Sequential Spectrophotometric Method for the Simultaneous Determination of Amlodipine, Valsartan, and Hydrochlorothiazide in Coformulated Tablets

Table 2

Determination of AML, VAL, and HCT in Exforge HCT tablets by the proposed method and the reported HPLC method [23] and application of standard addition technique.

Product	Drug	Proposed method	Reported method^a	Standard addition
				Taken (μg/mL)	Added (μg/mL)	Found (μg/mL)	Recovery %^b
Exforge HCT 5/160/12.5	AML	99.91±1.069	100.40±0.636	6	4	3.994	99.85
					6	6.074	101.23
					8	7.884	98.55
						Mean  ±  RSD	99.88  ±  1.344
	VAL	99.50±0.951	100.13±0.884	16	12	12.259	102.16
					16	16.14	100.88
					20	20.175	100.88
						Mean  ±  RSD	101.30  ±  0.730
	HCT	99.83±1.282	100.13±0.729	9.375	6.25	6.329	101.27
					9.375	9.319	99.4
					12.5	12.645	101.16
						Mean  ±  RSD	100.61  ±  1.041
Exforge HCT 5/160/25	AML	101.01±1.650	99.85±0.970	6	4	3.985	99.61
					6	6.121	102.02
					8	7.987	99.84
						Mean  ±  RSD	100.49  ±  1.326
	VAL	100.27±1.403	100.00±0.859	16	12	11.935	99.46
					16	16.379	102.37
					20	20.171	100.86
						Mean  ±  RSD	100.89  ±  1.440
	HCT	99.26±1.493	99.71±0.693	9.375	6.25	6.334	101.34
					9.375	9.533	101.68
					12.5	12.524	100.19
						Mean  ±  RSD	101.07  ±  0.774
Exforge HCT 10/320/25	AML	100.20±1.173	100.37±0.712	6	4	4.01	100.24
					6	5.934	98.91
					8	8.038	100.47
						Mean  ±  RSD	99.87  ±  0.846
	VAL	99.93±0.897	100.55±0.595	16	12	12.101	100.84
					16	15.949	99.68
					20	19.797	98.99
						Mean  ±  RSD	99.84  ±  0.939
	HCT	99.75±1.045	100.23±0.825	9.375	6.25	6.344	101.5
					9.375	9.27	98.88
					12.5	12.761	102.09
						Mean  ±  RSD	100.82  ±  1.695

aHPLC method using Luna C₁₈ column, a mobile phase consisting of methanol-phosphate buffer (30 mM, pH 5.5) (62 : 38 by volume) at a flow rate of  1 mL/min, and UV detection at 234 nm.
bAverage of three determinations.