Repaglinide-Solid Lipid Nanoparticles in Chitosan Patches for Transdermal Application: Box-Behnken Design, Characterization, and In Vivo Evaluation.

Background: Repaglinide (REP) is an antidiabetic drug with limited oral bioavailability attributable to its low solubility and considerable first-pass hepatic breakdown. This study aimed to develop a biodegradable chitosan-based system loaded with REP-solid lipid nanoparticles (REP-SLNs) for controlled release and bioavailability enhancement via transdermal delivery. Methods: REP-SLNs were fabricated by ultrasonic hot-melt emulsification. A Box-Behnken design (BBD) was employed to explore and optimize the impacts of processing variables (lipid content, surfactant concentration, and sonication amplitude) on particle size (PS), and entrapment efficiency (EE). The optimized REP-SLN formulation was then incorporated within a chitosan solution to develop a transdermal delivery system (REP-SLN-TDDS) and evaluated for physicochemical properties, drug release, and ex vivo permeation profiles. Pharmacokinetic and pharmacodynamic characteristics were assessed using experimental rats. Results: The optimized REP-SLNs had a PS of 249±9.8 nm and EE of 78%±2.3%. The developed REP-SLN-TDDS demonstrated acceptable characteristics without significant aggregation of REP-SLNs throughout the casting and drying processes. The REP-SLN-TDDS exhibited a biphasic release pattern, where around 36% of the drug load was released during the first 2 h, then the drug release was sustained at around 80% at 24 h. The computed flux across rat skin for the REP-SLN-TDDS was 2.481±0.22 µg/cm2/h in comparison to 0.696±0.07 µg/cm2/h for the unprocessed REP, with an enhancement ratio of 3.56. The REP-SLN-TDDS was capable of sustaining greater REP plasma levels over a 24 h period (p<0.05). The REP-SLN-TDDS also reduced blood glucose levels compared to unprocessed REP and commercial tablets (p<0.05) in experimental rats. Conclusion: Our REP-SLN-TDDS can be considered an efficient therapeutic option for REP administration.

Parallel artificial liquid membrane extraction coupled with UPLC-ESI-MS/MS method for high-throughput quantitation of repaglinide in diabetic patients.

A high-throughput therapeutic monitoring method was developed for repaglinide (RPG) in diabetic patients, combining parallel artificial liquid membrane extraction (PALME) with ultraperformance liquid chromatography electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). PALME was performed using a 96-well donor plate comprising a donor solution containing a plasma sample, 50 mM phosphate buffer (pH = 8.0), and cetirizine (CTZ) as internal standard. A polypropylene (PP) porous membrane served as a selective support for the liquid membrane (SLM), preventing nonspecific binding produced by other membranes. The extraction was accomplished across SLM made of PP membrane with dodecyl acetate and 1 % trioctylamine (w/w), and the acceptor solution comprised DMSO and 200 mM formic acid (50:50, v/v). The simple workflow for PALME provided analyte enrichment, highly efficient sample cleanup, high throughput analysis, and excellent reproducibility. Method validation met FDA criteria, with a linear plasma calibration range (0.1-100 ng mL-1, r = 0.9995) and a lower limit of quantitation (LLOQ) of 0.1 ng mL-1. Recovery results at 98.9 % affirmed method reliability. The ability to analyze 198 samples per hour, coupled with a reduced amount of solvents, underscores the method's high throughput and eco-friendly profile. The PALME-UPLC-ESI-MS/MS method was successfully applied to therapeutic drug monitoring of RPG in diabetic patients following 2 mg RPG tablet administration, establishing its effectiveness.

Utilization of a TiO2-CuO Bimetallic/Polyaniline Nanocomposite as a Transducer in a Solid Contact Potentiometric Sensor for the Determination of Vildagliptin.

Current fundamental electrochemical research shows the potential of utilizing polymeric nanostructured materials as ion-to-electron transducers. In this paper, aniline was polymerized in the presence of TiO2 and CuO nanoparticles to yield a bimetallic/PANI nanocomposite. It was applied as a transducer in a carbon paste electrode for the potentiometric determination of vildagliptin in the presence of 18-crown-6-ether as a recognition element. The electrode's potentiometric performance was studied according to the IUPAC guidelines. It exhibited a wide linearity range of 1 × 10-2 M to 1 × 10-8 M, remarkable sensitivity (LOD of 4.5 × 10-9 M), and a fast response time of 10 s ± 1.3. The sensor did not show any potential drift due to the absence of the water layer between the carbon paste and the metallic conductor. This endowed the sensor with high stability and a long lifetime, as 137 days passed without the need to change the carbon paste surface. The electrode was utilized for the determination of the concentration of vildagliptin in bulk, pharmaceutical tablets, and human plasma, with average recovery ranging from 97.65% to 100.03%.

The Impact of Serum Levels of Reactive Oxygen and Nitrogen Species on the Disease Severity of COVID-19.

Elucidation of the redox pathways in severe coronavirus disease 2019 (COVID-19) might aid in the treatment and management of the disease. However, the roles of individual reactive oxygen species (ROS) and individual reactive nitrogen species (RNS) in COVID-19 severity have not been studied to date. The main objective of this research was to assess the levels of individual ROS and RNS in the sera of COVID-19 patients. The roles of individual ROS and RNS in COVID-19 severity and their usefulness as potential disease severity biomarkers were also clarified for the first time. The current case-control study enrolled 110 COVID-19-positive patients and 50 healthy controls of both genders. The serum levels of three individual RNS (nitric oxide (NO•), nitrogen dioxide (ONO-), and peroxynitrite (ONOO-)) and four ROS (superoxide anion (O2•-), hydroxyl radical (•OH), singlet oxygen (1O2), and hydrogen peroxide (H2O2)) were measured. All subjects underwent thorough clinical and routine laboratory evaluations. The main biochemical markers for disease severity were measured and correlated with the ROS and RNS levels, and they included tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), the neutrophil-to-lymphocyte ratio (NLR), and angiotensin-converting enzyme 2 (ACE2). The results indicated that the serum levels of individual ROS and RNS were significantly higher in COVID-19 patients than in healthy subjects. The correlations between the serum levels of ROS and RNS and the biochemical markers ranged from moderate to very strongly positive. Moreover, significantly elevated serum levels of ROS and RNS were observed in intensive care unit (ICU) patients compared with non-ICU patients. Thus, ROS and RNS concentrations in serum can be used as biomarkers to track the prognosis of COVID-19. This investigation demonstrated that oxidative and nitrative stress play a role in the etiology of COVID-19 and contribute to disease severity; thus, ROS and RNS are probable innovative targets in COVID-19 therapeutics.

Effects of ketamine or dexmedetomidine on postoperative cognitive dysfunction after cataract surgery: A randomized controlled trial.

Background and Aims: Ketamine and dexmedet omidine have neuroprotective effects that may reduce the occurrence of postoperative cognitive dysfunction (POCD) when they are used by intravenous infusion in geriatric patients scheduled for cataract extraction. Methods: Ninety patients aged 65-85 years old, ASA physical status II and III, and scheduled for cataract extraction under peribulbar block were randomly distributed equally among three groups: control group, in which patients received normal saline; ketamine group, in which patients received 0.3 mg/kg/h of ketamine; and dexmedetomidine group, in which patients received 0.5 µg/kg/h of dexmedetomidine. Medications were administrated by intravenous infusion and started 10 min before the surgery and continued throughout the duration of surgery. The analysed parameters included the incidence of POCD (primary outcome) through composite score of neuropsychological testing at one week and 3 months after surgery, postoperative pain score, postoperative sedation score, changes in haemodynamic parameters, changes in intraocular pressure, and incidence of complications. Results: In comparison with control group, ketamine and dexmedetomidine groups exhibited a significant decline in number of patients who developed POCD (P < 0.0001), a decrease in the postoperative pain score 4 h after surgery (P = 0.038), and an increase in the postoperative Ramsay sedation Score (P = 0.0002, 0.0003, and 0.011), without significant changes in the vital parameters, intraocular tension, or incidence of complications. Ketamine and dexmedetomidine groups were comparable. Conclusion: Intravenous administration of ketamine or dexmedetomidine in elderly patients undergoing cataract surgery under peribulbar anesthesia significantly decreases the incidence of POCD.

The Impact of Serum Levels of Vitamin D3 and Its Metabolites on the Prognosis and Disease Severity of COVID-19.

Vitamin D is among the increasingly consumed dietary supplements during the COVID-19 pandemic. It plays a regulatory role in the immune system and moderates the renin-angiotensin system, which is implicated in infection pathogenesis. However, the investigation of serum levels of vitamin D3 forms and their relative ratios in COVID-19 patients is worth investigation to understand the impacts of disease severity. Hence, we investigated the serum levels of vitamin D3 (cholecalciferol) and its metabolites (calcifediol and calcitriol), in addition to their relative ratios and correlations with angiotensin-converting enzyme 2 (ACE2), interleukin-6 (Il-6), and neutrophil-lymphocyte ratio (NLR) in COVID-19 patients compared with healthy controls. Oropharyngeal specimens were collected from the study subjects for polymerase chain reaction testing for COVID-19. Whole blood samples were obtained for blood count and NLR testing, and sera were used for the analysis of the levels of the vitamin and its metabolites, ACE2, and IL-6. We enrolled 103 patients and 50 controls. ACE2, Il-6, and NLR were significantly higher in the patients group (72.37 ± 18.67 vs. 32.36 ± 11.27 U/L, 95.84 ± 25.23 vs. 2.76 ± 0.62 pg/mL, and 1.61 ± 0.30 vs. 1.07 ± 0.16, respectively). Cholecalciferol, calcifediol, and calcitriol were significantly lower in patients (18.50 ± 5.36 vs. 29.13 ± 4.94 ng/mL, 14.60 ± 3.30 vs. 23.10 ± 3.02 ng/mL, and 42.90 ± 8.44 vs. 65.15 ± 7.11 pg/mL, respectively). However, their relative ratios were normal in both groups. Levels of the vitamin and metabolites were strongly positively, strongly negatively, and moderately negatively correlated with ACE2, Il-6, and NLR, respectively. COVID-19 infection severity is associated with a significant decrease in vitamin D3 and its metabolites in a parallel pattern, and with a significant increase in ACE2, Il-6, and NLR. Higher levels of vitamin D and its metabolites are potentially protective against severe infection.

Boosting Tadalafil Bioavailability via Sono-Assisted Nano-Emulsion-Based Oral Jellies: Box-Behnken Optimization and Assessment.

Tadalafil (TAD) is a poorly soluble, phosphodiesterase inhibitor used to treat erectile dysfunction. The primary goal of this project was to prepare nano-emulsions using ultrasonic technology to address TAD bioavailability concerns. The Box−Behnken design was employed to find prominent correlations between factors impacting the sono-emulsification process. The emulsifier concentration, amplitude level, and ultrasonication time were the independent factors, whereas the average droplet size (ADS) and polydispersity index (PDI) were designated as the response variables. TAD-loaded nano-emulsions (93−289 nm) were generated and the emulsifier concentration showed a crucial role in directing emulsion droplet size. The model desirability function was utilized to optimize a nano-emulsion with a small ADS (99.67 ± 7.55 nm) and PDI (0.45 ± 0.04) by adjusting the emulsifiers concentration, amplitude level, and ultrasonication time at 9.85%, 33%, 49 s, respectively. The optimized nano-emulsions did not demonstrate any precipitation or phase separation after stability stress tests. TAD jellies were formulated based on the optimized nano-emulsion and subjected to in vitro evaluation for physical characteristics; TAD content, pH, spreadability, viscosity, syneresis, and taste-masking ability. An optimized nano-emulsion-based jelly (NEJ) formulation showed more than 96% drug dissolution in 30 min relative to 14% for the unprocessed TAD. In vivo assessment of NEJ in experimental rats demonstrated a significant enhancement (p < 0.05) of TAD bioavailability with an AUC0−24h of 2045 ± 70.2 vs. 259.9 ± 17.7 ng·h·mL−1 for the unprocessed TAD. Storage stability results revealed that NEJ remained stable with unremarkable changes in properties for 3 months. Overall, NEJ can be regarded as a successful therapeutic option for TAD administration with immediate-release properties and improved bioavailability.

Fabric phase sorptive extraction coupled with UPLC-ESI-MS/MS method for fast and sensitive quantitation of tadalafil in a bioequivalence study.

The current study coupled fabric phase sorptive extraction (FPSE) with ultraperformance liquid chromatography method with electrospray ionization and tandem mass detection (UPLC-ESI-MS/MS) for fast and sensitive determination of tadalafil (TAD) in a bioequivalence study. Fabric phase sorptive extraction allowed direct extraction of TAD from the sample matrix with improved selectivity, repeatability, and recoveries. A sol-gel Carbowax 20 M (CX-20 M) coated FPSE membrane revealed the best extraction efficiency for TAD because of its strong affinity for analytes via intermolecular interactions, high mass transfer rate to FPSE membrane, and high permeability. An automated multiple reaction monitoring (MRM) optimizer was employed for the best selection of the precursor and product ions, ion breakdown profile, the fine adjustment of the fragmentor voltages for each precursor ions, and the collision energies for the product ions. The chromatographic separation was conducted using a mobile phase A: 5.0 mM ammonium acetate with 0.1 % formic acid in water and mobile phase B: formic acid (0.1%) in acetonitrile in ratio (55:45, v/v) through isocratic elution mode on an Agilent EclipsePlus C18 (50 × 2.1 mm, 1.8 µm) column and the flow rate was adjusted at 0.4 mL min-1. The total run time per sample was 1.0 min. The method was validated by FDA standards for bioanalytical method validation over a concentration range of 0.1-100 ng mL-1 with a correlation coefficient of 0.9993 and the lower limit of quantitation (LLOQ) was 0.1 ng mL-1 in rat plasma. Intra- and inter-assay precision (%RSD) were lower than 4.1% and accuracy (%RE) was within 2.4%. The developed FPSE-UPLC-ESI-MS/MS method was effectively used in a randomized, two-way, single-dose, crossover study to compare the bioequivalence of two TAD formulations from different companies in male rats and verified to be bioequivalent.

Tadalafil-Loaded Self-Nanoemulsifying Chewable Tablets for Improved Bioavailability: Design, In Vitro, and In Vivo Testing.

This research aimed to develop innovative self-nanoemulsifying chewable tablets (SNECT) to increase oral bioavailability of tadalafil (TDL), a nearly insoluble phosphodiesterase-5 inhibitor. Cinnamon essential oil, PEG 40 hydrogenated castor oil (Cremophor® RH 40), and polyethylene glycol 400 served as the oil, surfactant, and cosurfactant in the nanoemulsifying system, respectively. Primary liquid self-nanoemulsifying delivery systems (L-SNEDDS) were designed using phase diagrams and tested for dispersibility, droplet size, self-emulsifying capability, and thermodynamic stability. Adsorption on a carrier mix of silicon dioxide and microcrystalline cellulose was exploited to solidify the optimum L-SNEDDS formulation as self-nanoemulsifying granules (SNEG). Lack of crystalline TDL within the granules was verified by DSC and XRPD. SNEG were able to create a nanoemulsion instantaneously (165 nm), a little larger than the original nanoemulsion (159 nm). SNECT were fabricated by compressing SNEG with appropriate excipients. The obtained SNECT retained their quick dispersibility dissolving 84% of TDL within 30 min compared to only 18% dissolution from tablets of unprocessed TDL. A pharmacokinetic study in Sprague−Dawley rats showed a significant increase in Cmax (2.3-fold) and AUC0−24 h (5.33-fold) of SNECT relative to the unprocessed TDL-tablet (p < 0.05). The stability of TDL-SNECT was checked against dilutions with simulated GI fluids. In addition, accelerated stability tests were performed for three months at 40 ± 2 °C and 75% relative humidity. Results revealed the absence of obvious changes in size, PDI, or other tablet parameters before and after testing. In conclusion, current findings illustrated effectiveness of SNECT to enhance TDL dissolution and bioavailability in addition to facilitating dose administration.

An ultrasensitive UHPLC-ESI-MS/MS method augmented with a controlled microwave derivatization reaction for quantitation of vitamin D3 and its major metabolites in COVID-19 patients.

It is established that vitamin D deficiency is correlated with the disease severity in COVID-19 patients. However, the reliable and sensitive quantitation of vitamin D3 (D3) and its metabolites remains a difficult challenge. Herein, a novel ultrasensitive and reliable UHPLC-ESI-MS/MS method was developed and validated for the quantitation of D3 and its major metabolites in COVID-19 patients. The mass spectral sensitivity was augmented via controlled microwave-assisted derivatization reaction (CMDR) with 2-nitrosopyridine (Pyr-NO) at 65 °C for 2 min. CMDR hyphenation with UHPLC-MS/MS improves detection sensitivity while shortening separation and derivatization reaction times. The precursor to product ion transitions for D3, 25-hydroxy D3 (25(OH)D3), 1,25-dihydroxy D3 (1,25-(OH)2D3) and calcipotriol (CPT) as an internal standard were m/z 493.4 â†’ 231.3, m/z 509.4 â†’ 231.3, m/z 525.4 â†’ 247.3, and m/z 521.4 â†’ 247.3; respectively. The separation of the formed derivatives was conducted using a gradient elution mode with mobile phase A: formic acid (0.1%) in water and mobile phase B: formic acid (0.1%) in acetonitrile. The elution started with 40% (v/v) of B for 0.3 min then increased linearly to 90% (v/v) at 2 min on an Agilent EclipsePlus C18 (50 × 2.1 mm, 1.8 µm) column at a flow rate of 0.3 mL min-1. The method was validated using FDA standards for bioanalytical method validation over a concentration range of 0.02-50 ng mL-1 with correlation coefficient ≥0.9987 and the lower limit of quantitation (LLOQ) were 0.02-0.05 ng mL-1 in human plasma. The developed method has demonstrated excellent comparability to a well-established chemiluminescent immunoassay (CLIA) method for the analysis of D3 metabolites in human samples. The developed UHPLC-ESI-MS/MS method was implemented for routine and reliable quantitation of D3 and its major metabolites in COVID-19 patients.

Effect of erector spinae plane block on postoperative analgesia after pediatric hip surgery: Randomized controlled study.

BACKGROUND: Erector spinae plane block (ESPB) in pediatric patients presenting for hip surgery may improve the postoperative analgesia. AIM: The study aimed to investigate the effect of ultrasound-guided ESPB on postoperative analgesia after a pediatric hip surgery. METHODS: Forty children scheduled for hip surgeries were included in this trial and randomly distributed into; Control group, patients received sham ultrasound-guided ESPB at the level of L3 or ESPB group, patients received real ultrasound-guided ESPB at the level of L3 with an injection of 0.4 ml/kg of plain bupivacaine 0.25%. The time for the first call of rescue analgesia, intraoperative fentanyl consumption, postoperative morphine consumption, Children's Hospital Eastern Ontario Pain Scale (CHEOPS), and Objective Behavioral Pain score (OPS) were recorded. RESULTS: As compared to the control group, the use of ESPB significantly prolonged the time for first request of rescue analgesia from 170.50 ± 44.066 to 256.50 ± 66.434 min (p < 0.0001), decreased the intraoperative fentanyl consumption from 1.025 ± 0.379 to 0.775 ± 0.343 µg/kg (p = 0.035), decreased the postoperative morphine consumption from 0.105 ± 0.036 to 0.065 ± 0.023 mg/kg (p = 0.0002). Also, it significantly decreased postoperative CHEOPS and OPS scores 2, 4, and 6 h after the surgery (p < 0.05) with an insignificant difference between the two groups at all other time intervals (p Ëƒ 0.05). CONCLUSION: The use of ESPB in pediatric patients undergoing hip surgery prolonged the time for the first call of analgesia, decreased the intraoperative and postoperative opioid consumption, and decreased the postoperative pain.

Role of ultralow dose of naloxone as an adjuvant to fentanyl-bupivacaine in thoracic paravertebral block analgesia after modified radical mastectomy: Randomized controlled trial.

OBJECTIVE: We evaluated the effect of the addition of 100 ng of naloxone to fentanyl-bupivacaine mixture used in thoracic paravertebral block (PVB) on the duration and the quality of post-mastectomy analgesia. DESIGN: A randomized double-blinded trial. SETTING: Oncology surgery unit. PATIENTS AND PARTICIPANTS: This study included 135 patients, aged 40-60 years of either sex presented for elective unilateral-modified radical mastectomy. INTERVENTIONS: Patients were divided randomly into three groups: group I, received 0.3 mL/kg of 0.25 percent bupivacaine; group II, received 0.3 mL/kg of 0.25 percent bupivacaine, fentanyl 50 µg, and naloxone 100 ng; group III, received 0.3 mL/kg of 0.25 percent bupivacaine and fentanyl 50 µg. MAIN OUTCOME MEASURE(S): The visual analog scale was assessed immediately post-operative, every 2 hours till 12 hours, and then every 6 hours for 24 hours; the time of first and total amount of rescue analgesia and side effects during the first 24 hours were recorded. RESULTS: Group II showed a significant prolonged analgesia with a delayed first request of rescue analgesia and lower amount of morphine (592.1 ± 14.9 minutes and 7.28 ± 7.81 mg, respectively) than groups I (127.7 ± 35.1 minutes and 19.84 ± 2.56 mg, respectively) and III (232.2 ± 9.27 minutes and 13.52 ± 1.74 mg, respectively) as p < 0.001. CONCLUSION: Using naloxone as additives in PVB has been promising and effective in controlling post-mastectomy pain.

Superficial cervical plexus block alone or combined with interscalene brachial plexus block in surgery for clavicle fractures: a randomized clinical trial.

BACKGROUND: The regional anesthesia technique which is suitable for fracture clavicle is a matter of debate. This study aimed to compare the use of superficial cervical plexus alone or in combination with interscalene block in patients undergoing internal fixation of fractured clavicle. METHODS: Seventy patients undergoing internal fixation of fractured clavicle were enrolled in this clinical trial and randomly distributed into two groups; superficial cervical plexus block (CPB) group and combined superficial cervical plexus block and interscalene block (ISB) group. The regional anesthesia techniques were performed before induction of general anesthesia. The intraoperative fentanyl and isoflurane consumption, the postoperative morphine consumption, the postoperative pain score, the duration of postoperative analgesia, the incidence of perioperative complications, and the patient's satisfaction were recorded. RESULTS: In comparison to the use of combined CPB and ISB, the use of CPB alone did not significantly change the postoperative morphine consumption (8.4±3.3 mg versus 7.3±3.2 mg [P=0.2]), the time to the first request of postoperative analgesia (396.7 193.4 min versus 407.7±150.0 min [P=0.8]), or the postoperative pain score (P˃0.05). Also, it did not change the intraoperative fentanyl consumption (P=0.3), the intraoperative isoflurane consumption (P=0.7), the incidence of perioperative complication, or the degree of patient's satisfaction (P˃0.05). It significantly decreased the incidence of phrenic nerve palsy (P=0.03). CONCLUSIONS: In patients undergoing internal fixation of clavicular fracture, the perioperative analgesic effect of SCP alone is equally effective to its use in combination with ISB.

The Effect Of The Use Of Pre-Emptive Oral Pregabalin On The Postoperative Spinal Analgesia In Patients Presented For Orthopedic Surgeries: Randomized Controlled Trial.

BACKGROUND: Preoperative oral pregabalin could improve postoperative analgesia and prevent chronic pain development. The aim of this study is to evaluate the effect of oral pregabalin on the duration and quality of postoperative analgesia in spinal anesthesia. METHODS: Sixty adult patients presented for internal fixation of femoral fracture under spinal anesthesia were included in the study. They were randomly distributed to a placebo group and a pregabalin group receiving 150 mg pregabalin capsules 1 hr before surgery. The onset, duration, and regression of sensory and motor block were recorded. Rescue analgesia consumption, postoperative pain score, and quality of sleep were also assessed. RESULTS: Oral pregabalin significantly prolonged the time to two-segment regression of sensory block, reaching 86.67±17.88 mins, the time required to regression of spinal block to L2, reaching 155.33± 34.71 mins, and the duration of motor block, reaching 138 ± 23.5 mins, with no effect on the onset of sensory or motor block (P = 0.60 and 0.62). It significantly decreased the VAS score 4 hrs, 6 hrs, and 12 hrs postoperatively, prolonged the duration of postoperative analgesia, reaching 392.00±47.23 mins, and decreased morphine consumption to 7.67±3.65 mg. It also improved the quality of sleep in the first night after surgery. CONCLUSION: Preemptive oral pregabalin prolonged the time to the first request for postoperative analgesics and improved sleep in the first night after surgery.

A Validated High-Throughput Fluorometric Method for Determination of Omeprazole in Quality Control Laboratory via Charge Transfer Sensitized Fluorescence.

A high-throughput 96-microwell plate fluorometric method was developed and validated to determine omeprazole (OMZ) in its dosage forms. The method was based on the charge-transfer (CT) sensitized fluorescence reaction of OMZ with 2, 3-dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ). This fluorescence reaction provided a new approach for simple, sensitive and selective determinations of OMZ in pharmaceutical preparations. In the present method, the fluorescence reaction was carried out in 96-microwell plates as reaction vessels in order to increase the automation of the methodology and the efficiency of its use in quality control laboratories. All factors affecting the fluorescence reaction were carefully studied and the conditions were optimized. The stoichiometry of the fluorescence reaction between OMZ and DDQ was determined and the reaction mechanism was suggested. Under the optimum conditions, the linear range was 100-6000 ng/ml with the lowest LOD of 33 ng/ml. Analytical performance of the proposed assay, in terms of accuracy and precision, was statistically validated and the results were satisfactory; RSD was <2.6 % and the accuracy was 98.6-101.6 %. The method was successfully applied to the analysis of OMZ in its dosage forms; the recovery values were 98.26-99.60 ± 0.95-2.22 %. The developed methodology may provide a safer, automated and economic tool for the analysis of OMZ in quality control laboratories.

A validated spectrofluorimetric method for determination of some psychoactive drugs.

Five psychoactive drugs namely, chlorpromazine HCl, thioridazine HCl, clomipramine HCl, imipramine HCl and desipramine HCl were analyzed by a simple spectrofluorimetric method. The method is based on oxidation of the studied drugs using cerium(IV) in presence of sulphuric acid and monitoring the fluorescence of the formed cerium(III) at lambda(ex.) = 254 nm and lambda(em.) = 355 nm. All variables affecting the reaction conditions such as; cerium(IV) concentration, sulphuric acid concentration, heating time, temperature and dilution solvents were carefully studied. The effect of potential interference due to common ingredients as glucose, sucrose, lactose, citric acid and propylene glycol were investigated. A validation study of the proposed method was carried out according to USP 2002. Beer's law was obeyed for all the studied drugs in the concentration range of 0.05-1.3 microg/ml. Limits of detection range was 0.035-0.038 microg/ml and limits of quantitation of 0.116-0.125 microg/ml were obtained. The method was successfully applied for the assay of the studied drugs in pure form and in pharmaceutical dosage forms. Results were compared with official methods. The t- and F-values were calculated and compared with the theoretical values, which indicate high accuracy and good precision of the proposed method.