Photochemical Induced Fluorescence for the Determination of Prednisolone and Triamcinolone

Abstract

In the present work, a photochemical derivatization procedure to induce fluorescence from two synthetic glucocorticoids (triamcinolone acetonide and prednisolone) was developed. The procedure consisted of the exposure of analyte acidic solutions to ultraviolet (UV) radiation (254 and 300 nm) in a photochemical reactor at 65°C. Experimental parameters such as type and concentration of the acid, composition of the solvent system, and sample treatment time in the reactor were found to be critical, and, therefore, they were carefully optimized. The intensity of the fluorescence (240/350 nm) and the stability of the signal were, appropriated for analytical purposes. Limits of detection (LD) of 5 and 6 µg L^?1, respectively, for triamcinolone acetonide and prednisolone were achieved. Linear dynamic range for both analytes extended up to 20 mg L^?1. The spectrofluorimetric determination of prednisolone and triamcinolone acetonide was tested by the analysis of different anti‐inflammatory pharmaceutical formulations (tablets, ointment, and veterinary parenteral suspensions). The recoveries achieved were between 95% and 107%. A study to evaluate the effect of potential interferents (polimixine B and benzocaine) on the fluorescence signal of the analytes also has been done.     

Submicron Size Formulation of Linseed Oil Containing Omega-3 Fatty Acid for Topical Delivery

The aim of the present study was to design and develop topical submicron size gel formulation of linseed oil with enhanced permeation through the skin for the management of psoriasis. Linseed oil contains significant amount of α-linolenic acid (ALA) an omega-3 fatty acid, which is responsible for its pharmacological actions. In order to enhance permeation through skin, microemulsion based gel formulation was prepared and characterized. Microemulsions were prepared by aqueous phase titration method, using linseed oil, Unitop 100, PEG 400, and distilled water as the oil phase, surfactant, cosurfactant and aqueous phase, respectively. Selected formulations were subjected to physical stability studies and consequently in vitro skin permeation studies. Surface morphology studies of optimized formulation were done by transmission electron microscopy (TEM). The droplet size of microemulsions ranged from 70 to 500 nm with average particle size 186 nm. The optimized microemulsion was converted into hydrogel using carbopol 971 which had a viscosity of 498 ± 0.04 cps. During in vitro permeation study the flux of microemulsion formulation and gel was found to be 19.05 and 10.2 µg/cm²/hr, respectively, which indicated better penetration of linseed oil through the skin. These result indicated that the developed ME formulation may be a good approach for topical therapy for the management of psoriasis.     

Shelf Life Extension and Quality Improvement of Cucumber Slices Impregnated in Infusions of Edible Herbs

Abstract

Development of functional food through their enrichment with herbal extracts is gaining much attention from the food industry. The present study evaluates the benefits, such as the oxidative stability and quality retention, of the enrichment of cucumber (Cucumis sativus) with natural phenolic compounds through immersion into a variety of herbal infusions. After a preliminary experiment with gallic acid solutions, the beneficial effect of hypotonic solutions was observed and the optimal process conditions were defined. The second step of the study involved the immersion of cucumber in the herbal infusions for 2.5?h at 70?°C. The total phenolic content (TPC), antiradical and antioxidant activity of osmo-treated slices were determined to evaluate the extent of bioactive compounds’ impregnation. During the immersion, TPC, antioxidant and antiradical activity significantly increased irrespective of the type of the herbal infusion. The TPC varied greatly, ranging from 1.41 to 781.14?mg GAE/kg of cucumber. The highest total phenolics were found in cucumber treated with Origanum vulgare infusion, followed by Jasminum officinale and Mentha spicata infusions. The aforementioned osmo-treated slices were also highly appreciated by the sensory panel; therefore, for those best performing herbal infusions, the third phase of this work involved the study of quality degradation under subsequent storage of the osmo-treated slices vs. the untreated ones. The results regarding color, texture, and visual assessment demonstrated the superior quality retention of the osmo-treated samples that exhibited a shelf life extension ranging from two- to almost four-fold compared to the untreated tissue.     

Measurement of Ceftriaxone in Peritoneal Dialysis Solutions by High-Performance Liquid Chromatography

Abstract

A simple, rapid, and reproducible reverse phase high-performance liquid chromatographic method for the measurement of ceftriaxone in peritoneal dialysis solutions is described. the mobile phase contained acetonitrile, phosphate buffer, deionized water and an ion pair agent. the samples were injected onto a C18 column and detector was set at 280 nm. the retention time for ceftriaxone and the internal standard was 7.04 and 3.74 min, stability of ceftriaxone was 12 hours in each dialysis solution at 37°C (Table 3).     

Simultaneous Quantification of Ceftazidime and Pyridine,its Main Degradation Product,by High-Performance Liquid Chromatography

ABSTRACT

A high performance liquid chromatographic method for the simultaneous assay of ceftazidime and pyridine, the principal degradation product of ceftazidime, is described. The method was fully validated in terms of recovery, linearity, selectivity and precision. An application was done on stability of ceftazidime at 40 mg.mL¹ in infusion solutions 0.9% NaCl and 5% glucose on 24 hours in ambulatory infusion device. Quantification results of pyridine were more linear and accurate than ceftazidime. Pyridine was a good label in ceftazidime stability studies.     

Liquid chromatographic method to follow-up ceftazidime and pyridine in portable elastomeric infusion pumps over 24 h

Portable infusion pumps are an interesting solution to continue outpatient parenteral antimicrobial therapy (OPAT) at the patient's home. However, the use of ceftazidime for such applications is challenging in view of its relatively poor stability in solution. In this study, elastomeric infusion pumps with 6 or 7 g of ceftazidime were deflated over 24 h in an oven at 33°C while ceftazidime and its degradation product, pyridine, were regularly monitored. Hereto, a fast and sensitive liquid chromatographic (LC) method has been developed using a Kinetex^® C18 (150 × 3 mm, 2.6 μm) column with gradient elution. Ammonium formate 20 mM and acetonitrile (ACN) were mixed in a ratio of 98:2 v/v for mobile phase A and 85:15 v/v for mobile phase B. Both were adjusted to pH 4.5 with formic acid. The flow rate was set at 0.4 mL/min. The solution with a starting dose of 6 g ceftazidime was found to be degraded 10% after an average of 19 h 11 min so that an administration of 6 g to the patient was not reached. For the solution with a starting dose of 7 g of ceftazidime, 10% degradation was observed after an average of 18 h 42 min. However, by starting from a higher dose, an average of 6.56 g of ceftazidime could be administered over 24 h. In addition, 1.0% of pyridine versus ceftazidime pentahydrate with sodium carbonate (=mixture for injection) was formed over 24 h.     

In vitro solar protection factor,antioxidant activity,and stability of a topical formulation containing Benitaka grape (Vitis vinifera L.) peel extract

Abstract

A flavonoid enriched extract (FE) was obtained from grape peels, and in vitro SPF, antioxidant activity, and effects on cell viability of this extract were tested with the intent to develop a cosmetic product. A formulation was developed with the FE, and the stability of this mixture was evaluated in terms of pH, density, viscosity, and SPF (90-days). FE showed no cytotoxicity to human keratinocytes and an in vitro SPF of 18.56 (UV-spectrophotometry). Further, FE showed a UVA protection factor of 3.17?±?0.2, a critical wavelength of 318.0?±?0.1 and a UVA/UVB of 0.9. Antioxidant activity assays resulted in 92.08% and 86.85% of activity against DPPH and ABTS (IC₅₀ = 296.90?±?1.2?µg/mL and 643.13?±?0.9?µg/mL), respectively. Finally, SPF of formulation with FE was 12.45. Results from the in vitro SPF and product stability tests (especially storage under refrigeration), indicate that FE is a promising compound for use as an innovative sunscreen formulation.     

Some Observations on the Stability of Uric Acid in Alkaline Solutions

Abstract

The stability of uric acid in alkaline solutions has been studied by spectrophotometric, enzymic and chemical methods. Aqueous triethanolamine was shown to maintain stability of uric acid for a range of concentrations at around 2O°C and to considerably reduce the degradation loss at the higher temperature of 37°C.     

Simple Spectrophotometric Determination of Total Carbonate by Re-Extraction Via Ligand Exchange Using Chloroform Solutions of Uranyl Quinolin-8-Olate

Abstract

A method based on the decoloration of dilute chloroform solutions of ura nyl quinolin-8-olate by shaking with aqueous solution of anions is proposed for the spectrophotometric determination of carbonate. The effects of several variables on the decoloration (pH, shaking time, volume ratio, etc.) were established. The spectral stability of an organic solution of the metal chelate is increased with an excess of quinolin-8-ol in the organic phase, and it avoids its stripping with water. The decoloration of chloroformic solutions varies linearly with the carbonate concentration between 10 and 50 μg.ml^?1 in the aqueous phase (apparent molar absorptivity is found to be 2.03×10³ l.mol^?1 .cm^?1 at 390 nm). Interferences of many foreign ions (cations and anions) are also established. The method is relatively free from anion interferences.     

Nonaqueous Liquid-Liquid Extraction. Extraction of Zinc from Methanol-Water Solution of Chloride by Trioctylphosph1Ne Oxide in Decaline

Abstract

The distribution of zinc was studied between the decaline phase having tri-n-octylphosphine oxide (TOPO) and the methanol-water phase (4:1 in molar ratio) having chloride ion, and the stability constants of zinc with chloride in the methanolic solution were calculated from the extraction experiments (K₁ = 2.4 × 10³, K₂ = 1.9 × 10²at 298°K).     

A Chemometrical Approach to Optimization and Validation of an HPLC Assay for Rizatriptan and its Impurities in Tablets

Abstract

An isocratic reversed‐phase high‐performance liquid chromatographic method was developed and validated for the analysis of a novel antimigraine drug, rizatriptan benzoate, in a dosage form along with its two impurities, L‐749.019 and L‐783.540. The method used a C₁₈ XTerra? (150×3.9 mm), 5 µm column. The mobile phase consisted of a mixture of methanol, TEA (1%) and 10 mM KH₂PO₄ (5:9.5:85.5 v/v) at a flow rate of 1.2 ml min^?1 (pH of the water phase was adjusted to 5.5 with 85% orthophosphoric acid). Column temperature was 20°C and the detection was performed at 225 nm. The central composite design technique and the response surface method were used in the robustness test considerations. The method was applied satisfactorily to the analysis of commercial rizatriptan formulation.     

Stability-Indicating High Performance liquid Chromatographic Determination of Diltiazem Hydrochloride

Abstract

A rapid, selective and accurate high-performance liquid chromatography method (HPLC) for the determination of diltiazem hydrochloride using clonazepam as internal standard is developed. The investigated compounds were eluted from 5 u Micropak MCH-5 reversed phase column at ambient temperature with a mobile phase comprising of acetonitrile-water (48:52%) at pH 3.3 and containing 0. 01M sodium-n-octane sulfonate as an ion pairing substance. The mobile phase was pumped at a flow rate of 1 ml min^?1 and the effluent was monitored at 239 nm. The retention times of the internal standard and diltiazem were at 3 min and 9 min, respectively. A linear relationship was derived between the peak height ratio (diltiazem/clonazepam) and diltiazem concentration over the range 1–10 μg ml^?1. Detection limit for the drug is 0.2 μg ml^?1 at 0.01 aufs. The developed procedure was applied to study the stability of diltiazem in the presence of its degradation products as well as in the presence of formulation excipients.     

Chiral discotic derivatives of 1,3,5-triphenyl-6-oxoverdazyl radical

Two derivatives of 1,3,5-aryl-6-oxoverdazyl containing two 3,4,5-trioctyloxyphenyl and one 3,4,5-tri((S)-3,7-dimethyloctyloxy)phenyl group in position C(3) (1b) or N(1) (1c) were investigated by thermal, X-ray diffraction and magnetic methods. The results were compared to those obtained for achiral derivative 1a containing three 3,4,5-trioctyloxyphenyl groups. All three compounds exhibit an ordered columnar hexagonal phase, Col_h(o), and for chiral derivatives, 1b and 1c, a superstructure with doubled periodicity was found. The introduction of the three chiral alkoxy substituents in 1a lowered the mesophase stability by about 50 K and induced a Col_h phase in 1c. Thermochromic analysis showed a hypsochromic shift upon formation of the Col_h(o) phase similar for all three derivatives 1 (~0.3 eV), which coincides with a 5% drop in effective magnetic moment, μ_eff, for 1c. Analysis of magnetisation data in a range of 2–370 K at 200 Oe revealed weak antiferromagnetic interactions (θ = – 4 K) in the Col_h(o) phase.     

Photoinitiating capabilities of vinyl polyperoxides and metamorphosis of block-into-block copolymer

This article describes the first comprehensive study on the use of a vinyl polyperoxide, namely poly(styrene peroxide) (PSP), an equimolar alternating copolymer of oxygen and styrene, as a photoinitiator for free radical polymerization of vinyl monomers like styrene. The molecular weight, yield, structure and thermal stability of polystyrene (PS) thus obtained are compared with PS made using a simple peroxide like di-t-butyl peroxide. Interestingly, the PS prepared using PSP contained PSP segments attached to its backbone preferably at the chain ends. This PSP–PS–PSP was further used as a thermal macroinitiator for the preparation of another block copolymer PS-b-PMMA by reacting PSP–PS–PSP with methyl methacrylate (MMA). The mechanism of block copolymerization has been discussed. © 1996 John Wiley & Sons, Inc.     

Determination of Oxazepam in Pharmaceutical Formulation by HPTLC UV-Densitometric and UV-Derivative Spectrophotometry Methods

Abstract

Methods for determination of oxazepam in pharmaceutical formulation by derivative ultraviolet (UV) spectrophotometry as well as high-performance thin-layer chromatography (HPTLC) UV densitometry were described. For UV-derivative spectrophotometry, some derivatives and wavelengths may be recommended for routine quality control of the drug of interest. On the other hand, HPTLC provided good results, but only when the calibration curve was estimated using nonlinear regression analysis. The HPTLC method was developed with silica F₂₅₄ plates, a mobile phase of benzene/ethanol (5:1, v/v), and densitometric detection at 204 nm receiving R _f  = 0.47. Developed methods were validated and found to be sufficiently precise and reproducible for established conditions.     

Development and validation of a UHPLC‐UV method for the determination of a prostate secretory protein 94‐derived synthetic peptide (PCK3145) in human plasma and assessment of its stability in human plasma

PCK3145 is a synthetic peptide, derived from the Prostate Secreted Protein 94 (PSP94), with promising in vitro and animal in vivo results in prostate cancer. The aim of the present study was to develop and validate a fast and robust ultra‐high‐performance liquid chromatography with ultraviolet detection for the determination of PCK3145 in human plasma which would be suitable for the assessment of PCK3145 stability to proteolytic degradation. Following protein precipitation, chromatographic separation was carried out on an Aeris Peptide C₁₈ column with mobile phase consisting of acetonitrile–water at a flow‐rate of 0.50 mL/min. The calibration curve was linear over the range 0.50–20.00 μg/mL. Intra‐ and inter‐day percentage relative standard deviation and relative error were ≤10%. The limit of detection and the lower limit of quantification were 0.15 and 0.50 μg/mL, respectively. Recovery of PCK3145 from human plasma was ≥96%. The peptide presented high stability in whole blood and in human plasma (>98% intact peptide after 24 h incubation at 37°C in human plasma), which represents a distinctive advantage in the therapeutic use of the compound. This is the first validated UHPLC method for the determination of PCK3145 reported, and it was successfully applied in the study of the proteolytic stability of PCK3145 in human plasma ex vivo. Copyright © 2016 John Wiley & Sons, Ltd.     

High Performance Liquid Chromatographic Procedure for Retinoic Acid in Ophthalmic Solution

Abstract

A fast and simple procedure has been developed for the quantitation of retinoic acid in ophthalmic solutions. the procedure involves the use of reverse phase high performance liquid chromatography with a mobile phase containing an amine modifier. This procedure is specific for retinoic acid in the presence of its degradation products and formulation excipients. the method is linear over a wide range of concentrations.     

Nanoparticles based on gadolinium(iii) and europium(iii) complexes for biovisualization

Complexes Ln(TTA)₃ and [Ln(TTA)₃·1] (Ln = Eu, Gd; ТТА is thenoyltrifluoroacetyl-acetonate; 1 is 2-(5-chlorophenylene-2-hydroxy)-2-phenylethylene-bis(2-methoxy)phosphine oxide) in individual form, and as a part of a core of the polyelectrolyte stabilized colloids have been studied by Mössbauer spectroscopy and X-ray powder diffraction. The photophysical and colloidal characteristics of the solutions of polyelectrolyte nanoparticles were studied in water, artificial cerebrospinal fluid solution, solution of bovine serum albumin, and human blood serum. A stability of a luminescent response of the nanoparticles in solutions of bovine serum albumin and human blood serum at 37 °С for 2 hours has been revealed. This is a prerequisite for the potential application of studied nanoparticles for biovisualization.

     

Sonochemical synthesis and structural characterization of a nano-structure Pb(II) benzentricarboxylate coordination polymer: new precursor to pure phase nanoparticles of Pb(II) oxide

Microcrystals of a new Pb(II) coordination polymer, [Pb₂(1,3,5-HBTC)₂(H₂O)₄] · H₂O (1) (1,3,5-H₃BTC = 1,3,5-benzentricarboxylic acid), was synthesized by a sonochemical method. The structure was characterized by scanning electron microscopy, X-ray powder diffraction, elemental analyses, and IR spectroscopy. Thermal stability was studied by thermal gravimetric and differential thermal analyses. After the calcination of nanosized 1 at 400°C, pure phase nanosized Pb(II) oxide has been produced.     

Stability evaluation of morphine,hydromorphone, metamizole and esketamine containing analgesic mixtures applied for patient-controlled analgesia in hospice and palliative care

In this study, different injection solutions containing opioid and nonopioid compounds used for patient-controlled analgesia in hospice and palliative care were evaluated in terms of analyte stability. Investigated injection solutions contained different combinations of morphine, hydromorphone, metamizole and esketamine. For the practical implementation, samples from infusion pumps were daily drawn over a period of 7 days at 22 and 37°C. Quantitative measurements were performed on a high-performance liquid chromatography system with ultraviolet detection applying a validated analytical method. All compounds apart from morphine showed no evident changes in concentration. However, a significant loss of morphine was observed for injection mixtures containing both morphine and metamizole at 37°C. After 7 days, only 72% of the initially measured morphine concentration was measured in the binary and 77% in the ternary mixture. Furthermore, an additional compound was detected that could represent the morphine-metamizole-adduct, “metamorphine”. Based on these results, a significantly reduced morphine concentration must be expected after only 3 days if an injection solution mixture containing both morphine and metamizole is administered to a patient at 37°C. Since the analgesic effects of morphine–metamizole adducts have not yet been thoroughly investigated, further clinical studies are necessary before accurate conclusions can be drawn in this regard.