Synthesis, characterization, solubility and stability studies of hydrate cocrystal of antitubercular Isoniazid with antioxidant and anti-bacterial Protocatechuic acid

• Hydrate cocrystals of Isoniazid with anti-oxidant Protocatechuic acid.
• Single Crystal XRD studies of the Isoniazid-hydroxy benzoic acid cocrystals.
• Infra-red (IR) studies of the Isoniazid-hydroxy benzoic acid cocrystals.
• Differential Scanning Calorimetric (DSC) studies of the Isoniazid-hydroxy benzoic acid cocrystals.
• Solubility and Stability studies.

Isoniazid is an important component used in “triple therapy” to combat tuberculosis. It has reduced Tabletting formulations stability. Anti-oxidants are obligatory to counter oxidative stress, pulmonary inflammation, and free radical burst from macrophages caused in tuberculosis and other diseases. In the present study a hydrate cocrystal of Isoniazid with anti-oxidant and anti-inflammatory and anti-bacterial Protocatechuic acid (3,4-dihydroxybenzoic acid) in 1:1 is reported. This Cocrystal may have improved tabletting stability and anti-oxidant properties. Cocrystal structure analysis confirmed the existence of pyridine-carboxylic acid synthon in the Cocrystal. Other synthons of different graph sets involving NH···O and OH···N bonds are formed between hydrazide group of isoniazid and coformer. Solubility studies revealed that cocrystal is less soluble as compared to isoniazid in buffer at pH 7.4 at 22 °C while stability studies at 80 °C for 24 h period disclosed the fact that cocrystal has higher stability than that of isoniazid.

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