Controlled Release of Aseptic Drug from Poly(3-hydroxybutyrate) Films: A Combination of Diffusion and Zero-order Kinetics

2008 ◽  
pp. 353-360
Keyword(s):  
Controlled Release ◽  
Zero Order ◽  
Zero Order Kinetics

scholarly journals Study of Immobilization by Esteric Bond of 2-(m-Nitrophenyl)-4-(β- Carboxymethyl)-Δ2-Oxazolinone-5 on Gellan

2016 ◽  
Vol 5 (2) ◽  
pp. 121
Author(s):  
Popa Marcel ◽  
Sunel Valeriu ◽  
Balaita Rusu Lacramioara ◽  
Basu Cristina
Keyword(s):  
Controlled Release ◽  
Ir Spectroscopy ◽  
Release Kinetics ◽  
Coupling Reaction ◽  
Zero Order ◽  
Experimental Program ◽  
Active Principle ◽  
Covalent Bonds ◽  
Zero Order Kinetics ◽  
Basic Hydrolysis

The paper studies the coupling reaction, through ester-type covalent bonds, of an oxazolone derived from the N-(m-nitrobenzoyl)-L-asparagic acid, on gellan (a polysaccharide of microbian synthesis), in conditions of activation with dicyclohexyl carbodiimide. Based on a centered, rotatory, composed, second order experimental program, the regression equation describing the dependence of the amount of active principle, chemically bounded to the support, on the reaction’s parameters (support/active principle ratio, active principle/activator ratio, duration) is obtained. One may observe that the efficiency of the coupling reaction is maximum when employing the parameters’ highest values, over the variation domain established. The coupling product has been characterized through elemental analysis and IR spectroscopy. For the establishment of the capacity of the active principle’s controlled release by the polymer-active principle system thus obtained, drug’s release kinetics from the polysaccharidic support is studied in conditions of basic hydrolysis. The oxazolone release from the coupling products, by basic hydrolysis proceeds conformely to a zero order kinetics, proving their retard activity.

Formulation and Evaluation of Nelfinavir Extended Release Trilayer Matrix Tablets by Design of Experiment

2018 ◽  
Vol 11 (5) ◽  
pp. 4259-4268
Author(s):  
Nirmala Rangu ◽  
Gande Suresh
Keyword(s):  
Controlled Release ◽  
Drug Release ◽  
Hydroxypropyl Methylcellulose ◽  
Magnesium Stearate ◽  
Zero Order ◽  
Matrix Tablets ◽  
Drug Dissolution ◽  
Crystalline Cellulose ◽  
Dissolution Profile ◽  
Release Formulation

The present study was aimed to develop once-daily controlled release trilayer matrix tablets of nelfinavir to achieve zero-order drug release for sustained plasma concentration. Nelfinavir trilayer matrix tablets were prepared by direct compression method and consisted of middle active layer with different grades of hydroxypropyl methylcellulose (HPMC), PVP (Polyvinyl Pyrrolidine) K-30 and MCC (Micro Crystalline Cellulose). Barrier layers were prepared with Polyox WSR-303, Xanthan gum, microcrystalline cellulose and magnesium stearate. Based on the evaluation parameters, drug dissolution profile and release drug kinetics DF8 were found to be optimized formulation. The developed drug delivery system provided prolonged drug release rates over a period of 24 h. The release profile of the optimized formulation (DF8) was described by the zero-order and best fitted to Higuchi model. FT-IR studies confirmed that there were no chemical interactions between drug and excipients used in the formulation. These results indicate that the approach used could lead to a successful development of a controlled release formulation of nelfinavir in the management of AIDS.

Formulation Development and Characterization of controlled release core in cup matrix tablets of venlafaxine HCl

2020 ◽  
Vol 15 ◽  
Author(s):  
Balaji Maddiboyina ◽  
Vikas Jhawat ◽  
Gandhi Sivaraman ◽  
Om Prakash Sunnapu ◽  
Ramya Krishna Nakkala ◽  
...  
Keyword(s):  
Controlled Release ◽  
Drug Release ◽  
Release Rate ◽  
Zero Order ◽  
Water Soluble ◽  
Matrix Tablets ◽  
Drug Dissolution ◽  
Crystalline Cellulose ◽  
Hydrophobic Polymers

Background: Venlafaxine HCl is a selective serotonin reuptake inhibitor which is given in the treatment of depression. The delivery of the drug at a controlled rate can be of great importance for prolonged effect. Objective: The objective was to prepare and optimize the controlled release core in cup matrix tablet of venlafaxine HCl using the combination of hydrophilic and hydrophobic polymers to prolong the effect with rate controlled drug release. Methods: The controlled release core in cup matrix tablets of venlafaxine HCl were prepared using HPMC K5, K4, K15, HCO, IPA, aerosol, magnesium sterate, hydrogenated castor oil and micro crystalline cellulose PVOK-900 using wet granulation technique. Total ten formulations with varying concentrations of polymers were prepared and evaluated for different physicochemical parameters such FTIR analysis for drug identification, In-vitro drug dissolution study was performed to evaluate the amount of drug release in 24 hrs, drug release kinetics study was performed to fit the data in zero order, first order, Hixson–crowell and Higuchi equation to determine the mechanism of drug release and stability studies for 3 months as observed. Results: The results of hardness, thickness, weight variation, friability and drug content study were in acceptable range for all formulations. Based on the In vitro dissolution profile, formulation F-9 was considered to be the optimized extending the release of 98.32% of drug up to 24 hrs. The data fitting study showed that the optimized formulation followed the zero order release rate kinetics and also compared with innovator product (flavix XR) showed better drug release profile. Conclusion: The core-in-cup technology has a potential to control the release rate of freely water soluble drugs for single administration per day by optimization with combined use of hydrophilic and hydrophobic polymers.

The Influence of Temperature and Concentration on Copper Deposition Kinetics in Supercritical Carbon Dioxide

2004 ◽  
Vol 812 ◽  
Author(s):  
Yinfeng Zong ◽  
James J. Watkins
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Supercritical Fluids ◽  
Zero Order ◽  
Copper Deposition ◽  
Deposition Kinetics ◽  
Zero Order Kinetics ◽  
Concentration Interval ◽  
Kinetics Of ◽  
Supercritical Carbon

AbstractThe kinetics of copper deposition by the hydrogen-assisted reduction of bis(2,2,7- trimethyloctane-3,5-dionato)copper in supercritical carbon dioxide was studied as a function of temperature and precursor concentration. The growth rate was found to be as high as 31.5 nm/min. Experiments between 220 °C and 270 °C indicated an apparent activation energy of 51.9 kJ/mol. The deposition kinetics were zero order with respect to precursor at 250 °C and 134 bar and precursor concentrations between 0.016 and 0.38 wt.% in CO2. Zero order kinetics over this large concentration interval likely contributes to the exceptional step coverage obtained from Cu depositions from supercritical fluids.

Development and Evaluation of Compression Coating Gastro-Floating Tablet of Alfuzosin Hydrochloride for Zero-Order Controlled Release

2018 ◽  
Vol 19 (7) ◽  
pp. 3277-3286 ◽  
Author(s):  
Ling Gong ◽  
Yanyan Sun ◽  
Miao Yu ◽  
Ying Gao ◽  
Meijuan Zou ◽  
...  
Keyword(s):  
Controlled Release ◽  
Zero Order ◽  
Floating Tablet ◽  
Alfuzosin Hydrochloride ◽  
Compression Coating

Spectroscopic Study of Photosensitized Oxidation of Polyisoprene

1977 ◽  
Vol 50 (4) ◽  
pp. 704-713 ◽  
Author(s):  
M. A. Golub ◽  
M. L. Rosenberg ◽  
R. V. Gemmer
Keyword(s):  
Zero Order ◽  
Double Bonds ◽  
Photosensitized Oxidation ◽  
The Third ◽  
Type Process ◽  
Zero Order Kinetics ◽  
Hydroperoxide Formation ◽  
Cis And Trans ◽  
In Cis ◽  
Suitable Measure

Abstract The microstructural changes which occur in cis- and trans-1,4-polyisoprenes and in squalene during photosensitized oxidation were investigated with the aid of infrared and proton and carbon-13 NMR spectroscopy. The singlet oxygenation of these isoprenic compounds resulted in allylic hydroperoxides with shifted double bonds, according to the expected “ene”-type process. In contrast to trans-1,4-polyisoprene and squalene, which displayed the three possible double bond shifts, cis-1,4-polyisoprene showed essentially two of the shifts (to di- and trisubstituted double bonds) and very little of the third (to exomethylene groups). A suitable measure of the extent of hydroperoxidation was afforded by the absorbance ratio, A3400/A1440≡A′. Similar correlations of A′ with oxygen uptake were obtained for the three isoprenic compounds, using chlorophyll or methylene blue as sensitizer. The use of rose bengal gave erratic results indicative of some autoxidation accompanying the hydroperoxide formation. The singlet oxygenation followed zero-order kinetics, the relative rates for cis- and trans-1,4-polyisoprenes being approximately 1.0:1.5.

The catalytic decomposition of ethers on evaporated tungsten films

1968 ◽  
Vol 302 (1470) ◽  
pp. 385-398 ◽  
Keyword(s):  
High Activity ◽  
Water Vapour ◽  
Metal Surface ◽  
Initial Period ◽  
Catalytic Decomposition ◽  
Zero Order ◽  
Transitional Period ◽  
Zero Order Kinetics ◽  
Rate Of Reaction ◽  
Combined Action

The reactions of diethyl and di- n -propyl ethers have been studied in the presence of hydrogen on evaporated films of tungsten. In the temperature range from 200 to 260°C ethane and ethylene were formed from diethyl ether and small amounts of butenes were also produced. Each film had an initial high activity, especially for the formation of ethane, but the activity declined to a steady value during a transitional period. Subsequently, the decomposition of the ether occurred with zero order kinetics. A similar transitional period was observed during the decomposition of di- n -propyl ether but the change in the character of the reactions was more marked. Propane and propylene were formed initially, but very little further propane was produced after the initial period. If the surface of the tungsten was oxidized before exposure to ether, a high activity for the dehydration of the propyl ether was observed. Evidence from a number of experiments showed that irreversible changes were occurring to the catalyst during the transitional periods in which the metal surface was being converted to a different type of surface under the combined action of the ether and water vapour which was either added or formed by reaction. Most of the results could be interpreted on the assumption that two types of surface were formed—an oxidized surface of high activity for dehydration and an inactive surface covered by strongly adsorbed hydrocarbon residues. Subsidiary experiments were carried out with n -propanol on oxidized tungsten and evidence was found that the dehydration of the alcohol which was strongly adsorbed probably controlled the rate of reaction of the ether.

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