Quality Control

Quality control or standardization of drug means confirmation of its identity and determination of its quality and purity and detection of nature of adulterant by various parameters like morphological, microscopical, physical, chemical and biological observations.

Adulteration

Adulteration is defined as partial or complete replacement of original crude drug with impure, cheap, filthy, defective, harmful or putrid substances. In simple terms adulteration means debasement of original materials. The substances which are added or replaced are known as adulterants.

The adulterants generally do not possess any chemical or therapeutic properties but only resembles the original drug in respect to its morphological appearance. Herbal adulteration is common malpractice associated with herbal drugs to increase weight or decrease the cost.

The extent of adulteration depends upon whether the drug is indigenous or obtained from other countries.

An adulteration of a drug may be deliberate or accidental.

Reasons for Adulteration

Following are the reasons for crude drug adulteration:

1. Scarcity of the drug.
2. High price of the drug in the market, Eg: Clove(लवंग), cinnamon(दालचिनी), cardamom(वेलची).
3. Adulteration is very common with the contraband drugs/drug which are sold illegally, Eg: Opium(अफू).

Various Ways of Adulteration:

1. Inferiority
2. Spoilage
3. Deterioration
4. Admixture
5. Sophistication
6. Substitution

Types of Adulteration Explained

1. Inferiority: Inferiority refers to any sub-standard drug. eg. Powder ginger may be diluted with starch with colorant for color correction.
2. Spoilage: Spoilage could be due to attack of micro-organisms, rendering the product unfit for consumption.
3. Deterioration: Deterioration means impairment in quality of the drug.
4. Admixture: Admixture is the addition of one article to other through ignorance, carelessness or an accident.
5. Sophistication: Sophistication means intentional or deliberate kind of adulteration.
6. Substitution: Substitution occurs when an entirely different article is sold or used in place of one original drug. eg. Cheap Cotton-seed oil in place of Olive oil.

Methods of Drug Adulteration

1. Deliberate Adulterations

The following are the various types of deliberate adulterations:

1. By means of artificially manufactured substances.
2. By means of inferior commercial varieties of drugs.
3. By means of exhausted drug.
4. By means of superficially similar inferior natural items.
5. By means of vegetative part of the same plant.
6. By means of toxic materials.
7. Adulteration of powders.

i. By means of artificially manufactured substances

In this type of adulteration, the original substances are adulterated by materials that are artificially manufactured. The materials are prepared in a way that their general form and appearance resemble the original crude drug morphologically.

Examples:

• Artificial invert sugar is used in place of honey.
• Paraffin wax coloured yellow and is been substituted for beeswax.
• Bass-wood is cut exactly the required shape of nutmeg(जायफळ) and used to adulterate nutmeg.

ii. By means of inferior commercial varieties

In this type of adulteration, the original drugs are substituted using inferior quality drugs that may be similar in morphological characters, chemical constituents or therapeutic activity.

Examples:

• Hog gum or hog tragacanth for tragacanth gum (Ghost Tree, bhutyā, भुत्या).
• Mangosteen fruits (Kokum fruit) for bael fruits.
• Arabian senna, obovate senna and provence senna are used to adulterate senna. (Marathi names of Senna - Bhitarvada, Mulkacha, सोनमुखी Sonamukhi)
• Medicinal grade ginger being adulterated with cochin, african and japanese ginger.

iii. By means of exhausted drugs

In this type of substitution, the active medicaments of the main drugs are extracted out and are used again. this could be done for the commodities that would retain its shape and appearance even after extraction, or the appearance and taste could be made to the required state by adding coloring or flavoring agents. This technique is frequently adopted for the drugs containing volatile oil, such as clove, Fennel, etc.

Examples:

• After extraction, Saffron(केसर, Kesar) and red rose petals are recolored by artificial dyes.
• The bitterness of exhausted gentian is restored by adding aloes.

iv. By means of superficially similar inferior natural substances

Here the adulterants/ substituents used may be morphologically similar but will not be having any relation to the genuine article in their constituents or therapeutic activity.

Examples:

• Ailanthus leaves(मरुख Marukh, माहरुख Mahrukh) are substituted for belladonna.
• Senna leaves, Saffron mixed with safflower.
• Peach kernels and apricot(जर्दाळू) kernel for almonds.

v. By means of the vegetative part of the same plant

The presence of vegetative parts of the same plant are mixed with the drug in excessive amount due to their resemblance in morphology and sometimes constituents.

Examples:

• Epiphytes, such as mosses, liverworts and lichens that grow over the barks are incorporated in unusual amounts with the original crude drugs.
• Excessive number of stems incorporated in leaf drugs like lobelia, stramonium, hamamelis leaves, etc.

vi. By means of toxic materials

In this type of adulteration, the adulterants are toxic in nature and may be harmful to the body if taken internally. They are mixed due to their morphological resemblance.

Examples:

• Amber coloured glass pieces in colophony.
• Pieces of lime stone found with asafoetida.
• Lead shots in opium.
• Big masses of stones found mixed with liquorice roots.

vii. Adulteration of powders

Powdered drugs are found to be adulterated very frequently. Adulterants used for powders are generally powdered waste products of a suitable colour and density.

Examples:

• Powdered olive stones for powdered gentian, liquorice(ज्येष्ठमध), pepper.
• Brick powder mixed with powdered barks.

2. Undeliberate Adulteration

This type of adulteration is also known as admixture and occur unintentionally. They occur naturally due to carelessness, negligence, due to improper methods or accidental. Unintentional adulteration may occur due to the following reasons.

1. Confusion in vernacular names between indigenous systems of medicine and local dialects.
2. Lack of knowledge about the authentic plant.
3. Non availability of the authentic plant.
4. Similarity in morphology/aroma.
5. Careless collection.
6. Other unknown reasons.

Evaluation of Crude Drugs

Evaluation of a drug ensure the identity of a drug and determines the quality and purity of drugs.

• Identity - identification of biological source of the drug.
• Quality - the quantity of the active constituents present.
• Purity - the extent of foreign organic material present in a crude drug.

The evaluation of herbal drugs is necessary because of three main reasons.

• a. Biochemical variation in the drug.
• b. Deterioration due to improper processing and storage.
• c. Adulteration and substitution.

There are five methods by which the drug can be evaluated:

1. Morphological/Organoleptic Evaluation
2. Microscopical Evaluation
3. Chemical Evaluation
4. Physical Evaluation
5. Biological Evaluation

1. Morphological/Organoleptic Evaluation

Organoleptic evaluation means the study of drugs using organs of senses. It refers to the methods of analysis like colour, odour, taste, size, shape and special features, such as touch, texture, etc. Obviously, the initial sight of the plant or extract is so specific that it tends to identify itself. If this is not enough, perhaps the plant or extract has a characteristic odour or taste. The study of form of a crude drug is morphology while description of the form is morphography.

Examples:

• Brown colour: Cinnamon
• Aromatic odour: Umbelliferous fruits (e.g., Fennel, coriander, caraway, dill)
• Sweet taste: Liquorice
• Fractured surface: Cinchona
• Wavy shape: Rauwolfia
• Size (7-8mm width, 25-60mm length): Senna leaf
• Ovoid tears: Gum acacia
• Vermiform ribbon: Tragacanth
• Quills (tightly rolled): Cinnamon
• Conical Shape: Aconite
• Pungent taste: Capsicum, Ginger

2. Microscopical Evaluation

Every species has a unique anatomy, the study of which helps us in their identification process.

Microscopic evaluation is useful for the organized drugs (i.e. drugs having cellular structure).

T. S. & L.S. of the drugs are observed under the microscope.

T. S. & L.S. of the drugs are studied under the microscope with the help of the staining agent.

Special attention is given to the type of tissues, their arrangement, presence or absence of special substances like calcium oxalate crystals, starch grains, size and shape of starch grains, cell contents etc.

Examples:

• Lignified trichomes in nux vomica,
• warty trichomes of senna,
• wavy medullary rays of cascara bark.

The techniques like microscopic linear measurements, determination of leaf constants and quantitative microscopic are also used in this evaluation.

Linear measurements include size of starch grains, length and width of fibres, trichomes, etc.

Determination of leaf constants include stomatal number, stomatal index, vein islet, veinlet termination number and palisade ratios.

• Stomatal number: average number of stomata per sq. mm of epidermis of the leaf.
• Stomatal index: it is the percentage which the numbers of stomata form to the total number of epidermal cells, each stoma being counted as one cell. Stomatal index can be calculated by using the following formula:
  Stomatal index(S.I.)= S/(E+S)×100
  Where, S=Number of stomata per unit area, E= Number of epidermal cells in the same unit area.
• Vein-islet number: It is defined as the number of vein islet per sq.mm of the leaf surface midway between the midrib and the margin. It is a constant for a given species of the plant and is used as a characteristic for the identification of the allied species.
• Veinlet termination number: It is defined as the number of veinlet termination per sq. mm of the leaf surface midway between midrib and margin. A termination is the ultimate free termination of veinlet.
• Palisade ratio: It is defined as the average number of palisade cells beneath each epidermal cell. Unlike vein-islet number for the determination of which an unbroken portion of the leaf is required, palisade ratio can be determined with the powdered drug.

Quantitative microscopy (Lycopodium spore method)

This is an important technique employed in identification of crude drug when chemical and physical methods are inapplicable. It is inexpensive technique with official status. Lycopodium spores are very characteristic in shape and appearance and exceptionally uniform in size(25µm). on an average 94,000 spores per mg of powdered lycopodium are present.

A powdered drug is evaluated by this technique, if it contains:

1. Well defined particles which may be counted, e.g. starch grains or pollen grains
2. Single layered cells or tissue, the area of which may be traced under suitable magnification and actual area calculated
3. The objects of uniform thickness, the length of which can be measured under suitable magnification and actual area calculated.

3. Chemical Evaluation

This method of evaluation consists of isolation, purification & identification of the active chemical constituent from the crude drug.

This method consists of following test: Acid value, saponification value, Iodine value, Ester value, Acetyl value and Determination of methoxy group.

Chemical evaluation also consists of titration, gravimetric analysis, chromatographic analysis, spectrophotometer analysis, etc.

Chemical tests are also helpful for the identification of crude drugs. e. g.

1. Van urk’s test for Ergot.
2. Halphenes test for Arachis oil.
3. Borntrager tests for Anthraquinone Glycoside.

Ex. Starch gives blue color with iodine. It forms a thick viscous solution with water.

The estimation of chief constituents or group of active constituents is an integral part of chemical evaluation e.g. total sennosides in senna, morphine in opium, citral in lemongrass oil etc.

The chemical tests also help in proper identification of varieties of the crude drugs eg. the solution of lead acetate or lead subacetate is used specifically for chemical identity of gums.

4. Physical Evaluation

Following are methods of physical Evaluation.

• A) Determination of moisture content
• B) Determination of Viscosity
• C) Determination of Melting point.
• D) Determination of Optical rotation.
• E) Determination of Refractive Index
• F) Determination of ash content
• G) Determination of Extractives
• H) Determination of volatile oil content

A) Determination of moisture content

Water content is determined by removing moisture and then by measuring weight loss;

B) Determination of Viscosity

Determined by experiments with a ball sinking into the liquid. The speed at which a ball sinks to the ground in a fluid is directly dependent on the viscosity of the fluid.

C) Determination of Melting point.

Most basic method determination is the capillary method. Placing the sample in a capillary tube. Heat the sample until it reaches melting point. Record the temperatures at which melting begins.

D) Determination of Optical rotation.

Measured with an instrument called a polarimeter. Light Emitting Diode (LED) produces a beam of ordinary light. This light first passes through a polarizer (polarization filter) in order to obtain a defined orientation of the plane of polarization. The polarized light then passes through the sample cell.

E) Determination of Refractive Index

Measured with an instrument called a refractometer. Calculated from the ratio of the speed of light in a vacuum to that in a second medium of greater density.

F) Determination of ash content

The total ash content equals the weight of the ash divided by the weight of the original sample multiplied by 100%.

G) Determination of Extractives

Extractives amount was calculated as the percentage weight loss based on the initial dried biomass used for extraction.

H) Determination of volatile oil content

Volatile oil is separated by water distillation, water-oil distillate, saturated with salt then extracted with ether. Solvent; evaporated in a tared container. The weight of the remaining volatile oil is calculated and % volatile oil is calculated.

5. Biological Evaluation (BIOASSAY)

When the estimation of potency of crude drug or its preparation is done by means of its effect on living organisms like bacteria, fungal growth or animal tissue or entire animal, it is known as bioassay. This method is generally called for, when standardisation is not adequately done by chemical or physical means and also for conformity of therapeutic activity of raw material and finished product. In other words, bioassay is the measure of sample being tested capable of producing biological effect as that of the standard preparation. Such activity is represented in units known as international unit (I.U.)

The specific biological activity contained in each I.U. of the few drugs is mentioned as under:

• Digitalis - 1 IU is contained in 76 mg of standard preparation
• Vit A - 1 IU is present in 0.344 micrograms of standard preparation

Biological assay methods are mainly of 3 types:

• Toxic
• Symptomatic
• Tissue methods

In toxic and symptomatic techniques, the animals are used, whereas in tissue method, the effect of a drug is observed on isolated organ or tissue. Among the drugs that are subjected to bioassay are cardiac glycosides, natural pesticides and antibiotics.