Suppositories (Suppositories)

Products

Many drugs are available in the form of suppositories. The most commonly administered in the office are acetaminophen suppositories for the treatment of fever and pain in infants and children (photo, click to enlarge).

Definition

Suppositories are single-dose medicinal preparations with a solid consistency. They usually have an elongated, torpedo-like shape and a smooth surface. They are intended for use in the rectum. The mass is usually between 1 to 2 g. The definition of suppositories sometimes includes the rounder and usually somewhat heavier vaginal suppositories and the very rarely used urethral suppositories. However, the pharmacopoeia defines suppositories as rectal suppositories and distinguishes them from vaginal suppositories.

Manufacture

Active pharmaceutical ingredients are dispersed in a base mass that melts at body temperature or disperses or dissolves on contact with liquid. Base masses used include hard fat (Adeps solidus), macrogols (PEG), and gelatin masses made from gelatin, glycerol, and water. Cocoa butter is rarely used today, partly because it becomes rancid and the production of suppositories is more complicated. The active ingredients are present dissolved or dispersed in the base. Various excipients such as colorants, preservatives, fillers, surface-active substances or lubricants can be added. During manufacture, the base compound with the active ingredients and excipients is usually melted and poured into molds in which the compound solidifies. Less commonly, suppositories are also pressed.

Properties

Basically, a distinction is made between local and systemic application. In the case of application, the active ingredients exert their effects in the rectum or at the anus. Typical examples are laxatives and hemorrhoidal suppositories. Salicylates such as mesalazine are given for inflammation of the rectal mucosa (proctitis). When applied, the active ingredients contained are absorbed through the mucosa into the blood vessels and into the bloodstream, thus reaching their site of action in the body. In this process, the first-pass metabolism is partially bypassed because, in particular, the blood from the lower hemorrhoidal veins bypasses the liver and enters the inferior vena cava and thus the bloodstream. Several other advantages exist over peroral administration:

• Suppositories do not need to be swallowed and are suitable for infants, toddlers, children, for patients with difficulty swallowing and for nausea and vomiting.
• Side effects in the digestive tract and nausea and vomiting can be avoided.
• Administration is also possible in poor general condition or unconsciousness.
• Administration is not painful, unlike an injection.

Caution: often the maximum plasma concentration (Cmax) is reached later with suppositories than with oral administration. So if a rapid onset of action is desired – for example, in a migraine – other dosage forms may be preferable. This also applies, for example, to paracetamol suppositories, for which Cmax is only reached after about 1.5 to 2 hours, according to the product information. Often, suppositories also have lower bioavailability.

Use

According to the SmPC and package insert.

• The bowel should be empty because administration of the suppository may trigger the defecation reflex. Of course, this does not apply to the use of laxatives.
• Wash hands with soap and water or put on gloves or a fingerstall.
• Carefully remove the suppository from the package.
• Insert the suppository deeply into the rectum behind the sphincter in the supine position and with the legs drawn. If a local effect is desired, for example, against hemorrhoids, do not insert too far (still palpable).
• To facilitate the application, greasy suppositories can be slightly warmed and PEG suppositories moistened with warm water.
• Wash hands with soap and water.

Pointed or blunt end first?

Suppositories are usually inserted into the rectum with the pointed end facing forward. Manufacturers also usually specify this. However, since the publication of Abd-el-Maeboud et al (1991), it has also been recommended that suppositories be administered with the end facing forward, because this is thought to make it more difficult to slide out.However, this idea is controversial (Bradshaw & Price, 2007).

Are suppositories allowed to be shared?

Sharing of suppositories is not intended by manufacturers. Suppositories do not contain breaking grooves, and sharing is rarely mentioned in the drug label. In addition, the active ingredient in a suppository may theoretically be unevenly distributed. Suppositories can break, become contaminated, and sharing is laborious. For the above reasons, suppositories should be divided only in exceptional cases. This should be done under hygienic conditions and lengthwise, as this is more likely to result in two equal parts.

Storage

Suppositories should usually be stored at room temperature between 15 to 25°C. They are kept out of the reach of children. Suppositories may begin to melt at high temperatures. This is especially important in summer and on vacation. Therefore, when compiling a first-aid kit for travel, suppositories should be avoided if possible.

Undesirable effects

Specific possible adverse effects of suppositories include local irritation, pain, and triggering of the defecation reflex. Intimate administration is uncomfortable and embarrassing for some patients. It is more complicated compared with tablets or capsules.

Accidental ingestion of suppositories

Suppositories are intended for rectal use in the rectum and should not be ingested. What happens if a suppository is accidentally swallowed instead of inserted? The base materials used, such as hard fat, macrogols or gelatin, are not problematic for the body. They are either digested in the intestine and their components are absorbed. Or they are excreted unchanged in the stool. Suppositories are designed to melt inside the body and release their active ingredients. Release also occurs with oral use and the active ingredients can be absorbed. However, pharmacokinetics differ, for example, due to first-pass metabolism with oral administration. Furthermore, some active ingredients, such as local anesthetics, are intended exclusively for topical use. Side effects are possible. For example, salicylates may irritate the gastric mucosa. The consequences of ingestion depend on the active ingredients, the dose and the patient and must be assessed on an individual basis. Patients should contact a healthcare professional immediately.