BRIEFING

 Doxepin Tablets. Because there is no existing USP monograph for this drug product, a new monograph based on validated methods of analysis is proposed.

1. The liquid chromatographic procedure in the Assay was validated using the Licrosphere RP-Select B brand of column with L7 packing. The typical retention times for the doxepin (E)-isomer and doxepin (Z)-isomer are about 16 and 18 min, respectively.

2. The liquid chromatographic procedure in the test for Organic Impurities was validated using the Inertsil C8-3 brand of column with L7 packing. The typical retention time for doxepin is about 18 min.

3. The liquid chromatographic procedure in Dissolution Test 1 was validated using the Licrosphere RP-Select B brand of column with L7 packing. The typical retention times for the doxepin (E)-isomer and doxepin (Z)-isomer are about 10 and 11 min, respectively.

 (SM4: Q. Huynh)

 Case ID—SUB-471, SUB-1595