William Cook on pills and solid extracts
Medical Herbalism 11(3):16
We continue our column on herbal pharmacy tips that appear in The Physiomedicalist Dispensatory by William Cook, originally published in 1869
Solid extracts are mistakenly considered a new herbal form by some contemporary herbalists. In pharmacy, a solid extract is the gummy or powdery residue left over after evaporating a tea, tincture, or plat juice extract. The form is quite old, and has long been a basis for making pills in Western herbalism. Even standardization or concentration of specific plant constituents in Western herbalism is at least 120 years old – John Uri Lloyd’s “Specific Medicines”, so often used by the eclectic physicians, were liquid extracts with certain constituents removed and others concentrated. Solid extracts and herbal pills were widely used all branches of medicine, including Physiomedicalist and Eclectic medicine, in the mid-nineteenth century.
The United States Pharmacopoeia (Tenth edition) defines “extracta" as “. . . pasty or semi-solid masses, or dry, solid or powdered products, prepared by exhausting drugs [herbs] with appropriate solvents, carefully evaporating the solutions so obtained to the prescribed consistency and adjusting the products to the fixed standards. . . The pasty or semi-solid extracts are designated ‘piluar extracts’ because they are extensively used in pill masses.”
Here are some guidelines on preparation by Cook, one of the last physicians to make most of his own medicines, rather than rely on those available from the growing pharmaceutical industry.
Obtained by evaporating the liquid from the juice, the water extraction, or the hydro-alcoholic extract of the plant.
Represent the qualities of a plant quite well (when properly prepared).
Not appropriate for volatile agents or those easily injured by heat.
Juices: the juice is obtained by pressure. A small amount of water can be added to the crushed plant material. Evaporate as quickly as possible on low heat to prevent mold.
Water extracts: Preferred to the above for non-juicy plants. Macerating the plant material in cold or lukewarm water will prevent excess extraction of starchy material, which could cause easy growth of molds. No long boiling of the material should be used. Decoction of freshly powdered material maximizes extraction of constituents. Filter the water extraction. Re-extraction of the marc one or more times will yield more constituent material. Percolation with cold water will yield as good an extract as maceration with hot water.
Hydro-alcoholic extracts: Percolate
first with alcohol, then with water. Evaporate the resulting products
separately to the consistency of a syrup. Then mix the two and continue
Evaporation: At least some insoluble material (that will not go back into solution) is formed during the evaporation process. To minimize this material, which is generally medicinally inert, evaporation should be conducted at as low a heat as is possible. For aqueous solutions, divide the decoction among several broad and shallow vessels, such as broad baking dishes, and conduct the evaporation so that the material never reaches the boiling point. As the solution becomes condensed, the risk of burning increases, and it should be transferred to a water or steam bath. As the mass approaches solidity, it should be stirred repeatedly and the heat made even more moderate. Evaporation in broad flat vessels in a room at 100 degrees is the safest method. A fruit or vegetable dryer might also be used. For evaporation of hydro-alcoholic extracts, a closed still that will collect the evaporated alcohol is necessary (alcohol vapors present the risk of explosion).
Preservation: The soft extracts, somewhat plastic in consistency, are placed in airtight jars. Most cannot be reduced to a powder. A piece of filter paper soaked in alcohol may be placed on top of the extract before the lid is put on.
Making pills: Extracts may be mixed with powders of the herb from which they are made, to make pills, or the gummy extracts can be mixed with a suitable carrier.
Some plants well-suited to making such extracts are licorice, hawthorne berry, schizandra berry, or resihi mushroom
Copyright 2001 Paul Bergner