VIA ORALE, also called PER OS, from the Latin for, meaning through, and from Latin òs, òris, which means mouth (OS is also an acronym dI Oral Administration, which means Oral Administration).
Routes of Administration
- ENTERAL
- Oral
- Sublingual
- Rectal
- PARENTERALS
- Intravenous
- Intramuscular
- Subcutaneous
- INHALATION
- TRANSCUTANEOUS
Features
Through oral administration, only a small part of the drug reaches the absorption and the site of action. Citing the example of a tablet, the latter will undergo considerable disintegration starting from the mouth, and then continue in the stomach and intestines. At this point, what remains of the drug will be absorbed and transported to the liver, where it will undergo metabolisations due to the first hepatic passage. At the end of all these breakdowns and metabolisations, the drug will be distributed in the body. The combination of all these phenomena determines the bioavailability of the drug inside our body.
The bioavailability of the drug is the non-degraded fraction of drug that reaches the systemic circulation and is able to distribute itself throughout the body.
Bringing a comparison between oral and intravenous administration routes, the first has a significantly lower bioavailability than the second, because the drug, before reaching the bloodstream, undergoes significant changes. All this does not happen if we inject the drug directly into the bloodstream (intravenously).
Easy execution
Economic
Little risky
Absorption modulation
Irritations
Inactivations by enzymatic hydrolysis (insulin and protein substances)
Inactivations due to gastric acidity (penicillin G)
First hepatic passage and intestinal flora destruction
Other advantages of oral administration:
- it is the most natural way that exists.
- It allows for greater patient participation in the care plan.
- It requires no training, just information.
Additional disadvantages of oral administration:
- It may no longer be appreciated by the patient.
- Ineffective in the presence of pathologies of the gastrointestinal tract.
- Impractical in dysphagia patients.
- Not usable in the last hours of life.
- Needs good cooperation from the patient.
- It cannot be used for drugs which are destroyed by gastric juices, which form with non-absorbable complex foods or which are extensively metabolized by the liver before reaching the general circulation.
- As absorption may be uneven, there is little control over the posology.
- Since absorption is slow it cannot be used in emergency therapies.
Remember that if a drug is absorbed in the oral cavity or in the lower and middle hemorrhoidal plexus, the first hepatic passage is avoided, therefore further modifications to the drug. If, on the other hand, the drug is absorbed at the level of the upper hemorrhoidal plexus and at the gastrointestinal level, it undergoes the first hepatic passage, therefore before entering the circulation the drug undergoes modifications.
Other articles on "Oral route of administration, per os"
- Enteral routes of administration
- Sublingual route of administration
