Stability Indicating Liquid Chromatographic Method for Estimation of Trihexyphenidyl Hydrochloride and Risperidone in Tablet Formulation: Development and Validation Consideration

Table 3

Degradation of THP and RSP at different stress conditions.

Stress condition/strength/duration	Drugs	Peak area	% Assay of drug after degradation	% Degradation
Acidic/2 N HCl/45 min	RSP	68539	79.09%	20.90%
	THP	20852	82.46%	17.53%
Basic/1 N NaOH/60 min	RSP	75677	87.29%	12.70%
	THP	20710	89.79%	18.09%
Oxidative/6% H2O2/2 hr	RSP	74820	86.33%	13.66%
	THP	19901	75.53%	24.46%
Thermal/dry heating/80°C/60 min	RSP	86689	99.99%	No degradation
	THP	25286	99.99%	No degradation
Photolytic/UV light/60 min	RSP	76385	91.60%	11.88%
	THP	22528	95.02%	10.90%