Biguanides

Biguanides are a class of organic compounds that contain two guanidine groups connected by a central framework. They occur in a variety of contexts, but two areas dominate: antidiabetic medications and antiseptic disinfectants.

In medicine, the best known biguanides are the antidiabetic agents, led by metformin. Metformin reduces hepatic glucose production and improves insulin sensitivity, effects that are partly mediated by activation of AMP-activated protein kinase (AMPK). It is widely used as a first-line therapy for type 2 diabetes and is typically taken orally as part of a lifestyle plan that includes diet and exercise. Unlike some other glucose-lowering drugs, metformin does not usually cause hypoglycemia when used alone. Common adverse effects are gastrointestinal, and a rare but serious risk is lactic acidosis, especially in people with significant renal impairment, liver disease, or conditions predisposing to hypoxia. Historically, phenformin and buformin were also used, but phenformin was withdrawn in many countries due to the risk of lactic acidosis.

Biguanides are also used as antiseptics and disinfectants. Compounds such as chlorhexidine and polyhexamethylene biguanide (PHMB) have broad-spectrum activity and are employed in skin antisepsis, wound care, mouthwashes, and various consumer and healthcare products. Their antimicrobial action involves disruption of microbial membranes and coagulation of cytoplasmic contents, with efficacy influenced by concentration and formulation. Safety considerations include potential skin irritation and rare systemic effects if large amounts are absorbed.