Salcaprozate Sodium: Breakthrough Oral Absorption Enhancer for Peptide Drug Delivery Systems

1. Description

Salcaprozate Sodium (SNAC) is a synthetic small-molecule compound with the chemical name sodium 8-(2-hydroxybenzoylamido)octanoate. Its molecular formula is C₁₅H₂₀NNaO₄, and its molecular weight is approximately 301.31 Da. It appears as a white to off-white or pale yellow solid powder. Regarding solubility, it is soluble in DMSO (solubility up to 50 mg/mL) and slightly soluble in water. Storage conditions require refrigeration at 2–8°C in a sealed, moisture-proof container; the powder can be stored for 3 years at –20°C. This compound acts as an intestinal osmotic enhancer; by increasing lipophilicity, it promotes non-covalent macromolecular complexation, thereby enhancing passive transcellular transport in small intestinal epithelial cells.

2. Application

(1) Oral drug delivery research: Used as an absorption enhancer to improve intestinal absorption of drugs with poor oral bioavailability (such as peptides and proteins); the most typical application is in the development of oral semaglutide formulations.

(2) Formulation development and process research: Used in formulation and process studies for oral solid dosage forms; as a functional excipient, it improves the drug’s ability to penetrate the intestinal mucosa.

(3) Drug Delivery System Research: Used as an absorption enhancer in oral formulations of somatostatin analogs (e.g., octreotide enteric-coated capsules) to increase cell permeability by altering gastrointestinal membrane fluidity.

(4) Oral Delivery Research for Macromolecular Drugs: Used to explore the feasibility of oral delivery for macromolecular drugs such as heparin and vitamin B12.

(5) Research on permeation mechanisms at the cellular level: Used in Caco-2 cell monolayer models to study changes in the apparent permeability coefficient of drugs and their mechanisms of action.

3. Main Efficacy

(1) Enhancement of intestinal drug absorption: By increasing lipophilicity through non-covalent macromolecular complexation, SNAC promotes passive transcellular permeation of drugs through small intestinal epithelial cells, thereby improving oral bioavailability. In vitro studies showed that SNAC (at concentrations of 50 and 200 μg/mL) increased the apparent permeability coefficient of the test drug by 2.14-fold and 3.68-fold, respectively.

(2) Improving the bioavailability of oral formulations: In in vivo studies in rats, SNAC improved oral drug absorption and increased bioavailability.

(3) Safety profile at the cellular level: In Caco-2 cells, SNAC (12.5–400 μg/mL; 24 hours) exhibited no significant cytotoxicity, with cell survival rates remaining above 90% even at a concentration of 200 μg/mL.

(4) Stability as a functional excipient: It functions stably as an absorption enhancer in oral solid dosage forms and has been used in approved oral peptide drug formulations.

(5) Modulation of cell membrane permeability: It enhances cell permeability by altering the fluidity of gastrointestinal cell membranes and increasing the release of intracellular proteins.

(6) Safety profile: The U.S. FDA has classified it as Generally Recognized as Safe (GRAS). In subchronic toxicity studies in rats, no mortality was observed at doses as high as 1000 mg/kg/day.