Sublingual glands or salivary glands are located on the floor of the mouth underneath the tongue. Drugs with characteristics like rapid onset of action, drugs effective in small doses, poor GI absorption, low molecular weight, and lipid solubility are suitable for sublingual delivery. Sublingual tablets are designed in such a way that they are kept below the tongue and dissolved and absorbed into the bloodstream directly through tissues of the mouth. Through this route, the drug directly enters the systemic circulation enhancing bioavailability.

Some advantages of the sublingual drug delivery system

• Sublingual delivery of drugs bypasses the first-pass metabolism thereby significantly enhancing the bioavailability.
• Rapid onset of action
• High bioavailability as drugs directly enters into the systemic circulation.
• This is a non-invasive method and its easy by the patient to take the medicine.

Types of sublingual tablets

1. Fast disintegrating tablets
2. Bio adhesive sublingual tablets
3. Lipid matrix sublingual tablets
4. Sublingual vitamin tablets
5. Sublingual immunotherapy

Methods of Preparation of Sublingual tablets

• Direct compression method
• Compression molding
• Freeze drying
• Hot melt extrusion
• Patented techniques like – Orasolv , Flash tab, oraquick etc.

The most often used sublingual tablets are nitroglycerin tablets used for the treatment of angina -chest pain. Vitamin tablets are taken sublingually for people who cannot absorb vitamins through digestive tract. Antianxiety drugs like lorazepam taken sublingually to relive symptoms of anxiety.so smaller drug molecules are better absorbed through sublingual mucosa and drugs like cardiovascular drugs, analgesics, antianxiety drugs, hormones, vitamins are some of the examples of sublingual route of administration.