Extracts

These are amongst the most commonly prescribed excipients. When they occur as active ingredients in pills, the quantities are frequently much in excess of what would be required to make powders into pills of reasonable size. One part of extract will mass at least 2 parts of a powder, or more if the powder is largely water-soluble, so that if more than 2 grains of an extract is prescribed in one pill it is often necessary to evaporate carefully on a water-bath, and mass with tragacanth and liquorice as in the case of ergotin.

Ext. Cannabis Indicae. - When prescribed alone this extract makes a good mass with powdered liquorice. If aqueous extracts are present, a troublesome mass frequently results. The addition of 5 or 10 per cent of powdered tragacanth and sufficient dispensing-syrup answers in many cases.

Although both extracts for No. I. were soft, a crumbly unworkable mass resulted. The addition of 1 drop of a mixture of glycerin and spirit (equal parts) acted like magic and gave a splendid mass. Rectified spirit made a very good mass of No. II.

Ext. Cascarse Sagradae. - Stiffen with tragacanth and liquorice, and varnish the pills. Thus made they keep their shape perfectly.

Ext. Lactucae. - The following prescription gave unexpected trouble to the compounder :

Misce et divide in pilulas xxiv.

The pills, although made hard and varnished, were returned soft and adhering to the box ; but when rolled in lycopodium and sent out in a bottle almost filled with lycopodium, they did not become soft, although not in this instance varnished.

Ext. Taraxaci. - This preparation is one of the worst extracts in the Pharmacopoeia, because it is generally in a state of incipient fermentation, and merely requires dilution with anything to become quite active, giving strange results, as in the following instance :

M. Fiant pil. xij. (in arg.).

The mass was made with liquorice, and the pills split after being silvered, even though varnished. The swelling was no doubt due to evolution of gas from the extract of taraxacum. It should be noted that some vegetable extracts (gentian, taraxacum, and others) are so acid as to give rise to peculiar and unexpected changes in a mass. Some powdered tragacanth should be used along with a fibrous powder in massing ; the mass should not be made too hard, and the pills should be allowed to stand for half an hour before they are silvered or coated.