biguanidi

Biguanides are a family of organic compounds characterized by two guanidine functional groups linked through a central scaffold. The term covers a range of substances with diverse uses, notably the antidiabetic drug metformin (a dimethylbiguanide) and various antiseptics such as chlorhexidine and polyhexamethylene biguanide. While sharing a common structural motif, individual members differ in activity, toxicity, and clinical indications.

Chemically, biguanides feature two related guanidine units connected by carbon-nitrogen linkages, yielding a highly polar, polycationic molecule at physiological pH. This configuration underlies interactions with biological membranes and enzymes and influences pharmacokinetics and antimicrobial properties. Substituents on the guanidine nitrogens modulate lipophilicity and spectrum of activity.

In medicine, metformin, the most widely used biguanide, serves as first-line therapy for type 2 diabetes. It lowers hepatic glucose production, improves insulin sensitivity, and modestly reduces intestinal glucose absorption, with a low risk of causing hypoglycemia. Other biguanides such as phenformin and buformin were once prescribed but were associated with lactic acidosis and were withdrawn in many markets. Metformin remains standard in many clinical guidelines.

Biguanides with antiseptic activity include chlorhexidine and polyhexamethylene biguanide (PHMB). They act by binding to negatively charged cell membranes, disrupting integrity and causing leakage. They have broad-spectrum activity against bacteria and fungi and are used in mouthwashes, skin disinfectants, wound care, and coated medical devices. Toxicity is generally low but can include mucosal irritation in some formulations.

The biguanide class thus spans both therapeutic drugs and antiseptic agents. Safety considerations and regulatory status vary by compound and intended use.