Wednesday, June 2, 2010

Extracts

Q: Define Extract?

Ans: Extracts are defined as concentrated preparation of vegetable or animal drugs obtained by removal of active constituents of the respective drug with menstruum, evaporation of all or nearly all of solvent, and adjustment of the residual masses or powders to the prescribed Standards.

Q: How many types of extracts are there?
Ans:
There are three types of extracts:

• Semi liquid

• Solid extracts (Plastic masses)

• Powdered extracts (Dry powder)

Q: How the extracts are mostly prepared?
Ans: Mostly, extracts are prepared by extracting the drug by percolation.

Q: Why extracts are to be protected from heat?
Ans: The use of heat is avoided where possible because of potential injurious of active constituents

Q: Give some examples of extracts.
Ans: The examples of extracts are

• Extracts of Pure glycyrrhiza

• Extracts of Belladonna

Q: Define Fluid Extract?
Ans: USP define Fluid extract as being preparation of vegetable drugs containing alcohol as solvent or as a preservative or both, so that unless otherwise specified in an individual monograph, each milliliter contains the therapeutic constituents of 1g of the standard drug it represents.

Q: How unwanted colloidal material is separated and removed from fluid extract?
Ans: The fluid extract can be separated from the oil, concentrated by evaporation and re-extracted with strong alcohol to removed unwanted colloidal material.

Q: How degradation of fluid extract can occur?
Ans: Fluid extracts are subject to degradation by enzyme action.

Q: How degradation by enzyme is inhibited?
Ans: This can be inhibited by including alcohol to give a concentration of 25% or more but enzyme is not destroyed and concentration must be taken to avoid subsequent condition in which the enzyme activity can be restored.

Q: What are the Solvents and their advantages used in fluid extract?
Ans: Solvents used in fluid extract are

• Alcohol

• Water

• Solvent ether

Acetic acid

Advantages of water and/or alcohol:

• It is cheap.

• It is non toxic.

• It can dissolve wide range of chemical substances.

• It flame and non-flamable.

Further Reading:
Remington: The Science and Practice of Pharmacy (Remington the Science and Practice of Pharmacy)

British Pharmacopoeia 2010
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