Capsule

The capsules are single-dose pharmaceutical preparations, intended for oral administration.Consisting of a hard or soft shell, of various shapes and capacities, the capsules contain granulates, powders or oily mixtures; if the contents of the capsule are liquid, it is more commonly referred to as pearls.

These last preparations very often contain oily active ingredients, essential oils or other volatile substances; their casings, of various shapes, are often made up of gelatin with the addition of glycerin up to 30% (responsible for their softness and elasticity).

The content of the capsule can be made up of the active substances alone or alone, or more commonly the set of active ingredients, adjuvants and excipients. Among the latter we mention solvents, diluents, lubricants and breakdown agents.

Capsules are used above all to replace other less tolerated pharmaceutical forms, such as herbal teas or syrups, in the event that the drugs or supplements have bitter or unwelcome tastes; moreover, it is often necessary to resort to capsules due to the technical impossibility of forming tablets.

The capsule shell is generally made of food gelatin, or other substance, the consistency of which can be adjusted by adding a plasticizing agent (glycerin, sorbitol, simple syrup, starch); preservatives are also often added (for example small quantities of sulfur dioxide to prevent the growth of mold and bacteria on the gelatine). If necessary, the capsule shell may contain flavoring, but also natural and opacifying dyes. The choice of colors of the capsules is not causal, but is often based on marketing (many supplements) or therapeutic elements:

SEDATIVES: dark blue-brown;
STIMULANTS: orange - yellow;
LAXATIVES: olive / light brown (olive acts on the vegetative system as a relaxant and stimulant);
SEDATIVE OF COUGH: brown / light blue (brown causes a block of excitement and repels stimulating influences, light blue is relaxing);
DISINFECTANTS: turquoise / blue - clear (turquoise is perceived as a cold color and cold freezes growth and makes it sterile; light blue is a symbol of lightness, purity).

Advantages of the capsules

1) they mask unpleasant smells and tastes;

2) they dissolve easily in the stomach, releasing the active ingredients in less than 15 minutes;

3) the machines for the production of capsules have a relatively low cost and are easy to handle;

4) the choice of excipients is quite simple and does not pose the typical difficulties of tablets;

5) the psychological effect given by the colors of the capsules contributes to the therapeutic success of the drug.

The casings consist of two pre-formed cylindrical portions (body and lid), which close by self-sealing the capsule; for both, one end is closed, while the other is open. To the manufacturer, the capsules are supplied with the body inserted into the lid by pressing lightly, so as to easily separate the two parts. The production technique involves four phases:

1. Orientation of empty capsules
2. Opening the capsules
3. Filling of the body, alignment of the two parts of the capsule and "snap" closure
4. Expulsion

All this takes place in special machines that allow filling up to 150,000 cps / h.

The casings can have animal origin, if gelatin obtained by partial hydrolysis, acid or alkaline, of COLLAGEN, or vegetable is used; in the latter case, hydroxypropylcellulose is used. Before use, for the manufacture of capsules, gelatine is obviously analyzed as a BSE risk material ("mad cow").

Instead of the classic gelatin, the shell of the capsule can be replaced by starch; in this case we speak of starch capsules, cachets or wafers. The shell of the wafer is made of unleavened bread, usually of wheat flour, and it consists of two flattened and preformed cylindrical sections. To ingest a cachet it is necessary to moisten it completely, making it as soft and pasty as possible.

After taking, the gelatin capsules dissolve rapidly in the acidic environment of the stomach. To convey directly into the intestine those substances that can be inactivated by gastric acidity, or gastrolesive, the so-called gastro-resistant capsules, such as the keratinizing ones, are used.

The keratin, in fact, is not attacked by the gastric juices and releases the active principle directly into the intestinal fluid (kilo).

Disadvantages of the capsules

1) it is not possible to divide it into several parts;

2) the appearance is sometimes unnatural, similar to plastic.

As seen in the article, as a general rule it is important to avoid crushing the capsules or opening them, unless this is explicitly indicated on the package insert (under penalty of ineffectiveness of the drug). or the wrapper contain special excipients, or are prepared by a particular process that modifies the speed or the site at which the active ingredient is released.