Development and Validation of a Stability-Indicating RP-HPLC Method for the Simultaneous Estimation of Guaifenesin and Dextromethorphan Impurities in Pharmaceutical Formulations
Table 2
(a) Structures of Guaifenesin impurities. (b) Structures of Dextromethorphan impurities.
(a)
Impurity name
Chemical name
Chemical structure
Impurity A (degradant)
2-Methoxyphenol
Impurity B (degradant)
2-(2-Methoxyphenoxy)propane-1,3-diol
Impurity C (degradant)
1,1′-Oxybis[3-(2-methoxyphenoxy)propan-2-ol]
Impurity D (process related impurity)
1,3-Bis(2-methoxyphenoxy)propan-2-ol
(b)
Impurity name
Chemical name
Chemical structure
Impurity A (degradant)
Ent-3-methoxymorphinan
Impurity B (degradant)
Ent-17-methylmorphinan-3-ol
Impurity C (degradant)
Ent-3-methoxy-17-methylmorphinan-10-one
N-Oxide (degradant)
3-Methoxy-N-methylmorphinan N-oxide
N-Formyl Morphine (NFM) (process related impurity)