In our extemporaneous directions, it is necessary to apportion with
accuracy the quantity of active materials which we may wish each pill to
contain, and since the proportion of the _constituent_ can rarely be
exactly defined, the equable division of the whole mass, into a given
number of pills, will be safer than defining the weight of each pill.
A pill, the bulk of whose ingredient is vegetable matter, ought not to
exceed five grains in weight, but where the substances which compose it
are metallic and ponderous, it may without inconvenience weigh six or
even eight grains.
TROCHISCI. _Troches_, or _Lozenges_.
As these are regarded as objects rather of confectionary than of
pharmacy, the London and Dublin Colleges have not condescended to notice
them; the Edinburgh Pharmacopœia, however, contains several formulæ for
their preparation; and as the form of lozenge offers a very commodious
and efficacious method of administering certain remedies, the theory of
its operation deserves some notice in the present work. It is
principally useful in cases where it is an object that the remedy should
pass _gradually_ into the stomach, in order to act as powerfully as
possible upon the pharynx and top of the trachea, as in certain
demulcents or astringents; for instance, _Nitre_, when intended to
operate in relaxed or inflamed states of the tonsils, is best applied in
this manner; so is _Sulphate of Zinc_ in chronic coughs, attended with
inordinate secretion. In order to retard as long as possible the
solution of the lozenge in the mouth, it ought to be composed of
_several_ demulcent substances, such as farinaceous matter, sugar, gum,
and isinglass; for such a mixture will be found to answer the purpose
better than any _one_ of these articles taken by itself; thus the
farinaceous matter will prevent the sugar and the gum from being too
soon dissolved; the viscidity of the sugar and gum will prevent the
farinaceous matter from being swallowed as soon as it would otherwise
be; and the isinglass will give a softness to the whole, and thus
prevent any sharp points from stimulating the membrane.