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Drug-drug interactions may amplify or diminish their intended effects, or even produce entirely new effects. Multicomponent mixture HPLC analysis offers a thorough and effective method for comprehending the makeup and behavior of complicated materials, advancing research and development across a range of scientific and industrial domains. A novel experimental design-assisted HPLC methodology for the concurrent investigation of the drug-drug interaction of pholcodine, ephedrine, and guaifenesin in biological fluids has been established. Rather than the routine methodology, the application of the factorial design-HPLC method offers a powerful and efficient tool for the analysis of these compounds. Both mixed and full factorial designs were employed to assess the impact of variable factors on chromatographic results. Utilizing an isocratic elution mode on a C18 column, the chromatographic separation was carried out. 15% Methanol, 5% acetonitrile, and 80% phosphate buffer with 0.1%(v/v) triethylamine set to pH 3 make up the mobile phase flowing at rate 1.0 mL/min. The calibration curves of the drugs show excellent linearity over a concentration ranges: 0.20–13.0 µg/mL for PHO, 0.50–20.0 µg/mL for EPH and 0.70–20.0 µg/mL for GUA with LOQ values of 0.18, 0.38 and 0.50. The fast separation and quantitation in less than 6 min is an advantage. Also, the method includes a robust sample preparation protocol for the analysis of complex biological samples, ensuring high selectivity and precision. The ease, speed and cost-effectiveness of the method are ideal for supporting in vitro studies, including drug-drug interaction investigations, especially in bioanalytical labs. [ABSTRACT FROM AUTHOR]

To evaluate the propofol-sparing and hemodynamic effects of guaifenesin administered for co-induction of anesthesia in sheep. Prospective, blinded, two-way crossover experimental study. Thirteen healthy adult female sheep. Anesthesia was induced without premedication with intravenous (IV) guaifenesin 5% at 100 mg kg–1 (GGE) or an equivalent volume of physiologic saline (SAL), followed by IV propofol at a controlled rate (1 mg kg–1 min–1). Heart rate (HR), respiratory rate and oscillometric noninvasive arterial blood pressure (NIBP) were recorded at baseline after co-induction administration, following endotracheal intubation and every 2 minutes thereafter for 10 minutes. Propofol doses required to achieve intubation after each co-induction treatment were compared by independent Student's t -test. Values of p < 0.05 were considered statistically significant. The propofol dose required (mean ± standard deviation) to achieve intubation was significantly lower (p = 0.001) in the GGE treatment (3.40 ± 0.74 mg kg–1) than in the SAL treatment (5.94 ± 1.09 mg kg–1). HR was increased after anesthetic induction compared with baseline in both treatments. HR was generally lower in the GGE treatment than in the SAL treatment. NIBP did not vary between GGE and SAL treatments. Guaifenesin, when administered as a co-induction agent with propofol in sheep, reduces propofol dose requirements and maintains hemodynamic variables within a clinically acceptable range. [ABSTRACT FROM AUTHOR]

Abstract Drug-drug interactions may amplify or diminish their intended effects, or even produce entirely new effects. Multicomponent mixture HPLC analysis offers a thorough and effective method for comprehending the makeup and behavior of complicated materials, advancing research and development across a range of scientific and industrial domains. A novel experimental design-assisted HPLC methodology for the concurrent investigation of the drug-drug interaction of pholcodine, ephedrine, and guaifenesin in biological fluids has been established. Rather than the routine methodology, the application of the factorial design-HPLC method offers a powerful and efficient tool for the analysis of these compounds. Both mixed and full factorial designs were employed to assess the impact of variable factors on chromatographic results. Utilizing an isocratic elution mode on a C18 column, the chromatographic separation was carried out. 15% Methanol, 5% acetonitrile, and 80% phosphate buffer with 0.1%(v/v) triethylamine set to pH 3 make up the mobile phase flowing at rate 1.0 mL/min. The calibration curves of the drugs show excellent linearity over a concentration ranges: 0.20–13.0 µg/mL for PHO, 0.50–20.0 µg/mL for EPH and 0.70–20.0 µg/mL for GUA with LOQ values of 0.18, 0.38 and 0.50. The fast separation and quantitation in less than 6 min is an advantage. Also, the method includes a robust sample preparation protocol for the analysis of complex biological samples, ensuring high selectivity and precision. The ease, speed and cost-effectiveness of the method are ideal for supporting in vitro studies, including drug-drug interaction investigations, especially in bioanalytical labs.

Abstract Guaifenesin (GUA) is determined in dosage forms and plasma using two methods. The spectrofluorimetric technique relies on the measurement of native fluorescence intensity at 302 nm upon excitation wavelength “223 nm”. The method was validated according to ICH and FDA guidelines. A concentration range of 0.1–1.1 μg/mL was used, with limit of detection (LOD) and quantification (LOQ) values 0.03 and 0.08 µg/mL, respectively. This method was used to measure GUA in tablets and plasma, with %recovery of 100.44% ± 0.037 and 101.03% ± 0.751. Furthermore, multivariate chemometric-assisted spectrophotometric methods are used for the determination of GUA, paracetamol (PARA), oxomemazine (OXO), and sodium benzoate (SB) in their lab mixtures. The concentration ranges of 2.0–10.0, 4.0–16.0, 2.0–10.0, and 3.0–10.0 µg/mL for OXO, GUA, PARA, and SB; respectively, were used. LOD and LOQ were 0.33, 0.68, 0.28, and 0.29 µg/mL, and 1.00, 2.06, 0.84, and 0.87 µg/mL for PARA, GUA, OXO, and SB. For the suppository application, the partial least square (PLS) model was used with %recovery 98.49% ± 0.5, 98.51% ± 0.64, 100.21% ± 0.36 & 98.13% ± 0.51, although the multivariate curve resolution alternating least-squares (MCR-ALS) model was used with %recovery 101.39 ± 0.45, 99.19 ± 0.2, 100.24 ± 0.12, and 98.61 ± 0.32 for OXO, GUA, PARA, and SB. Analytical Eco-scale and Analytical Greenness Assessment were used to assess the greenness level of our techniques.

Guaifenesin (GUA) is determined in dosage forms and plasma using two methods. The spectrofluorimetric technique relies on the measurement of native fluorescence intensity at 302 nm upon excitation wavelength "223 nm". The method was validated according to ICH and FDA guidelines. A concentration range of 0.1–1.1 μg/mL was used, with limit of detection (LOD) and quantification (LOQ) values 0.03 and 0.08 µg/mL, respectively. This method was used to measure GUA in tablets and plasma, with %recovery of 100.44% ± 0.037 and 101.03% ± 0.751. Furthermore, multivariate chemometric-assisted spectrophotometric methods are used for the determination of GUA, paracetamol (PARA), oxomemazine (OXO), and sodium benzoate (SB) in their lab mixtures. The concentration ranges of 2.0–10.0, 4.0–16.0, 2.0–10.0, and 3.0–10.0 µg/mL for OXO, GUA, PARA, and SB; respectively, were used. LOD and LOQ were 0.33, 0.68, 0.28, and 0.29 µg/mL, and 1.00, 2.06, 0.84, and 0.87 µg/mL for PARA, GUA, OXO, and SB. For the suppository application, the partial least square (PLS) model was used with %recovery 98.49% ± 0.5, 98.51% ± 0.64, 100.21% ± 0.36 & 98.13% ± 0.51, although the multivariate curve resolution alternating least-squares (MCR-ALS) model was used with %recovery 101.39 ± 0.45, 99.19 ± 0.2, 100.24 ± 0.12, and 98.61 ± 0.32 for OXO, GUA, PARA, and SB. Analytical Eco-scale and Analytical Greenness Assessment were used to assess the greenness level of our techniques. [ABSTRACT FROM AUTHOR]

The clinical study on electrocardiographic evaluation of two modalities of general anaesthesia was conducted in 12 clinical cases of cattle of either sex. The animals were randomly divided into two groups, consisting of 6 animals in each group. The cattle in both groups were premedicated with an intravenous injection of 50 mg/kg guaifenesin. The cattle in group-I were sedated with inj. xylazine (0.1 mg/kg I/V) and induced with inj. etomidate (0.5 mg/kg I/V). The cattle in group-II were sedated with inj. dexmedetomidine (2.5 µg/kg I/V) and induced with inj. ketamine (3 mg/kg I/V). Cattle from both groups were maintained under isoflurane anaesthesia. The morphological abnormalities were not detected in electrocardiography in cattle of any of the groups, except for changes in the amplitude and duration of the P wave, QRS complex, T wave, PR interval, and QT interval. [ABSTRACT FROM AUTHOR]

The clinical study was conducted in 12 clinical cases of cattle of either sex, presented to the department of Veterinary Surgery and Radiology, Veterinary College, Bidar. They were randomly divided into two groups consisting of 6 animals in each group. The cattle in both the groups were premedicated with inj. guaifenesin (50 mg/kg I/V). The cattle in group-'! were sedated with inj. xylazine (0.1 mg/kg I/V) and induced with inj. etomidate (0.5 mg/kg I/V). The cattle in group-a! were sedated with inj. dexmedetomidine (2.5 µg/kg I/V) and induced with inj. ketamine (3 mg/kg I/V). Cattle of both the groups were maintained under isoflurane anaesthesia. Haematological parameters fluctuated within the normal physiological limit except for haemoglobin and PCV decreased significantly at the end of anaesthesia in both the groups. There were no changes in biochemical parameters except for AST which increased significantly in both the groups. [ABSTRACT FROM AUTHOR]

Guaifenesin and pholcodine are frequently co‐formulated in certain dosage forms. A new fast first derivative synchronous spectrofluorometric method has been used for their simultaneous analysis in mixtures. Here, first derivative synchronous spectrofluorometry enabled the successful simultaneous estimation of guaifenesin at 283 nm and pholcodine at 275 nm using a wavelength difference (Δλ) of 40 nm. The method was fully validated following International Council of Harmonization guidelines. For guaifenesin and pholcodine, linearity was determined within the corresponding ranges of 0.05–0.30 and 0.10–6.0 μg/ml. The two drugs were effectively analyzed using the developed approach in their respective formulations, and the results showed good agreement with those attained using reference methods. The method demonstrated excellent sensitivity, with detection limits down to 0.007 and 0.030 μg/ml and quantitation limits of 0.020 and 0.010 μg/ml for guaifenesin and pholcodine, respectively. Therefore, the procedure was successful in determining these drugs simultaneously in vitro in spiked plasma samples and syrup dosage form. The developed methodology also offered an environmentally friendly advantage by utilizing water as the optimal diluting solvent throughout the whole work. Different greenness approaches were investigated to ensure the method's ecofriendly properties. [ABSTRACT FROM AUTHOR]

Chiral high performance liquid chromatographic technique usually employs polysaccharide‐based stationary phases in a normal phase mode. This frequently generates large waste of organic solvents. Using shorter columns of 50 mm length as well as a mobile phase with a high water percentage are common approaches for greening this analytical technique. In this context, a new chiral chromatographic technique was developed for simultaneous enantio‐separation of phenylephrine HCl and guaifenesin racemates. Four 50 mm cellulose‐based columns were experimented to separate the four enantiomers in a reversed phase mode. A face centered design was then employed to optimize the mobile phase acetonitrile% and flow rate on Lux Cellulose‐1 (50 × 4.6 mm, 5 μm). The simultaneous resolution of the cited drugs enantiomers was achieved using acetonitrile–water (30:70, by volume), with a flow rate of 0.5 ml min−1. These optimized chromatographic conditions separate the enantiomers in 7 min running time, generating about 1.0 ml acetonitrile per run. The proposed method was favorably compared with other reported chiral ones in terms of waste volume generated and analysis time required. [ABSTRACT FROM AUTHOR]

ABSTRACT A study was designed to compare two sedation protocols to be used in horses undergoing orchiectomy when standing. In both protocols, the induction to the sedative state was performed with bolus detomidine at a dose of 10 µg/kg, intravenously (IV). In the first protocol (eight horses), the sedative state was maintained with 1% glyceryl guaiacol ether (GGE) in continuous infusion, at a dose of 1ml/kg/hour IV. In the second protocol (eight horses) this sedative effect was maintained with detomidine in continuous infusion at the same dose and induction route. Orchiectomy was performed on all animals. The two protocols allowed the surgeries to be performed when standing. However, horses kept under sedation by the GGE showed greater relaxation and a more intense degree of sedation. It should be noted that the use of GGE to maintain the sedative state in horses is unprecedented in the literature. The drug is used in anesthetic protocols in the species, but only in pre-anesthetic medication in general anesthesia. It was concluded that the two sedation protocols allowed the performance of orchiectomy with the horses when standing. However, the protocol in which 1% GGE was used showed more profound sedation, without adverse effects.

An efficient sensing surface is fabricated through incorporating ruthenium on electropolymerized poly-(4-aminodiphenylamine)(Padpa) film by potentiodynamic cycling of 4-aminodiphenylamine (4-adpa) in an acidic medium. The mechanism of electropolymerization comprises the conversion of protonated monomer to di-imine species and generates positively charged radical-intermediate via dimerization step. The surface morphology of deposited film on electrode surface is studied using SEM and XPS techniques. The electrocatalytic appraisal of constructed (Ru/Padpa/GCE) sensing interface is examined towards the electro-oxidation of guaifenesin (GUA) by differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and chronoamperometric (CA) methods. The Ru/Padpa/GCE sensing interface displayed a linear response of GUA from 1.5 to 45 µg/mL with the limit of detection (LOD) of 48.8 ng/mL (S/N = 3). The obtained higher activity of Ru/Padpa/GCE is mainly attributed to its larger active surface area, faster electron transfer kinetics, and higher catalytic sites from the interface. The Ru/Padpa/GCE sensing interface is further applied for the determination of GUA in pharmaceutical (cough syrup, and human urine) samples with a recovery of 97.1–101.0 %. The diffusion coefficient of GUA (1.51 × 10-6 cm2/s) is also obtained via theoretical electrochemical method, which ensures that Ru/Padpa/GCE sensing interface can be considered as a potential candidate for clinical diagnostic analysis.

This work describes the development of the RP-HPLC method for the simultaneous estimation of Guaifenesin, codeine phosphate, phenylephrine, and sodium benzoate. This method separates Guaifenesin, codeine phosphate, phenylephrine, and sodium benzoate nicely. This RP-HPLC method uses the Shimadzu HPLC instrument with Chromegabond WR C18 column 5 μm 120 A 30 cm * 3.9 mm. The mobile phase is a mixture of 1% o-phosphoric acid, methanol: acetonitrile (80 : 10: 10), and the pH was adjusted to 3.1. Isocratic elution mode was used with 1 ml/min as the flow rate. The detection for all compounds is carried out at 254 nm. The retention time of Guaifenesin, codeine phosphate, phenylephrine, and sodium benzoate was 14.11, 5.75, 3.9, and 20.52, respectively. The method has been validated concerning accuracy, linearity, and precision. This method is simple, accurate, and reproducible. This validated method was used to estimate these drugs in syrup pharmaceutical form.

The respiratory tract infections have a growing concern by healthcare specialists. Carbocisteine, guaifenesin, and oxomemazine are widely used as co-formulated anti-cough drugs. For the first time, a precise, accurate, and green HPLC method has been developed and validated for their determination in their combined dosage forms. The separation was accomplished using a photodiode array detector at 220 nm with an isocratic green mobile phase consisting of phosphate buffer 0.025 M, (pH 3) and ethanol (75:25, v/v) at a flow rate of 1.0 mL/min and ambient temperature. The developed method was validated in accordance with ICH guidelines. Carbocisteine, guaifenesin, and oxomemazine were separated in less than 12 min at 1.569 ± 0.005 min, 8.546 ± 0.007 min, and 10.877 ± 0.008 min, respectively. The linear ranges for carbocisteine, guaifenesin, and oxomemazine were 31.25–187.50, 25–150, and 0.5–3.0 µg/mL, respectively. The developed method can be used in quality control laboratories for the simultaneous determination of the investigated drugs in their pharmaceutical dosage forms. In addition, it proved its superiority over the reported methods in terms of greenness using different assessment tools.

Aim. To evaluate the efficacy and safety of a combination drug containing ambroxol, guaifenesin, and levosalbutamol, oral solution, versus Ascoril Expectorant, syrup (combination of bromhexine, guaifenesin, and salbutamol) in the treatment of productive cough in adult patients with acute bronchitis. Materials and methods. This open-label, randomized, phase III study included patients with acute bronchitis who had a productive cough with difficulty in sputum expectoration. 244 patients were randomized in a 1:1 ratio and received 10 mL of the study drug or reference drug 3 times daily for 2 weeks. After 7 and 14 days of treatment, the physician evaluated patients subjective complaints and the efficacy of therapy. The primary endpoint was the proportion of patients with high and very high efficacy. Results. The primary endpoint was reached by 70 (0.5738) patients in the study drug group and 54 (0.4426) in the reference drug group (p=0.04). The intergroup difference was 0.1311 [95% confidence interval: 0.0057; 0.2566]. The lower limit of the 95% confidence interval was above zero, which confirms the superiority of therapy with the study drug over therapy with Ascoril Expectorant. The proportion of patients with a 1-point total score reduction and with complete resolution of all symptoms according to the Modified Cough Relief and Sputum Expectoration Questionnaire after 7 and 14 days was numerically higher in the study drug group versus the reference drug group. There were no statistically significant differences between the groups in the incidence of adverse events. Conclusion. The efficacy of a new combination drug containing ambroxol, guaifenesin, and levosalbutamol in the treatment of productive cough in adult patients with acute bronchitis is superior to the efficacy of Ascoril Expectorant. The safety profiles of the study drug and the reference drug were comparable.

Guaifenesin, a widely used ingredient in over‐the‐counter cough and cold medications, has been a subject of debate regarding its efficacy in treating respiratory conditions. Despite its historical use and US Food and Drug Administration approval, recent studies have questioned its claimed expectorant effect and its effectiveness in managing symptoms. This article examines the available evidence, highlighting the lack of significant benefits over placebo for upper respiratory disease. The rationale for clinical use is examined alongside the potential downside and alternatives to recommending guaifenesin as a treatment option. [ABSTRACT FROM AUTHOR]

Both guaifenesin and dextromethorphan are routinely available nonprescription medications that are also common drugs of abuse amongst young adults. We describe a presentation of guaifenesin and dextromethorphan misuse resulting in acute renal failure due to bilateral nephrolithiasis. The patient underwent placement of bilateral ureteral stents but again formed small renal stones bilaterally. While most renal calculi are not drug-induced, this case highlights the potential for nephrolithiasis after guaifenesin and dextromethorphan ingestion. It suggests that in this combination ingestion multiple mechanisms lead to a prolonged period of nephrolith formation.

An environmentally safe, economic, yet simple approach was presented in this study for the removal of the traces of guaifenesin (GUA) and amprolium (AMP) drugs from wastewater using chitosan (CS) biopolymer. The removal capacity was investigated under several variables including pH, contact time, adsorbent dose, and drug capacity. The study of adsorption isotherm models demonstrates that Langmuir model is more likely to illustrate the adsorption process more than Freundlich with correlation coefficient (R²) of 0.984 and 0.994 with (qm) of 2.78 and 1.33 for both GUA and AMP, respectively. Four kinetic models were assessed for the adsorption process. The results indicate that the adsorption system follows the pseudo-second-order model which was confirmed by its higher correlation coefficient (R² ≈ 0.99) for both GUA and AMP, suggesting that chemical adsorption is the rate-limiting step of the adsorption mechanism. Thermodynamic studies were carried out to determine ΔH°, ΔG°, ΔS°. The positive values of ΔH° and ΔG° indicated that the sorption of both drugs onto CS is an endothermic nonspontaneous and the system gained energy from an external source. [ABSTRACT FROM AUTHOR]

The cough epoch is a cluster of cough counts, SP 1 sp which may reveal the severity of coughs and cough patterns that are indiscernible with cough count alone. The system's AI-powered cough detection and quantification capabilities provide continuous and non-intrusive monitoring and has the potential to improve patient care, cough research and support drug development through continuous, more accurate and reliable cough monitoring. One of the few previous studies was conducted on the nighttime cough epoch focused on COPD patients. SP 2 sp In this study, we observed both the cough counts and cough epochs in patients with asthma and interstitial lung disease (ILD). B Results b B : b Our co-primary endpoints are hourly tabulations of time-stamped coughs based on two complementary units of analysis: individual coughs and cough-seconds (a second during which at least one individual cough occurs). [Extracted from the article]

To evaluate the heart rate (HR) and systemic arterial pressure (sAP) effects, and propofol induction dose requirements in healthy dogs administered propofol with or without guaifenesin for the induction of anesthesia. Prospective blinded crossover experimental study. A total of 10 healthy adult female Beagle dogs. Dogs were premedicated with intravenous (IV) butorphanol (0.4 mg kg–1) and administered guaifenesin 5% at 50 mg kg–1 (treatment G50), 100 mg kg–1 (treatment G100) or saline (treatment saline) IV prior to anesthetic induction with propofol. HR, invasive sAP and respiratory rate (f R) were recorded after butorphanol administration, after guaifenesin administration and after propofol and endotracheal intubation. Propofol doses for intubation were recorded. Repeated measures analysis of variance (anova) was used to determine differences in propofol dose requirements among treatments, and differences in cardiopulmonary values over time and among treatments with p < 0.05 considered statistically significant. Propofol doses (mean ± standard deviation) for treatments saline, G50 and G100 were 3.3 ± 1.0, 2.7 ± 0.7 and 2.1 ± 0.8 mg kg–1, respectively. Propofol administered was significantly lower in treatment G100 than in treatment saline (p = 0.04). In treatments G50 and G100, HR increased following induction of anesthesia and intubation compared with baseline measurements. HR was higher in treatment G100 than in treatments G50 and saline following induction of anesthesia. In all treatments, sAP decreased following intubation compared with baseline values. There were no significant differences in sAP among treatments. f R was lower following intubation than baseline and post co-induction values and did not differ significantly among treatments. When administered as a co-induction agent in dogs, guaifenesin reduced propofol requirements for tracheal intubation. HR increased and sAP and f R decreased, but mean values remained clinically acceptable. [ABSTRACT FROM AUTHOR]

The problem of respiratory diseases and their therapy options still retains much of its urgency. Respiratory diseases in children are still super common. According to the data on infectious morbidity among children in the Russian Federation for the period 2018–2020, current trends have not changed, and the acute respiratory infections (ARI) are still ranked number one in terms of the frequency of registered diseases. According to the official records, the frequency of ARI in children among infectious diseases is 71,850.02 per 100,000 population, or 71%. Such well-known symptom as cough is one of the most frequent manifestations of respiratory diseases. It causes the greatest discomfort for both the little patients and their parents, the quality of life of the children and those around them worsens, many domestic and foreign authors mention this symptom in their works. And it is this problem that doctors of various specialties most often face. The cough is currently treated with drugs with different effects depending on the characteristics and manifestations of the disease. Systematic reviews and multicenter studies show that prescription of mucoactive drugs to treat cough in children with underlying ARI is substantiated and feasible. The authors substantiated the necessity of using combinations of various drugs aimed to reduce inflammation of the airways, improve mucociliary clearance, thin out and promote sputum discharge and, accordingly, reduce cough. The article briefly discusses the mechanisms of the development of cough in ARI, the action of drug substances included in the combination drugs used to treat cough in children, the possibility of using the combination of muco- and bronchoactive drugs of synthetic and plant origin.

Ineffective over-the-counter (OTC) drugs should be removed from the US market. Despite solid research showing that oral phenylephrine is ineffective as a decongestant, the US Food and Drug Administration has failed to respond to a 2015 citizen's petition to remove it from the OTC nasal decongestant monograph. Other examples of scientifically proven ineffective OTC medications include guaifenesin as an expectorant, dextromethorphan as a cough suppressant, and chlorpheniramine for cold symptoms. [ABSTRACT FROM AUTHOR]

Recently, cold and cough dosage forms have gained significant attention due to their use in the supportive protocols for managing COVID-19 symptoms. In this study, a pharmaceutical formulation containing Paracetamol (PAR), Guaifenesin (GUA), and Phenylephrine hydrochloride (PHE) was investigated for spectral resolution and quantification using advanced spectrophotometric methods. The spectra of these components were significantly overlapped and present in their combined tablet in a challenging ratio of 250:100:5 for PAR, GUA, and PHE, respectively. The established approaches were employed for the simultaneous determination of these drugs in their pharmaceutical formulation without interference from matrix excipients. The study involved various manipulation steps, allowing each component in the combination to be analyzed by more than one approach. Integrating these methods with smart mathematical techniques, the issue of spectral data overlap was resolved without the need for preliminary separation steps. The developed methods are dual wavelength, first derivative, derivative ratio, ratio difference, constant center coupled with spectrum subtraction, and constant multiplication paired with spectrum subtraction. The proposed methods were linear over the concentration range of 3.0-35.0 μg/mL for GUA and 3.0-30.0 μg/mL for PHE. While the PAR ranges for the first derivative and constant multiplication methods were 2.5-35.0 μg/mL and 2.5-25.0 μg/mL, respectively. Excellent linearity of the suggested methods was demonstrated by the high correlation coefficients (R2), ≥ 0.9998 for all the tested compounds. These methodologies were validated according to ICH guidelines. Validation results demonstrated excellent accuracy, with recovery percentages ranging from 98 to 102 %, and precision, with RSD values less than 2 %. The obtained results were statistically compared with the official ones using F-test, Student's t-test, and one-way ANOVA, revealing no significant differences. The proposed methods are accurate, green, smart, fast, and cost-effective. Their compliance with Green Analytical Chemistry principles was evaluated and compared to a published method using various tools to enable a more holistic evaluation from different perspectives. The promising results revealed that the investigated methods are superior green alternatives for routine analysis of the cited drugs in laboratories with limited resources and without access to expensive instruments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Guaifenesin (GFS), phenylephrine (PHE) and paracetamol (PAR), drugs used in combination for the relief of cold and flu symptoms, were determined at electrochemically pretreated pencil graphite electrode. Differential pulse voltammetry (DPV) was used for the first time for the concomitant determination of the target compounds based on the electro-oxidation of PAR at 0.43 V, PHE at 0.74 V and GFS at 1.14 V in Britton–Robinson buffer pH 6.0. Under optimized experimental conditions, two linear ranges were obtained for PAR (2.50 × 10−6 M–1.00 × 10−5 M and 1.00 × 10−5 M–1.00 × 10−4 M) and for PHE and GFS linearity was proved between 5.00 × 10−6 M–2.00 × 10−4 M and 2.50 × 10−6 M–2.00 × 10−4 M, respectively. The detection limits were 8.12 × 10−7 M for PAR, 1.80 × 10−6 M for PHE and 8.29 × 10−7 M for GFS. The selective and sensitive DPV method and the electrochemically treated electrode were employed for simultaneous analysis of the analytes in pharmaceutical samples with good recoveries. [ABSTRACT FROM AUTHOR]

New voltammetric and flow amperometric methods for the determination of guaifenesin (GFE) using a perspective screen-printed sensor (SPE) with boron-doped diamond electrode (BDDE) were developed. The electrochemical oxidation of GFE was studied on the surface of the oxygen-terminated BDDE of the sensor. The GFE provided two irreversible anodic signals at a potential of 1.0 and 1.1 V (vs. Ag|AgCl|KCl sat.) in Britton-Robinson buffer (pH 2), which was chosen as the supporting electrolyte for all measurements. First, a voltammetric method based on differential pulse voltammetry was developed and a low detection limit (LOD = 41 nmol L−1), a wide linear dynamic range (LDR = 0.1–155 μmol L−1), and a good recovery in the analysis of model and pharmaceutical samples (RSD <3.0 %) were obtained. In addition, this sensor demonstrated excellent sensitivity and reproducibility in the analysis of biological samples (RSD <3.2 %), where the analysis took place in a drop of serum (50 μL) without pretreatment and additional electrolyte. Subsequently, SP/BDDE was incorporated into a flow-through 3D printed electrochemical cell and a flow injection analysis method with electrochemical detection (FIA-ED) was developed, resulting in excellent analytical parameters (LOD = 86 nmol L−1, LDR = 0.1–50 μmol L−1). Moreover, the mechanism of electrochemical oxidation of GFE was proposed based on calculations of HOMO spatial distribution and spectroelectrochemical measurements focused on IR identification of intermediates and products. [Display omitted] • Unique simple electrochemical sensor for guaifenesin (GFE) determination. • Analytical approach with excellent LOD for GFE analysis at nanomolar levels. • Mechanism proposal for the electrochemical oxidation of GFE. • Serum analysis without sample pretreatment and no need of electrolyte. • Flow injection analysis with electrochemical detection. [ABSTRACT FROM AUTHOR]

The palatability of a pharmaceutical preparation is a significant obstacle in developing a patient-friendly dosage form. Bitter taste is an important factor for patients in (i) selecting a certain drug from generic products available in the market and (ii) adhering to a therapeutic regimen. The various methods developed for identification of bitter tasting and bitter-taste modulating compounds present a number of limitations, ranging from limited sensitivity to lack of close correlations with sensory data. In this study, we demonstrate a fluorescence-based assay, analyzing the bitter receptor TAS2R-linked intracellular pH (pHi) of human gastric parietal (HGT-1) cells as a suitable tool for the identification of bitter tasting and bitter-taste modulating pharmaceutical compounds and preparations, which resembles bitter taste perception. Among the fluorometric protocols established to analyze pHi changes, one of the most commonly employed assays is based on the use of the pH-sensitive dye SNARF-1 AM. This methodology presents some limitations; over time, the assay shows a relatively low signal amplitude and sensitivity. Here, the SNARF-1 AM methodology was optimized. The identified bicarbonate extrusion mechanisms were partially inhibited, and measurements were carried out in a medium with lower intrinsic fluorescence, with no need for controlling external CO2 levels. We applied the assay for the screening of flavonoids as potential bitter-masking compounds for guaifenesin, a bitter-tasting antitussive drug. Our findings revealed that eriodictyol, hesperitin and phyllodulcin were the most potent suitable candidates for bitter-masking activity, verified in a human sensory trial. [ABSTRACT FROM AUTHOR]