A Stability-Indicating High Performance Liquid Chromatographic Assay for the Simultaneous Determination of Pyridoxine, Ethionamide, and Moxifloxacin in Fixed Dose Combination Tablets

Table 1

Preparation of seven different concentrations of pyridoxine, ethionamide, and moxifloxacin standards for linearity determination.

(a)

Stock standard solution preparation
Pyridoxine:	12.5 mg/25 mL* = 500 mcg/mL
Ethionamide:	125 mg/25 mL* = 5000 mcg/mL
Moxifloxacin:	200 mg/25 mL* = 8000 mcg/mL
Final concentration of APIs in assay
Pyridoxine	10 mcg/mL
Ethionamide	100 mcg/mL
Moxifloxacin	160 mcg/mL

∗Diluent = {1 : 1 : 2, DMSO : methanol : mobile phase (A)}.

(b)

Concentration	Pyridoxine		Ethionamide		Moxifloxacin		mL of I.S.^†
(%)	Conc. (mcg/mL)	mL of stock Sol.	Conc. (mcg/mL)	mL of stock Sol.	Conc. (mcg/mL)	mL of stock Sol.
175	17.5	3.5	175	3.5	280	3.5	10
150	15	3	150	3	240	3	10
125	12.5	2.5	125	2.5	200	2.5	10
100	10	2	100	2	160	2	10
75	7.5	1.5	75	1.5	120	1.5	10
50	5	1	50	1	80	1	10
25	2.5	0.5	25	0.5	40	0.5	10
Total vol. required	—	14	—	14	—	14	70

†0.5 mg/mL of ciprofloxacin (I.S.) in diluent.