Indinavir-Loaded pH-Sensitive Microparticles for Taste Masking: Toward Extemporaneous Pediatric Anti-HIV/AIDS Liquid Formulations with Improved Patient Compliance

The aim of this work was to develop indinavir pediatric anti-HIV/AIDS formulations enabling convenient dose adjustment, ease of oral administration, and improved organoleptic properties by means of the generation of drug-loaded microparticles made of a polymer that is insoluble under intake conditions and dissolves fast in the stomach in order to completely release the active agent. Indinavir-loaded microparticles made of a pH-dependent polymeric excipient soluble at pH < 5, Eudragit E100, were prepared using a double emulsion solvent diffusion technique and the in vitro release profiles characterized. Finally, taste masking properties were evaluated in blind randomized sensory experiments by ten healthy human volunteers. The use of a w/o/o emulsion system resulted in indinavir loads around 90%. Thermal analysis of the microparticles by differential scanning calorimetry revealed that indinavir appeared mainly dispersed at the molecular level. Concentrations of residual organic solvents as determined by gas chromatography were below the upper limits specified by the European Pharmacopeia for pharmaceutical oral formulations. Then, the behavior of drug-containing microparticles in aqueous media at different pH values was assessed. While they selectively dissolved in gastric-like medium, in tap water (intake conditions), the matrix remained almost unchanged and efficiently prevented drug dissolution. Finally, sensoring taste tests performed by volunteers indicated that systems with indinavir loads ∼15% displayed acceptable taste. This work explored the production of indinavir-containing microparticles based on a common pharmaceutical excipient as a means for the improvement of medicines of drugs involved in the treatment of HIV/AIDS. For systems containing about 15% drug, taste studies confirmed the acceptability of the formulation. In pediatric regimes, this composition would require an acceptable amount of formulation (0.7–1.5 g). Diego A. Chiappetta and ángel M. Carcaboso contributed equally to this work.     

Optimization of a culture medium for xylanase production by Bacillus sp. using statistical experimental designs

The concentrations of oat spelt xylan, casein hydrolysate and NH4Cl in the culture medium for production of xylanase from Bacillus sp. I-1018 were optimized by means of response surface methods. The path of steepest ascent was used to approach the optimal region of the medium composition. The optimum composition of the nutrient medium was then easily determined by using a central composite design and was found to be 3.16g/l of xylan, 1.94g/l casein hydrolysate, 0.8g/l of NH4Cl. The xylanase production was increased by 135% when the strain was grown in the optimized medium compared to initial medium.     

Optimization of a medium for enhancing nicotine biodegradation by Ochrobactrum intermedium DN2

AIMS: To optimize a medium for nicotine degradation by Ochrobactrum intermedium DN2 in presence of yeast extract, glucose and Tween 80 using response surface methodology (RSM). METHODS AND RESULTS: In this study, the effects of yeast extract, glucose and Tween 80 on nicotine degradation were investigated in flasks using a novel nicotine-degrading bacterium, O. intermedium DN2. A full factorial central composite design was applied in the design of experiments and in the analysis of the experimental data. The results showed that the most significant variable influencing nicotine degradation was yeast extract, followed by glucose, and then Tween 80. Moreover these three factors interacted with each other and combined to produce positive effects on nicotine degradation. The experimental data also allowed the development of an empirical model (P < 0.0001) describing the inter-relationship between independent and dependent variables. By solving the regression equation, the optimal values of the variables were determined as: yeast extracts 0.094%, glucose 0.101% and Tween 80 0.080%. Using the medium obtained, about 1,220 mg l(-1) of nicotine was degraded (95.55%) within 10 h at the specific biodegradation of 116.59 mg l(-1) h(-1) in 30-l bioreactor containing 25-l tobacco extract. CONCLUSIONS: An optimal medium of nicotine degradation by the strain DN2 was obtained. SIGNIFICANCE AND IMPACT OF THE STUDY: RSM proved to be reliable in developing the model, optimizing factors and analysing interaction effects. The results provide better understanding on the interactions between yeast extract, glucose and Tween 80 for nicotine biodegradation.     

Optimization of Lipase-catalysed Synthesis of Butyl Butyrate Using a Factorial Design

Summary A lipase from Candida rugosa immobilized on styrene-divinylbenzene copolymer was used to catalyse the direct esterification of butanol and butyric acid. A factorial design was employed to evaluate the effects of temperature (37–50 °C), substrate molar ratio of butyric acid to butanol (0.6 to 2.0) and enzyme amount (0.2–0.4 g) on the ester yield. The main effects were fitted by multiple regression analysis to a linear model and maximum ester yield could be obtained working at 41 °C with 0.4 g of lipase. The mathematical model obtained, representing the ester yield has been found to describe adequately the experimental results. Under optimal conditions, concentration of 32.4 g butyl butyrate/l that corresponds to a yield of 75% was obtained.     

Use of Experimental Factorial Design for Optimization of Hexavalent Chromium Removal by a Bacterial Consortium: Soil Microcosm Bioremediation

Hexavalent chromium Cr(VI) is regularly introduced into the environment through diverse anthropogenic activities. It is highly toxic, mutagenic and carcinogenic, and because of its solubility in water, chromate contamination can be difficult to contain. Bacteria can reduce chromate to insoluble and less toxic trivalent chromium Cr(III), and thus increasing attention is paid to chromate bioremediation to reduce its ecotoxicological impacts. In this study, the factorial design 2³ was employed to optimize critical parameters responsible for higher Cr(VI) removal by a bacterial consortium. The factors considered were pH, temperature, and inoculum size at two markedly different levels. All three dependent variables have significant effect on Cr(VI) reduction. Optimal Cr(VI) removal by the bacterial consortium occurred at pH 9, temperature 37°C, and inoculum size OD = 3. Analysis of variance (ANOVA) showed a high coefficient of determination (R²) value of 0.984, thus ensuring a satisfactory adjustment of the second-order regression model with the experimental data. In addition, the effect of bioaugmentation of Cr(VI)-polluted soil microcosms with the bacterial consortium was investigated using the best factor levels. Contaminated soil by 20 and 60 mg/Kg of Cr(VI) showed reductions of 83% and 65% of initial Cr(VI) by the bacterial consortium, suggesting that this bacterial consortium might diminish phytoavailable Cr(VI) in soil and be useful for cleaning up chromium-contaminated sites.     

Optimization of a two‐step process comprising lipase catalysis and thermal cyclization improves the efficiency of synthesis of six‐membered cyclic carbonate from trimethylolpropane and dimethylcarbonate

Six‐membered cyclic carbonates are potential monomers for phosgene and/or isocyanate free polycarbonates and polyurethanes via ring‐opening polymerization. A two‐step process for their synthesis comprising lipase‐catalyzed transesterification of a polyol, trimethylolpropane (TMP) with dimethylcarbonate (DMC) in a solvent‐free system followed by thermal cyclization was optimized to improve process efficiency and selectivity. Using full factorial designed experiments and partial least squares (PLS) modeling for the reaction catalyzed by Novozym®435 (N435; immobilized Candida antarctica lipase B), the optimum conditions for obtaining either high proportion of monocarbonated TMP and TMP‐cyclic‐carbonate (3 and 4), or dicarbonated TMP and monocarbonated TMP‐cyclic‐carbonate (5 and 6) were found. The PLS model predicted that the reactions using 15%–20% (w/w) N435 at DMC:TMP molar ratio of 10–30 can reach about 65% total yield of 3 and 4 within 10 h, and 65%–70% total yield of 5 and 6 within 32–37 h, respectively. High consistency between the predicted results and empirical data was shown with 66.1% yield of 3 and 4 at 7 h and 67.4% yield of 5 and 6 at 35 h, using 18% (w/w) biocatalyst and DMC:TMP molar ratio of 20. Thermal cyclization of the product from 7 h reaction, at 110°C in the presence of acetonitrile increased the overall yield of cyclic carbonate 4 from about 2% to more than 75% within 24 h. N435 was reused for five consecutive batches, 10 h each, to give 3+4 with a yield of about 65% in each run. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2013.     

Optimization of Dimethoate Degradation by Brevundimonas sp. MCM B-427 Using Factorial Design: Studies on Interactive Effects of Environmental Factors

Microbial cultures were isolated from soil exposed to dimethoate, an organophosphorus insecticide. The isolate that showed maximum degradation of dimethoate was identified as Brevundimonassp. MCM B-427. The curve relating biomass accumulation and degradation revealed that aeration appeared to enhance growth rather than degradation. For optimization of environmental factors, a 2⁴ factorial experimental design was used, wherein four factors namely pH, temperature, inoculum density and aeration condition were varied simultaneously. The interaction between the factors was analyzed using MINITAB package. Degradation of dimethoate was affected by a large number of factors interacting in a complex way. Six two-way and two three-way interactions of various environmental factors were found to be statistically significant. In all the two-way interactions, the effect of one factor was more pronounced when the other was at its optimum. The three-way interactions revealed that optimization of pH, inoculum size and aeration was more critical at 40 °C than at 30 °C.The results imply the importance of studying interactions of parameters rather than optimizing individual parameters one by one. These results demonstrate complexity of the interaction and thereby imply the need for better experimental and statistical models.     

Optimization Studies on Design and Evaluation of Orodispersible Pediatric Formulation of Indomethacin

In the present study, the aim was to optimize an orodispersible formulation of indomethacin using a combined approach of subliming agent and superdisintegrant. The tablets were made by non-aqueous wet granulation technique with superdisintegrant incorporated both intragranularly and extragranularly. A 2³ factorial design was used to investigate the effects amount of subliming agents namely camphor and ammonium bicarbonate and taste masking and soothening hydrophilic agent mannitol as independent variables and disintegration time and crushing strength as dependent responses. The volatilization time of eight hours at 50°C was optimized by conducting solid-state kinetic studies of optimized formulations. Optimized orodispersible tablets were evaluated for wetting time, water absorption ratio, porosity and in vitro and in vivo disintegration tests. Results show that higher levels of camphor and mannitol and a lower level of ammonium bicarbonate is desirable for orodispersion. Scanning electron microscopy (SEM) revealed the porous surface morphology and kinetic digital images substantiated the orodispersible property. Differential Scanning Calorimetry (DSC) studies exhibited physiochemical compatibility between indomethacin and various excipients used in the tablet formulation. Stability studies carried out as per ICH Q₁ A guidelines suggested the stable formulations for the tested time period of 6 months. The systematic approach of using subliming and disintegrating agents helped in achieving a stable, optimized orodispersible formulation, which could be industrially viable.     

Media and culturing protocol using a full 25 factorial design for the production of submerged aggregates by the potential bio-herbicide Plectosporium alismatis against weed species of Alismataceae

The potential bio-herbicide Plectosporium alismatis produces drying and UV tolerant micro-sclerotia-like structures named aggregates, effective against the weed Alisma plantago-aquatica. In this study, we evaluated (i) optimal liquid culture conditions that supported the high dry weight, conidia and aggregate yields and (ii) stress-tolerance and effectiveness of aggregates. Using a full factorial 2⁵ design, we studied the impact of agitation (A), glucose concentration (B), Tween 80 concentration (C), malt extract concentration (D), and inoculum density (E), on P. alismatis growth yields. The inoculum density (E), the agitation rate (A), and 3-factor interactions involving E and/or A had significant effects on aggregate yields (average 213 aggregates mL^?1; main effect of E: +112.87; main effect of A: ?74.81), but no significant effect on conidial yields and dry weight. The agitation was maintained at 100?rpm and increasing numbers of conidia were inoculated into the culture media. Maximal aggregate yields (3.6?×?10³ aggregates mL^?1) were obtained with an initial conidial density of 4?×?10⁶ conidia mL^?1. While freshly-harvested, dried and/or UV exposed aggregates germinated at high rates (respectively: 100%; 99%; 76%; 85%), sporogenesis significantly decreased after stress exposure. In bioassays using leaf discs of A. plantago-aquatica, chlorosis and/or necrosis was observed after 8 days incubation, regardless of whether aggregates had been exposed to desiccation and/or UV-radiations prior to application on leaf discs. These data provide a cultural protocol for the production of high numbers of UV and drying resistant aggregates effective against weed species of Alismatacae.     

Optimization of culture media for large‐scale lutein production by heterotrophic Chlorella vulgaris

Lutein is a carotenoid with a purported role in protecting eyes from oxidative stress, particularly the high‐energy photons of blue light. Statistical optimization was performed to growth media that supports a higher production of lutein by heterotrophically cultivated Chlorella vulgaris. The effect of media composition of C. vulgaris on lutein was examined using fractional factorial design (FFD) and central composite design (CCD). The results indicated that the presence of magnesium sulfate, EDTA‐2Na, and trace metal solution significantly affected lutein production. The optimum concentrations for lutein production were found to be 0.34 g/L, 0.06 g/L, and 0.4 mL/L for MgSO₄·7H₂O, EDTA‐2Na, and trace metal solution, respectively. These values were validated using a 5‐L jar fermenter. Lutein concentration was increased by almost 80% (139.64 ± 12.88 mg/L to 252.75 ± 12.92 mg/L) after 4 days. Moreover, the lutein concentration was not reduced as the cultivation was scaled up to 25,000 L (260.55 ± 3.23 mg/L) and 240,000 L (263.13 ± 2.72 mg/L). These observations suggest C. vulgaris as a potential lutein source. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:736–743, 2014     

Optimization of bilayer floating tablet containing metoprolol tartrate as a model drug for gastric retention

The purpose of the present study was to develop an optimized gastric floating drug delivery system (GFDDS) containing metoprolol tartrate (MT) as a model drug by the optimization technique. A 2³ factorial design was employed in formulating the GFDDS with total polymer content-to-drug ratio (X₁), polymer-to-polymer ratio (X₂), and different viscosity grades of hydroxypropyl methyl cellulose (HPMC) (X₃) as independent variables. Four dependent variables were considered: percentage of MT release at 8 hours, T_50%, diffusion coefficient, and floating time. The main effect and interaction terms were quantitatively evaluated using a mathematical model. The results indicate that X₁ and X₂ significantly affected the floating time and release properties, but the effect of different viscosity grades of HPMC (K4M and K10M) was nonsignificant. Regression analysis and numerical optimization were performed to identify the best formulation. Fickian release transport was confirmed as the release mechanism from the optimized formulation. The predicted values agreed well with the experimental values, and the results demonstrate the feasibility of the model in the development of GFDDS.     

Optimization of Cultivation Medium for the Production of Bacillus intermedius 3-19 Glutamyl Endopeptidase

The effect of some components of cultivation medium on the growth of the streptomycin-resistant Bacillus intermedius strain 3-19 and on the production of glutamyl endopeptidase was investigated using factorial experimental design, which allowed the concentrations of peptone and inorganic phosphate to be optimized for the maximum production of the enzyme. Experiments with different peptones and casamino acids showed that the enzyme production is maximum with peptone 3 of plant origin. The addition of casamino acids or amino acids to the peptone-containing cultivation medium inhibited the production of glutamyl endopeptidase.     

Formulation Design and Optimization of Novel Taste Masked Mouth-Dissolving Tablets of Tramadol Having Adequate Mechanical Strength

The purpose of this work was to develop novel taste masked mouth-dissolving tablets of tramadol that overcomes principle drawback of such formulation which is inadequate mechanical strength. Tramadol is an opioid analgesic used for the treatment of moderate to severe pain. Mouth-dissolving tablets offer substantial advantages like rapid onset of action, beneficial for patients having difficulties in swallowing and in conditions where access to water is difficult. The crucial aspect in the formulation of mouth-dissolving tablets is to mask the bitter taste and to minimize the disintegration time while maintaining a good mechanical strength of the tablet. Mouth-dissolving tablets of tramadol are not yet reported in the literature because of its extreme bitter taste. In this work, the bitter taste of Tramadol HCl was masked by forming a complex with an ion exchange resin Tulsion335. The novel combination of a superdisintegrant and a binder that melts near the body temperature was used to formulate mechanically strong tablets that showed fast disintegration. A 3² full factorial design and statistical models were applied to optimize the effect of two factors, i.e., superdisintegrant (crospovidone) and a mouth-melting binder (Gelucire 39/01). It was observed that the responses, i.e., disintegration time and percent friability were affected by both the factors. The statistical models were validated and can be successfully used to prepare optimized taste masked mouth-dissolving tablets of Tramadol HCl with adequate mechanical strength and rapid disintegration.     

利用正交设计建立与优化北美驼绒藜ISSR-PCR反应体系

利用正交试验设计的方法,对北美驼绒藜ISSR-PCR反应的5因素(Taq酶、dNTP、引物、Mg²⁺和模板DNA)4水平进行试验,试验结果运用MINITAB软件进行分析,建立了适合北美驼绒藜的既稳定又谱带多的ISSR-PCR最佳反应体系,即20 μL的反应体系中含有1×buffer,1.5 U Taq酶,0.2 mmol·L^-1 dNTP,0.5 μmol·L^-1引物,2.5 mmol·L^-1 Mg²⁺和10 ng模板DNA。这一优化的ISSR-PCR反应体系的建立,为今后利用ISSR技术进行驼绒藜属植物种质资源分类、遗传图谱构建和遗传变异奠定了技术基础。     

云南松SSR-PCR反应体系的建立与优化

为了建立适宜云南松SSR-PCR的反应体系和扩增程序,利用近缘种火炬松的引物,采用正交设计L16(45)对云南松SSR-PCR反应体系的5因素(Taq酶、Mg2+、模板DNA、dNTP、引物)在4个水平上进行优化,筛选出各反应因素的最佳水平,建立了适于云南松的SSR反应体系.在10μL的反应体系中,模板DNA的用量为30.0 ng,Taq DNA聚合酶的用量为1.0 U,Mg2+的浓度为2.0 mmol/L,dNTPs浓度为0.4 mmol/L,引物的浓度为0.2 μmol/L.扩增程序为:94℃预变性4 min;94℃变性45 s,48℃退火30 s,72℃延伸30 s,30个循环;72℃延长10 min,4℃保存.最后利用1个居群对该体系进行稳定性验证,结果可用于云南松SSR标记的研究.     

利用正交设计优化小苍兰ISSR-PCR反应体系

通过L₁₆(4⁵)正交试验,研究了镁离子浓度、dNTP浓度、模板DNA浓度、Taq DNA聚合酶浓度、引物浓度这5个因素在4个水平上对ISSR-PCR的影响,建立了适合于小苍兰ISSR-PCR的反应体系。优化体系为：25 μL PCR反应体系中含有1×Taq酶缓冲液(10 mmol·L^-1 KCl,8 mmol·L^-1(NH₄)₂SO₄,10 mmol·L^-1 Tris·HCl,pH 9.0,0.05% NP-40),2 mmol·L^-1 MgCl₂,0.06 U·μL^-1 Taq酶,0.4 μmol·L^-1引物,4.0 ng·μL^-1模板DNA,dATP、dCTP、dGTP、dTTP各0.6 mmol·L^-1。利用温度梯度PCR,确定了最适宜的退火温度为51.5℃。该优化体系的建立为下一步对小苍兰进行ISSR分子标记奠定了基础。     

Design and evaluation of proniosomes as a carrier for ocular delivery of lomefloxacin HCl

The current investigation aims to develop and evaluate novel ocular proniosomal gels of lomefloxacin HCl (LXN); in order to improve its ocular bioavailability for the management of bacterial conjunctivitis. Proniosomes were prepared using different types of nonionic surfactants solely and as mixtures with Span 60. The formed gels were characterized for entrapment efficiency, vesicle size, and in vitro drug release. Only Span 60 was able to form stable LXN-proniosomal gel when used individually while the other surfactants formed gels only in combination with Span 60 at different ratios. The optimum proniosomal gel; P-LXN 7 (Span 60:Tween 60, 9:1) appeared as spherical shaped vesicles having high entrapment efficiency (>80%), appropriate vesicle size (187?nm) as well as controlled drug release over 12?h. Differential scanning calorimetry confirmed the amorphous nature of LXN within the vesicles. Stability study did not show any significant changes in entrapment efficiency or vesicle size after storage for 3 months at 4?°C. P-LXN 7 was found to be safe and suitable for ocular delivery as proven by the irritancy test. The antibacterial activity of P-LXN 7 evaluated using the susceptibility test and topical therapy of induced ocular conjunctivitis confirmed the enhanced antibacterial therapeutic efficacy of the LXN-proniosomal gel compared to the commercially available LXN eye drops.