besilate

Besilate is a chemical term used in pharmacology and chemistry to denote a salt formed from a basic compound with benzenesulfonic acid, resulting in a benzenesulfonate salt. The term is used in the naming of certain drug substances; in some sources the salt is referred to as a besylate (or benzenesulfonate), with spelling variants depending on jurisdiction.

In a besilate, the drug molecule typically exists as a positively charged cation paired with the negatively charged benzenesulfonate (C6H5SO3−) anion. The exact stoichiometry depends on the base, particularly for polybasic centers that can form mono- or polyprotonated forms. The solid form generally appears as crystalline salt.

Besilates are prepared by neutralization or salt metathesis reactions, combining the free base or an existing salt of the drug with benzenesulfonic acid or its salt. They often improve water solubility, facilitate manufacturing and formulation, and can influence dissolution rate and, in some cases, bioavailability. The besilate moiety itself is an inert counterion in most pharmaceutical contexts.

Applications and considerations: Besilate salts are widely used in pharmaceutical formulations to enable oral or injectable administration. The choice of salt form depends on factors such as solubility, stability, taste masking, and regulatory or patent considerations. The therapeutic activity is attributed to the parent drug; the besilate serves primarily to modulate physicochemical properties.

See also: Besylate; Benzenesulfonate; Salt form (pharmacology). Safety and regulatory notes: consult product labeling, as sulfonate-containing salts can interact with specific formulations or patient conditions, though primary pharmacology remains that of the active drug.