From the Guidelines
Chlorhexidine works primarily by disrupting bacterial cell membranes, causing leakage of cellular components and inhibiting membrane-bound enzymes, leading to a bacteriostatic or bactericidal effect, depending on the concentration. This antiseptic agent carries a positive charge that attracts it to the negatively charged bacterial cell surfaces, where it binds to phospholipids in the cell membrane 1. At low concentrations, chlorhexidine causes leakage of low-molecular-weight cellular components and inhibits membrane-bound enzymes, creating a bacteriostatic effect. At higher concentrations, it penetrates the cell membrane completely, causing precipitation of cellular contents and cell death, making it bactericidal.
Key Characteristics of Chlorhexidine
- Chlorhexidine demonstrates substantivity, meaning it binds to oral tissues and skin, allowing for prolonged antimicrobial activity for up to 12 hours after application 1
- It has a broad spectrum of activity against gram-positive and gram-negative bacteria, some viruses, and fungi, though it is less effective against bacterial spores
- Chlorhexidine is commonly used as a 0.12% or 0.2% oral rinse for dental applications, and as a 2-4% solution for skin antisepsis before surgical procedures
Important Considerations for Use
- For optimal effectiveness in oral applications, chlorhexidine should be used after brushing, with at least 30 minutes between brushing and rinsing, as toothpaste surfactants can inactivate chlorhexidine 1
- The prolonged contact time and persistent activity make chlorhexidine particularly valuable for infection control in both dental and medical settings
- Chlorhexidine has been shown to be more effective than povidone iodine in reducing bacterial colonization and infection rates in certain clinical settings 1
From the FDA Drug Label
CLINICAL PHARMACOLOGY Paroex ® provides antimicrobial activity during oral rinsing. The mechanism of action of chlorhexidine is not explicitly stated in the drug label, but it is known to provide antimicrobial activity.
- The label mentions a general reduction of counts of certain assayed bacteria, both aerobic and anaerobic, but does not explain how this reduction occurs.
- It is implied that chlorhexidine gluconate has antibacterial properties, but the exact mechanism is not described. 2