Preparation of Drug Extracts

Powdered drug (I g) is extracted by shaking at room temperature for 10 min with 10 ml methanol. The filtrate is evaporated and the residue dissolved in 1 ml toluene depending on the cannabinoid concentration, 5-50 fil is used for TLC. 

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Tn comparing the content of drug extract in the final product, teas in granule form are usually very much inferior to instant teas which arc prepared from spray-dried extracts teas in granular form, in addition to 97 -98% filler and carrier substances often contain only 2-3% dry extract, while in spray-dried products almost ten times as much, viz on average 20%, drug extract is present. 

The process of drug discovery from plants involves several steps, from plant collection and vouchering through the preparation of plant extracts to bioassay of the extracts and isolation and structure elucidation of bioactive constituents. An important aspect of this project was that it was conducted with the full informed consent not only of the government of Suriname but also of the Saramaka Maroon tribal people of our collection sites. The way this was done is important, as it sets a standard for future work of this type. 

The use of solid-phase extraction (SPE) for the sample preparation of drugs and pharmaceuticals has increased over the last 15 years because of ease of operation, increased selectivity with many new phases, and interfacing of automation and robotics. A simple strategy now exists for SPE methods development of drugs and pharmaceuticals, which makes sample preparation extremely straightforward. This strategy is the use of generic mixed-mode SPE and is discussed in detail in this chapter. 

Dixit, V. and Dixit, V. M. 1990. A solid-phase extraction technique for preparation of drugs-of-abuse samples Am. Lab., May/June, 47-51. 

As described in Chapter 3, several SCF techniques are available for the preparation of drug delivery systems. These include rapid expansion of supercritical solutions (RESS), gas antisolvent recrystallization (GAS), supercritical antisolvent recrystallization (SAS), supercritical antisolvent with enhanced mass transfer (SAS-EM), solution-enhanced dispersion by supercritical fluids (SEDS), supercritical fluid nucleation (SFN), precipitation with compressed antisolvent (PCA), and aerosolized supercritical extraction of solvents (ASES). While RESS and SFN involve the expansion of a supercritical fluid solution of a drug to form drug particles, GAS, SAS, SAS-EM, SEDS, PCA, and ASES use a supercritical fluid as an antisolvent to precipitate particles of a drug dissolved in an organic solvent (5). General RESS and GAS processes are further elaborated in Sections 1.1.1 and 1.1.2. 

Kurchi bark is principally used in India as a remedy for amoebic dysentery, and in recent years there has been a revival of medical interest in the drug in this eonneetion. It is generally used in the form of a bark extract but, in imitation of emetine bismuth iodide, kurchi bismuth iodide, consisting of the bismuth iodides of the mixed alkaloids of the bark, has also been used. On the pharmaceutical side Datta and Bal have studied the pharmacognosy of the bark and a method of alkaloidal assay has been devised by Schroff and Dhir, who have also described a process for the preparation of kurchi bismuth iodide, a product for which they, and also Mukherjee and Dutta, have provided methods of assay. 

Although griseofulvin is probably still prepared commercially by extraction from fermentation beers, numerous total syntheses of the drug have been reported. 

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