Abstract
Two spectrophotometric methods are described for the determination of isoniazid (INH) in pharmaceuticals. In the first method (FCR method), INH is reacted with Folin-Ciocalteu reagent in Na2CO3medium and the resulting blue colored chromogen measured at 760 nm. Iron(II), formed as a result of reaction between INH and iron(III), is made to react with ferricyanide, and the resulting Prussian blue is measured at 760 nm, basing the second method (FFC method). The conditions for better performance are optimized. Beer’s law is obeyed in the concentration ranges 0.5–10 and 0.2–3.0 μg mL−1for FCR method and FFC methods, respectively, with corresponding molar absorptivity values of1.12×104and4.55×104 L mol−1 cm−1. The methods are validated for accuracy, precision, LOD, LOQ, robustness, and ruggedness as per the current ICH guidelines. The validated methods were successfully applied to quantify INH in its commercial formulation with satisfactory results; hence the methods are suitable for isoniazid determination in bulk drugs and pharmaceuticals.
Highlights
Isoniazid (INH) (Figure 1), chemically known as pyridine4-carboxylic acid hydrazide, is an antitubercular drug widely used together with rifampicin and streptomycin for the chemotherapy of tuberculosis
The drug is official in Indian Pharmacopoeia (IP) [1], British Pharmacopoeia (BP) [2], and United State Pharmacopoeia (USP) [3]
Apart from the above official methods, a number of methods based on several techniques are found in the literature for INH and include titrimetry [4,5,6,7], voltammetry [8,9,10,11,12,13], ion selective electrode-potentiometry [14,15,16,17,18,19], amperometry [20, 21], spectrofluorimetry [22, 23], chemiluminescence spectrometry [24,25,26,27,28,29,30,31,32,33], high performance liquid chromatography (HPLC) [34,35,36,37], gas chromatography (GC) [38,39,40], LC/LC-MS [41], and capillary electrophoresis [42,43,44]
Summary
Isoniazid (INH) (Figure 1), chemically known as pyridine4-carboxylic acid hydrazide, is an antitubercular drug widely used together with rifampicin and streptomycin for the chemotherapy of tuberculosis This has prompted many investigators to devise methods for its determination in its pure form as well as in its tablet form. Methods were based on a variety of reaction schemes such as nucleophilic substitution [45], condensation [46,47,48,49], charge-transfer and ionpair [50], derivatization [51,52,53,54], diazo-coupling [55, 56], oxidative coupling [57, 58], complex formation [59,60,61], and redox followed by complexation [62,63,64,65] These methods suffer from one or more of the disadvantages such as drastic experimental conditions, use of organic solvent, longer standing time, poor sensitivity, and narrow linear range.
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