Drug Adulteration
Adulteration is a 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 and therapeutic properties. Adulteration in simple terms, is debasement of an article. The motives for intentional adulteration are normally commercial one and are originitiated mainly with the intention of enhancement of profits. Some of the reasons that can be cited here are scarcity of drug and its high price prevailing in market. The adulteration is done deliberately, but it may occur accidentally in-some cases. It is also very common with the contraband drugs Adulteration involves different conditions such as deterioration,admixture,sophistication, substitution, inferiority and spoilage. Deterioration is impairment in the quality of drug, while admixture is addition of one article to another due to ignorance or carelessness or by accident. Sophistication 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 substandard drug, and spoilage is due to the attack of microorganisms.
A variety of adulterants are found in natural drugs by which the methods employed for such practices can be enumerated. During the routine quality control, various tests are applied for their detection. The present chapter deals with different techniques used in adulterating crude drugs and laboratory methods for their detection.
Types of Adulteration
Generally, the drugs are adulterated by substitution with substandard commercial varieties, inferior drugs or artificially manufactured commodities. The different types of adulterants found in market are given here.
i) Substitution with substandard commercial varieties: The adulterants used here may resemble original crude drug by morphological, chemical or therapeutic characters, but are substandard in nature and hence cheaper in cost. This is rather a most common practice of adulteration. The examples are presence of Strychnous nux-blanda or S. potatorum in place of S. Nux-vomica; Capsicum minimum replaced by C. anuum.
ii) 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 natural drug. Due to their morphological resemblance to authentic drug, they are marked as adulterants. Bellsdonna leaves are substituted with Ailanthus leaves; saffron is admixed with dried floers of Carthamus tinctorius.
iii) Substitution with artificially manufactured substances: It has been also observed that substances artificially prepared to resemble original drug are used as substitutes. Generally, this practice is followed for much costlier drugs. Compressed chicory in place of coffee; paraffin wax made yellow colored and substituted for beeswax properly cut and shaped baswood for nutmeg are some of the examples representing this type of adulteration.
iv) Substitution of exhausted drugs: In this type, the same drug is admixed but is devoid of any medicinally 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 color and taste are manipulated by adding other additives and then it is substitutes, e.g exhausted gentian made bitter with aloes, artificial colouring of exhausted saffron, etc.
v) Besides these common practices, sometimes other methods are employed like use of synthetic chemicals to enhance the natural characters as in case of addition of benzyl benzoate to balsam of Peru, citral to citrus oils like oil of lemon and orange oil, etc.
vi) Presence of vegetative matter from the same plant: Sometimes, the other miniature plants growing along with medicinal plant are mixed with drug due to their resembling color, odour and in some cases constituents. The lower plants like moss liver worts and epiphytes growing on bark portion are mixed with cascara or cinchona. The stem portions are mixed along with leaf drugs like stramonium, lobelia, and senna.
vii) Harmful adulterants: Several times, the wastes from market are collected and admixed with authentic drugs. This is particularly noticed for liquids or un organised drugs. The examples like pieces of amber colored glass in colophony,limestones in asafoetida, lead shot in opium, white oil in coconut oils cocoa butter mixed with stearin or paraffin indicate this type of adulteration practice. The addition of rodent faecal matter to cardamom seed is a very harmful adulterant.
viii) Adulteration of powders: Besides the entire drugs, the powdered forms are frequently, found to be adultered. Some examples which can be cited here are dextrin in ipecacuanha, powdered liquorice or gentian admixed with powdered olive stones, exhausted ginger powder in powdered colocynth or ginger, red sanders wood in capsicum, etc. The powdered bark is frequently found to be adulterated with brick powder.