Cetylpyridinium Chloride Monohydrate - Antimicrobial CAS 6004-24-6

Cetylpyridinium Chloride Monohydrate - Properties, Applications, and Safety

1. Introduction

Cetylpyridinium chloride monohydrate (CPC, CAS 6004-24-6) is a cationic quaternary ammonium compound with a long cetyl (C16) hydrophobic chain attached to a pyridinium ring. It is a white to off-white crystalline powder that is soluble in water and alcohols. As a surface-active agent with potent antimicrobial properties, CPC is widely used in oral care products, disinfectants, cosmetics, and industrial applications. Its mechanism of action relies on the disruption of microbial cell membranes through electrostatic interactions, leading to cell lysis and death.

2. Chemical and Physical Properties

CPC monohydrate has the molecular formula C₂₁H₃₈ClN·H₂O and a molecular weight of 358.01 g/mol. Key physicochemical properties include:

• Appearance: White to off-white or faint beige crystalline powder

• Melting Point: 81–86°C

• pH (10 g/L, H₂O, 20°C): 5.0–5.4

• Water Solubility: 50 g/L at 20°C

• Bulk Density: Approximately 370 kg/m³

• Purity: ≥98% (typical), with USP specifications of 98.0–102.0% calculated on the anhydrous basis

The compound is incompatible with strong oxidizing agents, acids, and anionic detergents, which may precipitate CPC from solution.

3. Mechanism of Antimicrobial Action

CPC exerts its antimicrobial effect through a well-established mechanism. As a cationic surfactant, the positively charged pyridinium head group interacts electrostatically with the negatively charged components of microbial cell membranes. This interaction disrupts membrane integrity, causing leakage of intracellular components and ultimately leading to cell lysis and death. CPC is effective against a broad spectrum of microorganisms, including Gram-positive and Gram-negative bacteria, fungi, and certain viruses. Studies have demonstrated significant in vitro activity against Helicobacter pylori with MICs ranging from 0.16 to 0.62 μg/mL.

4. Applications

Oral Care Products: CPC is widely used as an antiseptic in mouthwashes, toothpastes, throat sprays, and lozenges. It is effective in preventing dental plaque and reducing gingivitis. Combined use with sodium fluoride in mouthrinses can control oral bacteria and protect tooth enamel.

Disinfectants and Antiseptics: Used in antiseptic solutions, wound cleansers, and surface disinfectants due to its broad-spectrum antimicrobial activity.

Cosmetics and Personal Care: Incorporated into creams, lotions, shampoos, and deodorants as a preservative and antimicrobial agent.

Industrial Applications: Used as a surfactant, emulsifier, and antimicrobial agent in textile processing, cleaning products, and industrial formulations.

5. Safety and Toxicology

CPC monohydrate is classified as a hazardous substance with the following hazard statements:

• H302: Harmful if swallowed

• H315: Causes skin irritation

• H318: Causes serious eye damage

• H330: Fatal if inhaled

• H335: May cause respiratory irritation

• H410: Very toxic to aquatic life with long-lasting effects

CPC is considered a moderate to severe irritant to the skin and eyes. It is also recognized as a pharmaceutically active ingredient. When used in oral care products at recommended concentrations (typically 0.05–0.1%), CPC is considered safe and effective for its intended use.

6. Storage and Handling

CPC monohydrate should be stored in tightly sealed containers in a cool, dry place, protected from light and moisture. The compound is combustible and incompatible with strong oxidizing agents and acids. Use appropriate personal protective equipment (gloves, safety goggles, protective clothing) when handling. In case of skin or eye contact, rinse thoroughly with water and seek medical attention if irritation persists. Do not let the product enter drains or waterways.

7. Conclusion

Cetylpyridinium chloride monohydrate (CAS 6004-24-6) is a versatile cationic quaternary ammonium compound with potent antimicrobial and surface-active properties. Its ability to disrupt microbial cell membranes makes it an effective antiseptic in oral care products, disinfectants, and personal care formulations. When used at recommended concentrations, CPC provides reliable antimicrobial protection with an acceptable safety profile. Ongoing research continues to explore its potential in new applications, including anti-virulence strategies against drug-resistant pathogens and combination therapies for enhanced efficacy.