Transmucosal

Transmucosal refers to the passage of substances across mucous membranes, including oral (buccal, sublingual), nasal, ocular, rectal, vaginal, and other mucosa-lined surfaces. In pharmacology, transmucosal administration means delivering drugs across a mucous membrane to achieve systemic absorption or local effect, often bypassing first-pass metabolism in the liver. The mucosa consists of a mucus layer and an epithelium; permeability depends on drug properties (lipophilicity, molecular size, ionization) and formulation.

Common transmucosal routes include buccal and sublingual tablets or films dissolved in the mouth for rapid absorption; nasal sprays for systemic or local action; rectal and vaginal suppositories or gels; and ocular drops for local treatment. Formulations aim to maximize residence time and permeation, often using permeation enhancers, mucoadhesive polymers, or lipophilic prodrugs.

Advantages include rapid onset, ease of administration, non-invasiveness, and avoidance of hepatic first-pass metabolism, while limitations comprise limited surface area, variable absorption due to saliva, mucosal pH, enzyme activity, mucosal irritation, and formulation stability. Dose accuracy can be affected by swallowing or nasal drainage.

Clinically, transmucosal routes support pain management with opioids such as fentanyl, antiemetics for nausea, and local anesthetics in dentistry, among others. Safety considerations focus on mucosal irritation, local tissue effects, and potential systemic exposure requiring careful dosing and monitoring.

Overall, transmucosal delivery represents a versatile interface between dosage form and mucosal biology, offering rapid, non-oral routes for systemic or local drug delivery, with ongoing research to improve consistency and widen applicability.