Development and Validation of Stability-Indicating RP-UPLC Method for Simultaneous Determination of Related Substances of S(−)Amlodipine and S(−)Metoprolol Succinate in Fixed Dose Combination Tablet Dosage Form

Table 2

Forced degradation conditions and results.

Condition	Degrading agents/conditions	Exposure period	% degradation
			Metoprolol Succinamide impurity	Amlodipine related compound-A	Any individual impurity	Total Impurities
Control sample	Untreated	NA		BLQ	0.071	0.177
Heat degradation (solid state)	—	60°C for 4 hours	BLQ	BLQ	0.078	0.186
Heat degradation (solution state)	—	60°C for 1 hour	BLQ	BLQ	0.077	0.185
Humidity degradation	75% R.H.	24 hours	BLQ	BLQ	0.073	0.120
Photolytic degradation	—	1.2 million lux hours and 200 watt hrs./m^2	BLQ	0.680	0.120	0.938
Acid degradation	0.5 N HCl, 2 mL	For 1 hour at 80°C	BLQ	0.301	0.390	0.749
Base degradation	0.5 N NaOH, 2 mL	For 1 hour at 80°C	BLQ	0.267	0.085	0.532
Peroxide degradation	5% H2O2, 5 mL	For 2 hours at 80°C	0.263	3.600	2.484	13.965

: below quantitation limit.