Determination of pholcodine alone or in combination with ephedrine in human plasma using fluorescence spectroscopy

Abstract

In this study, sensitive, facile, and cost-effective spectrofluorimetric approaches were developed for the determination of pholcodine and ephedrine. Method I is a novel spectrofluorimetric method depending on measuring the native fluorescence of pholcodine at 337 nm after excitation at 284 nm over a concentration range of 0.01–2.4 μg/mL. The method sensitivity reached quantitation and detection limits down to 10.0 and 5.0 ng/mL, respectively. Method II relied on the simultaneous estimation of pholcodine and ephedrine using synchronous fluorimetry for the first time. The cited drugs were measured concurrently at 286 and 304 nm for pholcodine and ephedrine, respectively at Δλ of 40 nm without interference. Excellent linear relationship between concentration and response was obtained over the ranges of 0.05–6.0 μg/mL and 0.02–1.0 μg/mL for pholcodine and ephedrine, respectively. The method showed distinct sensitivity and exhibited quantitation limits of 20.0 and 10.0 ng/mL and detection limits of 10.0 and 5.0 ng/mL, respectively. The method was successfully applied to the syrup dosage form. The two developed approaches were also applied to in-vitro plasma samples, showing good bioanalytical applicability and providing further insights for monitoring drug abuse. The proposed methods were validated according to ICHQ2(R1) guidelines. The proposed methodologies' greenness profiles were evaluated using two greenness assessment tools.

Fast concurrent determination of guaifenesin and pholcodine in formulations and spiked plasma using first derivative synchronous spectrofluorimetric approach

“…It has been reported that the maximum plasma concentration (Cmax) for PHO was 12.8 μg/ml after one single dose [17]. Adult GUA (Cmax) concentration after administration of 400 mg of the drug was 2.316 μg/ml [32].…”

“…In the published literature, various methods, including spectrophotometric [16], spectrofluorimetric [17] and chromatographic methods [18][19][20] have been reported for its determination.…”

Spider diagram with greenness evaluation metrics for assessing the new synchronous spectrofluorimetric determination of bicalutamide and resveratrol in human plasma

“…A fluorescence quenching of BIC could be shown after mixing the two drugs, suggesting that the fluorescence quenching of BIC by RES may be produced through the inner filter effect (IFE) and/or Förster resonance energy transfer (FRET) [23]. Additionally, SFS offers several benefits such as increased selectivity, less spectral overlap, ease of use, and a crisp, narrow spectrum, which are especially helpful for analyzing biological and pharmaceutical matrices [20,24,25]. This led to an improvement in the SFS approach's sensitivity and spectrum overlap (Figures 3 and 4).…”

Exploiting the power of UPLC in separation and simultaneous determination of pholcodine, guaiacol along with three specified guaiacol impurities

“…PHL is an official drug in the British Pharmacopoeia (BP) in which a non-aqueous titration technique is described for its assay [ 1 ]. On the reviewing literature of the last decade, PHL was determined either in a single form or combined with other drugs by several methods, namely; UV spectrophotometric [ 2 , 3 ], infrared spectroscopic [ 4 ], fluorimetric [ 5 , 6 ], chromatographic [ 7 – 9 ] and potentiometric [ 10 , 11 ] ones.…”