Biomedical Engineering Reference
In-Depth Information
solvent, or a liquid-liquid extraction (LLE) using a non-miscible phase (sometimes
adjusted at a pH that takes advantage of the mostly basic nature of TKIs) or, alter-
nately, using either an off-line or online solid phase extraction (SPE) step.
Most analytical methods published to date using liquid chromatography cou-
pled to mass spectrometry (LC-MS) have focused on the assay in human biologi-
cal fluids, generally plasma, of a single TKI, namely imatinib [
103-
110
] (see
Table
2
). Most proposed methods use generic protein precipitation by acetonitrile
(ACN) [
104-
106,
108,
109
] of whole blood [
107
] or plasma [
106,
108,
109
] , prior
to imatinib quantification in supernatants. A semiautomated protein precipitation
step within a 96-well plate format is also described [
104
] . A methodology using
LLE with hexane-ethylacetate (30:70, v/v), followed by evaporation and reconsti-
tution in acetonitrile/water/formic acid (30:70:0.1 %, v/v/v) [
103
] or in 4 mM
ammonium formate buffer/methanol (1:1, v/v) [
110
], is an alternative method for
sample preparation that was performed by two other groups. The described sam-
ple extraction procedures for the bioanalysis of the closely related TKI nilotinib
involved plasma protein precipitation by acetonitrile [
111
], as well as LLE with
methyl
tert-
butyl ether, evaporation and reconstitution in acetonitrile/0.2 %
formic acid (1:9, v/v) [
112
] .
The two methods published for the assay of sunitinib have used LLE of plasma
with methyl
tert-
butyl ether solvent, evaporation and reconstitution in acetonitrile/
water/formic acid (20:80:0.1, v/v/v) [
113
] and acetonitrile [
114
] .
Two articles have described analytical methods for the determination of sorafenib
plasma concentrations, involving a similar protein precipitation step with acetonitrile
[
115,
116
]. There is at present only one published method for the quantification of
lapatinib in human plasma after off-line SPE onto C18 cartridge, followed by evap-
oration and reconstitution in ACN/5.0 mM ammonium formate pH 3/formic acid
(1,000:50:1, v/v/v) [
117
] .
An assay has been described for the determination of vandetanib in human
plasma and in cerebrospinal fluid. The assay consists in an LLE with
tert
-butyl
methyl ether in the presence of ammonium hydroxide, followed by evaporation of
the top organic layer and reconstitution in ACN/10 mM ammonium formate pH 5,
prior to reversed-phase LC tandem MS [
118
] .
Analytical methods have been published also for the more recent TKIs in early
or late phase of clinical development, which comprise vatalanib [
119
] and axitinib
[
120
]. Abbas et al. have developed an analytical method for measurement of the
anti-CML bosutinib in plasma of healthy subjects [
88
] . Samples were extracted
from plasma by LLE with carbonate buffer pH 10 and 1-chlorobutane (1:10, v/v)
prior to evaporation and reconstitution in water/methanol solution (50:50, v/v).
The assays of these TKIs in plasma involve mostly reversed-phase liquid chro-
matography. The chromatographic principles and separation mechanisms are the
same for High Performance Liquid Chromatography (HPLC) and Ultra Perfor-
mance Liquid Chromatography (UPLC), while speed, sensitivity, and resolution are
improved from UPLC [
121
]. The main advantage of UPLC is a significant reduction
of analysis time, resulting in a decrease in solvent consumption, turnaround time
