Analytical and semi‐preparative enantioresolution of (RS)‐ketorolac from pharmaceutical formulation and in human plasma by HPLC

Abstract

An efficient, simple, validated, analytical and semi-preparative HPLC method has been developed for direct enantioresolution of (RS)-Ketorolac (Ket) using monochloro-methylated derivatives of cellulose and amylose, i.e. cellulose (tris-3-chloro-4-methylphenylcarbamate) and amylose (tris-5-chloro-2-methylphenylcarbamate) as chiral stationary phases (CSPs) with photo diode array detection at 320 nm. Enantioresolution was carried out in samples of human plasma spiked with (RS)-Ket under normal and reversed-phase elution modes with suitable mobile phase compositions. The effect of nature of alcohols (MeOH, EtOH, PrOH and n-BuOH) and other solvents (MeCN and MeOH) as organic modifiers in the mobile phase was investigated on the separation performance of two CSPs in terms of retention and separation of enantiomers. The best resolution was observed on cellulose-based CSP using EtOH, while using 2-PrOH (15%) and amylose-based CSP obtained the highest retention. Under reversed-phase elution mode the best enantioseparation was observed using 30% MeCN with ammonium formate buffer. The elution order of enantiomers was ascertained by determining specific rotations. The limit of detection and quantitation values were 5 and 15.5 ng/mL for each enantiomer of (RS)-Ket, respectively. Copyright © 2016 John Wiley & Sons, Ltd.

Liquid chromatographic enantioseparation, determination, bioassay and isolation of enantiomers of Ketorolac: A review

“…The LOD and LOQ values were 5 ng mL À1 and 15.5 ng mL À1 for each enantiomer of (RS)-Ket, respectively. The LOQ was lesser [38] in comparison to the values of 0.02 mg mL À1 and 0.043 mg mL À1 reported, respectively, by Ing-Lorenzini et al, [29] and Maher et al, [37] using polysaccharide-based CSPs. Earlier, it was observed that reversal of elution order of enantiomers of Ket (and several other chiral carboxylic acid drugs) was a function of the nature of polysaccharide-based chiral columns and of the use of polar organic mobile phase in HPLC [41].…”

“…Effect of acid additive in mobile phase using polysaccharide-based CSPs. It is interesting to take note of the reports that Ket has pKa 3.54 and its enantioresolution was observed on amylose based CSP [containing tris-(5-chloro-2-methylphenylcarbamate)] with the mobile phase having TFA [37] (pKa 0.59) while enantioresolution was observed on cellulose based CSP containing [(tris-3-chloro-4-methylphenylcarbamate)], with mobile phase containing formic acid [38] (pKa 3.75) or acetic acid [35] (pKa 4.75). Since Ket is an acidic compound and its dissociation in the mobile phase is hard to avoid, therefore, an acid (TFA or acetic or formic acid) is added to suppress the dissociation of Ket.…”

“…Guaifenesin (Gua, having expectorant properties) is known to enhance the bioavailability of coadministered Ket, therefore, dosage adjustment of the latter is important to avoid the severe side effects that may arise with increased Ket levels upon ingestion of a normal dose. In 2014, Maher et al, [37] collected the plasma sample of a healthy female volunteer who was administered orally 100 mg Gua and 10 In 2016, two polysaccharide-based CSPs, namely, Lux Amylose-2 (LA-2) and Lux Cellulose-2 (LC-2) containing amylose (tris-5-chloro-2-methylphenylcarbamate) and cellulose (tris-3-chloro-4-methylphenylcarbamate), respectively, were found successful for an analytical and semipreparative HPLC enantioresolution of (RS)-(Ket) [38]. For enantioresolution of (RS)-Ket in spiked plasma sample, aqueous ammonium formate buffer (20 mM, pH, 3.8)-MeCN (70:30, v/v) was successful under RP conditions using photo diode array detection at 320 nm on both the columns and better resolved on amylose based column.…”

“…Formic acid (pKa 3.75) was used as preferred acidic additive, for improving Rs and peak shapes of ionizable acidic analytes [39] over TFA [40]. For complete analysis [38] it required around 7.9 min at room temperature (25 8C) which was lesser as compared to ∼20 min, 12 min, and 10 min required for direct determination of Ket by HPLC using polysaccharide-based CSP (amylose-2) under NP mode [37] using AGP chiral column, and ChiralPak AD-RH column [38], respectively. The LOD and LOQ values were 5 ng mL À1 and 15.5 ng mL À1 for each enantiomer of (RS)-Ket, respectively.…”

Chiral Stationary Phases for Liquid Chromatography: Recent Developments

“…This type of CSPs is recognized as being the most successful and widely applied for both analytical [61,62,63,64,65,66,67,68,69] and preparative enantioseparations [17,70,71,72,73,74,75,76], being responsible for about 99% of reported chiral separations [50]. Among the developed polysaccharide-based CSPs, the 3,5-dimethylphenyl tris -phenylcarbamates of amylose and cellulose proved to have the best enantiorecognition performance [77,78,79,80].…”