Isolation and characterization of novel degradation products of Doxofylline using HPLC, FTIR, LCMS and NMR.

Forced degradation of Doxofylline (DFL) in different stress (base and peroxide) conditions gave rise to two potential unknown impurities. These unknown degradation products DFL DEG-I and DFL DEG-II were evaluated using a new-reverse-phase high performance liquid chromatography (HPLC), where it was eluted at 0.44 and 1.09 relative retention times to DFL peak. DFL DEG-I and DFL DEG-II were isolated using preparative HPLC from degradation mixtures. The structure of DFL DEG-I and DFL DEG-II were elucidated using high resolution MS, multi-dimensional NMR and FTIR spectroscopic techniques, and characterized. The stereochemistry of the enantiomers in DFL DEG-II has further been investigated using computational techniques. To the best of our knowledge, DFL DEG-I and DFL DEG-II are novel impurities and not reported elsewhere.

Isolation and structural characterization of novel photolytic degradation impurities of Deflazacort using Q-TOF, 2D-NMR and FTIR.

Forced Degradation of Deflazacort drug substance in ultraviolet light condition resulted into a number of significant degradation products. Two of these degradation products were found to be unknown during the study and marked as DD-I and DD-II. Thus, the objective of this work is to investigate and identify these two novel degradation products of DFZ. The isolation method for these new degradation products were developed using a new reverse-phase high performance liquid chromatography (HPLC). DD-I and DD-II, eluting at 0.53 and 1.57 relative retention times with respect to Deflazacort (DFZ) peak respectively, were isolated from reaction mass using preparative HPLC and their structures were elucidated using high resolution MS, multidimensional NMR and FTIR spectroscopic techniques. To best of our knowledge, these two degradation products are novel impurities which are not discussed in any form of publication yet.

The novel acid degradation products of losartan: Isolation and characterization using Q-TOF, 2D-NMR and FTIR.

Forced degradation of losartan potassium in acidic condition resulted into three potential unknown impurities. These unknown degradation products marked as LD-I, LD-II and LD-III were analyzed using a new reverse-phase high performance liquid chromatography (HPLC), eluting at 3.63, 3.73 and 3.91 relative retention times with respect to losartan potassium (LOS) peak. All three were isolated from reaction mass using preparative HPLC and their structures were elucidated using LC-MS/MS, multidimensional NMR and FTIR spectroscopic techniques, as 5(2),11(2)-dibutyl-5(4),11(4)-dichloro-1(1)H,5(1)H,7(1)H,11(1)H-1(5,1),7(1,5)-ditetrazola-5,11(1,5)-diimidazola-2,8(1,2),3,9(1,4)-tetrabenzenacyclododecaphane,(Z)-5(2),11(2)-dibutyl-5(4),11(4)-dichloro-1(1)H,5(1)H,7(2)H,11(1)H-1(5,1),7(2,5)-ditetrazola-5,11(1,5)-diimidazola-2,8(1,2),3,9(1,4)-tetrabenzenacyclododecaphane, and 5(2),11(2)-dibutyl-5(4),11(4)-dichloro-1(2)H,5(1)H,7(2)H,11(1)H-1(5,2),7(2,5)-ditetrazola-5,11(1,5)-diimidazola-2,8(1,2),3,9(1,4)-tetrabenzenacyclododecaphane, respectively. To best of our knowledge, all three degradation products are novel impurities which are not discussed at any form of publication yet.

A novel UV degradation product of Ebastine: isolation and characterization using Q-TOF, NMR, IR and computational chemistry.

Forced degradation of Ebastine (1-(4-(1,1-dimethylethyl)phenyl)-4-(4-(diphenylmethoxy) piperidin-1-yl)butan-1-one) drug substance in ultraviolet light condition resulted into an unknown significant degradation product. This degradation product was analyzed using a newly developed reverse-phase HPLC, where it was eluted at 2.73 relative retention time to Ebastine peak. UV degradation product was isolated from reaction mass using preparative HPLC and its structure was elucidated using high resolution MS, multidimensional NMR and FTIR spectroscopic techniques. UV degradation product has been characterized as 2-(4-(benzhydryloxy)piperidin-1-yl)-1-(4-(tert-butyl)phenyl)-2-methylcyclopropanol. (1)H and (13)C NMR chemical shift values were generated using computational chemistry for possible two diastereomers (7R10S and 7R10R) and later 7R10R was confirmed (and its enantiomer) as final structure given it showed close agreement with experimental NMR data. Formation of UV degradation product as a recemic mixture was further verified by computational chemistry evaluation, chiral HPLC and polarimetery. To best of our knowledge, this is a novel degradation product which is not discussed at any form of publication yet.

Isolation and characterization of a novel acid degradation impurity of Amlodipine Besylate using Q-TOF, NMR, IR and single crystal X-ray.

Forced degradation of Amlodipine Besylate (AMD) in acidic condition gave rise to a potential unknown impurity. This unknown acid degradation product (ADP) was evaluated using a new-reverse-phase high performance liquid chromatography (HPLC), where it was eluted at 1.24 relative retention time to AMD peak. ADP was isolated using preparative HPLC from degradation mixture. Later, structure of ADP was elucidated using high resolution MS, multidimensional NMR and FTIR spectroscopic techniques, and characterized as ethyl-6-(2-chlorophenyl)-8-methyl-3,4,6,7-tetrahydro-2H-benzo[b][1,4]oxazine-5-carboxylate. The presence of ADP recemic mixture was confirmed by polarimeter and chiral HPLC. Given the complexity associated with ADP generation, single crystal X-ray crystallography technique was used to confirm proposed structure. In addition, reaction mechanism was postulated and confirmed using computational chemistry. To our knowledge, it is a novel impurity and not reported elsewhere.

Role of excipients on N-oxide raloxifene generation from raloxifene-excipients binary mixtures.

Raloxifene HCl (RHCl) is known to be susceptible to oxidation and forms the corresponding N-oxide derivative as the primary degradation product. The purpose of this study was to evaluate the role of excipients on the generation of the N-oxide derivative from the corresponding RHCl-excipient binary mixtures. Binary mixtures of RHCl with crospovidone, povidone, magnesium stearate, Tween 80 and anhydrous lactose in drug: excipients ratio of 1:1 (crospovidone and povidone); 10:1 (Tween 80 and magnesium stearate) and 1:5 (anhydrous lactose) were prepared by both dry blending (trituration) and wet blending (to improve contact between drug and excipients). The prepared binary mixtures were then stored at 25, 40, 75 and 125 degrees C and generation of the N-oxide derivative was monitored over six months using a validated HPLC method. Pure drug and excipients stored similarly acted as controls. Further, all the individual excipients (used as control) were monitored for peroxide impurity generation using an in-house colorimetric method. The results showed that N-oxide generation was observed from all binary mixtures and the amount of N-oxide derivative formed were always higher from the mixtures prepared by wet blending and the amount of N-oxide derivative formed was dependent on storage temperature. This study thus shows that the presence of peroxide in the excipient and its role in oxidative degradation of drug substance calls for monitoring of the peroxide impurity present in the excipients used for formulating of drug sensitive to oxidation as used herein.