Differential Scanning Calorimetry Patterns Research Articles

Optimisation of spray drying process parameters of curcumin nanosuspension

The aim of this study was to optimise spray drying process parameters of curcumin nanosuspension. Method: an I-Optimal experimental model was designed by Design Expert software including 22 experiments. The independent variables were inlet temperature (oC), pump speed (ml/minute) and weight ratio of curcumin-loaded nanoparticles and carrier and nanoparticle; the dependent variables were particle size after redispersing (nm), polydispersity index, dispersion time (second) and spray drying yield. After the optimal parameters had been verified by experiments, some quality requirements of spray-dried powders were evaluated. Then the physical and chemical properties of curcumin in spray-dried powders were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and fourier-transform infrared spectroscopy (FT-IR). Results: the optimal parameters were established with the inlet temperature of 140oC, the pump speed of 5 ml/minute, the weight ratio of carrier and nanoparticle of 2:1. The obtained results of verification experiments were highly repeatable and were similar to the predicted ones from the software. The comparison of XRD spectra between curcumin crystal and spray-dried powders showed that curcumin in spray-dried powders existed in amorphous form. Furthermore, DSC patterns and FT-IR spectra of curcumin crystal and spray-dried powder demonstrated that there were interactions among curcumin, chitosan and lipoid S100. Conclusion: nano curcumin powders have met the quality requirements of preparation in laboratory-scale. This is a platform for further research later and eventually put into industrial-scale production.

Dissolution Enhancement of Eplerenone using Solvent Melt Method

Background: Eplerenone (EPL) is a BCS class II drug, thus, having poor water solubility. The poor water solubility of this drug leads to poor dissolution and ultimately shows poor bioavailability. To overcome this problem, the solid dispersion of EPL was prepared in this study. Methods: This was accomplished by using the solvent melt method as the solid dispersion technique. In this method, Pluronic F-68 and F-127 were used as the carrier and different formulations were prepared using varying ratios of a drug and carrier (1:1, 1:2, 1:3, 1:4, 1:5). The mixture of drug solution and carrier was prepared at 70°C, using the digital magnetic stirrer. The resultant mixture was dried at 40°C in a hot air oven and optimized EPL-solid dispersion was undergone for their characterization using drug content, drug entrapment efficiency (%) and drug loading content (%), Scanning Electron Microscopy (SEM), Infra-Red spectroscopy, Differential Scanning Calorimetry (DSC), stability study and in-vitro dissolution studies. Results: The result indicated that there was no interaction between EPL and Pluronics (Pluronic F-68 & F-127), and optimized formulation (P127-2) of EPL-solid dispersion had encapsulation efficiency > 95%. Experimental work also showed that optimized formulation has 31.7% of drug loading content which was greater than other existing solid dispersion having less than 30% of drug loading content. Out of different batches, the optimized batch exhibits the faster dissolution rate in comparison to other batches. It released the almost total amount of drug (98.96%) in 30 minutes. The stored ESM-solid dispersion also exhibited remarkable stability and remains in a solid state, when it was exposed to 25°C/60% relative humidity and room temperature (38ºC) for two months. Such stability was confirmed by DSC method. The DSC thermogram of optimized formulation exhibited a melting endotherm at an onset temperature of 160°C, a peak temperature of 165°C and a heat of fusion of 25.68 J/gm. Similarly, the DSC thermogram of the physical mixture of bulk EPL/- pluronic F-127 also exhibited the onset of temperature at 165°C, and a peak temperature at 171°C. Thus, the result indicated that both samples showed almost similar DSC pattern and no sample altered its state after the treatment of temperature and humidity used in stability testing. SEM study was also performed in this research and the result indicated that the particle size of optimized formulation was varied, having irregular matrices due to the porous nature of the carrier. Conclusion: Based on different findings, it can be concluded that the solvent melt method could be a potential method for preparing the solid dispersion of EPL like BCS class-II Drugs and will be able to solve the dissolution and solubilization related problem of poorly soluble drugs.

Thermal Analysis of Ca<sub>1+<i>x</i></sub>Cu<sub>3</sub>Ti<sub>4</sub>O<sub>12+<i>x</i></sub> Precursor in Nitrogen and Oxygen Environment at 1000 °C

The thermal kinetic analyses are prepared on Ca1+xCu3Ti4O12+x powders using simultaneous thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC) measurement in a dual atmospheric gases environment. Initially, the nitrogen gas flowed from room temperature to 1000 °C, and then the environment was shifted and hold for 1 hour with oxygen. The result shows that the TGA patterns of the temperature and mass loss are disorderly with x values. The mass loss % patterns slightly decreased with increased additional Ca-based element. The decreased of oxygen absorption as the values of x increased also can be explained by the reduction of single-phase CCTO structure when excess Ca ions. The DSC pattern shows two prominent endothermic peaks and two exothermic peaks that relate to the melting point of the reactant and crystalline phase changes of samples, while the significant endothermic peak at 1000 °C is corresponding to the formation of CCTO compounds as identified by XRD analysis.

Preparation, characterization and improved release profile of ibuprofen-phospholipid association

Ibuprofen is a widely prescribed non-steroidal and anti-inflammatory drug, which is practically insoluble in water and causes gastrointestinal (GI) side effects. Ibuprofen-phosphathidylcholine association (IPA) was prepared by refluxing ibuprofen and phosphathidylcholine in three different molar ratios (1:0.25, 1:0.5 and 1:1) in aim to induce the amorphous nature of ibuprofen and increase its solubility. The characteristics of IPA were evaluated by H1-NMR, FT-IR spectra, X ray diffraction (XRD), differential scanning calorimetry (DSC), drug content, photon correlation spectroscopy, computational molecular simulation, solubility and in vitro dissolution study. Computational molecular simulation, DSC, FT-IR, H1-NMR and XRD patterns confirmed the reaction between carboxyl group of ibuprofen and polar moiety of phosphathidylcholine. IPAs showed an increase in solubility in phosphate buffer medium (pH 7.2) and a decrease in solubility in HCl medium (pH 1.2). The IPA dissolution rate increased in the simulated intestinal medium, whereas the dissolution rate of the IPA decreased in the simulated gastric medium. It is concluded that the phosphatidylcholine association of ibuprofen may be of potential use for improving the ibuprofen solubility and hence its bioavailability. Furthermore, considering decrease of dissolution rate of IPA in acidic medium, it may also reduce GI toxicity of ibuprofen. Moreover, comparing different molar ratios of IPA, there is no significant difference in their characteristics and dissolution profiles.

Enhanced solubility of microwave-assisted synthesized acyclovir Co-crystals

This study aimed to enhance the kinetic solubility of ACV by using microwave-assisted technique to form ACV co-crystals and overcome its limited aqueous solubility. Co-crystallization is one of the commonly used techniques to improve the dissolution rates of active pharmaceutical ingredients (APIs). Acyclovir (ACV) has a limited efficacy due to its low oral bioavailability resulted from its poor aqueous solubility and permeability. Acyclovir co-crystals were formulated by microwave assisted solvent extraction (MASE) in equimolar ratio of 1:1 with different co-formers. Physical and structural characterization by differential scanning calorimetry (DSC), powder x-ray diffraction (PXRD), and Fourier transform infrared (FTIR) spectroscopy were performed. Further evaluation of the co-crystals solubility, dissolution rate and content were carried out using the ultraviolet (UV) spectrophotometry. Co-crystals of acyclovir and tartaric acid (ACV-TA) in equimolar ratio of 1:1 produced by MASE using the glacial acetic acid as a solvent were more soluble compared to plain drug. The dissolution rate was increased from only 59.0% of pure acyclovir up to 85.0% of ACV co-crystals within 1 hour. DSC and PXRD patterns of co-crystals were distinguished from that of individual components. The UV-spectroscopic analysis represented 62.5% of acyclovir in the co-crystals, which was directly related to the theoretical percentage of the drug and its co-former (ACV: 60.01%, TA: 39.99%). This study revealed that the optimal ratio of the ACV-TA co-crystal is 1:1, which was successfully prepared using MASE technique. This method provides a promising alternative for enhancing the solubility of acyclovir with ultimately less time and solvent consumption.

Physical, mechanical, thermal and structural characteristics of nanoencapsulated vitamin E loaded carboxymethyl cellulose films

Nanoencapsulated vitamin E (α-tocopherol) incorporated into the carboxymethyl cellulose (CMC) films using film-forming cast solution method. Then, some physical, mechanical, thermal and structural attributes of the active films were scrutinized. From the obtained results, addition of α-tocopherol nanocapsules significantly (p < 0.05) decreased the water vapour permeability (WVP), tensile strength (TS) and Young’s modulus, while elongation at break (EAB) significantly (p < 0.05) increased. Morphology of CMC films revealed that nanocapsules cause porosity and changes in film matrix structure. The DSC (differential scanning calorimetry) patterns exhibited a drop in melting points of the film composites as a result of α-tocopherol addition. The FTIR (Fourier transform infrared spectroscopy) spectra confirmed the successful loading of α-tocopherol into the structure of CMC films, due to the formation of carbonyl group (CO) via phenol part of α-tocopherol at 1710 cm−1 within the CMC film. α-tocopherol loaded CMC composite films could be proposed for sheltering food items containing lipids or fats which stored at the ambient temperature.

Free radicals formation on thermally decomposed biomass

Pyrolysis provides an attractive alternative for the upgrading of agro-wastes to energy and chemicals. However, consistent quality of the final products is still a goal to be achieved at industrial level. The present study aims at complementing existing results recently published by the authors and investigating the physico-chemical evolution and oxidative reactivity of solid products of pyrolysis of citrus waste. Chars derived from slow pyrolysis (50 °C min−1, 200–650 °C peak temperature) of orange and lemon pulp (OP and LP) in a horizontal batch reactor were characterized by means of Thermo-Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Electron Paramagnetic Resonance (EPR) and Raman spectroscopy. Results show how the onset of breaking of covalent bonds in matrix is triggered by reaching pyrolysis temperatures of 330–350 °C. Around those temperatures, the population of free-radicals significantly increases on solids and chars become more reactive, thereby favoring retrogressive, recombination and secondary solid-vapor reactions. Results also show that the higher content of lignin on LP may facilitate the formation of aromatic networks via lignin fragmentation and condensation above 500 °C. This trend is also confirmed by DSC patterns in which, above 500 °C, significantly more endothermic reactions occur in LP as a comparison to OP. This conclusion is further corroborated by more pronounced G-band Raman shifts shown for LP as a comparison to OP. The present results shed new light on the thermochemical breakdown of solid agro-wastes and provide insights for development of slow pyrolysis technology toward the production of valuable renewable carbonaceous materials.

PREPARATION, CHARACTERISATION AND EVALUATION OF ROPINIROLE HYDROCHLORIDE LOADED CONTROLLED RELEASE MICROSPHERES USING SOLVENT EVAPORATION TECHNIQUE

Objective: The major objective of the research work was to design, characterise and evaluate controlled release microspheres of ropinirole hydrochloride by using non-aqueous solvent evaporation technique to facilitate the delivery of the drug at a predetermined rate for a specific period of time.Methods: Ropinirole hydrochloride microspheres were prepared by using different low-density polymers such as eudragit RL 100, eudragit RS 100 and ethylcellulose either alone or in combination with the help of non-aqueous solvent evaporation technique. All the formulated microparticles were subjected to various evaluation parameters such as particle size analysis, micrometric properties, drug entrapment efficiency, percentage drug loading, percentage yield and in vitro drug release study. The compatibility of the drug and polymers was confirmed by physical compatibility study, fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and x-ray diffraction study (XRD). The formation of the most optimized batch of the microsphere (F12) was confirmed by scanning electron microscopy (SEM), DSC, FTIR, and XRD. In vitro drug release study and in vitro drug release kinetics study of the formulated microspheres were also carried out.Results: Drug-polymer compatibility studies performed with the help of FTIR and DSC indicated that there were no interactions. Results revealed that non-aqueous solvent evaporation technique was a suitable technique for the preparation of microspheres as most of the formulations were discrete, free-flowing and spherical in shape with a good yield of 55.67% to 80.09%, percentage drug loading of 35.52% to 94.50% and percentage drug entrapment efficiency of 36.24% to 95.07%. Different drug-polymer ratios, as well as the combination of polymers, played a significant role in the variation of over-all characteristics of formulations. Based on the data of various evaluation parameters such as particle size analysis, percentage drug loading, percentage drug entrapment, percentage yield, rheological studies and in vitro drug release characteristics, formulation F12 was found to fulfil the criteria of ideal controlled release drug delivery system. F12 showed controlled release till the 14th hour (97.99%) and its in vitro release kinetics was best explained by zero-order kinetics and followed Korsemeyer-Pappas model (Non-Fickian mechanism). SEM of F12 revealed the formation of spherical structures. The FTIR study of F12 confirmed the stable nature of ropinirole in the drug-loaded microspheres. DSC and XRD patterns showed that ropinirole hydrochloride was dispersed at the molecular level in the polymer matrix.Conclusion: The controlled release microparticles were successfully prepared and from this study, it was concluded that the developed microspheres of ropinirole hydrochloride can be used for controlled drug release to improve the bioavailability and patient compliance and to maintain a constant drug level in the blood target tissue by releasing the drug in zero order pattern.

Febuxostat-Minoxidil Salt Solvates: Crystal Structures, Characterization, Interconversion and Solubility Performance

Three febuxostat-minoxidil salt solvates with acetone (ACE), tetrahydrofuran (THF) and isopropanol (IPA) are synthesized by solvent-assisted grinding and characterized by infrared (IR), nuclear magnetic resonance (1H-NMR), single crystal and powder X-ray diffraction (PXRD), thermogravimetry (TG) and differential scanning calorimetry (DSC). These febuxostat-minoxidil salt solvates feature isostructural with the same stoichiometries (1:1:1 molecule ratio). The proton transfers from the carboxylic group of febuxostat (FEB) to imino N atom of minoxidil (MIN), which forms the motif with combined R 2 2 (9) R 4 2 (8) R 2 2 (9) graph set in the three solvates. The solvents occupy the different positions related to the motif, which results in the apparent differences in PXRD patterns before/after desolvation although they are isostructures. The FEB-MIN·THF was more thermostable than FEB-MIN·ACE and FEB-MIN·IPA relative to solvent removal from DSC patterns, which is different from the results from the solvent-exchange experiments in chemical kinetics. All three salt solvates exhibit increased equilibrium solubility compared to FEB in aqueous medium.

Mixed matrix membranes of polyurethane with nickel oxide nanoparticles for CO2 gas separation

We developed highly selective polyurethane (PU) membranes with incorporated NiO nanoparticles for gas-phase carbon dioxide separation. PU was synthesized with polytetramethylene glycol and isophoronediisocyanate, and 1,4-butandiamine/1,4-butandiol as the chain extender (1:3:2 molar ratio). Mixed matrix membranes (MMMs) composed of PU and NiO nanoparticles were fabricated using the solution casting method. Scanning electron microscopy (SEM) confirmed the even distribution of NiO in the PU matrix at the nanoscale. Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) were used to examine the phase separation between the soft and hard domains of PU, and the distribution of NiO nanoparticles in both domains. DSC and X-ray diffraction (XRD) pattern confirmed that the crystalline structures in both soft and hard segments are changed by NiO incorporation. The effects of NiO nanoparticles on the gas permeability, diffusivity, and solubility of pure CO2, CH4, O2, and N2 gases were studied at various temperatures and feed pressures. A large increase in the CO2/N2 permselectivity with a simultaneous reduction in the gas permeability of CH4, O2, and N2 was observed. When the NiO content was low (1wt%), the CO2/N2 permselectivity increased by 79.21%, and the CO2 permeability increased by 1.57%. Increasing the nanoparticle load to 5wt% increased the CO2/N2 permselectivity by 161.1%, while the CO2 permeability was decreased by 3.31%.

Formulation and Evaluation of Naringenin Nanosuspensions for Bioavailability Enhancement.

The clinical potential of naringenin (NRG) is compromised due to its poor aqueous solubility and low oral bioavailability. The study is aimed at addressing these issues by means of naringenin nanosuspensions (NRG-NS) formulated using polyvinylpyrrolidone (PVP K-90) as stabiliser via antisolvent sonoprecipitation method. Optimisation of sonication time, drug concentration and stabilisers was done based on particle size. Characterisation of pure NRG and NRG-NS was carried out by scanning electron microscopy, differential scanning calorimetry (DSC), x-ray powder diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR). In vitro dissolution, intestinal absorption by non-everted rat intestinal sac model and in situ single pass intestinal perfusion techniques were performed for further investigation. Nanosuspensions prepared using PVP K-90 lead to minimum particle size (117±5nm) with zeta potential of -14.6±5.6mV. The particle size was affected by increasing sonication time, concentration of stabiliser and drug. Nanosizing process converted the crystalline drug into amorphous form as predicted from DSC and XRD patterns. FTIR demonstrated the formation of hydrogen bonds between drug and polymer. NRG-NS displayed a higher dissolution amount (91±4.4% during 60min) compared to NRG powder (42±0.41%). The apparent and effective permeability of NRG-NS was increased as compared to the pure NRG. The in vivo pharmacokinetics demonstrated that the C max and AUC0-24h values of NRG-NS were approximately 2- and 1.8-fold superior than the pure drug. Hence, overall results confirmed nanosuspensions as promising approach for NRG delivery with high absorption in gastrointestinal tract, improved dissolution and oral bioavailability.

Biophysical evaluation of aminoclay as an effective protectant for protein stabilization during freeze-drying and storage.

This study aimed to evaluate aminoclay (3-aminopropyl-functionalized magnesium phyllosilicate) as an effective protectant for the stabilization of protein formulation in freeze-drying. Bovine serum albumin (BSA), as a model protein, was freeze-dried with aminoclay at various concentrations, and the effects of aminoclay on the structural stability of proteins were compared with those of the conventional stabilizers. The structural characteristics of the protein were determined by size exclusion chromatography (SEC), circular dichroism (CD), and Fourier transform infrared (FTIR) spectroscopy. Furthermore, physicochemical and morphological characteristics were examined by X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). XRPD and DSC patterns indicated that the glass transition temperature (Tg) of the amorphous formulation of aminoclay mixed with proteins was gradually elevated as the concentration of aminoclay increased. FTIR and CD spectral analysis suggested that the protein structure was well maintained with aminoclay during the freeze-drying process and 3 months of storage at 4°C and 40°C. Furthermore, aminoclay conferred the greatest protection against aggregation and retained the monomer content of BSA even at a high temperature. The morphological characteristics of lyophilized proteins were also well conserved during the storage with aminoclay. These results suggested that aminoclay may be useful as an alternative stabilizer for maintaining the structural stability of protein formulations.

EFFECT OF GAMMA-IRRADIATION ON BIODEGRADABLE MICROSPHERES LOADED WITH RASAGILINE MESYLATE

In the present study, the influence of gamma-irradiation was evaluated on the physicochemical characteristics and in vitro release of rasagiline mesylate (RM), a selective MAO-B inhibitor used in Parkinson’s disease, from poly(D,L-lactide- co -glycolide) (PLGA) microspheres. Microspheres were prepared using PLGA 50:50 by the solvent evaporation technique (O/W emulsion). Microspheres were sterilized by gamma-irradiation and their influence was assessed by scanning electron microscopy (SEM), laser light diffraction, differential scanning calorimetry (DSC), X-ray diffraction (XRD), gel permeation chromatography (GPC), encapsulation efficiency (EE) and in vitro drug release. Gamma-irradiation of RM-loaded microspheres did not affect EE, DSC and XRD patterns. After gamma-irradiation, changes on the surface were observed by SEM, but no significant difference in mean particle size was observed. GPC measurements showed a decrease in molecular weight of the polymer after five days of in vitro release. The similarity factor value between irradiated and non-irradiates microspheres was <50, indicating the non-similarity of the release profiles. The sterilization technique had an effect on the integrity of polymeric system, significantly affecting in vitro release of RM from PLGA microspheres. Therefore, from our results we conclude that gamma-irradiation is not a suitable sterilization procedure for this formulation.

Induced Electronic and Thermal Effects of 86 MeV Nickel Ions in Bisphenol-A Polycarbonate

ABSTRACTBisphenol-A polycarbonate films were irradiated with 86 MeV swift heavy nickel ions at varying fluences, ranging from 1 × 1011 to 1 × 1013 ions cm−2, under vacuum at room temperature, to analyze the induced electrical and thermal modifications. AC conductivity measurements and UV-visible spectroscopy, Fourier transform infra-red (FTIR) spectroscopy, thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) techniques were applied to analyze the changes. A significant, exponential increase in conductivity at higher frequency was observed with the increase of nickel ion fluence. UV-visible analysis corroborated the results of the AC conductivity measurement, revealing the increase in size of the carbon clusters embedded in the polymer network, with the increase of heavy ion fluence. FTIR analysis revealed the formation of alkene and alkyne end groups at higher doses, which further supported the suggestion that the variation in electrical properties induced by the ion irradiation of the polymer was due to development of a carbonaceous phase inside the polymer due to the irradiation. Thermal analysis, i.e., TGA and DSC patterns, showed that chain-scission was the leading phenomena in the heavy ion-irradiated polycarbonate samples, resulting in degradation of their thermal stability.

Improved dielectric performance of polypropylene/multiwalled carbon nanotube nanocomposites by solid‐phase orientation

ABSTRACTBy means of a die‐drawing technique in the rubbery state, the effect of the orientation of the microstructure on the dielectric properties of polypropylene (PP)/multiwalled carbon nanotube (MWCNT) nanocomposites was examined in this study. The viscoelastic behavior of the PP/MWCNT nanocomposites with MWCNT weight loadings ranging from 0.25 to 5 wt % and the dielectric performance of the stretched PP/MWCNT nanocomposites at different drawing speeds and drawing ratios were studied to obtain insight into the influences of the dispersion and orientation state of the MWCNTs and matrix molecular chains. A viscosity decrease (ca. 30%) of the PP/MWCNT‐0.25 wt % (weight loading) melt was obviously due to the free volume effect. Differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction were adopted to detect the orientation structure and the variation of crystal morphology of the PP/MWCNTs. Melting plateau regions, which indicated the mixed crystallization morphology for the stretched samples, were found in the DSC patterns instead of a single‐peak for the unstretched samples. We found that the uniaxial stretching process broke the conductive MWCNT networks and consequently increased the orientation of MWCNTs and molecular chains along the tensile force direction; this led to an improvement in the dielectric performance. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42893.

Comparative study on characteristics and in vitro fibril formation ability of acid and pepsin soluble collagen from the skin of catla (Catla catla) and rohu (Labeo rohita)

Catla (Catla catla) and Rohu (Labeo rohita) are the major carp fish produced by freshwater aquaculture in India. Processing of these carp fish generates potentially large quantities of by-products (waste) from non-edible fish parts by fish-processing factories and fish shops. The paper focuses on the extraction of the acid soluble collagen (ASC) and pepsin soluble collagen (PSC) from the skin of carp fish and subsequently their characteristics and in vitro fibril-forming ability. The extracted collagens are characterized as type I collagen based on the electrophoretic pattern. The denaturation temperature for all the collagens extracted was found to be 30.69–35.19°C by differential scanning calorimetry (DSC) analysis. The extracted collagens exhibited higher solubility at low concentration of NaCl (0–0.4M). All the ASC and PSC displayed different degrees of fibril-forming abilities and the scanning electron microscopy (SEM) analysis confirmed their well-defined fibril morphologies. The degree of collagen fibril formation was significantly (p≤0.05) higher (78%) in rohu skin collagen than catla skin collagen (36%). In general, the characteristics of two carp skin collagens were unique as evidenced by the electrophoretic, DSC, SEM and fibril-forming patterns. Overall, the results indicated the feasibility of using the carp skin as a good alternative source of realistic high-quality collagen.

A novel method for quantitative phase determination of cristobalite in ceramic cores using differential scanning calorimeter

The present research aims at developing a new quantitative thermal analysis method based on differential scanning calorimeter for determination of cristobalite phase content in ceramic cores. For this purpose, various control samples with different amounts of cristobalite phase were made based on the chemical composition of silica-based ceramic cores and analyzed via differential scanning calorimetry (DSC) technique. The surface area under the α → β cristobalite transition peak in the DSC curves was calculated via numerical integral of the peaks area, and the ratio of this area to the samples weight (A/W) was calibrated by cristobalite content of the samples. Afterward, for determining the cristobalite content of some industrial samples, the DSC patterns were plotted, and the A/W ratio of these samples was determined by the same method. Then the A/W ratios of the industrial samples were fitted on the calibration line, and the cristobalite content was derived using the equation of the calibration line. The method showed good accuracy, and the error values of the estimated cristobalite content of the industrial samples were below 2 %.

Development of a Doxazosin and Finasteride Transdermal System for Combination Therapy of Benign Prostatic Hyperplasia

The treatment of benign prostatic hyperplasia can be accomplished by the use of different drugs including, doxazosin, an α-1 adrenergic antagonist, and finasteride (FIN), a 5-α reductase inhibitor. Traditionally, treatments using these drugs have been administered as either a mono or combination therapy by the oral route. A transdermal delivery system optimized for doxazosin and FIN combination therapy would provide increased patient adherence and facilitate dose adjustment. Doxazosin base (DB) was prepared from doxazosin mesylate and characterized together with FIN, by X-ray powder diffraction (XRD), differential scanning calorimetry (DSC), and nuclear magnetic resonance (NMR). The permeation enhancers, azone and lauric acid, and the gelling agents, hydroxypropyl cellulose (HPC) and Poloxamer 407 (P407), were evaluated to determine their ability to promote in vitro permeation of drugs through the pig ear epidermis. Successful preparation of DB was confirmed by evaluating the XRD, DSC, and NMR patterns and in vitro studies revealed that 3% (w/w) azone was the best permeation enhancer. When P407 gel was compared with HPC gel, it showed reduced lag time and promoted higher permeation of both drugs. This may be because of the interactions of the former with the stratum corneum, which disorganizes the lipid structure and consequently promotes higher drug permeation.

Preparation and Characterization of Chloroquine Loaded Microspheres for Prophylactic Use

Malaria is one of the major public health problems in the developing countries. Numbers of drugs are available for the treatment of malaria but chloroquine diphosphate still remains a drug of choice. The aim of this study is to develop and characterize a suitable drug delivery system of antimalarial drug for prophylactic use. A depot system for controlled release of antimalarial drug was prepared. Drug loaded heat cross-linked gelatin microspheres were prepared by single emulsion thermal gelation technique. These were characterized by optical microscopy, scanning electron microscopy (SEM), percentage yield (63.20% to 86.13%), drug content (22.95% to 28.02%), encapsulation efficiency (41.46% to 68.26%), differential scanning calorimetry (DSC) and in vitro studies. Sizes of the microspheres as observed by optical microscopy were in the range of 44.06 ± 6.98 μm to 54.70 ± 8.19 μm, DSC pattern showed the absence of drug and polymer interaction. The gelatin microspheres were below 60 μm and spherical in shape as evidenced by the SEM photographs. Encapsulated chloroquine diphosphate was released slowly for 24 ± 1 hrs. The study indicated optimum drug release behavior (84.5% ± 0.96) in 25 hrs.

Improvement of Solubility and Dissolution Rate of Sirolimus by Solid Dispersions in Combination with Surface Adsorbent

Sirolimus has a poor solubility in water ranging from 2-6 µg/mL. The mean bioavailability is approximately 14%. The present study was carried out with a view to enhance the dissolution rate of poorly water-soluble drug sirolimus using Gelucire® as carriers and lactose monohydrate as an adsorbent. A combination of melt and adsorption techniques was employed for the preparation of solid dispersions (SD) to make final product free flowing. Phase solubility study was conducted to evaluate the effect of carriers on aqueous solubility of sirolimus. In order to elucidate the mechanism of dissolution enhancement, solid state characteristics were investigated using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD). Mathematical modeling of in vitro dissolution data of optimised batch indicated the best fitting with Korsemeyer–Peppas model and the drug release kinetics primarily as fickian diffusion. All prepared solid dispersions showed dissolution improvement compared to pure drug. Almost similar dissolution profile was obtained as a function of storage time; this can be explained by no change in XRD and DSC patterns after 45 days of storage period. Keywords: Sirolimus, Gelucire®, Solid dispersion (SD), Adsorbent, Dissolution enhancement, Stability studies.