Research Article

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 conditionsGuaifenesin
% degradedPurity anglePurity thresholdMass balance (%)

Photo. stress (1.2 million lux hours followed by 200 Watt hours)0.063.5854.142100.2
Exposed to humidity at 25°C and 90% RH for about 7 days0.073.8814.24199.8
Refluxed with purified water for about 12 hours at 60°C0.053.2853.84598.6
Refluxed with 0.5 N HCL solution for about 2 hours at 60°C0.105.2937.07399.2
Refluxed with 0.5 N NaOH solution for about 2 hours at 60°C0.063.0673.48998.9
Refluxed with 10% H2O2 solution for about 30 min at 60°C0.132.7553.60798.3
Exposed to dry heat for about 15 hours at 105°C0.073.3464.33199.4

(b)

Degradation conditionsDextromethorphan
% degradedPurity anglePurity thresholdMass balance (%)

Photo. stress (1.2 Million lux hours followed by 200 Watt hours)0.010.1150.24299.8
Exposed to humidity at 25°C and 90% RH for about 7 days0.010.1240.26199.5
Refluxed with purified water for about 12 hours at 60°C0.010.1010.26198.9
Refluxed with 0.5 N HCL solution for about 2 hours at 60°C0.020.1540.26298.1
Refluxed with 0.5 N NaOH solution for about 2 hours at 60°C0.010.1030.25699.2
Refluxed with 10% H2O2 solution for about 30 min at 60°C1.050.1020.25099.7
Exposed to dry heat for about 15 hours at 105°C0.010.0990.26198.7