A quiet analytical research laboratory at night, racks of glass vials along a dim bench.

Sublingual and Buccal Delivery

Sublingual and buccal routes send drug straight into systemic circulation, bypassing the gut and the liver on first pass. They work for small, potent, reasonably lipophilic molecules and struggle with anything large, polar or high dose. Saliva washout is the main enemy.

Anatomy and limits

The sublingual mucosa is thin and highly vascular, which makes it fast but leaky: swallowing and saliva flow carry much of a dose to the stomach within minutes. Buccal mucosa is thicker and slower but tolerates a patch or film held in place for longer. Total surface area is small, so practical doses are milligrams, not grams. Molecules below about 500 Da with moderate lipophilicity absorb best; peptides absorb poorly without enhancers.

Reference products

Sublingual nitroglycerin, buprenorphine films, asenapine and fentanyl tablets show the route works for potent small molecules at low doses. Buccal insulin was studied for years without reaching approval in the US or EU, which marks the ceiling for peptides. In supplements, sublingual formats are common for melatonin and vitamin B12, although for many of these ingredients the absorbed fraction via the mucosa versus swallowing is rarely measured. The route is proven for drugs; for most supplement ingredients it is assumed.

Design variables

Residence time, dissolution speed and taste govern performance. Orally dissolving films, lozenges and mucoadhesive tablets differ mainly in how long they hold the active against the mucosa. Formulators also control local pH, which changes the ionized fraction of weak acids and bases and therefore permeation. Taste masking is essential because the product dissolves in the mouth. Film and tablet disintegration times are measured in simulated saliva, and residence is assessed before any claim about sublingual absorption is made.

Key facts

Sublingual mucosa is thinner and more permeable than buccal mucosa, but continuous saliva flow limits residence time (Shojaei 1998, J Pharm Pharm Sci 1:15)
Buprenorphine and naloxone sublingual film is FDA approved, demonstrating systemic delivery by the sublingual route (FDA label, Suboxone film 2010)
Oral melatonin undergoes extensive first-pass metabolism, with mean bioavailability about 15% (Harpsøe et al. 2015, Eur J Clin Pharmacol 71:901)

How our delivery technology applies

The limiting factor here is residence, not protection. A mucoadhesive outer biopolymer layer, such as chitosan or a cellulose derivative, holds encapsulated particles against the mucosa against saliva flow. Inner layers mask taste and control release so the active is presented at the surface over minutes rather than swallowed at once. For peptides the route remains a research question.

Develop a sublingual or buccal format with Vegalab's team.