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Medications: Injections, suppositories and other dosage forms

For medications to reach their target inside of the body, a suitable dosage form is selected when they are produced. This choice is made based on what physical and chemical properties the drug has and where it should take effect, among other things. Medicine that should have an effect on the lungs can be breathed in, for example. And drugs for treating a vaginal infection can be inserted using a vaginal suppository.

On our website you can find out more about oral medications and medications that are applied to the skin. This text is about the remaining medical dosage forms.

Injections

In injections, active ingredients are dissolved in a liquid and then injected. A drug is often injected into a vein (intravenous administration) if it is to have as fast an effect as possible, for instance in an emergency. This avoids a longer uptake time through the gastrointestinal tract. When an injection is to have a slower effect or when the active ingredient should not enter the bloodstream directly, it can also be injected into muscle (intramuscular) or under the skin into fat tissue (subcutaneous).

Some medications have to be injected: otherwise, they would break down in the stomach or bowel. Insulin is one example. Most vaccines also have to be injected for this reason. Many injection solutions only keep for a short time after they are opened if they are not cooled.

Hygiene is especially important when dealing with injection solutions, syringes and needles. They need to be kept free of germs (sterile) because otherwise these germs can enter the body very easily. After use the instruments must be disposed of safely.

Infusions

Infusions usually involve having a little tube placed into a vein (venous catheter) for some amount of time. Liquid can then flow into the bloodstream through this tube. Infusions are used when they are the only way to constantly and evenly administer an active ingredient into the body for a certain time period – but also when the body does not have enough fluids, for example. A venous catheter may also be important when an emergency requires medications to be given very quickly. For this reason a venous catheter is used in many operations as a precaution. Hygiene is also very important when doing an infusion – just as it is for an injection.

When infusions are done repeatedly for a longer period of time, so-called port systems can also be used. They consist of a flat container with a short tube that is implanted in a minor operation under the skin, for example near the collar bone. This container can be refilled with medication through the skin using a syringe. Then the container slowly releases the medication through the tube into the vein. Port systems can remain under the skin for several weeks, where they are protected from infection. They are used in chemotherapy, for example.

For relieving pain or numbing part of the body, anesthetics can be injected through a catheter into the so-called epidural space. This is a liquid filled space surrounding the spinal cord in the spine. First an epidural catheter is put in so that an anesthetic can be injected many times without having to stick in a needle each time. Pain-relieving infusions can also be given like this, for example to dull labor pains during childbirth.

Depots: Implants and injections

Depot implants are made of foreign material that is put into the body, and remains there for a longer time to continuously release medication. When the effect weakens, the implant is removed or it dissolves itself. This way, a drug can have a steady effect over several months. One example is a hormonal contraceptive implant.

In depot injection, a medication is injected under the skin or into muscle, and the drug is only gradually released. This can be achieved by mixing the active ingredient with oils or special salts that the body can only break down slowly. Examples of depot injections are longer-acting insulin, cortisone depot injections and the three-month injection for contraception.

Suppositories

Some medications can be inserted into the anus (rectal) as a suppository. They may contain active ingredients that are to have a local effect. But it is also possible to use medications rectally that are to take effect elsewhere in the body. The active ingredients are absorbed by the intestinal lining, enter the bloodstream and then have an effect on their target. Suppositories are often used when it is difficult to take drugs orally, for example in cases of vomiting or when children have a fever and do not want to or cannot take a tablet.

Vaginal suppositories, tablets and ointments

Some drugs are put into the vagina to treat inflammations or fungal infections there, for example. Vaginal tablets and ointments often come with a plastic insertion aid (applicator). These types of medications dissolve in the vagina and release their active ingredients there.

Eye and ear drops, eye ointments and gels

There are medications in drop form for treating eye and ear infections, for example, that are applied directly to the eye or ear. Ear drops should not be allowed to get too cold, otherwise they can cause pain or dizziness. There are also eye ointments and gels that are applied to the inner side of the lower eyelid. It is especially important to keep eye medications germ-free.

Nasal drops and sprays

Medications in the form of nasal drops and sprays are often used for treating colds and allergies. Either a certain number of drops or a specific amount of the spray is put into the nose. It is important to keep the pipette (dropper) or spray release pressed together when taking it back out of the nose, so that the medication is not contaminated by nasal discharge.

Inhalants

Medications that are breathed in (inhaled) can be a good idea if they are to have an effect directly in the lungs. Many asthma medications are available as sprays that are inhaled, for example. Because the lungs are so well supplied with blood, medications can also be breathed in that are then taken up by the blood to have an effect on the entire body. One well-known example is general anesthesia, where the anesthetic is breathed in through a mask.

When an active ingredient that is liquid or solid is finely suspended in air or another gas, the mixture is called an aerosol. Metered dose inhalers are an example of medical devices for applying aerosols. They finely disperse the drug and combine it with a propellant gas. This is how you use it: breathe out, close your lips around the mouthpiece, press the spray activation (puff) and then at the same time breathe in deeply. The finer the liquid or powder is dispersed, the deeper it can enter the lungs. It is important to give the device a regular, thorough cleaning, since it always touches the inside of the mouth when you inhale while using the device. This can attract germs.

Substances like essential oils can also be breathed in using hot steam, for example to relieve colds. Hot water allows the oils to vaporize more quickly, increasing the effect on the mucous membranes.

Medicated chewing gum

This type of chewing gum contains active ingredients that are usually absorbed into the rest of the body through the oral mucosa (mucous membranes lining the mouth). One well-known example is nicotine gum for helping to quit smoking.

You can find more detailed information about managing your medicines for the long term here.

Author: German Institute for Quality and Efficiency in Health Care (IQWiG)