Bisbiguanide

Bisbiguanide refers to a class of antiseptic compounds that contain two biguanide groups. The best known member is chlorhexidine, a cationic antiseptic used widely in healthcare and dentistry. In chlorhexidine, two 4-chlorophenyl biguanide units are linked by a hexamethylene chain, and the compound is typically applied as a digluconate salt. The multiple positive charges promote strong binding to negatively charged surfaces such as bacterial cell walls and mucous membranes, contributing to rapid antimicrobial action and substantial residual activity.

The mechanism of action involves disruption of microbial cell membranes and leakage of intracellular contents, along with interference with cytoplasmic proteins. This leads to rapid bactericidal or fungicidal effects depending on the organism. Chlorhexidine exhibits broad-spectrum activity, effective against many Gram-positive and Gram-negative bacteria and some yeasts, with limited activity against bacterial spores and certain non-enveloped viruses. Its effectiveness can be reduced when it binds to anionic substances or organic matter, and it is generally not considered active against spores.

Common uses include mouthrinses (often 0.12% or 0.2%), topical antisepsis for skin and wound care, and preoperative skin preparation in clinical settings. In dentistry, chlorhexidine is used to reduce dental plaque and gingivitis. It is sometimes found in irrigants and endodontic procedures. Cautions include potential tooth staining, taste alteration, and mucosal irritation with prolonged use; rare allergic reactions can occur. It is often inactivated by anionic detergents and certain dentifrices, so products containing chlorhexidine are usually used separately from such substances.