High Purity Salcaprozate Sodium SNAC Oral Absorption Enhancer

1. Description

Salcaprozate Sodium is a synthetic small-molecule osmotic enhancer. Its chemical name is sodium N-[8-(2-hydroxybenzoyl)amino]octanoate, and it is a sodium salt of a salicylic acid N-acetylated amino acid derivative. It appears as a white to off-white crystalline solid powder, is soluble in water and organic solvents, and has a melting point of 150–160°C. Its molecular formula is C₁₅H₂₀NNaO₄, and its molecular weight is approximately 301.31 Da. This compound has an amphiphilic molecular structure, containing a hydrophobic aromatic group (2-hydroxybenzamide) and a hydrophilic carboxylic acid group, capable of forming sodium carboxylate and phenolic structures. Storage conditions: the powder can be stored for 3 years at -20°C or sealed at 4°C. The U.S. FDA classifies it as a substance generally recognized as safe (GRAS).

2. Application

(1) Oral drug delivery research: Used as an absorption enhancer to improve the oral bioavailability of macromolecular drugs (such as peptides and proteins). The most successful application was in the formulation development of oral semaglutide tablets, the world’s first approved oral glucagon-like peptide-1 receptor agonist.

(2) Formulation Development and Process Research: Used in formulation and process studies for oral solid dosage forms, acting as a functional excipient to improve drug permeability through the intestinal mucosa. In a Caco-2 monolayer model, SNAC significantly increases the apparent permeability coefficient of drugs (by 2.14-fold and 3.68-fold at concentrations of 50 and 200 μg/mL, respectively).

(3) Oral Delivery Studies of Macromolecular Drugs: Feasibility studies on the oral delivery of macromolecular drugs such as heparin and vitamin B12. A composite formulation of SNAC and vitamin B12 (Eligen®-B12) has been approved by the FDA as a medical food.

(4) Studies on permeation mechanisms at the cellular level: Used in Caco-2 monolayer models to investigate changes in the apparent permeability coefficient of drugs and their mechanisms of action. Studies indicate that SNAC exhibits no significant cytotoxicity to Caco-2 cells within a concentration range of 12.5–400 μg/mL; cell survival rates remain above 90% even at a concentration of 200 μg/mL.

(5) Research on novel delivery systems: By preparing different salt forms of SNAC (e.g., choline salt, phosphatidylcholine salt), its solubility, stability, and permeation-enhancing efficiency are improved, thereby enhancing the oral delivery performance of macromolecular drugs.

3. Main Efficacy

(1) Formation of hydrophobic ion pairs and increased lipophilicity: SNAC interacts hydrophobically with peptide/protein drugs through the hydrophobic aromatic groups on its molecule, forming non-covalent complexes that increase the drug’s lipophilicity. The formation of these hydrophobic ion pairs is similar to the salt-forming process, which reduces the water solubility of ionizable peptides, thereby enhancing their transcellular permeability.

(2) Enhancement of Transcellular Permeation in Small Intestinal Epithelial Cells: By increasing the lipophilicity of the drug, SNAC promotes the passive transcellular transport of macromolecular drugs through small intestinal epithelial cells. In vitro studies show that SNAC treatment can increase the apparent permeability coefficient of the drug by 2.14–3.68-fold.

(3) Regulation of membrane fluidity and lipid dynamics: Solid-state NMR studies have quantitatively demonstrated for the first time that SNAC concentration-dependently enhances the fluidity of the phospholipid bilayer; at a concentration of 72 mM, it increases the fluidity of the hydrophobic core by 43%, which is significantly greater than the enhancement observed in the interfacial region. This membrane-disturbing effect promotes drug transmembrane transport.

(4) Local pH Modulation and Enzyme Inhibition in the Stomach: In the oral delivery of peptide drugs, SNAC elevates local pH in the stomach, promoting the drug’s existence in its monomeric form, while simultaneously inhibiting pepsin activity. This reduces enzymatic degradation of peptide drugs in the stomach and protects drug integrity.

(5) Enhancement of Oral Absorption of Macromolecular Drugs: In animal models, SNAC significantly improves the oral absorption and bioavailability of various macromolecular drugs, including heparin, vitamin B12, and growth hormone-releasing hormone analogues. In studies in rats, SNAC demonstrated a dose-dependent enhancement of absorption.