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Öğe Application of HPLC to Investigate the Physicochemical Properties and Intestinal Permeability of Ketoprofen(Bentham Science Publ Ltd, 2017) Kaynak, Mustafa Sinan; Celebier, Mustafa; Akgeyik, Emrah; Sahin, Selma; Altinoz, SacideThe main objective of this study was to investigate the effect of pH on the solubility and intestinal permeability of ketoprofen by using HPLC. Ketoprofen is a slightly soluble acidic drug, and its solubility in aqueous phase is affected by pH changes dramatically. However, there is no data in the literature to support whether this pH dependent water solubility of ketoprofen will influence its absorption/bioavailability. In this study, the distribution-coefficient (log D) of ketoprofen at various pH values between 4.5 and 7.5 were investigated using HPLC, and then it was made an attempt to correlate the log D values with the intestinal permeability values. For this reason, in vivo intestinal permeability studies were performed at pH 4.5 and pH 7.5. The concentrations of model and reference compounds and also the blank buffers passed though the rat intestine were analyzed by means of a validated HPLC method. A nonlinear relationship was found between the results of in vitro and in vivo studies indicating that the diffusion of ketoprofen was not only related with passive diffusion, but also could be related with active transport.Öğe ASSESSMENT OF PHARMACEUTICAL QUALITY AND RELEASE KINETICS OF METOPROLOL TARTRATE EXTENDED RELEASE TABLETS AVAILABLE IN TURKISH DRUG MARKET(2020) Gencer, Ayşe; Akgeyik, Emrah; Kaynak, Mustafa Sinan; Çelebier, Mustafa; Berkman, Murat Sami; Şahin, SelmaAbstract: Cardioselective ?-adrenergic blocker metoprolol tartrate, is used in the treatment of different diseases such as cardiac arrhythmias, hypertension, heart failure, angina pectoris, migraine, and hyperthyroidism. Beside dosage forms of the parenteral ampoule and conventional tablets of different manufacturers, there are extended release tablets of metoprolol tartrate in the Turkish Drug Market. In this research work, comparative quality control studies of metoprolol tartrate extended release tablets (original and generic) produced by two different pharmaceutical companies in the Turkey were carried out and evaluated according to the related guidelines. Thickness and diameter, hardness, weight variation, friability, content uniformity and dissolution rate were examined as quality control parameters. A new validated HPLC method for the quantification of metoprolol tartrate has been developed. An ACE column (C18, 5 µm, 250x4.6 mm) and acetonitrile: phosphate buffer (30: 70, v/v) mobile phase were used for the determination of metoprolol tartrate. The tablets showed extended release for 8 hours (70.74% release from drug A, 76.87% from the drug B). Both products have acceptable hardness, friability and weight variation values. Content of the active ingredient of the tablets was consistent with label claim (99.45% for drug A and 96.45% for drug B). The dissolution data were evaluated by model dependent and model independent methods using DDSolver program. The obtained results showed that release kinetics of both drugs were well fitted with the Korsmeyer-Peppas model.Öğe Determination of the Physicochemical Properties of Piroxicam(Turkish Pharmacists Assoc, 2020) Celebier, Mustafa; Nenni, Merve; Kaplan, Ozan; Akgeyik, Emrah; Kaynak, Mustafa Sinan; Sahin, SelmaObjectives: The aim of this study was to determine the acid dissociation constant (pKa) of piroxicam using high performance liquid chromatography (HPLC) and ultraviolet-visible (UV-Vis) spectrophotometry, and to determine the partition coefficient (Log P), distribution coefficient (Log D), and Log kw values of piroxicam using HPLC. Materials and Methods: The HPLC studies were performed on a reversed-phase ACE C18 (150x4.6 mm ID, 5 mu m) column at a flow rate of 1.0 mL min-1. The detector was set to 360 nm. Log D at different pH values (3.0-6.5) was examined with a phosphate buffer (20 mM) and acetonitrile (30:70 v/v) mixture as the mobile phase. For pKa determination, HPLC studies were performed with a mixture of phosphate buffer (20 mM) and methanol within the pH range of 3.50-6.00. Log kw measurements were performed with phosphate buffer (20 mM) and MeOH (from 20:80 v/v to 10:90 v/v) mixtures within the pH range of 3.50-6.00. UV-Vis spectrophotometric pKa measurements were performed at 285 nm wavelength. Results: The pKa value of piroxicam was found to be 5.3 by HPLC and 5.7 by UV-Vis spectrophotometry. Log P of piroxicam was determined as 1.58 in our experimental conditions. Log D values were 1.57, 1.57, 1.44, 1.13, and 0.46 for pH values of 3.17, 3.79, 4.44, 5.42, and 6.56, respectively. Conclusion: In the literature, different Log P (3.1, 2.2, and 0.6) and pKa (6.3 and 4.8) values were reported for piroxicam. The Log P (1.58) and pKa (5.3 and 5.7) values obtained for piroxicam in our study were within the range of the literature values. All these results indicate that different experimental approaches used for the determination of physicochemical properties could provide different values. Although UV spectrophotometry is easy to apply, HPLC is a unique technique for simultaneous determination of pKa, Log D, and Log P values of compounds.Öğe Development of HPLC Methods for Individual Determination of 20 Active Pharmaceutical Ingredients for Ussing-Chamber Studies(Bentham Science Publ Ltd, 2017) Kaynak, Mustafa Sinan; Akgeyik, Emrah; Ates, Muge; Celebier, Mustafa; Sahin, SelmaBackground: The aim of this study was to develop HPLC methods for individual determination of 20 active pharmaceutical ingredients (amoxicillin sodium, antipyrine, atenolol, caffeine, carbamazepine, cimetidine, enalapril, furosemide, hydrochlorothiazide, ibuprofen, ketoprofen, metoprolol tartrate, methyldopa, naproxen sodium, pindolol, piroxicam, propranolol HCl, ranitidine, theophylline, and verapamil HCl) to be used for determination of their intestinal permeabilities across Ussing-Chamber. Method: Two different stationary phases (Waters X-Bridge C18-150 x 4.6 mm, 5 mu m; and ACE 5 C18- 150 x 4.6 mm, 5 mu m) were used for the separation of the compounds. Three different aqueous phases (20 mM phosphate buffers pH 3.0, pH 6.0 and water) and two different organic phases (methanol and acetonitrile) were used to prepare the mobile phases. Total analysis time was shorter than 7 minutes for all applications. Result: The developed methods were validated according to the ICII guideline and found to be linear, sensitive, selective, precise and accurate. The developed methods could be applied for analyses of these compounds not only for Ussing-Chamber studies but also for other permeability studies.Öğe Evaluation of Pharmaceutical Quality of Conventional Dosage Forms Containing Paracetamol and Caffeine Available in the Turkish Drug Market(Dissolution Technologies, Inc, 2016) Akgeyik, Emrah; Kaynak, Mustafa Sinan; Celebier, Mustafa; Altinoz, Sacide; Sahin, SelmaThe aim of this study was to evaluate the quality of conventional paracetamol- (PA) and caffeine- (CA) containing combined dosage forms in the Turkish drug market. For this purpose, weight variation, content uniformity, diameter and thickness, hardness, friability, disintegration, and dissolution tests were carried out. Content uniformity and dissolution tests were performed by a validated high-performance liquid chromatography (HPLC) method. Separations were carried on an ACE 5-C-18, 5-mu m LC column (250 x 4.6 mm) using isocratic elution with a methanol/water (40:60 v/v) mobile phase. The injection volume was 20 mu L, and UV detection was performed at 270 nm. The weight variation results were in accordance with content uniformity results. All dosage forms fulfilled the USP requirement of not less than 75% of active ingredients of the labeled claim dissolved within 60 min. Also, all tablets met the rapidly dissolving criterion (more than 85% of the labeled amount of the drug substance dissolved within 30 min). The results of this study indicate that PA- and CA-containing conventional dosage forms available in the Turkish drug market pass all the established quality control tests successfully, and they can be used interchangeably.Öğe Evaluation on reducing toxicity of fluoxastrobin with doped TiO2 nanoparticles(Tubitak Scientific & Technological Research Council Turkey, 2021) Gungordu, Abbas; Ozmen, Nesrin; Erdemoglu, Sema; Turhan, Duygu Ozhan; Asilturk, Meltem; Akgeyik, Emrah; Ozmen, MuratIn this study, toxic effects caused by the degradation of fluoxastrobin, which is a commonly used fungicide where newly synthesized manganese or sulfur-doped TiO2 nanoparticles exist were evaluated. The characterization study of nanoparticles was performed by scanning an electron microscopy (SEM), X-ray diffractometry, Brunau-Emmet-Teller analysis, X-ray fluorescence spectroscopy, and UV-Vis (ultraviolet-visible) reflectance spectra. Subsequently, the photocatalytic performance of nanoparticles, their toxicity, and the photocatalytic degradation products of fluoxastrobin with the same nanoparticles were tested during the two development stages of Xenopus laevis. The LC(50)s of fluoxastrobin were determined on test organisms, and a 5 mg L-1 fluoxastrobin was selected to evaluate the photocatalytic degradation capacity due to toxicity studies. The sublethal effects of the nanoparticles and the degradation product of fluoxastrobin were assessed with embryonic malformations and biochemical marker responses. Sulfur-doped TiO2 was found to be more effective compared to manganese-doped TiO2 for the degradation of fluoxastrobin, photocatalytically. On the other hand, even if the tested nanoparticles were not lethal, they caused effects such as growth retardation and changes in biochemical responses on organisms.Öğe İmidazolinon pestisit grubu "imazamox'un" s katkılanmış nano-TiO2 ile fotokatalitik parçalanması ve yıkım ara ürünlerinin belirlenmesi(İnönü Üniversitesi, 2014) Akgeyik, EmrahBu tez çalışmasında, bir dirençli organik kirlilik olan imazamoxun, S katkılanmış ve katkılanmamış nano TiO2 ile UV ve görünür bölge ışık altında fotokatalitik parçalanması araştırıldı. Reflux yöntemle sentezlenen katalizörlerin kristal büyüklüğü, yüzey morfolojisi, yüzey alanı gibi karakteristik özellikleri, XRD, SEM, TEM ve BET analizleri yapılarak belirlendi. Fotokatalitik yıkım etkinliği, katkılanan S oranı (molce %1-30), süspanse edilen katalizör miktarı (%0.05-1.0), ışınlama süresi (60-600 dk), başlangıç imazamox derişimi (5-30 ppm), pH (2-10) ve organik-inorganik matriks etkisi olmak üzere farklı parametreler kullanılarak belirlendi. Optimum koşullar altında hem UV bölgede hem de görünür ışık altında yapılan çalışmalar sonucunda imazamoxun ortalama %95 oranında fotokatalitik yıkıma uğradığı görüldü. Fotokatalitik yıkım etkinliği UV-Vis, TOC ve HPLC analizleri yapılarak belirlendi. LC-MS analizleri ile yıkım süresince ortamda oluşan ara ürünler izlendi ve fotokatalitik yıkıma ilişkin olası bir model önerildi.Öğe Photocatalytic degradation of amoxicillin using Co-doped TiO2 synthesized by reflux method and monitoring of degradation products by LC-MS/MS(Taylor & Francis Inc, 2020) Yilmaz, Hatice Caglar; Akgeyik, Emrah; Bougarrani, Salma; El Azzouzi, Mohammed; Erdemoglu, SemaPhotocatalytic degradation of Amoxicillin (AMX) in aqueous solution by Co-doped TiO2 and undoped TiO2 synthesized by reflux route was investigated. The catalysts were characterized using X-ray diffractometry, FT-IR spectroscopy, UV-Vis absorption spectroscopy, scanning electron microscopy and X-ray Fluorescence Spectroscopy, and using specific surface area, particle size and zeta potential measurements. Photocatalytic efficiency of Co-doped and undoped TiO2 was compared for degradation of AMX under UV-C and visible irradiation by investigating the effects of the parameters such as percentage of the cobalt doped, amount of catalyst, irradiation time, initial AMX concentration and pH of the medium. Effects of organic and inorganic ions in the aqueous solution were also studied. Results showed that degradation of AMX is improved by Co doping to TiO2. It was detected that complete removal is achieved within 240 min of irradiation under UV-C and 300 min under visible irradiation. 94%, 21% and 16% degradation efficiencies were achieved after 300 min of photocatalysis under visible light in the presence of Co-doped TiO2, undoped TiO2 and Degussa P25 TiO2, respectively. Degradation products were determined and followed using LC-MS/MS technique to describe the evolution of AMX. An attempt was made to estimate the photocatalytic cleavage pathway of AMX by LC-MS/MS [GRAPHICS] .Öğe Photocatalytic degradation of azo dye using core@shell nano-TiO2 particles to reduce toxicity(Springer Heidelberg, 2018) Ozmen, Nesrin; Erdemoglu, Sema; Gungordu, Abbas; Asilturk, Meltem; Turhan, Duygu Ozhan; Akgeyik, Emrah; Harper, Stacey L.Clean and safe water is fundamental for human and environmental health. Traditional remediation of textile dye-polluted water with chemical, physical, and biological processes has many disadvantages. Due to this, nano-engineered materials are drawing more attention to this area. However, the widespread use of nano-particles for this purpose may lead to photocatalytic degradation of xenobiotics, while increasing the risk of nano-particle-induced ecotoxicity. Therefore, we comparatively evaluated the toxicity of novel synthesized core@shell TiO2 and SiO2 nano-particles to embryonic stages of Danio rerio and Xenopus laevis. The ability of photocatalytic destruction of the synthesized nano-particles was tested using toxic azo dye, disperse red 65, and the effects of reducing the toxicity were evaluated. The reflux process was used to synthesize catalysts in the study. The samples were characterized by scanning electron microscopy, X-ray fluorescence spectroscopy, X-ray diffractometry, BET surface area, and UV-vis-diffuse reflectance spectra. It was determined that the synthesized nano-particles had no significant toxic effect on D. rerio and X. laevis embryos. On the other hand, photocatalytic degradation of the dye significantly reduced lethal effects on embryonic stages of the organisms. Therefore, we suggest that specific nano-particles may be useful for water remediation to prevent human health and environmental impact. However, further risk assessment should be conducted for the ecotoxicological risks of nano-particles spilled in aquatic environments and the relationship of photocatalytic interaction with nano-particles and xenobiotics.Öğe Polietilen imin modifiye edilmiş TiO2'in sentezi ve krom iyonlarının adsorpsiyonu ve/veya organik kirliliklerin fotokatalitik parçalanması için kullanılabilirliğinin araştırılması(İnönü Üniversitesi, 2022) Akgeyik, EmrahTez kapsamında; Anataz TiO2'in sentez aşamasında ortama polietilen imin ve gluteraldehit eklenerek TiO2-PEI-GA materyali reflux yöntemle sentezlendi ve atık sularda bulunan anyonik Cr6+'nın yani CrO42- iyonlarının adsorpsiyonu ve dirençli organik kirliliklerin fotokatalitik yıkımı için ''bifonksiyonel'' materyalin sentezi gerçekleştirildi. Ayrıca, sentezlenen bifonksiyonel materyal, farklı matriks ortamlarında bulunan düşük derişimdeki Cr6+ iyonlarını katı faz ekstraksiyonu (SPE) ile ayrılması ve ön-deriştirilmesi için kolon dolgu maddesi olarak kullanıldı. TiO2-PEI-GA materyalinin, XRD, FT-IR, SEM-EDX, BET, TGA, Dinamik ışık saçılması (DLS) ve Zeta potansiyel analizleri yapılarak karakterizasyonu yapıldı. CrO42-→Cr6+ iyonlarının optimum adsorpsiyon koşullarını belirlemek için batch yöntem kullanıldı ve çözelti pH, adsorbent miktarı, adsorpsiyon süresi, ortam sıcaklığı, başlangıç derişimi, çözelti hacmi, organik ve inorganik kirliliklerin etkisi ve ayrıca seçicilik faktörü araştırıldı. Cr6+ 'nın pH 3 çözelti ortamında 45 dk'da maksimum adsorpsiyon kapasitesi 156,0 mgg-1 olarak belirlendi. Fotokatalitik çalışmalar tannik asit, reaktif black 5, rodamin b ve metilen mavisi çözeltileri ile yapıldı. TiO2-PEI-GA'nin görünür ışık altında 4 saat ışınlama sonucu tannik asit ve boyar maddeleri neredeyse tamamen parçaladığı görüldü. Son olarak sentezlenen materyalin antimikrobiyal etkisi incelendi ve antifungal etki gösterdiği belirlendi.Öğe A Rapid Response Humidity Sensor for Monitoring Human Respiration with TiO2-Based Nanotubes as a Sensing Layer(Springer, 2020) Atalay, Selcuk; Erdemoglu, Sema; Kolat, Veli Serkan; Izgi, Tekin; Akgeyik, Emrah; Yilmaz, Hatice Caglar; Kaya, HarunThe use of TiO2-based samples with nanotube (NT) shape for humidity sensing has been investigated. Sample characterization was carried out using x-ray diffraction analysis, scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy. x-Ray diffraction analysis showed that the nanotubes had TiO2, NaO3, and H2Ti2O5 phases. SEM revealed that the NTs had diameters ranging from 20 nm to 200 nm and very different lengths. TiO2-based nanotubes were coated using the drop-casting method onto a quartz crystal microbalance (QCM). The synthesis of TiO2-based NTs was performed using a hydrothermal process. Humidity sensing measurements showed that the resonant frequency of TiO2-based NTs deposited onto the QCM was very sensitive to humidity changes. It was also shown that the sensor could be used for respiratory monitoring purposes.
