Appraisal of the greenness profile of a chromatographic method for the simultaneous estimation of carbamazepine and oxcarbazepine, along with two potential impurities and three formulation excipients

Structurally related carbamazepine (CBZ) and oxcarbazepine (OX) are two of the most commonly used antipsychotic drugs. The main impurities of CBZ, as described in both the USP and the BP, are iminodibenzyl (IMD) and iminostilbene (IST). Meanwhile, for non-pharmacopeial OX, the declared impurities include CBZ and IST. Prescribed oral suspensions of CBZ and OX contain additives including methyl paraben (MP), propyl paraben (PP) and sorbic acid (SA) as preservatives. An HPTLC method was introduced and developed for resolving the interference between CBZ, OX, their impurities, and the suspension additives in a single run, in addition to their quantitation with a high sensitivity that satisfies the USP requirements for the detection and quantitation of drug impurities. In the developed HPTLC method, CBZ and OX were measured in the range of 40–4000 ng per band, while IMD, IST, MP, PP and SA were in the range of 20–2000 ng per band, using a mixture of hexane : ethylacetate : formic acid : acetic acid (8 : 2 : 0.5 : 0.3, by volume) and UV scanning at 254 nm. The greenness profile of the method was evaluated by two different tools, the analytical Eco-Scale and the Green Analytical Procedure Index (GAPI), then a comparison between their results was conducted. This is the first time that the studied drugs, along with their impurities and suspension additives, were analyzed by a HPTLC method in a single run and within the limits required by the USP guidelines.

Structurally related carbamazepine (CBZ) and oxcarbazepine (OX) are two of the most commonly used antipsychotic drugs.

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

The review presents data from the last few years on bioanalytical methods used in therapeutic drug monitoring (TDM) of the 1st-3rd generation and the newest antiepileptic drug (AEDs) cenobamate in patients with various forms of seizures. Chemical classification, structure, mechanism of action, pharmacokinetic data and therapeutic ranges for total and free fractions and interactions were collected. The primary data on bioanalytical methods for AEDs determination included biological matrices, sample preparation, dried blood spot (DBS) analysis, column resolution, detection method, validation parameters, and clinical utility. In conclusion, the most frequently described method used in AED analysis is the LC-based technique (HPLC, UHPLC, USLC) combined with highly sensitive mass detection or fluorescence detection. However, less sensitive UV is also used. Capillary electrophoresis and gas chromatography have been rarely applied. Besides the precipitation of proteins or LLE, an automatic SPE is often a sample preparation method. Derivatization was also indicated to improve sensitivity and automate the analysis. The usefulness of the methods for TDM was also highlighted.