Elucidation and quantitative determination of some of commonly used penicillins (ampicillin, penicillin G and carbenicillin) in the presence of their main degradation product (penicilloic acid) were developed. Forced acidic and basic degradation processes were applied at different time intervals. The formed degradation products were elucidated and quantified using surface enhanced Raman spectroscopy (SERS). Silver nanoparticles (AgNPs) prepared by reduction of silver nitrate using hydroxylamine-HCl in alkaline medium were used as SERS substrate. The results obtained in SERS were confirmed by the application of LC/MS method. The concentration range was 100-600 ng/ml in case of the studied penicillins and 100-700 ng/ml in case of penicilloic acid. An excellent correlation coefficient was found in case of ampicillin (r= 0.9993) and in the case of penicilloic acid (r= 0.9997). Validation procedures were carried out including precision, robustness and accuracy by comparing F- and t-values of both the proposed and reported methods.

Elucidation and quantitative determination of some of commonly used penicillins (ampicillin, penicillin G and carbenicillin) in the presence of their main degradation product (penicilloic acid) were developed. Forced acidic and basic degradation processes were applied at different time intervals. The formed degradation products were elucidated and quantified using surface enhanced Raman spectroscopy (SERS). Silver nanoparticles (AgNPs) prepared by reduction of silver nitrate using hydroxylamine-HCl in alkaline medium were used as SERS substrate. The results obtained in SERS were confirmed by the application of LC/MS method. The concentration range was 100-600 ng/ml in case of the studied penicillins and 100-700 ng/ml in case of penicilloic acid. An excellent correlation coefficient was found in case of ampicillin (r= 0.9993) and in the case of penicilloic acid (r= 0.9997). Validation procedures were carried out including precision, robustness and accuracy by comparing F- and t-values of both the proposed and reported methods.

Biothiols play an essential role in a number of biological processes in living organisms including detoxification and metabolism. Fetal to neonatal transition poses a pro-oxidant threat for newborn infants, especially those born prematurely. A reliable and rapid tool for the direct determination of thiols in small volume whole blood (WB) samples would be desirable for its application in clinical practice. This study shows the feasibility of Surface Enhanced Raman Spectroscopy (SERS) using a silver colloid prepared by reduction of silver nitrate using hydroxylamine, as the SERS substrate for the quantification of thiols in WB samples after a simple precipitation step for protein removal. Bands originating from biothiols (790, 714 and 642 cm−1) were enhanced by the employed SERS substrate and the specificity of the detected SERS signal was tested for molecules presenting –SH functional groups. A statistically significant correlation between the obtained SERS signals and the thiol concentration measured using a chromatographic reference method in umbilical cord WB samples could be demonstrated. Using WB GSH concentrations obtained from the chromatographic reference procedure, a Partial Least Squares (PLS) regression model covering GSH concentrations from 13 to 2200 μM was calculated obtaining a root mean square error of prediction (RMSEP) of 381 μM when applied to an external test set. The developed approach uses small blood sample volumes (50 μL), which is important for clinical applications, especially in the field of neonatology. This feasibility study shows that the present approach combines all the necessary characteristics for its potential application in clinical practice.

A simple, fast and sensitive surface enhanced Raman spectroscopy (SERS) method for quantitative determination of fluoroquinolone antibiotic Ofloxacin (OFX) is presented. Also the stability behavior of OFX was investigated by monitoring the SERS spectra of OFX after various degradation processes. Acidic, basic and oxidative force degradation processes were applied at different time intervals. The forced degradation conditions were conducted and followed using SERS method utilizing silver nanoparticles (Ag NPs) as a SERS substrate. The Ag NPs colloids were prepared by reduction of silver nitrate using polyethyelene glycol (PEG) as a reducing and stabilizing agent. Validation tests were done in accordance with International Conference on Harmonization (ICH) guidelines. The calibration curve with a correlation coefficient (R = 0.9992) was constructed as a relationship between the concentration range of OFX (100–500 ng/ml) and SERS intensity at 1394 cm−1 band. LOD and LOQ values were calculated and found to be 23.5 ng/ml and 72.6 ng/ml, respectively. The developed method was applied successfully for quantitation of OFX in different pharmaceutical dosage forms. Kinetic parameters were calculated including rate constant of the degradation of the studied antibiotic.

Naproxen (nap) is belonging to Non-steriodal anti-inflammatory drugs (NSAIDs) group of drugs that characterized by their free carboxylic group. The therapeutic activity of nap is usually accompanied by GI untoward side effects. Recently synthesized naproxen amides of some amino acid esters prodrugs to mask the free carboxylic group were reported. Those prodrugs showed a promising colorectal cancer chemopreventive activity. The current study aims to investigate the fate and hydrolysis of the prodrugs kinetically in different pH conditions, simulated gastric and intestinal fluids with pHs of 1.2, 5.5 and 7.4 in vitro at 37 °C. The effect of enzymes on the hydrolysis of prodrugs was also studied through incubation of these prodrugs at 37 °C in human plasma and rat liver homogenates. The pharmacokinetic parameters of selected prodrugs and the liberated nap were studied after oral and intraperitoneal administration in male wistar rats. The results showed the hydrolysis of naproxen amides of amino acid esters to nap through two steps first by degradation of the ester moiety to form the amide of nap with amino acid and the second was through the degradation of the amide link to liberate nap. The two reactions were followed and studied kinetically where K1 and K2 (rate constants of degradation) is reported. The hydrolysis of prodrugs was faster in liver homogenates than in plasma. The relative bioavailability of the liberated nap in vivo was higher in case of prodrug containing ethyl glycinate moiety than that occupied l-valine ethyl ester moiety. Each of nap. prodrugs containing ethyl glycinate and l-valine ethyl ester moieties appears promising in liberating nap, decreasing direct GI side effect and consequently their colorectal cancer chemopreventive activity.

Naproxen (nap) is belonging to Non-steriodal anti-inflammatory drugs (NSAIDs) group of drugs that characterized by their free carboxylic group. The therapeutic activity of nap is usually accompanied by GI untoward side effects. Recently synthesized naproxen amides of some amino acid esters prodrugs to mask the free carboxylic group were reported. Those prodrugs showed a promising colorectal cancer chemopreventive activity. The current study aims to investigate the fate and hydrolysis of the prodrugs kinetically in different pH conditions, simulated gastric and intestinal fluids with pHs of 1.2, 5.5 and 7.4 in vitro at 37 °C. The effect of enzymes on the hydrolysis of prodrugs was also studied through incubation of these prodrugs at 37 °C in human plasma and rat liver homogenates. The pharmacokinetic parameters of selected prodrugs and the liberated nap were studied after oral and intraperitoneal administration in male wistar rats. The results showed the hydrolysis of naproxen amides of amino acid esters to nap through two steps first by degradation of the ester moiety to form the amide of nap with amino acid and the second was through the degradation of the amide link to liberate nap. The two reactions were followed and studied kinetically where K1 and K2 (rate constants of degradation) is reported. The hydrolysis of prodrugs was faster in liver homogenates than in plasma. The relative bioavailability of the liberated nap in vivo was higher in case of prodrug containing ethyl glycinate moiety than that occupied l-valine ethyl ester moiety. Each of nap. prodrugs containing ethyl glycinate and l-valine ethyl ester moieties appears promising in liberating nap, decreasing direct GI side effect and consequently their colorectal cancer chemopreventive activity.

In this study, the oxidation of rabeprazole sodium (RAB Na+), a widely used anti-ulcer drug, was investigated at a modified poly (bromocresol green)/ pencil graphite electrode (poly (BCRG)/PGE). A disposable, sensitive and selective electrochemical platform is proposed for the determination of RAB Na+ by recording its cyclic voltammetry (CV) and square wave adsorptive voltammetry (SWV) in Britton-Robinson buffer solution at pH of 7.0 using the modified PGE. The poly BCRG/PGE displayed a good electrochemical behaviour with significant enhancement of the peak current compared to the bare PGE. Under experimental conditions, the modified electrode had a linear response range from 10-180 × 10-8 M and 3-330 × 10-7 M for SWV and CV, respectively. The detection limit was found to be 3 × 10-8 M and 1 × 10-7 M for SWV and CV, respectively. These voltammetric methods were successfully applied for the direct determination of RAB Na+ in real samples. The effect of various interfering substances on the RAB Na+ peak current was also investigated

In this study, the oxidation of rabeprazole sodium (RAB Na+), a widely used anti-ulcer drug, was investigated at a modified poly (bromocresol green)/ pencil graphite electrode (poly (BCRG)/PGE). A disposable, sensitive and selective electrochemical platform is proposed for the determination of RAB Na+ by recording its cyclic voltammetry (CV) and square wave adsorptive voltammetry (SWV) in Britton-Robinson buffer solution at pH of 7.0 using the modified PGE. The poly BCRG/PGE displayed a good electrochemical behaviour with significant enhancement of the peak current compared to the bare PGE. Under experimental conditions, the modified electrode had a linear response range from 10-180 × 10-8 M and 3-330 × 10-7 M for SWV and CV, respectively. The detection limit was found to be 3 × 10-8 M and 1 × 10-7 M for SWV and CV, respectively. These voltammetric methods were successfully applied for the direct determination of RAB Na+ in real samples. The effect of various interfering substances on the RAB Na+ peak current was also investigated

In this study, the oxidation of rabeprazole sodium (RAB Na+), a widely used anti-ulcer drug, was investigated at a modified poly (bromocresol green)/ pencil graphite electrode (poly (BCRG)/PGE). A disposable, sensitive and selective electrochemical platform is proposed for the determination of RAB Na+ by recording its cyclic voltammetry (CV) and square wave adsorptive voltammetry (SWV) in Britton-Robinson buffer solution at pH of 7.0 using the modified PGE. The poly BCRG/PGE displayed a good electrochemical behaviour with significant enhancement of the peak current compared to the bare PGE. Under experimental conditions, the modified electrode had a linear response range from 10-180 × 10-8 M and 3-330 × 10-7 M for SWV and CV, respectively. The detection limit was found to be 3 × 10-8 M and 1 × 10-7 M for SWV and CV, respectively. These voltammetric methods were successfully applied for the direct determination of RAB Na+ in real samples. The effect of various interfering substances on the RAB Na+ peak current was also investigated

The effect of adding surfactants to electrolyte containing rabeprazole sodium (RAB sodium) on its voltammetric response at pencil graphite electrode (PGE) was explored. The current signal due to the oxidation process as a function of the amount of the cited drug, pH of the medium, type of surfactant and accumulation time at the electrode surface was evaluated. The use of sodium dodecyl sulphate in the presence of Britton-Robinson buffer (pH=6.0) for the electrochemical determination of RAB sodium using cyclic voltammetry (CV) and Square wave adsorptive stripping voltammetry (SWAdSV) at PGE was studied. The oxidation peak current has varied linearly with the drug concentration over the range of 0.006-2.5×10-7 M and 0.5-250 μM using SWAdSV and CV, respectively. The limit of detection was found to be 0.2 nM and 0.18 μM using SWAdSV and CV, respectively. The validity of the proposed method for the determination of the studied drug in pure, pharmaceutical formulation in addition to urine was conducted.