Fast pharmacological response and promising alternative to traditional routes.
Substances delivery via the oral mucous membrane is a promising alternative to the oral route. Sublingual route is useful when rapid initiation of action is desired with better patient compliance than orally ingested tablets or other liquid forms. Clinically studies have shown that sublingual substances delivery is equivalent to intravenous substances entry into the systemic circulation.
But what is the mechanism of action of sublingual administration, and how it really works?
Sublingual glands, also known as the salivary glands, are present in the floor of mouth underneath the tongue and play a key role in the sublingual absorption process. Sublingual glands produce mucin and help to promote the production of saliva. Along with providing lubrication, these glands also aid in the process of absorption. Because of the high permeability and the rich blood supply of the sublingual area of the oral cavity, the portion of substances absorbed through the sublingual blood vessels bypasses the hepatic first pass metabolic processes giving acceptable bioavailability or optimal use. For this reason, sublingual route is capable of producing a rapid initiation of action, which makes it the ideal route for substances with short delivery period and in frequent dosing regimen. The substances are released into the saliva and its subsequent spreading may cause the substances to be absorbed across the oral cavity in a much faster way. The absorption of the substances through the sublingual route is 3 to 10 times greater than oral route and is compared to an IV administration.
Sublingual administration of the substances means placement of the substances under the tongue and substances reaches directly in to the bloodstream without degradation through the ventral surface of the tongue and floor of the mouth. For these type formulations, even the small volume of saliva is usually sufficient to result in integration in the oral cavity.
Because of all the benefits it brings, the sublingual administration has been a developing field in the administration of many vitamins and minerals which are found to be readily and thoroughly absorbed by this method. Sublingually absorbed nutrition, which avoids exposure to the gastric system and liver, gives a whole new meaning to direct nutrition. Since the nutritional benefit is independent of gastro‐intestinal influences, this administration method is particularly important for sufferers of gastro‐intestinal difficulties and bad absorption syndrome.
Advantages of Sublingual Administration
- Fast initiation of action can be achieved compared to the oral route.
- Liver is bypassed and also substances are protected from degradation due to pH and digestive enzymes of the middle gastrointestinal tract.
- Improved patient acceptance due to the elimination of associated pain with injections.
- Low dosage gives high efficacy as hepatic first pass metabolism is avoided and reduces the risk of side effects.
- The large contact surface of the oral cavity contributes to rapid and extensive substances absorption.
- Due to rapidity in action sublingual dosage forms are widely used in emergency conditions (e.g. asthma).
- Fast dissolution in the oral cavity, without the need for water or chewing.
