Sublingual Troche

A troche is a soft lozenge that dissolves slowly while kept under the tongue. The mucosa there is thin, not keratinised and well supplied with blood, draining into the jugular vein, so whatever is absorbed reaches the circulation without first travelling through the gut or the liver. This sidesteps both protease digestion and hepatic first-pass metabolism — the two processes that cut oral bioavailability of peptides to a fraction of a percent.

Benefits and limits

The benefit exists but has clear limits. The absorbing area under the tongue is small, swallowing cuts contact time short, and the mucosa still prefers small, fairly lipophilic molecules. Peptides are large and hydrophilic, so sublingual uptake measured in studies tends to be modest and strongly dependent on formulation; permeation enhancers and pH modifiers in the base are as important as the peptide. Whatever is not absorbed gets swallowed and then behaves like an oral amount.

Troche bases usually consist of polyethylene glycol or gelatin plus a sweetener and a flavour — all of them excipients, and none of them listed on a peptide certificate of analysis unless the supplier discloses the full formulation. Examples in the catalogue are AOD-9604 troches and oxytocin troches; the oral peptides guide covers the trade-offs between formats.

Related terms

intranasal · oral and capsule formats