Simultaneous Determination of Carbamazepine and Carbamazepine-10,11-epoxide in Different Biological Matrices by LC-MS/MS

Abstract

An uncomplicated, sensitive liquid chromatography linked to mass spectrometry (LC/MS) for evaluation of carbamazepine and carbamazepine-10,11-epoxide (its metabolite) in human plasma, human saliva, rat plasma, and rabbit plasma was developed. Analyses were conducted on a Zorbax SB-C18, 100 mm × 3 mm ID, 3.5 μm column, at a column temperature of 40 ºC. The mobile phase was comprised of 0.1% formic acid in water and methanol in a 35 : 65 (v/v) ratio, with a flow rate of 0.4 mL/min. Lacosamide was utilized as internal standard. Under these chromatographic conditions, the retention times of lacosamide, carbamazepine-10,11-epoxide, and carbamazepine were 1.4 min, 1.6 min, and 2.2 min, respectively. The quantification of the analytes was performed using multiple reaction monitoring, with the use of a triple quadrupole mass spectrometer with electrospray positive ionization. The monitored ions were m/z 194 derived from m/z 237 for carbamazepine, m/z 180 derived from m/z 253 for carbamazepine-10,11-epoxide, and m/z 108 derived from m/z 251 for lacosamide. The samples were prepared by protein precipitation from 0.2 mL of plasma/saliva using 0.6 mL of internal standard solution in methanol. Calibration curves were constructed over the ranges 1.1-17.6 μg/mL and 0.23-5.47 μg/mL for carbamazepine and carbamazepine-epoxide, respectively. The coefficients of determination obtained by using a weighted (1/x) linear regression were greater than 0.994. The reported LC-MS/MS method was applied to preclinical pharmacokinetic studies and therapeutic drug monitoring.

New Methods Used in Pharmacokinetics and Therapeutic Monitoring of the First and Newer Generations of Antiepileptic Drugs (AEDs)

“…There are different methods (GC, LC, HPLC, High Performance Thin Layer Chromatography (HPTLC), LC-MS/MS, UHPLC-MS/MS, SFC-ESI-MS/MS) to measure the level of CBZ and its major metabolite in biological samples of epilepsy patients treated with this AED in monotherapy or polytherapy. The presented methods use biological samples such as: Plasma [47][48][49][50][51][52][53][54][55], serum [53,[56][57][58], urine [47,59], saliva [60], dried saliva [61] and respiratory condensate [62,63], dried blood spot [20,64,65]. In TDM of CBZ, plasma, serum, and urine are the most commonly used.…”

“…Detection is achieved by the use of spectrophotometric methods (UV) with various wavelengths (between 210 nm and 285 nm). In MS-MS detection with selective, both positive or negative electrospray ionization is also used, and analytes are measured in the multiple reaction monitoring modes (MRM) with a specific mass transition [54,68]. The described methods are selective, work in therapeutic range and are suitable for TDM of CBZ [69].…”

Assessment of adherence to carbamazepine using plasma and saliva samples, a study from Jordan

“…Measuring drugs in saliva can serve as an alternative modality for measuring drug concentration in body fluid, which is useful for therapeutic drug monitoring. Such an approach can allow for non-invasive home sampling, which the patient might prefer over traditional blood sampling, especially children [ 4 , 5 ].…”

“…However, saliva can be used to measure drug concentrations, and can be possible to be used in therapeutic drug monitoring for certain medications. If there was strong correlation between the drug's concentration in the saliva and its plasma concentration, this sampling technique would be extremely beneficial [ [5] , [6] , [7] , [8] ].…”