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Liquid chromatography tandem mass spectrometer (LC-MS/MS) is an advanced analytical technique, which offers high sensitivity, high selectivity, enhanced robustness, superior qualitative and quantitative capabilities to meet the rigorous analytical demand of various industries such as pharmaceuticals, biopharmaceuticals, forensic, industrial, food and environmental sector. In pharmaceuticals, LC-MS/MS has diverse applications which include mass elucidation, compound identification, characterization and quantitative analysis of drugs, vitamins and minerals in whole blood, plasma, serum and urine . Prior to analysis of actual study samples on LC-MS/MS, it is essential to first develop a specific analytical method for a particular drug/metabolite followed by method validation. The analytical method should be highly selective i.e. must be able to discriminate between analyte of interest and endogenous or exogenous interferents. Potential interfering substances in biological samples include endogenous matrix components such as salts, proteins, lipids, metabolites, decomposition products, concomitant medications and other xenobiotics . Concomitant medications or co-medications taken by subject population as part of general treatment, may potentially interfere with analysis of drug of interest. Hence, the assessment of the impact of co-medications is a prime consideration at the stage of method development and validation for a specific study and specific compound. If any interference is observed with quantitation of drug of interest, then it is required to eliminate the interference by modifying the analytical method. Various guidelines have been established globally, which advocate the importance for evaluation of co-medication effects on analytical methods [3-4]. The detailed description for such experiment designs to evaluate co-medication effects on analytical methods has not been published so far.
This study presents a simple, less laborious procedure to evaluate the impact of co-medication/ potentially interfering drug (PID) on LC-MS/MS based simultaneous quantitation of Olmesartan and Hydrochlorothiazide. Olmesartan and Hydrochlorothiazide are two most common drugs used in combination therapy for proper management of hypertension. Few most commonly consumed co-medications include Aspirin, Paracetamol, Ibuprofen, Caffeine, Diclofenac, Cetirizine, Ranitidine, Domperidone and Pheniramine. Therefore, a common dilution (AQS PID DILUTION) for the co-medications, viz. Aspirin, Paracetamol, Ibuprofen, Caffeine, Diclofenac, Cetirizine, Ranitidine, Domperidone and Pheniramine was prepared by dissolving their reference standard in methanol, as represented in Table No. 1. Thereafter, AQS PID dilution was spiked in six individual’s interference free human plasma to achieve their therapeutics concentration in plasma and the spiked samples were termed as “BLANK PID (1-6)”. Lower limit of quantitation (LLOQ) standards of both drugs i.e. Olmesartan and Hydrochlorothiazide were also spiked in each plasma lots and termed as “LLOQ (1-6)”. The above prepared samples (BLANK PID 1-6 and LLOQ 1-6) were processed and analyzed on LC-MS/MS by applying analytical method as reported previously by Arvind Kumar et al. . Chromatograms of Olmesartan and Hydrochlorothiazide observed for “BLANK PID” and “LLOQ” samples are represented in Fig. 1. As evident from the results (Fig. 1), there was no peak area response observed in BLANK PID samples at either RT or in proximity of RT of drug of interest (Olmesartan RT-1.49 minute and Hydrochlorothiazide RT – 2.04 minute). This experiment confirmed that presence of co-medication drugs in BLANK PID samples, did not cause any interference. Therefore, it can be concluded that the applied analytical method is highly selective and free of interference. This is the first detailed report on experimental design to assess the effect of co-medications (Aspirin, Paracetamol, Ibuprofen, Caffeine, Diclofenac, Cetirizine, Ranitidine, Domperidone and Pheniramine) on simultaneous quantitation of Olmesartan and Hydrochlorothiazide. This study presents a simple and effective strategy to evaluate the effect of co-medications on LC-MS/MS based quantitation of drugs in biological samples. This experimental design is likely to facilitate assessment of effect of co-medications on analytical methods applied in pharmacokinetics, drug development and therapeutic monitoring.
How to Cite
Co-medication, LC-MS/MS, Olmesartan, Hydrochlorothiazide, Biological samples, Pharmacokinetics
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