Routes of administration and bioavailability

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The route of administration determines what fraction of the peptide reaches its target intact. Each route has its own pharmacokinetic logic.

• Subcutaneous (SC): the dominant route for peptides. A depot in the fatty tissue under the skin with gradual absorption into the circulation; simple and with good bioavailability for most of these molecules.
• Intramuscular (IM): faster absorption because of greater muscle vascularization; less common for peptides used outside the clinic.
• Intranasal (IN): the nasal mucosa offers a route with relatively direct access to the CNS for certain neuropeptides, avoiding part of systemic metabolism. Its bioavailability depends on the formulation.
• Topical: relevant for dermal peptides (GHK-Cu); the challenge is penetration through the stratum corneum, which favors small molecules.
• Oral: the most difficult. Gastric/intestinal degradation and low permeability drastically reduce bioavailability; it requires special technologies (absorption enhancers, enzymatic protection). BPC-157 stands out for its relative gastric stability.

The general rule: the more "convenient" the route (oral, topical), the greater the bioavailability challenge; the parenteral route solves it by delivering the molecule intact.

Educational content for scientific purposes. It distinguishes preclinical from clinical evidence and is not medical advice, diagnosis or a recommendation for use. NeoPeptidos products are sold labelled for research use only (RUO).