In addition to the pure manufacture of medicines, other tasks also fall within the remit of galenic scientists: these scientists are also concerned with the efficacy, toxicity, tolerability and safety of a preparation. On the one hand, this is done via drug tests prior to the approval of a drug in study phases I, II and III. On the other hand, the use of the drug after its approval is also monitored with regard to effects and side effects. You can read more about this testing and monitoring of a drug in the article Drug approval.
Galenics – Definition: Galenics is the science of preparing and shaping drugs from active ingredients and excipients, including their technological testing.
Search for the right “packaging
Galenics is concerned with putting the active ingredient into the right “packaging” (dosage form) with suitable excipients (see below). This can be, for example, tablets, coated tablets, capsules, powders, solutions or active ingredient patches.
The galenic packaging – i.e. dosage form – then determines the form in which the active ingredient is administered (applied). Common forms of drug application are, for example:
- oral (peroral): through the mouth (by swallowing, e.g. tablet, drug juice)
- sublingual: under the tongue (e.g. tablet that then dissolves under the tongue)
- rectal: into the rectum (e.g. suppositories)
- nasal: via the nose (e.g. nasal spray)
- cutaneous: applied to the skin (e.g. ointment, cream)
- subcutaneous: under the skin (injection)
- transdermal: through the skin into the blood (e.g. active ingredient patch)
- intramuscular: into a muscle (injection)
- intravenous: into a vein (injection or infusion)
- pulmonary: into the deeper airways (e.g. inhalation)
When administered by mouth (e.g., orally, sublingually) or rectally, the active ingredient enters the gastrointestinal tract and is absorbed there. For this reason, we refer here collectively to enteral forms of administration (enteral = affecting the intestines or bowels).
The counterpart is parenteral forms of administration: Here, the active ingredient enters the body bypassing the gastrointestinal tract, i.e. it is administered intravenously, subcutaneously or pulmonarily, for example.
Onset of action and tolerability
The most appropriate dosage and application form for a drug depends, among other things, on where and how quickly the active ingredient is to be released. Some examples:
- Sublingual tablets allow the active ingredient to be absorbed into the blood via the oral mucosa. In this way, for example, a strong painkiller can be administered that is intended to take effect quickly.
- The onset of action of painkillers, for example, can also be achieved more quickly by injection. As with a sublingual tablet, the active ingredient reaches the bloodstream much faster than if it has to take a detour via the gastrointestinal tract (e.g., normal pain tablet for swallowing).
- Gastric juice-resistant tablets have a coating that prevents the drug from passing through the stomach undamaged and releases the active ingredient only in the intestine. This may be necessary, for example, if the acidic gastric juice would attack the active ingredient and render it ineffective.
- Retard preparations are designed to release the active ingredient at a slower rate (e.g., retard pain tablet). This allows a constant level of active ingredient in the blood over a longer period of time. Retard preparations that are not used orally, subcutaneously or intramuscularly (e.g. nicotine patch, three-month injection) are also called depot preparations.
- By means of inhalation, nasal spray or eye drops, an active ingredient can be delivered straight to its destination. For example, an asthma medication can be inhaled. A nasal spray can help against the common cold. Eye drops can be used to relieve dry eyes or – with the addition of antibiotics – bacterial eye infections.
The dosage and application form can also have an influence on possible risks and side effects. For example, the above-mentioned gastric juice-resistant coating on some tablets may even be due solely to better tolerability: Some active ingredients irritate the stomach lining and can trigger nausea and vomiting. For this reason, they should only be released in the intestine.
Auxiliary materials
In addition to one or more active ingredients, most drugs also contain excipients such as starch or gelatin. These do not have any pharmaceutical effect themselves, but rather serve as fillers, colorants or flavorings, preservatives, lubricants or as stabilizers and carriers. The various excipients thus ensure the correct storage capability, shelf life, better odor or taste, and also the correct appearance of the drug.
Excipients do not have to be fully indicated on the packaging. For people with a corresponding allergy (for example, to a certain dye), this can be problematic.
