Biguanidios

Biguanidios are a class of chemical compounds that feature two guanidine units linked to form a bisguanidine (biguanide) core. This arrangement gives many members a highly basic, water-soluble character and the ability to form multiple hydrogen bonds, contributing to strong interactions with biological molecules and surfaces.

Classification and structure

Biguanidios can be monomeric bis-biguanides, where two guanidine units are joined within a single molecule, or polymeric biguanides, where repeating biguanide units are linked by spacers. The core biguanide motif is responsible for much of their chemical behavior, including cationic charge under physiological conditions.

Examples and applications

In medicine, small-molecule biguanides such as metformin are widely used as antidiabetic agents that reduce hepatic glucose production and improve insulin sensitivity. Earlier biguanides like phenformin and buformin were used but largely withdrawn due to metabolic risks, notably lactic acidosis. In antiseptics, bisbiguanides such as chlorhexidine and polymeric biguanides like polyhexamethylene biguanide (PHMB) are used for their broad antimicrobial activity and material compatibility, including wound care and water treatment.

Production and chemistry

Biguanide units can be formed through condensation reactions of guanidine derivatives or related precursors. Polymeric biguanides are produced by stepwise or polycondensation methods that link repeating biguanide units with flexible spacers, yielding materials with persistent cationic character and strong binding properties.

Safety and regulation

Because the safety profile varies across the class, regulatory status follows specific compound and application. Metformin remains a first-line antidiabetic medicine with well-established safety monitoring. Phenformin and some other bisbiguanides have been restricted or withdrawn in many regions. Topical antiseptics like chlorhexidine and PHMB are generally considered safe within approved uses but can cause irritation or allergic reactions in some individuals.

See also

Guanidine, biguanide, metformin, chlorhexidine, polyhexamethylene biguanide.