Churna are fine dry powders of drugs. The term Churna may be applied to the powder of a single drug or a mixture of two or more drugs which are powdered separately prior to their being mixed to homogeneity.
1. The drugs enumerated in the recipe in clean and well dried state.
2. A mortar and pestle.
3. A fine sieve or fine cloth of close mesh. (In large scale manufacture in factories, disintegrators, pulvarisers and ball mills are employed for powdering. The sieving is done by mechanical sifters which handle large quantities of material in a short time.)
Process of Preparation
The drugs which are to be used in the preparation should be taken from recently collected material. Drugs which are aged by prolonged storage or changed in colour, taste or scent and those which are insect infested should be positively rejected. However, drugs like embelia fruits, long pepper, coriander seeds, honey, jaggery, and even cow’s ghee are preferred from old stock, which should be unspoilt otherwise.
In general, the aromatic drugs are slightly fried in order to increase or sweeten their aroma. Any extraneous material should be removed from the drugs.
The churna should be very fine, amorphous and should be perfectly dry. The fineness of the sieve used should be preferably 80 mesh per square inch or still finer.
The prepared churna should be stored in tightly stoppered glass bottles. Polythene and foil packing also gives damp proof protection.
It is said that the churna retain their potency for two months and then gradually deteriorate. In any case, unless otherwise spoilt by moisture or insects or fungi, the churna keep active for an year.
In these days, for easy handling in a convenient form the churna are pressed into tablets of uniform weight and packed in bottles or tubes made of glass or plastic.
Churna in Form of Tablets
Tablets are unit forms of solid medicinal substances with or without suitable diluents prepared by compressing and they are mostly discoid in form.
Churna are compressed in Tablet Punching Machines in the form of Tablets to provide efficient solid dosage forms for oral administration.
The ingredients are mixed in the form of granules before compressing them as tablets. To much fine powder refuse to form satisfactory tablets and so they must be mixed with some adhesive substances or binders such as Gum Acacia. To prevent the sticking of the tablets to the punches and dyes, a lubricant like liquid paraffin is added. If the tablet is to dissolve quickly, a disintegrator like Talcum Powder is added.