A nonionic water-insoluble surfactant used as cosurfactant in oral lipid-based formulation SEDDS and SMEDDS. Cosurfactant and solubilizer in topical dosage forms.

Names & synonyms

USP NF Name

Propylene Glycol Monocaprylate NF
[May also be labeled as Propylene Glycol Monocaprylate (type II) NF until December 1, 2026]

EP Name

/

UNII Code (FDA)

RT9P9S09QI

Preferred Substance Name (FDA)

PROPYLENE GLYCOL CAPRYLATE

Handbook of Pharmaceutical Excipients

Propylene glycol monocaprylate

Chemical description

Consists of propylene glycol esters of caprylic acid (C8), mainly composed of monoesters and a small fraction of diesters.

Key characteristics

Product form

Oily liquid

Viscosity (mPa.s)

20 (20°C)

HLB

5

oil_molecule

Main functionalities

Solubilizer for poorly-soluble APIs and bioavailability enhancer. Co-surfactant in LFCS Type II (SEDDS) and Type III (SMEDDS) formulations.

Solubilizer and skin penetration enhancer. Co-surfactant for microemulsion in topical formulation.

Safety of use is inferred by precedence of use in approved pharmaceutical products.

Main formulation technologies

Associated content

Excipients for solubility and bioavailability enhancement

Poor solubility, poor permeability, and pre-systemic elimination are factors that…

Selecting penetration enhancers, for transdermal delivery

To overcome the skin barrier properties, many strategies exist, among which the use…