Isonicotinic acid is a pyridinemonocarboxylic acid in which the carboxy group is at position 4 of the pyridine ring..It has a role as a human metabolite and an algal metabolite. It is a conjugate acid of an isonicotinate.
Isonicotinic acid or 4-pyridinecarboxylic acid is an organic compound with the formula C5H4N(CO2H). It is a derivative of pyridine with a carboxylic acid substituent at the 4-position. It is an isomer of picolinic acid and nicotinic acid which has the carboxyl group at the 2- and 3-position respectively compared to the 4-position for isonicotinic acid.