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Definition: Removal of soluble material from the insoluble residue, either liquid or solid, by treatment with a liquid solvent. The solvent used for extraction is called menstruum & the undissolved residue left behind called marc . The extracted preparation known as Galenicals . The process of extraction can be divided into five steps: Size reduction of drug Penetration of solvent into drug Dissolution of constituents Outward diffusion of solution from the drug Separation of dissolved portion 2 MANJUL P. SINGH

Types of extraction:: 

Types of extraction: The extraction of the drug can be done by four types: Infusion Decoction Maceration Percolation 3 MANJUL P. SINGH

Infusion & Decoction:: 

Infusion & Decoction: Sr. No. Infusion Decoction 1. Cold or boiling water is used as menstruum. Drug is boiled in water. 2. Drug having soft tissue is used. Drug having hard tissue is used. 3. Drug constituents may be volatile. Drug constituents should be non volatile. 4. Final volume is adjusted. Final volume is not adjusted. 5. When boiling water is used as menstruum, precaution are taken to prevent the escape of heat by covering the vessel with a cloth . No such precaution is required. 4 MANJUL P. SINGH


Maceration: The drug is placed with the whole of the menstruum in a closed vessel for 2-7 days with occasional shaking. After 2-7 days the liquid is removed & marc is pressed. Examples are: Tincture of orange, Tincture of squill . Maceration process divided into two types: Modified maceration Multiple maceration 5 MANJUL P. SINGH

Modified maceration:: 

Modified maceration: It is essentially used for extracting unorganized drugs. Ex : gums, resins etc. This process is quick because the soluble constituents are directly exposed to menstruum due to lack of cellular structure . The final product is adjusted to definite volume. The filtrate should be collected in a dry receiver or in a receiver rinsed with men strum because the resinous matter present in most of the unorganized drugs is insoluble in water affecting the clarity of the final product. Ex: preparation of tincture of opium . 6 MANJUL P. SINGH

Multiple maceration:: 

Multiple maceration: Multiple maceration is aimed at achieving maximum extraction by using portions of total volume of men strum for successive maceration. The drug: menstruum ratio is low. The volume of men strum for each maceration can be calculated as follows , For double maceration, Volume of menstrum (total volume - vol.retained drug)/2 + for 1 st maceration = vol. retained by drug. For triple maceration , Volume of men strum For 1 st maceration = (total volume – vol. retained by drug)/3 + vol. retained by drug 7 MANJUL P. SINGH


Percolation: Percolation process is divided into four types: Continuous hot percolation Simple percolation Reserve percolation Modified percolation 8 MANJUL P. SINGH

Continuous hot percolation:: 

Continuous hot percolation: Continuous hot percolation process or Soxhlet extraction Apparatus. The apparatus consists of three parts- A flask: For boiling of solvent. A Soxhlet extractor: Having the drug in thimble, a side tube & siphon tube A reflux condenser: For condensation of vapors 9 MANJUL P. SINGH

Simple percolation:: 

Simple percolation: Simple percolation process involves three stages: Imbibition: Uniform moistening of the raw material with the menstruum for a period of 4 hrs. in a separate closed vessel. After imbibition, the drug is packed evenly into the percolator. Maceration: Sufficient menstruum is added to maintain a small layer above the drug and allowed to stand for 24 h. The 24-h maceration period allows the solvent to diffuse through the drug, solubilize the constituents and leach out the soluble material. Percolation: The outlet is opened and the solvent is percolated at a controlled rate with continuous addition of fresh solvent. About 75% of the volume of the finished product is collected. 10 MANJUL P. SINGH

Reserved Percolation: : 

Reserved Percolation: In this case , a part of the percolate , generally ¾ th the volume of finished preparation is reserved. Then the percolation is continued till the drug is completely exhausted. The evaporation is done to convert into soft extract (semi solid) Modified Percolation process: Drug Imbibition Maceration Percolation & collect 1000 g for 4 hrs for 24 hrs 100 ml percolate Maceration Percolation & collect for 24 hrs 100 ml percolate Maceration Percolation & collect for 24 hrs 100 ml percolate This process is continued in case drug is not completely exhausted. 11 MANJUL P. SINGH

Factors affecting on extraction of drugs:: 

Factors affecting on extraction of drugs: Character of drug: Hard or soft drugs. Stability of drug: Thermolabile or thermostatic. Concentration of product: Tincture Therapeutic value of drug: Potent drug Cost of drug Solvent 12 MANJUL P. SINGH