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 2

(a) Structures of Guaifenesin impurities. (b) Structures of Dextromethorphan impurities.
(a)

Impurity nameChemical nameChemical structure

Impurity A (degradant)2-Methoxyphenol315145.tab.002a

Impurity B (degradant)2-(2-Methoxyphenoxy)propane-1,3-diol315145.tab.002b

Impurity C (degradant)1,1′-Oxybis[3-(2-methoxyphenoxy)propan-2-ol]315145.tab.002c

Impurity D (process related impurity)1,3-Bis(2-methoxyphenoxy)propan-2-ol315145.tab.002d

(b)

Impurity nameChemical nameChemical structure

Impurity A (degradant)Ent-3-methoxymorphinan315145.tab.002e

Impurity B (degradant)Ent-17-methylmorphinan-3-ol315145.tab.002f

Impurity C (degradant)Ent-3-methoxy-17-methylmorphinan-10-one315145.tab.002g

N-Oxide (degradant)3-Methoxy-N-methylmorphinan N-oxide315145.tab.002h

N-Formyl Morphine (NFM) (process related impurity)3-Methoxy-6,7,8,8a,9,10-hexahydro-5H-9,4b-(epiminoethano)phenanthrene-11-carbaldehyde315145.tab.002i

N-Formyl octabase (NFO) (process related impurity)(S)-1-(4-Methoxybenzyl)-3,4,5,6,7,8-hexahydroisoquinoline-2(1H)-carbaldehyde315145.tab.002j