Isopropyl Myristate-Emollient and Penetration Enhancer for Cosmetics

Isopropyl Myristate (IPM) - Properties, Applications, and Safety

Isopropyl myristate (CAS 110-27-0) is the ester of isopropyl alcohol and myristic acid, a saturated fatty acid commonly derived from vegetable sources such as coconut and palm kernel oils. It is a clear, colorless, low‑viscosity liquid with a faint, characteristic odor. This ester is one of the most widely used emollients and skin conditioning agents in the cosmetic, personal care, and pharmaceutical industries, prized for its excellent spreadability, rapid absorption, and ability to reduce the greasy feel of heavy oils.

Chemical and Physical Properties

Isopropyl myristate has the molecular formula C₁₇H₃₄O₂ and a molecular weight of approximately 270.45 g/mol. The compound has a density of about 0.85 g/mL at 25°C and a boiling point of approximately 193°C at 20 mmHg. Its melting point is around -5°C to 7°C. It is practically insoluble in water but readily miscible with alcohols, ketones, ethers, mineral oils, vegetable oils, fats, waxes, and other esters. It is stable under normal storage conditions and is compatible with both oil-in-water and anhydrous systems.

Mechanism of Action

As an ester, isopropyl myristate acts primarily as an emollient, skin conditioning agent, and penetration enhancer. It works by filling the spaces between skin cells, creating a smooth, soft, and flexible surface. Due to its low viscosity and rapid spreading properties, it forms a non‑occlusive, breathable film on the skin. It is also a well‑documented penetration enhancer in pharmaceutical formulations, facilitating the delivery of active ingredients through the stratum corneum, though its exact molecular mechanism is still under investigation.

Applications

Isopropyl myristate is a versatile ingredient with a wide range of applications.

Cosmetics and Personal Care: It is a key component in moisturizers, body lotions, skin creams, sunscreens, lipsticks, foundations, makeup colors, and powders. It serves as an emollient, solvent, lubricant, spreading agent, and sensory enhancer, improving product texture, slip, and softness while reducing the greasy feel of rich formulations. It is also used in bath oils, antiperspirants, deodorants, and hair care products. In cosmetic formulations, it is used at concentrations up to 82%.

Pharmaceuticals: It is used as a penetration enhancer in topical drug delivery systems, including transdermal patches and creams. It has also been evaluated as a pediculicide (head lice treatment) at 50% concentration.

Other Applications: It serves as a raw material for spin finishes and oiling agents in textiles, a rubber processing agent, a plastic lubricant, and a paint and ink additive.

Safety and Toxicology

Isopropyl myristate is considered a safe and well‑tolerated ingredient for use in cosmetics and personal care products. The Cosmetic Ingredient Review (CIR) Expert Panel has concluded that it is safe for use in cosmetics.

• Skin Irritation: Human primary skin irritation studies showed no reactions to isopropyl myristate alone and only mild irritation from formulations containing 15% to 58% isopropyl myristate. Repeated application of undiluted isopropyl myristate for 21 days produced only slight irritation. Up to 100% concentration, it was found to be non‑irritating, non‑sensitizing, non‑phototoxic, and non‑photoallergenic.

• Sensitization: Isopropyl myristate is considered an extremely weak sensitizer. It is not a human sensitizer at 15% to 50% concentration.

• Comedogenicity: It has been noted to have mild comedogenic potential in some individuals, particularly at higher concentrations.

• Inhalation Toxicity: The CIR Expert Panel determined that there is sufficient data demonstrating no inhalation toxicity.

• Genotoxicity: Isopropyl myristate was not genotoxic in the Ames assay.

• Environmental Impact: It may cause long‑lasting harmful effects to aquatic life (H413).

Storage and Handling

Isopropyl myristate should be stored in tightly sealed containers at 5–25°C, protected from light, moisture, and strong oxidizing agents. It is stable under normal storage conditions. Use appropriate personal protective equipment (gloves, safety goggles) when handling large quantities.