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A new drug combination of phenylephrine hydrochloride (PHE) and doxylamine succinate (DOX) has been introduced for treating allergic rhinitis. Stability testing is critical for uncovering degradation routes and assessing the stability of combined drugs. This study illustrates the application of two eco-friendly chromatographic techniques which are reversed phase high-performance liquid chromatography (RP-HPLC) and high-performance thin-layer chromatography (HPTLC), for assessing PHE and DOX when DOX oxidative degradation product (DOX DEG) is present. Using liquid chromatography- mass spectroscopy to identify DOX DEG. The HPLC method produced the best separation with isocratic elution and a mobile phase consists of ethanol and 0.01 M phosphate buffer pH = 5.0 (30: 70, v/v), and it was pumped at 1.0 mL/min. The analytes were measured at 260.0 nm using diode array detector (DAD), and the Xterra C 18 column (100 mm × 4.6 mm × 5 m) used as a stationary phase. The method demonstrated a linear response for DOX and PHE across a concentration range of 5.00 to 100.00 µg/mL. The range for DOX DEG was 5.00 to 30.00 µg/mL. The limits of detection (LOD) were determined to be 1.44 for DOX, 1.59 for PHE, and 0.84 µg/mL for DOX DEG. Correspondingly, the limits of quantification (LOQ) were 4.32, 4.77, and 2.52 µg/mL for DOX, PHE, and DOX DEG, respectively. The separation in HPTLC was accomplished by combining ethanol, methylene chloride, and ammonia 30% in ratio 7:2.5:0.5 (v/v/v) as a developing system. The drugs were then quantitatively determined at wavelengths of 260.0 nm using UV detector. The linearity range was 4.00–26.00 (µg/band) for DOX and PHE while it was 0.50–10.00 (µg/band) for DOX DEG. Values of LOD were 0.65 ,0.76 and 0.16 µg/band for PHE, DOX, DOX DEG, respectively. While1.95,2.28 and 0.48 µg/band were values of LOQ. Per ICH guidelines, two analytical methods were validated and proven to be reliable, reproducible, and selective. Additionally, sustainability assessments confirmed their green credentials and practical applicability.

The use of the successive projections algorithm (SPA) for elimination of uninformative variables in interval selection, and unfold partial least squares regression (U-PLS) modeling of excitation-emission matrices (EEM), when under the inner filter effect (IFE) is reported for first time. Post-calibration residual bilinearization (RBL) was employed against events of unknown components in the test samples. The inner filter effect can originate changes in both the shape and intensity of analyte spectra, leading to trilinearity losses in both modes, and thus invalidating most multiway calibration methods. The algorithm presented in this paper was named iSPA-U-PLS/RBL. Both simulated and experimental data sets were used to compare the prediction capability during: (1) simulated EEM; and (2) quantitation of phenylephrine (PHE) in the presence of paracetamol (PAR) (or acetaminophen) in water samples. Test sets containing unexpected components were built in both systems [a single interference was taken into account in the simulated data set, while water samples were added with varying amounts of ibuprofen (IBU), and acetyl salicylic acid (ASA)]. The prediction results and figures of merit obtained with the new algorithm were compared with those obtained with U-PLS/RBL (without intervals selection), and with the well-known parallel factors analysis (PARAFAC). In all cases, U-PLS/RBL displayed better EEM handling capability in the presence of the inner filter effect compared with PARAFAC. In addition, iSPA-U-PLS/RBL improved the results obtained with the full U-PLS/RBL model, in this case demonstrating the potential of variable selection.

The Food and Drug Administration recently banned the sale of ephedra alkaloids because of their association with arrhythmic sudden death, myocardial infarction, and stroke. This has resulted in the emergence of formulations marketed for weight loss and performance enhancement that are “ephedra free” but contain other sympathomimetic substances, the safety of which has not been established. We report a case of exercise-induced syncope in a healthy 22-year-old woman that occurred 1 hour after she took the second dose of Xenadrine EFX, an ephedra-free weight-loss supplement. Electrocardiography revealed prolongation of the QT interval (corrected QT, 516 milliseconds); this resolved in 24 hours. Results of echocardiography and exercise stress testing were normal. Nine months of monitoring with an implanted loop recorder revealed no arrhythmias in the absence of Xenadrine EFX. Although this product contains a number of compounds whose pharmacologic effect is poorly characterized, notable quantities of phenylephrine are present, and the proarrhythmic potential of this compound in the setting of exercise is discussed.

Spinal anesthesia often causes hypotension, with consequent risk to the fetus. The use of vasopressor agents has been highly recommended for the prevention of spinal anesthesia-induced hypotension during caesarean delivery. Many studies have shown that norepinephrine can provide more stable maternal hemodynamics than phenylephrine. We therefore tested the hypothesis that norepinephrine preserves fetal circulation better than phenylephrine when used to treat maternal hypotension consequent to spinal anesthesia. Prospective, randomized, double-blinded study. Operating room. We recruited 223 parturients with uncomplicated singleton pregnancies who were scheduled for elective caesarean section under combined spinal-epidural anesthesia. The patients received prophylactic intravenous infusion of either 0.08 μg/kg/min norepinephrine or 0.5 μg/kg/min phenylephrine for prevention of spinal anesthesia-induced hypotension. Changes in fetal heart rate and fetal cardiac output before and after spinal anesthesia were measured using noninvasive Doppler ultrasound. 90 subjects who received norepinephrine infusion and 93 subjects who received phenylephrine infusion were ultimately analyzed in the present study. The effects of norepinephrine and phenylephrine on the change of fetal heart rate and fetal cardiac output at 3 and 6 min after spinal block were similar. Although there was a statistically significant decrease in fetal cardiac output at 6 min after subarachnoid block initiation in both the norepinephrine group (mean difference 0.02 L/min; 95% CI, 0–0.04 L/min; P = 0.03) and the phenylephrine group (mean difference 0.02 L/min; 95% CI, 0–0.04 L/min; P = 0.02), it remained within the normal range. Prophylactic infusion of comparable doses of phenylephrine or norepinephrine has similar effects on fetal heart rate and cardiac output changes after spinal anesthesia. Neither phenylephrine nor norepinephrine has meaningful detrimental effects on fetal circulation or neonatal outcomes. •Prophylactic infusion of comparable doses of phenylephrine or norepinephrine has similar effects on fetal heart rate and cardiac output changes after spinal anesthesia.•Neither phenylephrine nor norepinephrine has meaningful detrimental effects on fetal circulation.

The consensus recommends maintaining the patient's systolic blood pressure at or above 90% of the baseline value, and highlights the use of vasopressors as the primary strategy for preventing and managing hypotension during cesarean section. This study was aimed to determine the ED90 of prophylactic infusions of norepinephrine and phenylephrine in preeclamptic patients under strict blood pressure management target (maintaining ≥90% of the baseline value). 60 preeclamptic patients were randomly assigned to either the norepinephrine or the phenylephrine group. The initial patients received an infusion of norepinephrine at 0.05 μg/kg/min or phenylephrine at 0.5 μg/kg/min. For subsequent patients, infusion rates were adjusted in increments or decrements of 0.01 or 0.1 μg/kg/min, respectively, to achieve strict blood pressure management targets before delivery. Secondary outcomes included patients' adverse events, umbilical artery blood gas analysis, and newborns' Apgar scores. The isotonic regression analysis revealed that the ED90 values of norepinephrine and phenylephrine infusions required to maintain a strict blood pressure management targets were 0.076 μg/kg/min (95% CI, 0.070-0.080) and 0.900 μg/kg/min (95% CI, 0.850-0.950), respectively. The secondary outcomes between groups were comparable. Under strict blood pressure management target in preeclamptic patients undergoing cesarean section, the ED90 values for norepinephrine and phenylephrine infusions are 0.076 μg/kg/min and 0.900 μg/kg/min, respectively. This study was registered at ClinicalTrials.gov on November 28, 2023 (No. NCT06158022).

Spinal anesthesia-induced hypotension can cause detrimental effects on both the mother and the fetus, and it remains a significant concern in obstetric anesthesia. The use of vasopressors is considered the most reliable and effective approach. Previous studies have shown that norepinephrine appears to be superior to phenylephrine in maintaining maternal heart rate and cardiac output. Therefore, we hypothesize that norepinephrine is more effective than phenylephrine in maintaining neonatal cerebral perfusion when used to prevent spinal anesthesia-induced hypotension. This study is a prospective, double-blinded, randomized trial. We enrolled 216 singleton parturients who were scheduled for elective cesarean delivery. The patients received a prophylactic intravenous infusion of either norepinephrine (0.08 μg/kg/min) or phenylephrine (0.5 μg/kg/min). Maternal cardiac output was not routinely monitored during the study period. Fetal ultrasound examinations were performed, with blood velocity measured in the middle cerebral artery and umbilical artery, and the cerebroplacental ratio calculated. Ninety subjects were ultimately analyzed in each group. The changes in blood velocity in the middle cerebral artery and umbilical artery, as well as the calculated cerebroplacental ratio at 3 and 6 minutes after spinal anesthesia, did not differ significantly between the two groups. The estimated difference of ΔCPR in two groups was - 0.01 (95% CI, -0.05-0.02, P = 0.491) at 3 minutes and was 0.02 (95% CI, -0.01-0.07, P = 0.204) at 6 minutes. Prophylactic infusion of norepinephrine or phenylephrine at comparable doses has similar effects on fetal cerebral perfusion.

The current study aimed to compare the effects of norepinephrine and phenylephrine on tissue oxygenation and clinical outcomes in Moyamoya disease patients. Sixty patients scheduled for superficial temporal artery-middle cerebral artery bypass were randomly assigned to either the norepinephrine group or the phenylephrine group. Standard doses of norepinephrine or phenylephrine were infused during surgery to maintain blood pressure fluctuating within ± 10% of baseline values. Cerebral oxygenation, muscle oxygenation, cardiac output, and urine volume were recorded at several timepoints: Before preoxygenation, After intubation, Skin cutting, Superficial temporal artery exposing, Middle cerebral artery exposing, and End of the surgery. Additionally, blood samples were collected from the superior vena cava and radial artery for blood gas analysis, to assess central venous oxygen saturation, blood lactate and calculate oxygen extraction rate. Length of hospital stay, incidence of neurological complications during hospitalization and mortality within 90 days were also recorded. Compared with phenylephrine group, the norepinephrine group exhibited significantly higher cerebral oxygenation, muscle oxygenation and cardiac output at Superficial temporal artery exposing, Middle cerebral artery exposing, and End of the surgery ( <0.05). No significant difference was observed between groups at any timepoints regarding urine output, central venous oxygen saturation, blood lactate levels, oxygen extraction rate. Length of hospital stay, incidence of neurological complications during hospitalization and 90-day mortality rate were comparable between groups. The use of norepinephrine, in contrast to phenylephrine, for managing hypotension during superficial temporal artery-middle cerebral artery bypass significantly enhances tissue oxygenation, which may be related to the effective maintenance of cardiac output by norepinephrine.

Background Compared with singleton pregnancy, twin gestation is featured by a greater increase in cardiac output. Therefore, norepinephrine might be more suitable than phenylephrine for maintaining blood pressure during cesarean section for twins, as phenylephrine causes reflex bradycardia and a resultant decrease in cardiac output. This study was to determine whether norepinephrine was superior to phenylephrine in maintaining maternal hemodynamics during cesarean section for twins. Methods Informed consent was obtained from all the patients before enrollment. In this double-blinded, randomized clinical trial, 100 parturients with twin gestation undergoing cesarean section with spinal anesthesia were randomized to receive prophylactic norepinephrine (3.2 μg/min) or phenylephrine infusion (40 μg/min). The primary outcome was the change of heart rate and blood pressure during the study period. The secondary outcomes were to compare maternal complications, neonatal outcomes, Apgar scores and umbilical blood acid-base status between the two vasopressors. Results There was no significant difference observed for the change of heart rate between two vasopressors. The mean standardized area under the curve of heart rate was 78 ± 12 with norepinephrine vs. 74 ± 11 beats/min with phenylephrine (mean difference 4.4, 95%CI − 0.1 to 9.0; P  = .0567). The mean standardized area under the curve of systolic blood pressure (SBP) was significantly lower in parturients with norepinephrine, as the mean of differences in standardized AUC of SBP was 6 mmHg, with a 95% CI from 2 to 9 mmHg ( P  = .0013). However, requirements of physician interventions for correcting maternal hemodynamical abnormalities (temporary cessation of vasopressor infusion for reactive hypertension, rescuing vasopressor bolus for hypotension and atropine for heart rate less < 50 beats/min) and neonatal outcomes were also not significantly different between two vasopressors. Conclusion Infusion of norepinephrine was not associated with less overall decrease in heart rate during cesarean section for twins, compared with phenylephrine. Trial registration Chinese Clinical Trial Registry ( ChiCTR1900021281 ).

Background Intravenous fluid administration and prophylactic vasopressor infusion are the primary methods for preventing spinal anesthesia-induced hypotension during cesarean delivery. However, evidence regarding the impact of different volumes of crystalloid solution on the phenylephrine infusion dosage for preventing this hypotension remains inconclusive. This study aimed to determine the effect of two IV fluid infusion rates (10 or 20 mL/kg/h) on phenylephrine requirement for preventing spinal anesthesia-induced hypotension. Methods Eighty healthy parturients undergoing elective cesarean delivery under combined spinal-epidural anesthesia were enrolled. Participants were randomly assigned to receive either 10 mL/kg/h (group 10) or 20 mL/kg/h (group 20) of lactated Ringer’s solution. The first patient in each group received 0.5 µg/kg/min of phenylephrine infusion immediately after intrathecal injection. The phenylephrine dose in subsequent patients was adjusted by increments or decrements of 0.05 µg/kg/min based on the previous patient’s response. The ED50 of phenylephrine infusion for preventing spinal-induced hypotension for cesarean delivery was estimated using a modified up-down sequential analysis, with probit analysis applied as a backup sensitivity analysis. Results The ED50 values for preventing spinal anesthesia-induced hypotension were 0.30 µg/kg/min (95% CI, 0.29–0.32 µg/kg/min) for group 10, and 0.19 µg/kg/min (95% CI, 0.16–0.22 µg/kg/min) for group 20, respectively. The estimated relative potency for phenylephrine in group 10 compared to group 20 was 1.52 (95%CI, 1.24–1.97), showing a significant difference in the ED50 values between the two groups. Conclusion This study found that a higher crystalloid co-loading rate significantly reduces prophylactic phenylephrine requirement for preventing spinal anesthesia induced hypotension. Trials registration https://www.chictr.org.cn/showproj.html?proj=125918 (Trial number: ChiCTR2100048002).

Background Phenylephrine and ephedrine are frequently used vasopressors for treating intraoperative hypotension. However, their impact on cerebral oxygenation and blood flow remains a subject of debate. This study aims to understand their effects on cerebral oxygen saturation and hemodynamics when used for treatment of intraoperative hypotension. Methods The adult patients undergoing major abdominal surgery under general anesthesia were randomly assigned into ephedrine (ED) group or phenylephrine (PE) group. They received an intravenous bolus of either ephedrine or phenylephrine for treating intraoperative transient hypotension. The primary outcome was their effects on regional cerebral oxygen saturation (rScO 2 ). The secondary outcomes included cerebral hemodynamics middle cerebral artery velocity (MCAvm), pulsatility index (PI), and resistance index (RI), as well as systemic hemodynamics arterial blood pressure (ABP), heart rate (HR), cardiac output (CO), cardiac index (CI), stroke volume (SV) and stroke volume index (SVI). Additionally, two indices of cerebral autoregulation, mean flow index (Mx a ) and cerebral oximetry index (CO X ), were calculated in real-time via ICM + software. Results Forty patients were included in this study. The initial results showed ephedrine increased rScO 2 ( p  < 0.001), while phenylephrine increased Mx a ( p  < 0.02) and CO X ( p  < 0.007), respectively. However, upon further linear-mix model analysis, the effects of both drugs on rScO 2 ( p  = 0.944), Mx a ( p  = 0.093) and CO X ( p  = 0.084) were found to be non-significant. Compared with the hemodynamic parameters during hypotension, the systolic blood pressure (SBP) ( p  < 0.001), diastolic blood pressure (DBP) ( p  < 0.001), mean arterial pressure (MAP) ( p  < 0.001), and MCAvm ( p  < 0.001) significantly increased after both ephedrine and phenylephrine administration. However, no significant differences were found between the two groups in terms of the changes in MAP ( p  = 0.549) and MCAvm ( p  = 0.173). And there were significant increases in CO ( p  < 0.001), HR ( p  < 0.001), and CI ( p  < 0.001) following ephedrine administration, while decreases in HR ( p  < 0.001), CO ( p  < 0.001), and CI ( p  < 0.001) after phenylephrine administration. Conclusion In the management of intraoperative hypotension, both phenylephrine and ephedrine effectively increase MAP and MCAvm, albeit with their differential effects on CO and HR. It seems that neither vasopressor has a significant impact on cerebral oxygenation and cerebral autoregulation.