.
8. ADULTERATION OF POWDERS:
Besides the entire drug the powdered forms are frequently found to be adulterated. Examples: dextrin in ipecacuanha,
powered liqourice or gentian admixed with powdered olive stones, exhausted ginger powder in powdered colocynth or ginger, red-sanders wood in capsicum, etc.