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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 Comparison of Dissolution Profiles of Commercially Available Lamivudine Tablets(Dissolution Technologies, Inc, 2015) Ozturk, Naile; Kaynak, Mustafa Sinan; Sahin, SelmaThe aim of this study was to investigate the influence of dissolution medium on the in vitro release of lamivudine (100 mg) from four commercially available lamivudine tablets (one reference and three generic). Three different buffer solutions (pH 1.2, 4.5, 6.8) and deaerated water were used as the dissolution media (900 mL), and the paddle rotation speed was kept at 50 rpm with twelve replicates. An RP HPLC method was developed for analysis of lamivudine in samples obtained from dissolution studies. The mobile phase consisted of acetonitrile/water (10:90) pH adjusted to pH 2.5 with o-phosphoric acid, a C-18 column (Ace 250 x 4.60 mm, 5 mu m) was used, and the flow rate was set at 1 mL/min. All the drugs tested were very rapidly dissolving (more than 85% of the labeled amount in 15 min), and the dissolution profiles of the generic tablets were thus considered similar to that of the reference tablet in each of the buffers at pH 1.2, 4.5, and 6.8, and deaerated water. Because of the dissolution results and the high solubility and borderline permeability, a biowaiver can be proposed for lamivudine immediate-release solid oral dosage forms provided that the excipient composition of the test product is the same as or similar to that of the reference product and the excipients that have an effect on bioavailability are qualitatively and quantitatively the same as that of the reference product.Öğe Determination of in vitro Dissolution Profiles of Amlodipine Besylate and Olmesartan Medoxomil Using a New HPLC Method(Chiminform Data S A, 2013) Kaynak, Mustafa Sinan; Celebier, Mustafa; Sahin, Selma; Altinoz, SpodeThe aim of this study was to develop an HPLC method for simultaneous determination of these active compounds and to apply this method to determine the dissolution of AML and OLM from a commercially available tablet. Valsartan (VAL) was used as an internal standard (IS). Separation of AML, OLM and VAL was performed using Phenomenex C-18 column (Luna 5 mu, 100A, 250x4.6 mm; California, USA) protected with a Phenomenex C-18 guard column (4.0x3.0 mm; California, USA). The chromatographic separation operated isocratically at room temperature using a mobile phase consisted of phosphate buffer (pH 4.0, 0.04 mol/L):methanol:acetonitrile (40:45:15, v/v/v) delivered at a flow rate of 0.8 mL/min and injection volume was 10 mu L. The diode array detector was set at 234 nm and 205 nm wavelengths for the quantification of AML and OLM respectively. In vitro dissolution studies revealed that 85% of the labeled amounts of AML and OLM were released within 25 min from their fixed combination tablet dosage form. The developed HPLC method was validated according to the ICH guidelines and it is proposed for dissolution studies of the combination dosage forms of these compounds.Öğe Determination of Regional Intestinal Permeability of Diclofenac and Metoprolol Using a Newly-Developed and Validated High Performance Liquid Chromatographic Method(Pharmacotherapy Group, 2015) Kaynak, Mustafa Sinan; Buyuktuncel, Ebru; Caglar, Hatice; Sahin, SelmaPurpose: To develop a simple and rapid reversed-phase high performance liquid chromatographic (HPLC) method with UV detection for the simultaneous determination of diclofenac, metoprolol tartrate, phenol red and propyl paraben in intestinal segments. Methods: The mobile phase consisted of 55% methanol, 45% of 12.5 mM potassium dihydrogen phosphate (KH2PO4) aqueous solution, adjusted to pH 7.0 using 0.2 N sodium hydroxide (NaOH) solution, and to which 0.3% (v/v) triethylamine was added. Analysis was run at a flow rate of 1.0 mL/min with a 12 min total run time at ambient temperature. The developed method was successfully applied to determination of the analytes in samples obtained from in situ single pass intestinal perfusion (SPIP) studies. Results: The calibration curves were linear for all compounds (r > 0.999) with a limit of detection (LOD) of 0.005, 0.1, 0.075 mu g/mL, and limit of quantification of 0.1, 0.3, 0.2 mu g/mL for metoprolol tartrate, phenol red and diclofenac respectively. The coefficient of variation for intra-day and inter-day precision was < 5% and accuracy was between 98 and 102%. Based on SPIP and HPLC studies, the estimated mean permeability in jejunum, ileum and colon was 0.319 +/- 0.184, 0.639 +/- 0.241 and 0.84 3 +/- 0.517 x 10(-4) cm/sec, respectively, for metoprolol tartrate while the corresponding permeability values were 1.585 +/- 0.729, 1.154 +/- 0.433 and 1.775 +/- 1.576 x 10(-4) cm/sec for diclofenac. Conclusion: The findings indicate that diclofenac is a highly permeable compound and its absorption occurs throughout the intestinal tract. Furthermore, the developed method is suitable for the analysis of diclofenac and metoprolol in intestinal regions.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 Effect of permeability enhancers on paracellular permeability of acyclovir(Wiley, 2016) Ates, Muge; Kaynak, Mustafa Sinan; Sahin, SelmaObjectives According to Biopharmaceutics Classification System (BCS), acyclovir is a class III (high solubility, low permeability) compound, and it is transported through paracellular route by passive diffusion. The aim of this study was to investigate the effect of various pharmaceutical excipients on the intestinal permeability of acyclovir. Methods The single-pass in-situ intestinal perfusion (SPIP) method was used to estimate the permeability values of acyclovir and metoprolol across different intestinal segments (jejunum, ileum and colon). Permeability coefficient (P-eff) of acyclovir was determined in the absence and presence of a permeation enhancer such as dimethyl beta-cyclodextrin (DM-beta-CD), sodium lauryl sulfate (SLS), sodium caprate (Cap-Na) and chitosan chloride. Key findings All enhancers increased the permeability of paracellularly transported acyclovir. Although Cap-Na has the highest permeability-enhancing effect in all segments, permeation-enhancing effect of chitosan and SLS was only significant in ileum. On the other hand, DM-beta-CD slightly decreased the permeability in all intestinal segments. Conclusions These findings have potential implication concerning the enhancement of absorption of paracellularly transported compounds with limited oral bioavailability. In the case of acyclovir, Cap-Na either alone or in combination with SLS or chitosan has the potential to improve its absorption and bioavailability and has yet to be explored.Öğe Effect of precipitation inhibitors on supersaturation and solubility of furosemide(Marmara Univ, 2021) Gulsun, Tugba; Ozturk, Naile; Kara, Asli; Sahin, Selma; Vural, ImranFurosemide is a widely used diuretic drug for the treatment of edema associated with heart, liver cirrhosis, renal diseases and hypertension. It is a Class IV drug with low aqueous solubility and low permeability according to Biopharmaceutics Classification System (BCS). Furosemide was chosen as a model drug to examine the effect of polymeric precipitation inhibitors (PPIs) on the supersaturation and solubility. Solubility and concentration change of furosemide as a function of time at pH 1.2 and 6.8 were determined to show the effects of PPIs on furosemide solubility. The 24 h equilibrium solubility of furosemide was 0.017 +/- 0.004 and 3.62 +/- 0.201 mg/mL at pH 1.2 and pH 6.8 buffer solutions, respectively. PPI type and concentration (0.05%, 0.25%) did not increase furosemide solubility at pH 1.2. However, both hydroxypropylmethylcellulose (HPMC) and polyvinylpyrrolidoneK17 (PVPK17) at two concentrations increased furosemide solubility at pH 1.2 and 6.8. In addition, viscosity of solutions was in the range of 2.2-3.7 centipoise, and it was not influenced by PPIs concentrations. Our results showed that designing supersaturated formulations using PPIs can be useful and promising to enhance solubility of furosemide.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 HPLC METHOD DEVELOPMENT AND VALIDATION: SIMULTANEOUS DETERMINATION OF DICLOFENAC, METOPROLOL AND PHENOL RED IN BIOLOGICAL MATRIX FOR INTESTINAL PERFUSION STUDIES(Elsevier Science Bv, 2009) Caglar, Hatice; Kaynak, Mustafa Sinan; Sahin, Selma; Buyuktuncel, Ebru[Abstract Not Available]Öğe HPLC method development for the simultaneous analysis of amlodipine and valsartan in combined dosage forms and in vitro dissolution studies(Univ Sao Paulo, Conjunto Quimicas, 2010) Celebier, Mustafa; Kaynak, Mustafa Sinan; Altinoz, Sacide; Sahin, SelmaA simple, rapid and reproducible HPLC method was developed for the simultaneous determination of amlodipine and valsartan in their combined dosage forms, and for drug dissolution studies. A C 18 column (ODS 2, 10 mu m, 200 x 4.6 mm) and a mobile phase of phosphate buffer (pH 3.6, 0.01 mol L-1): acetonitrile: methanol (46: 44: 10 v/v/v) mixture were used for separation and quantification. Analyses were run at a flow-rate of 1 mL min(-1) and at ambient temperature. The injection volume was 20 mu L and the ultraviolet detector was set at 240 nm. Under these conditions, amlodipine and valsartan were eluted at 7.1 min and 3.4 min, respectively. Total run time was shorter than 9 min. The developed method was validated according to the literature and found to be linear within the range 0.1 -50 mu g mL(-1) for amlodipine, and 0.05 - 50 mu g mL(-1) for valsartan. The developed method was applied successfully for quality control assay of amlodipine and valsartan in their combination drug product and in vitro dissolution studies.Öğe Preparation of nanosuspensions of a 1,4-dihydropyridine-based mixed L-/T-type calcium channel blocker by combined precipitation and ultrasonication methods(Elsevier, 2023) Pezik, Esra; Gulsun, Tugba; Gunduz, Miyase Gozde; Sahin, Selma; Ozturk, Naile; Vural, ImranM3, a condensed 1,4-dihydropyridine (DHP) derivative, targets both L- and T-type calcium channels and therefore, stands as a promising antihypertensive drug candidate. This study aims to improve the poor solubility of M3 using nanocrystal technology (a combination of precipitation and ultrasonication methods) to enhance its oral bioavailability. Pre-formulation studies were performed and M3 nanosuspensions were prepared using different stabilizers (polyvinyl pyrrolidone K30, polyvinyl alcohol, SoluPlus & REG;) and surfactants (poloxamer 188, poloxamer 407, sodium deoxycholate, sodium lauryl sulfate) at different concentrations (0.05, 0.1, 0.5, 1.0, 2.0%, w/v). The optimum nanosuspension formulation was freeze-dried using different cryoprotectants (mannitol, trehalose, glucose, sucrose, dextran) at different ratios (1.25, 2.5, 5.0%, w/v). It was determined that the most suitable cryoprotectant and ratio was 5.0% trehalose, resulting in nanocrystals with a size of 320.2 & PLUSMN; 15.3 nm and a zeta potential of -27.4 & PLUSMN; 0.1 mV. The physicochemical properties of M3, poloxamer 188, physical mixture and freeze-dried nanocrystals were evaluated by XRD, DSC and FT-IR analyses. Characterization studies showed amorphization of M3 in the freeze-dried nanocrystals prepared with poloxamer 188. The result of equilibrium solubility and permeability studies results indicated that M3 could be a BCS class 4 compound. Cell culture studies using Caco-2 cells showed that M3 had no significant toxic effect on the cells and had a Papp value of 2.2 x 10-7 cm/s. Compared to coarse M3 powder freeze-dried M3 nanocrystals showed a 200-fold increase in solubility and a 28.6-fold increase in apparent permeability. The cytotoxic effect of M3 was also reduced by using poloxamers as stabilizers in the formulation. M3 nanosuspensions were found to be a promising candidate for the oral administration of M3 for the potential treatment of hypertension due to the increase in solubility and permeability which could enhance its oral bioavailability.Öğe UV Spectrophotometric Method for Determination of the Dissolution Profile of Rivaroxaban(Dissolution Technologies, Inc, 2014) Celebier, Mustafa; Kaynak, Mustafa Sinan; Altinoz, Sacide; Sahin, SelmaRivaroxaban is an oral anticoagulant that is the first available orally active direct Factor Xa inhibitor. In this study, a UV spectrophotometric method was developed for the determination of rivaroxaban content in pharmaceutical formulations and the amount of rivaroxaban released in tablet dissolution studies. The dissolution profile of rivaroxaban was successfully determined with the validated method.
