Definition and properties
The administration or application of a drug refers to its use on the body. The dosage forms (drug forms) used for this purpose consist of the active ingredients and excipients. These include, for example, tablets, capsules, solutions, syrups, injectables, creams, ointments, eye drops, ear drops, and suppositories. Drugs can be liquid, semi-solid, solid and gaseous. They are administered by various methods of application, for which defined technical terms have become established:
- Intramuscular: into the muscle, e.g. vaccines.
- Intravenous: into a vein, e.g., injections, infusions.
- Nasal, intranasal: into the nasal cavity, e.g. nasal sprays.
- Oral, peroral, enteral: via the mouth into the digestive tract, usually with absorption, e.g., tablets
- Parenterally: bypassing the digestive tract, e.g., injections.
- Rectal: into the rectum, e.g. suppositories.
- Subcutaneous: into the subcutaneous tissue, e.g. insulins.
- Sublingual: under the tongue into the bloodstream, e.g. sublingual tablets.
- Transdermal: through the skin into the bloodstream, e.g. transdermal patches.
In topical application, the active ingredient is administered locally, for example, with a cream or eye drops. This in contrast to systemic application, in which the entire organism is exposed to the drug. So, for example, when a tablet is taken or injected into a vein. In general, topical administration is better tolerated and fewer adverse effects are to be expected. A drug that is applied locally may also develop systemic effects and side effects under certain circumstances. For example, the migraine drug sumatriptan is also administered in the form of a nasal spray. It rapidly passes into the bloodstream via the nasal mucosa. The dosage forms differ in the onset of action due to the different rates of absorption. Whereas the drug is distributed in the circulation within minutes with an injection, the peroral route takes between about 30 minutes to 2 hours to reach maximum plasma concentration.
