Chlorhexidine (CHX)

Chlorhexidine – Broad-Spectrum Biguanide Antiseptic and Disinfectant

Basic Information

• CAS Number: 55-56-1 (base) 

• Molecular Formula: C₂₂H₃₀Cl₂N₁₀ 

• Molecular Weight: 505.45 g/mol

• Appearance: White to off-white crystalline powder 

• Melting Point: 134–136°C 

• Solubility: Slightly soluble in water (approx. 0.08% at 20°C) ; soluble in DMSO and methanol 

• pKa: 10.78 

• Stability: Stable under normal conditions 

Overview
Chlorhexidine (CHX) is a chemical agent composed of two biguanide compounds linked by a hexamethylene bridge. This structure confers a positive charge with basic properties, enabling strong electrostatic interaction with negatively charged microbial cell surfaces. It is a broad-spectrum biocide active against Gram‑positive bacteria, Gram‑negative bacteria, and fungi. Chlorhexidine is considered one of the most effective and widely used antiseptic agents in medical practice.

Mechanism of Action
Chlorhexidine exerts its antimicrobial effects through membrane disruption. The positively charged chlorhexidine molecule binds to negatively charged phosphate groups on microbial cell surfaces, causing loss of osmoregulation and metabolic energy at low concentrations, and leakage of cytosolic contents at higher concentrations. It has both bacteriostatic (inhibits growth) and bactericidal (kills bacteria) mechanisms, depending on concentration.

Applications

• Healthcare: Skin antisepsis, surgical hand scrubs, wound cleansing, and catheter site disinfection.

• Dentistry: Mouthwashes, toothpastes, and periodontal therapy for plaque control and gingivitis reduction.

• Personal care: Antiseptic washes, soaps, and leave‑on products.

• Veterinary and agriculture: Disinfectant for bacterial control in agricultural and domestic environments.

• Industrial: Antimicrobial agent in paints, coatings, and textile finishes.

Key Benefits

• Broad-spectrum antimicrobial activity.

• Effective at low concentrations.

• Long-lasting residual activity on skin and mucous membranes.

• Low systemic toxicity when used topically.

• Available in multiple salt forms (gluconate, acetate, hydrochloride) for various applications.

Safety and Handling

• Generally recognized as safe for topical use at recommended concentrations.

• May cause mild skin or mucosal irritation in sensitive individuals.

• Avoid contact with eyes and prolonged exposure to high concentrations.

• Store in a cool, dry place, protected from light and moisture.

• Use appropriate personal protective equipment (gloves, safety goggles) when handling concentrated powder.

Quality Assurance
Each batch is tested for purity (≥98% by HPLC), melting point, and solubility to ensure consistent quality.