Biguanide

Biguanide is a class of organic compounds that contain two guanidine groups linked by a short aliphatic linker. The core features two amidinium-like units, giving a highly basic, water-soluble cationic character. The term encompasses both small-molecule drugs used in medicine and polymeric antiseptics employed in sanitation.

In medicine, the best-known biguanide is metformin, a first-line agent for type 2 diabetes. Historically, phenformin and buformin were used but were withdrawn in many markets due to safety concerns, particularly a higher risk of lactic acidosis. Metformin lowers hepatic glucose production and improves peripheral insulin sensitivity without increasing insulin secretion. It is typically well tolerated, though gastrointestinal effects are common, and the risk of lactic acidosis is increased in patients with renal impairment or certain comorbidities.

In disinfection and antisepsis, biguanides include bis-biguanide compounds such as chlorhexidine and polyhexamethylene biguanide (PHMB). They are widely used as skin antiseptics, wound cleansers, and in some ophthalmic formulations. Their antimicrobial action generally involves disruption of microbial cell membranes and interactions with cellular components, and they are typically applied at concentrations that balance efficacy with safety for host tissues.

Chemically, biguanides are basic and form salts with acids; many are highly water-soluble and can be formulated as small molecules or polymeric preparations. The class thus spans pharmaceutical agents with metabolic effects and polymeric disinfectants with broad-spectrum antimicrobial activity.

Examples include metformin, phenformin, buformin, chlorhexidine, and PHMB. The choice among them depends on the clinical or sanitization context and regulatory status.