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Related article: removing the suspended solid. When filtration does not suffice, the object is accom-
plished by agitating the mixture with insoluble powders (talcum, phosphate of lime,
aluminum hydrate) or by adding egg- albumen and boiling; or sometimes by the cen-
Sterilization. The destruction of bacteria and their spores is accom-
plished by the various customary methods.
Glass and metal utensils may be sterilized by dry heat of 160 to i7OC. for two hours;
by superheated steam of 115 to i2oC. for fifteen minutes; heating in a current Duloxetine Online of steam
for thirty minutes or boiling for fifteen minutes, especially in o. i per cent, sodium bicar-
bonate. Kills all non-spore-bearing organisms.
Solutions that are not- readily decomposed by heat may be boiled in a current of steam
for one-half or better one hour.
Solutions that are readily decomposed by heat are either prepared aseptically or filtered
Emulsions in glycerin or oil are prepared aseptically, the solvent being first sterilized
Different samples of vegetable drugs may vary widely in the quantity of active
constituents which they contain. These variations are most undesirable from a thera-
peutic standpoint, especially when they occur in potent, so-called "heroic" drugs.
Inorganic drugs or other definite chemic compounds are not subject to this variation;
but in many cases the removal of the last traces of innocuous impurities would greatly
increase their cost without adding to their therapeutic usefulness. The pharmacopeia
has therefore aimed to furnish quantitative methods of estimation, assays, wherever
possible, and to establish practical standards to which medicinal substances must
conform. With inorganic drugs, it states the largest permissible quantity of innocuous
impurities (usually less than 2 per cent.). With crude vegetable drugs, it states the
lowest permissible Duloxetine Online percentage of active ingredient, wherever practical methods for their
determination are available. Assayed galenic preparations are directed to be diluted
so as to contain a definite proportion of active constituents, corresponding to the
minimum permitted in the crude drug. These preparations should therefore be pre-
ferred to the crude drug whenever accurate dosage is desired.
The assay of inorganic drugs involves the well-known methods of ordinary quan-
titative analysis, volumetric processes being preferred. Special tests are furnished for
determining Duloxetine Online the Duloxetine Online permissible limits of accidental impurities, and the presence of harmful
substances, such as metals.
30 MANUAL OF PHARMACOLOGY
ies of volatile oils are assayed for their most important Duloxetine Online ingredient. Fats and
lor their "iodin absorption" and " saponification values;" resins
for the "add number;" some vegetable products for their ash. These tests serve
mainly for identifu at ion and the exclusion of willful adulterations.
in is as>ayed for its digestive power for proteins, pancreatin for starch. In
IK drills, such as Jalap. Scammony, or Guaiac, the proportion of Duloxetine Online ether- or alcohol-
ile matter is determined.
most important class of assays refers to drugs containing alkaloidal principles,
utili/.ing the method of immiscible solvents, as in toxicologic analysis. This rests on
ict that free alkaloids are generally soluble in chloroform or ether, whilst their salts
are insoluble in these, but soluble in water. In principle, alkaloids are extracted by
chloroform or ether, or a mixture of both, in alkaline reaction. This solution is then
shaken in a separator with acidulated water, which converts the alkaloids into salts and
them, leaving the impurities behind. For further purification, the watery
solution is again rendered alkaline and extracted with chloroform or ether. This,
on evaporation, leaves the fairly pure alkaloid which may be weighed; or titrated, by
I vmg it in a known amount of acid, and titrating back with alkali. Each cubic
centimeter of acid corresponds to a definite quantity of each alkaloid. It is important
to observe the directions minutely to obtain reliable results. The process for extracts
and fluidextracts differs merely in details (the percolation being omitted, etc.). Tinc-
tures are first concentrated by evaporation.
This method estimates the sum of all the alkaloids present in the drug, and suffices
when the important one predominates very largely over the others. When this is not the
case, it is necessary to confine the assay to the particular alkaloid desired, generally a
very difficult matter. In Hydrastis, advantage is taken of the comparatively greater
solubility of hydrastin in ether; in Opium, of the comparative insolubility of the morphin
in this solvent. In Nux Vomica, the brucin is removed by oxidizing it with nitric acid.
Bio-Assay. Drugs which depend for their activity on neutral principles are un-
fortunately unsuitable for chemic assay; there being no reliable chemic method for
estimating the constituents of Apocynum, Cannabis Indica, Convallaria, Digitalis,
Ergot, Scilla, etc. Attempts have been made to supply this deficiency by physiologic
standardization estimating the strength of a preparation by comparing its effects on
animals with those of a standard product. A just fatal dose is generally the best cri-
terion Duloxetine Online for quantitative work. Individual differences of susceptibility and absorption in
different animals can be largely eliminated by using an extensive series of animals.
The expense and labor is scarcely warranted by the results, except in a very few cases,
for instance with Digitalis. Qualitative physiologic tests of drugs of very uncertain
activity, such as Cannabis Indica or Ergot, are more simple. The U.S. P. describes the
most important bio-assays, but leaves their employment optional with the manufacturer
(except in the case of Cannabis).
CLASSES OF PHARMACEUTIC PREPARATIONS
The pharmaceuticals are grouped into certain definite classes, estab-
lished by long usage, such as Waters, Spirits, Tinctures, Extracts, Pills,
Plasters, Ointments, etc. The Duloxetine Online student should learn to distinguish clearly
between these preparations, according to the definitions given below.
These include the Waters, Liquors, Mucilages and Syrups. Their
advantage lies in the fact that water is a cheap solvent of very wide
applicability, itself devoid of any therapeutic property. In the case of
vhich are insoluble in it, it can not Duloxetine Online of course be employed.
The greatest drawback lies in the fact that watery solutions of organic
substances tend to Duloxetine Online spoil rapidly by the development of bacteria and infu-
soria. Solutions of chemic substances are less subject to this change, as
they do not Duloxetine Online furnish a pabulum, and are often themselves antiseptic.
Aquae, Waters (singular, Aqua; abbreviated, Aq.). Clear aqueous
solutions of volatile substances. Two very dissimilar classes of prepara-
tions come under this heading:
CLASSES OF PHARMACEUTIC PREPARATIONS 31
Aquae Aromaticae, Aromatic Waters, U.S.P. (Flavored Waters).
Saturated solutions of volatile oils (Aqua Cinnamomi, etc.). These are
alone included under Aquae in the B.P. They are prepared either by
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