Development and Validation of a Stability-Indicating RP-HPLC Method for the Simultaneous Estimation of Guaifenesin and Dextromethorphan Impurities in Pharmaceutical Formulations
Table 4
(a) Forced degradation data for Guaifenesin. (b) Forced degradation data for Dextromethorphan.
(a)
Degradation conditions
Guaifenesin
% degraded
Purity angle
Purity threshold
Mass balance (%)
Photo. stress (1.2 million lux hours followed by 200 Watt hours)
0.06
3.585
4.142
100.2
Exposed to humidity at 25°C and 90% RH for about 7 days
0.07
3.881
4.241
99.8
Refluxed with purified water for about 12 hours at 60°C
0.05
3.285
3.845
98.6
Refluxed with 0.5 N HCL solution for about 2 hours at 60°C
0.10
5.293
7.073
99.2
Refluxed with 0.5 N NaOH solution for about 2 hours at 60°C
0.06
3.067
3.489
98.9
Refluxed with 10% H2O2 solution for about 30 min at 60°C
0.13
2.755
3.607
98.3
Exposed to dry heat for about 15 hours at 105°C
0.07
3.346
4.331
99.4
(b)
Degradation conditions
Dextromethorphan
% degraded
Purity angle
Purity threshold
Mass balance (%)
Photo. stress (1.2 Million lux hours followed by 200 Watt hours)
0.01
0.115
0.242
99.8
Exposed to humidity at 25°C and 90% RH for about 7 days
0.01
0.124
0.261
99.5
Refluxed with purified water for about 12 hours at 60°C
0.01
0.101
0.261
98.9
Refluxed with 0.5 N HCL solution for about 2 hours at 60°C
0.02
0.154
0.262
98.1
Refluxed with 0.5 N NaOH solution for about 2 hours at 60°C
0.01
0.103
0.256
99.2
Refluxed with 10% H2O2 solution for about 30 min at 60°C