Learning Objective

• Different types of herbal dosage forms and their preparations

Herbal dosage forms include solid, liquid and semisolid preparations. The basic principles involved in the preparation of these dosage forms are similar to those of allopathic processes, but they differ in the technique and method of preparation.

Various herbal or Ayurvedic dosage forms are described as follows:

1. Arka—distillate
2. Kvatha—decoction
3. Avaleha—semisolid preparations
4. Asava, Arista—fermented preparations
5. Ghrita—medicated ghee and oil
6. Taila—herbal oils
7. Vartti or Anjana—eye preparations
8. Churna—fine powders
9. Pisti—very fine powders
10. Bhasma—calcinated residue
11. Vati or gutika—tablets and pills
12. Herbal capsules
13. Lepa—paste

1. Arka (distillate): This is prepared by the distillation method and is used for fresh and soft drugs, where the active constituents may get degraded by boiling. The drug to be extracted is washed thoroughly and wrapped in a muslin cloth. This cloth bag is kept in the water required for distillation, in the distillation apparatus. The apparatus is heated and the distillation process is performed. The first part of the distillate is not collected as it contains some impurities present in the condenser or unwanted volatile materials; the further obtained vapor is condensed and collected in a receiver. In general, 8 to 10 times of water is used for this distillation process. Dry and hard substances are powdered and allowed to macerate. The macerated drug along with sufficient quantity of water is subjected to distillation and the obtained distillate is collected in the receiver. Examples of arka include rose, fennel, sandal and peppermint.
2. Kvatha (decoction): This is a liquid preparation and is obtained by decoction. This method is used in the case of drugs that are free from volatile constituents. Hard and woody drugs are reduced to the size of coarse powder and then macerated for 12 hours. The macerated drug is boiled with a suitable solvent under constant stirring in a vessel for a specified time period. After boiling, it is allowed to cool and then filtered by passing through a muslin cloth. Kvathas are used for oral administration, fomentation action and cleaning the wounds. Examples are zinger, apamarga and kantakari.
3. Avaleha: This is a semisolid preparation obtained by evaporating kvatha or karra (decoction). Kvatha is evaporated to a semisolid consistency and then the medicine is incorporated, or it is further evaporated to get a solid product. Care must be taken to ensure that the material does not stick to the evaporating pan. Avaleha may also be prepared by adding the medicine to a simple syrup, which is then evaporated to get a product of desired consistency. Examples are Chyavanprash and Kantakari avaleha.
4. Asava and Arista (fermented preparations): These are liquid preparations that are prepared by fermentation process. The formulations prepared with the aid of heat are called Aristas, whereas those prepared without the aid of heat are called Asavas. The preparations may be either sweet or sour in taste. Kvatha, gur and honey are used for the preparation of Asava and Arista. Volatile substances or flavoring agents are added to impart flavor to the preparation. These formulations should be prepared and stored in wooden containers. The preparation should be at a suitable place and a particular temperature is maintained throughout the fermentation period. After fermentation, the material is filtered and stored in suitable containers. These preparations are used internally to improve digestion, to make the body active (revitalizer), for expulsion of gas (carminative), to increase the flow of urine and to treat various ailments. They are orally administered by mixing with an equal amount of water. Examples are Madhuka asava, Kanakasava, Ashokarista and Dasamularista.
5. Ghrita (medicated ghee): This is a liquid or semisolid dosage form of medicament meant for internal and external use. Medicated ghee is generally given internally for its nutritive value and to treat constipation. Examples are Amruta ghrita and Panchagavya ghrita.
6. Herbal oil (taila): This is a liquid dosage form of medicament meant for internal and external use. The liquid form is prepared with olive oil or any other suitable oil. The oils are applied externally for their antiseptic and fomentation action. They are extensively used for massage to a particular part or the whole body. Examples are Kanaka taila and Anu taila.
7. Vartti or Anjana (eye preparation): This is a solid dosage form of medicament meant for application to the eyes. Vartti is an elongated solid preparation, which is rubbed on a hard surface or stone with few drops of water and the contents are instilled into the eyes. Anjana is a very fine powder, which is meant for application into the eyes with the help of a glass stick. These preparations must be passed through a very fine sieve to remove gritty particles, which otherwise may lead to irritation and discomfort to the eyes. Examples are Vimala Vartti and Muktadi Mahanjana.
8. Churna(powder): It is a simple or compound solid dosage form of medicament meant for oral administration. Simple churna contains only one medicament, whereas compound churna contains two or more medicaments. It is administered with water, milk, fruit juices or any other suitable liquid depending on the nature of disease. In general, the dose is 2–3 grams, which may be increased or decreased according to age and severity of disease. Examples are Eladi churna and Triphala churna.The following are the precautions to be taken in the preparation of churna:
   1. Thoroughly cleaned and dried drugs should be used for the preparation of churna.
   2. The ingredients should be finely sifted or grinded.
   3. Each substance should be powdered separately and then mixed.
   4. Equipment used for reducing the particle size and mixing the substances should be clean and dry.
   5. The churna must be stored in a dry container.
9. Pisti (very fine powder): It is a solid dosage form of medicament meant for internal use. It is prepared from very expensive materials such as diamonds and pearls. These materials are thoroughly cleaned to remove impurities such as dust and other foreign particles. The materials are reduced to very fine powder by prolonged grinding using suitable milling equipment. After milling, they are passed through a very fine sieve to remove the gritty particles. Examples are Pravala pisti and Manikya pisti.
10. Bhasma (calcinated residue): It is a solid dosage form of medicament meant for internal administration. In general pearl, iron, gold, silver, lead, tin, zinc and black mica are used for the preparation. The material is cleaned and reduced to a coarse powder. The powdered material is mixed with a suitable liquid and kneaded to get a wet mass. The wet mass is then converted into small cakes. These cakes are dried in sunlight or in an oven and stored in earthen pots. Two pots are used at a time, the mouths of which are joined together and the joint is sealed by a cloth dipped in mud slurry and dried in the sun. Then, these earthen pots are kept in a heap of cow dung cakes, which are burnt later. The material is heated in the burning fire for 12 hours and is then allowed to cool slowly. The obtained mass is removed and the contents are ground by means of a mill. Examples are Tamra bhasma and Pravala bhasma.
11. Vatior Gutika(tablets and pills): These are the solid dosage form of medicaments meant for oral administration and are prepared by hand or machine. The powdered drug materials along with the excipients are mixed together and a suitable liquid is incorporated to make the wet mass. The wet mass is further kneaded in between the fingers so as to get a uniform mass. The mass so prepared is rolled on a hard surface and then divided into desired number of pieces and each piece is rounded by fingers and dried. The tablets and pills can also be prepared with rotary tablet punching machine by compressing the dried granules. Examples are Gandhaka vati and Eladi gutika.The following are the precautions to be taken in the preparation of vati or gutika:
    1. If the dose of the drugs is small, diluents may be added to increase the bulk. For potent drugs, lactose may be used as the diluent.
    2. The material should be finely powdered.
    3. Only substances that can dissolve in stomach should be used.
    4. If the pill breaks, then a binding agent such as gum acacia may be added.
    5. Cinnamon or Glycyrrhiza powder should be sprinkled over the pills to prevent them sticking with each other.
    6. The pills should not be too soft or too hard.
    7. Sugar coating should be given for volatile and bitter drugs.
12. Herbal capsules: Capsules are unit solid dosage form of medicament in which the dried and powdered herbs are placed into hard gelatin capsules shells. Most medicinal herbs are bitter in taste, so it is easier to mask the bitter taste by placing the drug in an inert shell made of gelatin. Most herbal capsules contain just one specific herb in them, but sometimes capsules containing combination of herbs are also available.
13. Lepa: Medicines in the form of paste used for external application are called lepas. These are classified into six types, namely pralepa, pradeha, alepa, doshagna lepa, vishagna lepa and varnya lepa. The drugs are made into fine powder and mixed with liquid medium such as water, cow’s urine, ghee or oil to obtain a paste. This paste is applied externally on the skin surface. Lepa should always be applied on the opposite direction of hair follicles. It should be removed immediately after drying. It should be freshly prepared and used. It should not be applied one layer over another. Examples are Kalaka lepa and Dasanga lepa.