Application of multiple response optimization technique to extended release formulations design

Crosslinked Polyesters as Fully Biobased Coatings with Cutin Monomer from Tomato Peel Wastes

Cutin, one of the main structural components of tomato peels, is a waxy biopolymer rich in hydroxylated fatty acids. In this study, 10,16-dihydroxyhexadecanoic acid (10,16-diHHDA) was extracted and isolated from tomato peels and exploited to develop fully crosslinked polyesters as potential candidates for replacing fossil-based metal protective coatings. A preliminary screening was conducted to select the base formulation, and then a design of experiments (DoE) was used as a methodology to identify the optimal composition to develop a suitable coating material. Different formulations containing 10,16-diHHDA and other biorefinery monomers, including 2,5-furandicarboxylic acid, were considered. To this end, all polyesters were characterized through differential scanning calorimetry (DSC) and gel content measurements to determine their Tg value and crosslinking efficiency. Compositions exhibiting the best trade-off between Tg value, chemical resistance, and sufficiently high 10,16-diHHDA content between 39 and 48 wt.% were used to prepare model coatings that were characterized for assessing their wettability, scratch hardness, chemical resistance, and adhesion to metal substrates. These polyester coatings showed a Tg in the range of 45-55 °C, a hydrophobic behavior with a water contact angle of around 100°, a good solvent resistance (>100 MEK double rubs), and an adhesion strength to steel higher than 2 MPa. The results obtained confirmed the potential of cutin-based resins as coatings for metal protection, meeting the requirements for ensuring physicochemical properties of the final product, as well as for optimizing the valorization of such an abundant agri-food waste as tomato peels.

Insight into the application of supercritical water oxidation for dichlorvos degradation: experimental and simulation aspects

Dichlorvos or 2,2-dichlorovinyl dimethyl phosphate (DDVP) ( C 4 H 7 C l 2 O 4 P ) is a chlorinated organophosphorus pesticide, which is frequently detected in agricultural wastewater. Herein, a batch reactor was used to carry out the supercritical water oxidation (SCWO) of a synthetic wastewater containing dichlorvos as a very hazardous agricultural pollutant. To do so, the impact of four operating parameters including dichlorvos concentration (100-500 ppm), oxidant coefficient (0.7-2), temperature (300-500°C) and time (0-100 s) on dichlorvos removal was optimized by the response surface method (RSM). According to the obtained results, at optimal conditions (i.e. initial concentration of dichlorvos 107.5 ppm, oxidation ratio 1.9234, temperature 419.9°C and time 79.94 s), as an index for dichlorvos removal, the chemical oxygen demand (COD) was found to be about 96.34%. Also, the results of high-performance liquid chromatography test showed that dichloroacetaldehyde (C2CL2H2O) and dichloroacetic acid (C2CL2H2O2) were created as intermediate substances during the dichlorvos degradation. Further, the molecular dynamics simulation was performed using ReaxFF force field to show the reaction path and products obtained in each step of the dichlorvos removal. Finally, as an indication, the simulation results indicated a good coordination with the experimental results.

Treatment of methyldiethanolamine wastewater using subcritical and supercritical water oxidation: parameters study, process optimization and degradation mechanism

In this examination, sub/supercritical water oxidation (SCWO) in a batch reactor was employed to degrade methyldiethanolamine (MDEA). To do so, the impact of different operating parameters including temperature (300-500 °C), time (0-100 s), initial MDEA concentration (1000-4000 ppm), oxidant coefficient (0.7-2), and pH (7.3-9.5) on MDEA degradation was separately and together investigated. Subsequently, the response surface method (RSM) was applied to optimize the operating condition of MDEA degradation. Based on the obtained results, a maximum amount of 97.4% MDEA degradation was achieved at the initial MDEA concentration of 1095 ppm in optimal condition (i.e., oxidant coefficient: 1.913, temperature: 472 °C and residence time: about 17 s). Furthermore, according to the HPLC analysis, there was a negligible amounts of formic acid (CH₂O₂) and nitrous acid (HNO₂) in the solution at the end of MDEA removal experiment. Eventually, the mechanism of MDEA degradation was acquired using molecular dynamics simulation (MDS), which had an acceptable coordination with the experimental results. In this way, the MDS results revealed that the presence of CH₂O₂ and HNO₂ compounds in the products was related to the degradation of MDEA and their production as by-products during the SCWO experiments.

Establishment of the upstream processing for renewable production of hydrogen using vermicomposting-tea and molasses as substrate

This study aimed to establish the optimal operational conditions for hydrogen production using vermicomposting-tea and sugarcane molasses as substrate. The experiments were carried out by triplicate in 110 ml serological bottles, a Box-Behnken design of experiments was performed in anaerobic dark conditions. The maximal hydrogen production (HP), hydrogen production rate (HPR), and hydrogen yield (HY) attained were 1021.0 mlL^-1, 5.32 mlL^-1h^-1, and 60.3 mlL_H2^-1/g_TCC, respectively. The statistical model showed that the optimal operational conditions for pH, molasses concentration, and temperature were 6.5; 30 % (v/v) and 25 °C. The bioreactor run showed 17.202 L of hydrogen, 0.58 Lh^-1, and 77.2 ml_H2g_TCC^-1 For HP, HPR, and HY. Chemometric analysis for the volatile fatty acids obtained at the fermentation showed that only two principal components are required to explain 90 % of the variance. The representative pathways for hydrogen production were acetic and butyric acids. This study established the operational conditions for the upstream processing amenable to pilot and industrial-scale operations. Our results add value to molasses within the circular economy for hydrogen production using a novel consortium from vermicompost.

Sour beer production in India using a coculture of Saccharomyces pastorianus and Lactobacillus plantarum: optimization, microbiological, and biochemical profiling

The study's objective was to develop a co-fermentation process with appropriate fermentation parameters to produce a sour beer (similar to a Belgium sour beer) with an ethanol content of 6-8% (v/v) using a coculture of Saccharomyces pastorianus and Lactobacillus plantarum. Statistical optimization was conducted to determine fermentation conditions to produce a sour beer with ~ 3 mg/mL of lactic acid, similar to the traditional sour beer levels. Studies were conducted on the microbial dynamics and volatile compounds produced during this fermentation and aging process. GC-MS studies revealed the generation of novel bioactive compounds as well as the depletion of some volatile compounds during co-fermentation. The study detailed a 5-day co-fermentation process of S. pastorianus and L. plantarum and a 21-day aging process to prepare a sour beer with biochemical properties along the lines of traditional lambic beers. The interrelationship between the two microorganisms and the biochemical changes in the sour beer fermentation process was elucidated and the sensorial attributes have been described.

Pharmacoscintigraphic evaluation and antidiabetic efficacy of gliclazide-loaded 99mTc-labelled mucoadhesive microspheres

Background

The current study was carried out to evaluate the possible application of Musa balbisiana starch in formulation of mucoadhesive microsphere for oral delivery of gliclazide (GLZ). The study objective was to improve the oral bioavailability along with prolongation of its duration of action for a better glycaemic control. Ionic gelation technique was employed in formulating the dosage form. Optimization of the batches was carried out by response surface methodology using 32 full factorial designs. The microsphere prepared was characterized for several parameters along with its in vitro release study. The gastrointestinal transit of the optimized batch of prepared microspheres after oral administration was studied in rabbits by using the gamma scintigraphy technique utilizing 99mTc as the labelling agent in the presence of stannous chloride. Also, the optimized batch was studied for its pharmacokinetic parameters. Moreover, the antidiabetic efficacy of the prepared microsphere was evaluated in rats by using the streptozotocin (STZ)-induced diabetic model.

Results

The factorial design experiment resulted in an optimum formulation coded as F8. The compatible nature of the drug and excipient was revealed from FTIR, DSC and IST studies. The scanning electron micrographs also showed the occurrence of spherical microspheres having a smooth surface. The in vitro release study provided an evidence of an initial burst effect that was followed by a prolong release phase. The pharmacokinetic parameters justified the ability of the prepared dosage form in sustaining the drug release with a 2.7-fold enhancement in drug bioavailability. The images obtained during the gamma scintigraphy study suggested the gastro-retentive nature of the dosage form with the gastro-retentive ability for more than 4 h. Also, the pharmacodynamics study carried out in diabetic rat model confirmed about the better efficacy of the dosage form in lowering the elevated blood glucose level.

Conclusion

The overall study data provide valuable information about the potential of this banana starch in formulation of a mucoadhesive dosage form that can be used for enhancement of bioavailability of drug-like gliclazide which in turn can provide a beneficial effect in the management of diabetes.

Anti-Caking Coatings for Improving the Useful Properties of Ammonium Nitrate Fertilizers with Composition Modeling Using Box-Behnken Design

Granular fertilizers (especially those based on ammonium nitrate (AN)) tend to agglomerate during storage. The aims of this research were to develop effective anti-caking coatings for ammonium nitrate fertilizers while improving the quality of fertilizers and to optimize the composition of effective anti-caking coatings. The influence of the composition of the prepared organic coatings on the effectiveness of preventing the caking of fertilizers was studied by response surface methodology (RSM) using Box–Behnken design (BBD). Additionally, the effect of the developed anti-caking agents on the quality of fertilizers was determined by measuring the crushing strength of the granules. The prepared coatings included fatty amine, stearic acid, surfactant, and paraffin wax. Gas chromatography–mass spectrometry (GC–MS) was used to analyze these coatings. The morphology of the fertilizers were examined by scanning electron microscopy (SEM). Composition studies, based on statistical assessment, showed the coating components had a varying influence on preventing the caking of fertilizers after granulation and after 30 days of storage. The results demonstrated that increasing the content of fatty amines and reducing surfactant in the composition of coating had positive effects on caking prevention. In this study, more effective and economically viable anti-caking coatings were developed. In addition, the present work could serve as a basis to further improve anti-caking coatings.

Suitability assessment of dumpsite soil biocover to reduce methane emission from landfills under interactive influence of nutrients

Biocovers are known for their role as key facilitator to reduce landfill methane (CH₄) emission on improving microbial methane bio-oxidation. Methanotrophs existing in the aerobic zone of dumped wastes are the only known biological sinks for CH₄ being emitted from the lower anaerobic section of landfill sites and even from the atmosphere. However, their efficacy remains under the influence of landfill environment and biocover characteristics. Therefore, the present study was executed to explore the suitability and efficacy of dumpsite soil as biocover to achieve enhanced methane bio-oxidation under the interactive influence of nutrients, carbon source, and environmental factors using statistical-mathematical models. The Placket-Burman design (PBD) was employed to identify the significant factors out of 07 tested factors having considerable impact on CH₄ bio-oxidation. The normal plot and Student's t test of PBD indicated that ammonical nitrogen (NH₄⁺-N), nitrate nitrogen (NO₃^--N), methane (CH₄), and copper (Cu) concentration were found significant. A three-level Box-Behnken design (BBD) was further applied to optimize the significant factors identified from PBD. The BBD results revealed that interactive interaction of CH₄ with NH₄⁺-N and NO₃^--N affected the CH₄ bio-oxidation significantly. The sequential statistical approach predicted that maximum CH₄ bio-oxidation of 27.32 μg CH₄ h^-1 could be achieved with CH₄ (35%), NO₃^--N (250 μg g^-1), NH₄+-N (25 μg g^-1), and Cu (50 mg g^-1) concentration. Conclusively, waste dumpsite soil could be a good alternative over conventional soil cover to improve CH₄ bio-oxidation and lessen the emission of greenhouse gas from waste sector.

Application of surface response method (RSM) to optimize ammonia nitrogen removal from fresh leachate using combination of ultrasound and ultraviolet

Ammonia nitrogen levels are very high in leachate. This study was conducted to optimize the removal of ammonia nitrogen from fresh landfill leachate using a combination of ultrasound waves and ultraviolet irradiation. A sample of fresh landfill leachate was obtained from a municipal landfill site, located in Shahroud (Semnan, Iran) and its ammonia nitrogen was measured by spectrophotometric method. Ultrasound and ultraviolet irradiation were simultaneously used to remove ammonia nitrogen. Box-Behnken design (BBD) based on response surface method (RSM) was applied to analyze and optimize ammonia nitrogen removal by different variables, including pH, contact time, ultrasound frequency and UV intensity. Based on this method, 29 samples with three replications were tested. The analysis of variance indicated quadratic model was significant for removal of ammonia nitrogen from leachate. According to the model, 99.7% removal efficiency (%) of ammonia nitrogen was obtained in the optimal conditions (pH at 9.7, contact time of 59.1 min, ultrasound frequency of 54 kHz and UV intensity of 40 W). The removal efficiency of ammonia nitrogen was obtained 98.6% from the laboratory experiment in these conditions, which agrees well with the predicted response value.

Formulation, Optimization, and In vivo Evaluation of Gastroretentive Drug Delivery System of Nifedipine for the Treatment of Preeclampsia

The study aimed to develop gastroretentive drug delivery system of nifedipine, its optimization, and in vivo evaluation. Bilayered tablet of nifedipine was prepared using central composite design with 3 factors, 5 responses, and 15 experimental trials. Response surface methodology along with numerical and graphical optimization was used to select the best formulation. Scanning electron microscopy study of optimized tablet at different time interval was carried out which showed formation of porous structure on the tablet surface. In vivo studies for optimized formulation were carried out on 10 healthy human volunteers and obtained pharmacokinetic parameters were compared with the marketed formulation, "Nicardia XL." Optimized formulation containing 3.083 mg HPMC K15M, 29.859 mg HPMC E15LV, and 3.541 mg Carbopol 974P releases the drug in a desired manner and remain buoyant for more than 12 h in human stomach. Both the formulations were found to have similar in vitro release profile (f1 4.5089 and f2 55.8274) and also were found to be bioequivalent. Finally, the stability study of the optimized formulation proved the integrity of the optimized formulation. Hence, the data suggest gastroretention as a promising approach to enhance bioavailability of nifedipine.

Mechanism and optimization of electrochemical system for simultaneous removal of nitrate and ammonia

In this study, an electrochemical system was established for simultaneous harmless removal of nitrate and ammonia multiple contamination in an undivided single cell. Cyclic voltammetry was used to investigate the electrochemical cathode and anode coupling redox mechanism and concurring evolution of nitrate and ammonia. The cyclic voltammograms showed the cathodic reduction of nitrate to ammonia and nitrite, the chloride ion conversion to hypochlorite and hypochlorous acid, and the oxidation of ammonia to nitrogen gas and nitrate. A circular transformation process was formed in the electrochemical system and the final product was harmless nitrogen gas. The multiple nitrogen pollutants in the original contaminated system were gradually removed with the reaction predominantly produced harmless nitrogen gas. Response surface methodology was used to build mathematical models for optimizing the operating conditions. The optimum time, NaCl concentration, and current density were 85.38 min, 0.24 g/L, and 45.13 mA/cm², respectively. Under the optimum conditions, the nitrate and ammonia concentrations in the treated solution were 9.17 and 0.00 mg/L, respectively.

Development and statistical optimization of nefopam hydrochloride loaded nanospheres for neuropathic pain using Box-Behnken design

Nefopam hydrochloride (NFH) is a non-opioid centrally acting analgesic drug used to treat chronic condition such as neuropathic pain. In current research, sustained release nefopam hydrochloride loaded nanospheres (NFH-NS) were auspiciously synthesized using binary mixture of eudragit RL 100 and RS 100 with sorbitan monooleate as surfactant by quasi solvent diffusion technique and optimized by 35 Box-Behnken designs to evaluate the effects of process and formulation variables. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetric (DSC) and X-ray diffraction (XRD) affirmed absence of drug-polymer incompatibility and confirmed formation of nanospheres. Desirability function scrutinized by design-expert software for optimized formulation was 0.920. Optimized batch of NFH-NS had mean particle size 328.36 nm ± 2.23, % entrapment efficiency (% EE) 84.97 ± 1.23, % process yield 83.60 ± 1.31 and % drug loading (% DL) 21.41 ± 0.89. Dynamic light scattering (DLS), zeta potential analysis and scanning electron microscopy (SEM) validated size, charge and shape of nanospheres, respectively. In-vitro drug release study revealed biphasic release pattern from optimized nanospheres. Korsmeyer Peppas found excellent kinetics model with release exponent less than 0.45. Chronic constricted injury (CCI) model of optimized NFH-NS in Wistar rats produced significant difference in neuropathic pain behavior (p < 0.05) as compared to free NFH over 10 h indicating sustained action. Long term and accelerated stability testing of optimized NFH-NS revealed degradation rate constant 1.695 × 10-4 and shelf-life 621 days at 25 ± 2 °C/60% ± 5% RH.

Multiple response optimization of processing and formulation parameters of Eudragit RL/RS-based matrix tablets for sustained delivery of diclofenac

CONTEXT

Multiple response optimization is an efficient technique to develop sustained release formulation while decreasing the number of experiments based on trial and error approach.

OBJECTIVE

Diclofenac matrix tablets were optimized to achieve a release profile conforming to USP monograph, matching Voltaren^®SR and withstand formulation variables. The percent of drug released at predetermined multiple time points were the response variables in the design. Statistical models were obtained with relative contour diagrams being overlaid to predict process and formulation parameters expected to produce the target release profile.

MATERIALS AND METHODS

Tablets were prepared by wet granulation using mixture of equivalent quantities of Eudragit RL/RS at overall polymer concentration of 10-30%w/w and compressed at 5-15KN.

RESULTS AND DISCUSSION

Drug release from the optimized formulation E4 (15%w/w, 15KN) was similar to Voltaren, conformed to USP monograph and found to be stable. Substituting lactose with mannitol, reversing the ratio between lactose and microcrystalline cellulose or increasing drug load showed no significant difference in drug release. Using dextromethorphan hydrobromide as a model soluble drug showed burst release due to higher solubility and formation of micro cavities.

CONCLUSION

A numerical optimization technique was employed to develop a stable consistent promising formulation for sustained delivery of diclofenac.

Overview on the Response Surface Methodology (RSM) in Extraction Processes

Response Surface Methodology (RSM) is an optimization tool that can identify interrelationship between variables as being adopted by experiment/ research studies in food and herbal plants extraction niche area. This review discusses the optimization approach through utilization of research surface methodology either using central composite design or Box-Behnken method specifically in extraction processes. The use of analysis of variance (ANOVA) to evaluate the degree of accuracy held by the derived model is based on several responses. RSM helps to determine the best experimental design in order to identify the relationship between variables. This paper also discusses on the utilization of RSM to derive a model equation that later can be applied for response prediction and the determination of optimal conditions.

Enhanced brain delivery of lamotrigine with Pluronic(®) P123-based nanocarrier

BACKGROUND

P-glycoprotein (P-gp) mediated drug efflux across the blood-brain barrier (BBB) is an important mechanism underlying poor brain penetration of certain antiepileptic drugs (AEDs). Nanomaterials, as drug carriers, can overcome P-gp activity and improve the targeted delivery of AEDs. However, their applications in the delivery of AEDs have not been adequately investigated. The objective of this study was to develop a nano-scale delivery system to improve the solubility and brain penetration of the antiepileptic drug lamotrigine (LTG).

METHODS

LTG-loaded Pluronic(®) P123 (P123) polymeric micelles (P123/LTG) were prepared by thin-film hydration, and brain penetration capability of the nanocarrier was evaluated.

RESULTS

The mean encapsulating efficiency for the optimized formulation was 98.07%; drug-loading was 5.63%, and particle size was 18.73 nm. The solubility of LTG in P123/LTG can increase to 2.17 mg/mL, making it available as a solution. The in vitro release of LTG from P123LTG presented a sustained-release property. Compared with free LTG, the LTG-incorporated micelles accumulated more in the brain at 0.5, 1, and 4 hours after intravenous administration in rats. Pretreatment with systemic verapamil increased the rapid brain penetration of free LTG but not P123/LTG. Incorporating another P-gp substrate (Rhodamine 123) into P123 micelles also showed higher efficiency in penetrating the BBB in vitro and in vivo.

CONCLUSION

These results indicated that P123 micelles have the potential to overcome the activity of P-gp expressed on the BBB and therefore show potential for the targeted delivery of AEDs. Future studies are necessary to further evaluate the appropriateness of the nanocarrier to enhance the efficacy of AEDs.

Formulation optimization of arecoline patches

The response surface methodology (RSM) including polynomial equations has been used to design an optimal patch formulation with appropriate adhesion and flux. The patch formulations were composed of different polymers, including Eudragit RS 100 (ERS), Eudragit RL 100 (ERL) and polyvinylpyrrolidone K30 (PVP), plasticizers (PEG 400), and drug. In addition, using terpenes as enhancers could increase the flux of the drug. Menthol showed the highest enhancement effect on the flux of arecoline.

Formulation development and optimization of sustained release matrix tablet of Itopride HCl by response surface methodology and its evaluation of release kinetics

The objective of this present investigation was to develop and formulate sustained release (SR) matrix tablets of Itopride HCl, by using different polymer combinations and fillers, to optimize by Central Composite Design response surface methodology for different drug release variables and to evaluate drug release pattern of the optimized product. Sustained release matrix tablets of various combinations were prepared with cellulose-based polymers: hydroxy propyl methyl cellulose (HPMC) and polyvinyl pyrolidine (pvp) and lactose as fillers. Study of pre-compression and post-compression parameters facilitated the screening of a formulation with best characteristics that underwent here optimization study by response surface methodology (Central Composite Design). The optimized tablet was further subjected to scanning electron microscopy to reveal its release pattern. The in vitro study revealed that combining of HPMC K100M (24.65 MG) with pvp(20 mg)and use of LACTOSE as filler sustained the action more than 12 h. The developed sustained release matrix tablet of improved efficacy can perform therapeutically better than a conventional tablet.

Transdermal microemulsion drug delivery system for impairing male reproductive toxicity and enhancing efficacy of Tripterygium Wilfordii Hook f

The present study is trying to produce a transdermal microemulsion drug delivery system (TMDDS) for Tripterygium Wilfordii Hook f. (TWHF) and attempting to solve male reproductive toxicity problem of TWHF. The formulation was optimized by the central composite design with response surface methodology and was decided as 12% oleic acid, 19.7% Labrasol S, 19.7% ethanol and 19.7% Pharmasolve, and 29% water. TMDDS for TWHF had stronger transdermal ability than free TWHF, and TWHF microemulsion significantly inhibited the adjuvant-induced arthritis and at the same time, had preferable anti-inflammatory effect with the long-time administration. Various pharmacodynamics parameters proved that TWHF microemulsion can reduce the male reproductive toxicity and hepatotoxicity of rats. All these suggested that TMDDS could be a suitable delivery system for TWHF.

Degradation of Acid Red 274 using H2O2 in subcritical water: application of response surface methodology

In this research, the degradation of Acid Red 274 (AR 274) was investigated under subcritical water conditions using H(2)O(2), which led to the oxidative degradation of Acid Red 274 up to its 80% of mineralization. The Box-Behnken design matrix and response surface methodology (RSM) were applied in designing the experiments for evaluating the interactive effects of the three most important operating variables. Thus, the interactive effects of temperature (100-250°C), oxidant (H(2)O(2)) concentration (50-250 mM), and time (30-60 min.) on the degradation of AR 274 were investigated. A total of 17 experiments were conducted in this research, and the analysis of variance (ANOVA) indicated that the proposed quadratic model could be used for navigating the design space. The proposed model was essentially in accordance with the experimental case with correlation coefficient R(2)=0.9930 and Adj-R(2)=0.9839, respectively. The results confirmed that RSM based on the Box-Behnken design was a compatible method for optimizing the operating conditions of AR 274 degradation.

Development, optimization, and anti-diabetic activity of gliclazide-loaded alginate-methyl cellulose mucoadhesive microcapsules

The purpose of this work was to develop and optimize gliclazide-loaded alginate-methyl cellulose mucoadhesive microcapsules by ionotropic gelation using central composite design. The effect of formulation parameters like polymer blend ratio and cross-linker (CaCl(2)) concentration on properties of gliclazide-loaded alginate-methyl cellulose microcapsules like drug encapsulation efficiency and drug release were optimized. The optimized microcapsules were subjected to swelling, mucoadhesive, and in vivo studies. The observed responses coincided well with the predicted values from the optimization technique. The optimized microcapsules showed high drug encapsulation efficiency (83.57 ± 2.59% to 85.52 ± 3.07%) with low T(50%) (time for 50% drug release, 5.68 ± 0.09 to 5.83 ± 0.11 h). The in vitro drug release pattern from optimized microcapsules was found to be controlled-release pattern (zero order) with case II transport release mechanism. Particle sizes of these optimized microcapsules were 0.767 ± 0.085 to 0.937 ± 0.086 mm. These microcapsules also exhibited good mucoadhesive properties. The in vivo studies on alloxan-induced diabetic rats indicated the significant hypoglycemic effect that was observed 12 h after oral administration of optimized mucoadhesive microcapsules. The developed and optimized alginate-methyl cellulose microcapsules are suitable for prolonged systemic absorption of gliclazide to maintain lower blood glucose level and improved patient compliance.

Enhanced bioavailability of buspirone from reservoir-based transdermal therapeutic system, optimization of formulation employing Box-Behnken statistical design

The purpose of the present study was to develop and optimize reservoir-based transdermal therapeutic system (TTS) for buspirone (BUSP), a low bioavailable drug. A three-factor, three-level Box-Behnken design was employed to optimize the TTS. Hydroxypropyl methylcellulose, D: -limonene and propylene glycol were varied as independent variables; cumulative amount permeated across rat abdominal skin in 24 h, flux and lag time were selected as dependent variables. Mathematical equations and response surface plots were used to relate the dependent and independent variables. The statistical validity of polynomials was established, and optimized formulation factors were selected by feasibility and grid search. Validation of the optimization study with seven confirmatory runs indicated high degree of prognostic ability of response surface methodology. BUSP-OPT (optimized formulation) showed a flux 104.6 microg cm(-2) h(-1), which could meet target flux. The bioavailability studies in rabbits showed that about 2.65 times improvement (p < 0.05) in bioavailability, after transdermal administration of BUSP-OPT compared to oral solution. The ex vivo-in vivo correlation was found to have biphasic pattern and followed type A correlation. Reservoir-based TTS for BUSP was developed and optimized using Box-Behnken statistical design and could provide an effective treatment in the management of anxiety.

Optimization of tamsulosin hydrochloride controlled release pellets coated with Surelease and neutralized HPMCP

This study was to optimize the coating level in the development of controlled release pellets coated with Surelease and neutralized hydroxypropyl methylcellulose phthalate (HPMCP) by a computer optimization technique based on a response surface methodology utilizing polynomial equation. A full factorial 32 design was used for the optimization procedure with coating level (X1) and HPMCP content (X2) as the independent variables. The drug release percent at 2, 3 and 5 h were the target responses, which were restricted to 12–39% (Y1), 44–70% (Y2) and 70–100% (Y3), respectively. The quadratic model was well fitted to the data, and the resulting equation was used to predict the responses in the optimal region. It was shown that the optimized coating formulation was achieved at the ratio of 3:1 (Surelease: neutralized HPMCP) with 20% coating level. The optimized formulation showed release profiles and responses, which were close to predicted responses. Therefore, a full factorial 32 design and optimization technique can be successfully used in the development of optimized coating formulations based on Surelease and neutralized HPMCP to achieve a controlled release drug delivery system containing tamsulosin hydrochloride.

Advanced oxidation and mineralization of simazine using Fenton's reagent

Removal of simazine from aqueous solution by Fenton's reagent oxidation was investigated. Box-Behnken statistical experiment design and the response surface methods were used to investigate the effects of simazine, H(2)O(2) and Fe (II) concentrations on simazine degradation and mineralization. Total organic carbon (TOC) and simazine removals were investigated at different reagent doses to determine the experimental conditions yielding the highest removal of simazine and TOC. Fe (II) concentration had more profound effect than H(2)O(2) for simazine removal while all parameters affected mineralization (TOC removal). Complete disappearance of simazine was achieved within 6 min reaction period. However, only 32% of simazine was mineralized after 15 min indicating formation of some intermediate products. The optimal H(2)O(2)/Fe (II)/simazine ratio resulting in the maximum pesticide (100%) and TOC removal (32%) was found to be 55/15/3 (mg L(-1)). The initial rate of simazine degradation was found to be first-order with respect to the initial simazine concentration.

Preparation and in vitro evaluation of solid dispersions of total flavones of Hippophae rhamnoides L

The purpose of this study was to enhance the dissolution of total flavones of Hippophae rhamnoides L. (TFH) by solid dispersions consisting of the drug and a polymeric carrier, poloxamer 188 (PXM). The solvent evaporation method was used to prepare solid dispersions. A 3(2) full-factorial design approach was used for optimization wherein the amount of solvent (X(1)) and the drug-to-polymer ratio (X(2)) were selected as independent variables and the percentage of TFH dissolved in 10 min (Q(10)) was selected as the dependent variable. Multiple linear regression analysis revealed that a suitable level of (1) and X(2) was required for obtaining higher dissolution of TFH from PXM solid dispersions. Solid dispersions were characterized by differential scanning calorimetry, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and dissolution tests. Characterization studies revealed that solid dispersion of TFH-PXM showed enhancement of TFH dissolution due to the conversion of TFH into a less crystalline and/or amorphous form. In conclusion, dissolution enhancement of TFH was obtained by preparing its solid dispersions in PXM using solvent method.

Dehalogenation, degradation and mineralization of diuron by peroxone (peroxide/ozone) treatment

Removal of diuron from aqueous solution by peroxone (hydrogen peroxide/ozone) oxidation was investigated using Box-Behnken statistical experiment design and the response surface methodology (RSM). Effects of diuron, H(2)O(2) concentrations and initial pH on the extent of diuron, total organic carbon (TOC) and adsorbable organic halogen (AOX) removals were investigated. Ozone dose was kept constant at 45 mg min(-1). Optimum reagent doses yielding the highest diuron, TOC and AOX removals were also determined. Hydrogen peroxide dose and pH were the most effective parameters for pesticide removal while hydrogen peroxide dose had the most significant effect on AOX removal (dehalogenation). All parameters affected mineralization (TOC removal) of diuron. Nearly complete removal of diuron was achieved within 5 minutes, while complete mineralization and dehalogenation were not achieved even within 60 minutes at high diuron doses indicating formation of some intermediate products. The optimal H(2)O(2)/pH/diuron ratio resulting in the maximum pesticide (100%), TOC (82%) and AOX (95%) removal was found to be 340/8/10.

Optimization of hydrogels for transdermal delivery of lisinopril by Box-Behnken statistical design

The aim of this study was to investigate the combined influence of three independent variables on the permeation kinetics of lisinopril from hydrogels for transdermal delivery. A three-factor, three-level Box-Behnken design was used to optimize the independent variables, Carbopol 971 P (X(1)), menthol (X(2)), and propylene glycol (X(3)). Fifteen batches were prepared and evaluated for responses as dependent variables. The dependent variables selected were cumulative amount permeated across rat abdominal skin in 24 h (Q (24); Y(1)), flux (Y(2)), and lag time (Y(3)). Aloe juice has been first time investigated as vehicle for hydrogel preparation. The ex vivo permeation study was conducted using Franz diffusion cells. Mathematical equations and response surface plots were used to relate the dependent and independent variables. The regression equation generated for the cumulative permeation of LSP in 24 h (Q(24)) was Y(1) = 1,443.3-602.59X(1) + 93.24X(2) + 91.75X(3) - 18.95X(1)X(2) - 140.93X(1)X(3) - 4.43X(2)X(3) - 152.63X(1)(2) - 150.03X(2)(2) - 213.9X(3)(2). The statistical validity of the polynomials was established, and optimized formulation factors were selected by feasibility and grid search. Validation of the optimization study with 15 confirmatory runs indicated high degree of prognostic ability of response surface methodology. The use of Box-Behnken design approach helped in identifying the critical formulation parameters in the transdermal delivery of lisinopril from hydrogels.

A statistical experiment design approach for advanced oxidation of Direct Red azo-dye by photo-Fenton treatment

Advanced oxidation of an azo-dye, Direct Red 28 (DR 28) by photo-Fenton treatment was investigated in batch experiments using Box-Behnken statistical experiment design and the response surface analysis. Dyestuff (DR 28), H(2)O(2) and Fe(II) concentrations were selected as independent variables in Box-Behnken design while color and total organic carbon (TOC) removal (mineralization) were considered as the response functions. Color removal increased with increasing H(2)O(2) and Fe(II) concentrations up to a certain level. High concentrations of H(2)O(2) and Fe(II) adversely affected the color and TOC removals due to hydroxyl radical scavenging effects of high oxidant and catalyst concentrations. Both H(2)O(2) and Fe(II) concentration had profound effects on decolorization. Percent color removal was higher than TOC removal indicating formation of colorless organic intermediates. Complete color removal was achieved within 5min while complete mineralization took nearly 15min. The optimal reagent doses varied depending on the initial dyestuff dose. For the highest dyestuff concentration tested, the optimal H(2)O(2)/Fe(II)/dyestuff ratio resulting in the maximum color removal (100%) was predicted to be 715/71/250 (mgL(-1)), while this ratio was 1550/96.5/250 for maximum mineralization (97.5%).

Optimization of ibuprofen gel formulations using experimental design technique for enhanced transdermal penetration

The aims of this study were to develop a transdermal gel formulation for ibuprofen using experimental design techniques and to evaluate its pharmacokinetic properties. The three factors chosen for factorial design were the concentrations of drug, polyoxyethylene(5)cetyl/oleyl ether and ethanol and the levels of each factor were low, medium and high. Skin permeation rates and lag times of ibuprofen were evaluated using the Franz-type diffusion cell in order to optimize the gel formulation. The permeation rate of ibuprofen significantly increased in proportion to the drug concentration, but significantly decreased in proportion to POE(5)cetyl/oleyl ether concentration. Ethanol concentration was inversely proportional to the lag time. The pharmacokinetic properties of the optimized formulation were compared with those of two marketed products in rats. The relative bioavailability of ibuprofen gel compared to the two marketed products was 228.8% and 181.0%. In conclusion, a transdermal ibuprofen gel was formulated successfully using the technique of experimental design and these results helped in finding the optimum formulation for transdermal drug release.

The Effect of Mixed-Solvent and Terpenes on Percutaneous Absorption of Meloxicam Gel

The purpose of the present study was to develop the meloxicam transdermal dosage form. The response surface methodology was used to obtain an appropriate mixed-solvent system of pH-7.4 buffer and ethanol for preparing meloxicam hydrogel. The enhancement effects of terpenes on drug precautious absorption were evaluated via in vitro and in vivo study. The result showed that the solubility of meloxicam was dependent on the pH value of buffer solution. The mixed-solvent system of pH-7.4 buffer and ethanol had a synergistic effect on the increase of drug solubility. The highest solubility was obtained in the ratio of 50/50 pH 7.4 buffer/ethanol. A series of terpenes were used as enhancer for improving the penetration rate of meloxicam. The penetration rates were significantly increased by about 70-593 fold and the lag times were shortened from 7.92 to 0.17 hr by enhancer incorporation. Among these terpenes, menthol showed the greatest effect. In vivo penetration study, the AUC(48h) was increased by about 1.7 fold by the addition of 5% menthol as enhancer.

Drug release behaviour from methyl methacrylate-starch matrix tablets: effect of polymer moisture content

The aim of this work was to study the effect of the initial moisture content of the polymer on the tabletting and drug release behaviour of controlled release inert matrices elaborated with methyl methacrylate (MMA)-starch copolymers. The copolymers, obtained by free radical polymerisation and dried by two different methods (oven-drying or freeze-drying), were equilibrated at different relative humidities (0%, 25%, 50% and 75% RH) at room temperature. From these copolymers, matrix systems were directly compressed containing either a slightly water-soluble drug (anhydrous theophylline) or a freely water-soluble drug (salbutamol sulphate), and their compaction properties and in vitro dissolution profiles were evaluated. The release profiles were compared following model-independent methods, such as the Qt parameter and the similarity factor f2. Moreover, several kinetic models were employed to evaluate the possible changes in the release mechanism. For anhydrous theophylline, the initial moisture content of the copolymers did not affect the release characteristics from the inert matrices under study, and a typical Fickian diffusion mechanism was observed for the different formulations. However, in case of salbutamol sulphate, the presence of moisture might induce a fast drug dissolution, promoting the weakness of the matrix structure and hence, its partial disintegration. So, an "anomalous" mixed phenomenon of diffusion and erosion was found, influenced by the initial moisture content of the copolymer.