Ali Nokhodchi | University of Sussex (original) (raw)

Papers by Ali Nokhodchi

Research paper thumbnail of Drug release from matrix tablets: physiological parameters and the effect of food

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Research paper thumbnail of Development and evaluation of buccoadhesive propranolol hydrochloride tablet formulations: effect of fillers

Il Farmaco, Feb 1, 2004

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Research paper thumbnail of An approach to engineer paracetamol crystals by antisolvent crystallization technique in presence of various additives for direct compression

International Journal of Pharmaceutics, Jan 27, 2014

Paracetamol is a popular over-the-counter analgesic and a challenging model drug due to its poor ... more Paracetamol is a popular over-the-counter analgesic and a challenging model drug due to its poor technological and biopharmaceutical properties such as flowability, compressibility, compactibility and wettability. This work was aimed to alter the crystal habit of paracetamol from elongated to polyhedral-angular via particle engineering whilst maintaining the stable polymorphic form (form I: monoclinic form). The engineered paracetamol crystals obtained in the present investigation showed better technological and biopharmaceutical properties in comparison to the commercial paracetamol. Engineered paracetamol crystals were obtained using antisolvent crystallization technique in the presence of various concentrations (0.1, 0.5 and 1%, w/w) of additives, namely, polyvinyl alcohol (PVA), Avicel PH 102 (microcrystalline cellulose), Brij 58, methylcellulose (MC) and polyethylene glycol having different molecular weights (PEGs 1500, 6000 and 8000). Paracetamols crystallized in the presence of Avicel (or physically mixed with Avicel), Brij 58 and PEG 6000 demonstrated the best compactibility over a range of compaction pressures. Brij-crystallized paracetamol provided the fastest dissolution rate among all the paracetamol batches. Paracetamols crystallized in the presence of PVA or Avicel, or physically mixed with Avicel demonstrated a reduced degree of crystallinity in comparison to the other paracetamols. This study showed that the type, the grade and the concentration of additives could influence the physical stability such as flow, crystallinity and polymorphic transformation of paracetamol, the technological and biopharmaceutical properties of paracetamol. Stable polymorphic form of paracetamol with optimal tableting characteristics can be achieved through particle engineering.

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Research paper thumbnail of An Investigation into the Stabilization of Diltiazem HCl Release from Matrices Made from Aged Polyox Powders

Aaps Pharmscitech, Jul 31, 2013

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Research paper thumbnail of The influence of physical properties and morphology of crystallised lactose on delivery of salbutamol sulphate from dry powder inhalers

Colloids and Surfaces B Biointerfaces, 2012

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Research paper thumbnail of Engineered mannitol as potential carrier for enhanced DPI performance

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Research paper thumbnail of Characterisation and Deposition Studies of Recrystallised Lactose from Binary Mixtures of Ethanol/Butanol for Improved Drug Delivery from Dry Powder Inhalers

The Aaps Journal, 2011

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Research paper thumbnail of A drug release study from hydroxypropylmethylcellulose (HPMC) matrices using QSPR modeling

Journal of Pharmaceutical Sciences, Dec 1, 2007

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Research paper thumbnail of A novel sensing technique for measurement of magnitude and polarity of electrostatic charge distribution across individual particles

International Journal of Pharmaceutics, Jan 30, 2013

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Research paper thumbnail of The enhanced aerosol performance of salbutamol from dry powders containing engineered mannitol as excipient

International Journal of Pharmaceutics, Apr 1, 2010

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Research paper thumbnail of The influence of drug solubility on release behavior from polyethylene oxide matrices stored at 40oC

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Research paper thumbnail of Anti-solvent crystallization to prepare lactose particles with enhanced dispersion performance from a dry powder inhaler

Journal of Aerosol Medicine and Pulmonary Drug Delivery, May 20, 2013

ABSTRACT Higher fine particle fractions of the drug were obtained for lactose powders with higher... more ABSTRACT Higher fine particle fractions of the drug were obtained for lactose powders with higher porosity, and lactose particles with higher specific surface area and higher fine particle content (<5 µm). With increasing the saturation degree of lactose solution used during crystallization, the specific surface area of lactose particles was reduced, whereas the amorphous lactose and β-lactose contents were increased. Thus, this study demonstrated that it is possible to prepare engineered lacrosse particles with favourable properties for DPI formulations using lactose solutions with a low degree of saturation during crystallization.

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Research paper thumbnail of Engineering novel paracetamol crystals for improved tabelting by direct compression for oral drug delivery

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Research paper thumbnail of An Investigation into Alternative Sugars as Potential Carriers for a Dry Powder Formulation of Budesonide and Formoterol

Biomedicine International, Jan 9, 2015

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Research paper thumbnail of Control of encapsulation efficiency in polymeric microparticle system of tolmetin

Http Dx Doi Org 10 3109 10837450903002173, Jan 21, 2010

Ethylcellulose microparticles containing tolmetin sodium, an anti-inflammatory drug, were prepare... more Ethylcellulose microparticles containing tolmetin sodium, an anti-inflammatory drug, were prepared by a solvent diffusion method based on the formation of multiple W/O(1)/O(2)-emulsion. The drug used was TOL, which is water-soluble and n-hexane was used as the non-solvent. Important parameters in the evaluation of a microencapsulation technique are actual drug loading, the encapsulation efficiency, the yield, solvent systems, dispersed phase to continuous phase ratio (DP/CP ratio), composition of continuous phase, drug distribution in microparticles and stability of primary emulsion. A small volume of internal aqueous phase and volume of organic solvent were favorable to achieve high drug encapsulation efficiencies. Since drug release during the initial stages depends mostly on the diffusion escape of the drug, major approaches to prevent the initial burst have focused on efficient encapsulation of the drug within the microparticles. For this reason, control of efficiency and the extent of initial burst are based on common formulation parameters. Most parameters affect encapsulation efficiency and initial burst by modifying solidification rate of dispersed phase. In order to prevent many unfavorable events such as pore formation, drug loss, and drug migration that occur while the dispersed phase is in the semi-solid state, it is important to understand and optimize these variables.

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Research paper thumbnail of Effect of formulation and processing variables on the characteristics of tolmetin microspheres prepared by double emulsion solvent diffusion method

Indian J Pharm Sci, 2010

The aim of this study was to evaluate microencapsulated controlled release preparations of tolmet... more The aim of this study was to evaluate microencapsulated controlled release preparations of tolmetin sodium using ethylcellulose as a retardant material. Microspheres were prepared by using water-in-oil-in-oil (W/O(1)/O(2)) double-emulsion solvent diffusion method, using different ratios of ethylcellulose to tolmetin sodium. Span 80 was used as the droplet stabilizer and n-hexane was added to harden the microspheres. The prepared microspheres were characterized for their micromeritic properties, drug content, loading efficiency, production yield, and particle size. Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray powder diffractometry and scanning electron microscopy were used to characterize microparticles. The in vitro release studies were performed in pH 1.2 and 7.4. The prepared microspheres were spherical in shape. The drug-loaded microspheres showed near to the theoretical of entrapment and release was extended up to 24. The X-ray diffractogram and differential scanning thermographs showed amorphous state of the drug in the microspheres. It was shown that the drug: polymer ratio, stirring rate, volume of dispersing medium and surfactant influenced the drug loading, particle size and drug release behavior of the formed microparticles. The results showed that, generally, an increase in the ratio of drug: polymer (0.5:1) resulted in a reduction in the release rate of the drug which may be attributed to the hydrophobic nature of the polymer. The in vitro release profile could be modified by changing various processing and formulation parameters to give a controlled release of drug from the microparticules. The release of tolmetin was influenced by the drug to polymer ratio and particle size and was found to be diffusion and erosion controlled. The best-fit release kinetic was achieved with Peppas model.

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Research paper thumbnail of Effects of process variables on micromeritic properties and drug release of non-degradable microparticles

Advanced Pharmaceutical Bulletin, 2011

The purpose of this investigation was to evaluate microencapsulated controlled release preparatio... more The purpose of this investigation was to evaluate microencapsulated controlled release preparation of theophylline using Eudragit RS 100 as the retardant material with high entrapment efficiency. Microspheres were prepared by the emulsion-solvent evaporation method. A mixed solvent system consisting of methanol and acetone and light liquid paraffin as oily phase were chosen. Sucrose stearate was used as the surfactant to stabilize the emulsification process. The prepared microspheres were characterized by drug loading, Fourier-transform infrared spectroscopy (FTIR), differential scanning colorimetry (DSC) and scanning electron microscopy (SEM). The in vitro release studies were performed at pH 1.2 and 7.4 aqueous medium. Increasing the concentration of emulsifier, sucrose fatty acid ester F-70, decreased the particle size which contributed to increased drug release rate. The drug loading microparticle Eudragit RS100(1:6) showed 60-75% of entrapment and mean particle size 205.93-352.76 μm.The results showed that, an increase in the ratio of polymer: drug (F5, 6: 1) resulted in a reduction in the release rate of the drug which may be attributed to the hydrophobic nature of the polymer. The release of theophylline is influenced by the drug to polymer ratio and particle size. Drug release is controlled by diffusion and the best-fit release kinetic is Higuchi model.

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Research paper thumbnail of Propranolol hydrochloride osmotic capsule with controlled onset of release

Drug Delivery, Oct 1, 2007

Hard gelatin capsule was coated by a cellulose acetate as a semipermeable membrane with or withou... more Hard gelatin capsule was coated by a cellulose acetate as a semipermeable membrane with or without castor oil and filled with propranolol hydrochloride and sorbitol as an osmotic agent. After sealing the capsule with white bees wax plug, the onset of release and dissolution rate of the drug were studied. Water penetration into the capsule from the dissolution medium increases simultaneously the osmotic and hydrostatic pressures of its content. When the hydrostatic pressure is high enough to overweigh the gravity and frictional forces of the plug, the expulsion of the plug occurs and drug release starts. The effects of thicknesses of the membrane and plug as well as the concentrations of cellulose acetate and castor oil on the onset of drug release were presented by a polynomial model. We found that the effect of plug thickness on the onset of release is more important when the membrane is thicker. The results showed that the presence of caster oil in coating formulation (cellulose acetate 10% or 15%) increased the onset of release (t(o) values). The onset of release varied from 0.6 to 10.5 hr among which the onset times of 4.2, 4.8, 5.9, 5.5, 7.5, 5.0, 7.8 and 10.5 hr could be of use for either chronotherapeutic purposes in protection of patients against heart attacks and strokes during early morning hours or reducing daily frequency of dosage.

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Research paper thumbnail of The microsponge delivery system of benzoyl peroxide: Preparation, characterization and release studies

International Journal of Pharmaceutics, Feb 3, 2006

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Research paper thumbnail of The dissolution and solid-state behaviours of coground ibuprofen–glucosamine HCl

Http Dx Doi Org 10 3109 03639045 2014 991401, Dec 11, 2014

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Research paper thumbnail of Drug release from matrix tablets: physiological parameters and the effect of food

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Development and evaluation of buccoadhesive propranolol hydrochloride tablet formulations: effect of fillers

Il Farmaco, Feb 1, 2004

Bookmarks Related papers MentionsView impact

Research paper thumbnail of An approach to engineer paracetamol crystals by antisolvent crystallization technique in presence of various additives for direct compression

International Journal of Pharmaceutics, Jan 27, 2014

Paracetamol is a popular over-the-counter analgesic and a challenging model drug due to its poor ... more Paracetamol is a popular over-the-counter analgesic and a challenging model drug due to its poor technological and biopharmaceutical properties such as flowability, compressibility, compactibility and wettability. This work was aimed to alter the crystal habit of paracetamol from elongated to polyhedral-angular via particle engineering whilst maintaining the stable polymorphic form (form I: monoclinic form). The engineered paracetamol crystals obtained in the present investigation showed better technological and biopharmaceutical properties in comparison to the commercial paracetamol. Engineered paracetamol crystals were obtained using antisolvent crystallization technique in the presence of various concentrations (0.1, 0.5 and 1%, w/w) of additives, namely, polyvinyl alcohol (PVA), Avicel PH 102 (microcrystalline cellulose), Brij 58, methylcellulose (MC) and polyethylene glycol having different molecular weights (PEGs 1500, 6000 and 8000). Paracetamols crystallized in the presence of Avicel (or physically mixed with Avicel), Brij 58 and PEG 6000 demonstrated the best compactibility over a range of compaction pressures. Brij-crystallized paracetamol provided the fastest dissolution rate among all the paracetamol batches. Paracetamols crystallized in the presence of PVA or Avicel, or physically mixed with Avicel demonstrated a reduced degree of crystallinity in comparison to the other paracetamols. This study showed that the type, the grade and the concentration of additives could influence the physical stability such as flow, crystallinity and polymorphic transformation of paracetamol, the technological and biopharmaceutical properties of paracetamol. Stable polymorphic form of paracetamol with optimal tableting characteristics can be achieved through particle engineering.

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Research paper thumbnail of An Investigation into the Stabilization of Diltiazem HCl Release from Matrices Made from Aged Polyox Powders

Aaps Pharmscitech, Jul 31, 2013

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The influence of physical properties and morphology of crystallised lactose on delivery of salbutamol sulphate from dry powder inhalers

Colloids and Surfaces B Biointerfaces, 2012

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Engineered mannitol as potential carrier for enhanced DPI performance

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Characterisation and Deposition Studies of Recrystallised Lactose from Binary Mixtures of Ethanol/Butanol for Improved Drug Delivery from Dry Powder Inhalers

The Aaps Journal, 2011

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A drug release study from hydroxypropylmethylcellulose (HPMC) matrices using QSPR modeling

Journal of Pharmaceutical Sciences, Dec 1, 2007

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Research paper thumbnail of A novel sensing technique for measurement of magnitude and polarity of electrostatic charge distribution across individual particles

International Journal of Pharmaceutics, Jan 30, 2013

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Research paper thumbnail of The enhanced aerosol performance of salbutamol from dry powders containing engineered mannitol as excipient

International Journal of Pharmaceutics, Apr 1, 2010

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Research paper thumbnail of The influence of drug solubility on release behavior from polyethylene oxide matrices stored at 40oC

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Anti-solvent crystallization to prepare lactose particles with enhanced dispersion performance from a dry powder inhaler

Journal of Aerosol Medicine and Pulmonary Drug Delivery, May 20, 2013

ABSTRACT Higher fine particle fractions of the drug were obtained for lactose powders with higher... more ABSTRACT Higher fine particle fractions of the drug were obtained for lactose powders with higher porosity, and lactose particles with higher specific surface area and higher fine particle content (<5 µm). With increasing the saturation degree of lactose solution used during crystallization, the specific surface area of lactose particles was reduced, whereas the amorphous lactose and β-lactose contents were increased. Thus, this study demonstrated that it is possible to prepare engineered lacrosse particles with favourable properties for DPI formulations using lactose solutions with a low degree of saturation during crystallization.

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Research paper thumbnail of Engineering novel paracetamol crystals for improved tabelting by direct compression for oral drug delivery

Bookmarks Related papers MentionsView impact

Research paper thumbnail of An Investigation into Alternative Sugars as Potential Carriers for a Dry Powder Formulation of Budesonide and Formoterol

Biomedicine International, Jan 9, 2015

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Control of encapsulation efficiency in polymeric microparticle system of tolmetin

Http Dx Doi Org 10 3109 10837450903002173, Jan 21, 2010

Ethylcellulose microparticles containing tolmetin sodium, an anti-inflammatory drug, were prepare... more Ethylcellulose microparticles containing tolmetin sodium, an anti-inflammatory drug, were prepared by a solvent diffusion method based on the formation of multiple W/O(1)/O(2)-emulsion. The drug used was TOL, which is water-soluble and n-hexane was used as the non-solvent. Important parameters in the evaluation of a microencapsulation technique are actual drug loading, the encapsulation efficiency, the yield, solvent systems, dispersed phase to continuous phase ratio (DP/CP ratio), composition of continuous phase, drug distribution in microparticles and stability of primary emulsion. A small volume of internal aqueous phase and volume of organic solvent were favorable to achieve high drug encapsulation efficiencies. Since drug release during the initial stages depends mostly on the diffusion escape of the drug, major approaches to prevent the initial burst have focused on efficient encapsulation of the drug within the microparticles. For this reason, control of efficiency and the extent of initial burst are based on common formulation parameters. Most parameters affect encapsulation efficiency and initial burst by modifying solidification rate of dispersed phase. In order to prevent many unfavorable events such as pore formation, drug loss, and drug migration that occur while the dispersed phase is in the semi-solid state, it is important to understand and optimize these variables.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Effect of formulation and processing variables on the characteristics of tolmetin microspheres prepared by double emulsion solvent diffusion method

Indian J Pharm Sci, 2010

The aim of this study was to evaluate microencapsulated controlled release preparations of tolmet... more The aim of this study was to evaluate microencapsulated controlled release preparations of tolmetin sodium using ethylcellulose as a retardant material. Microspheres were prepared by using water-in-oil-in-oil (W/O(1)/O(2)) double-emulsion solvent diffusion method, using different ratios of ethylcellulose to tolmetin sodium. Span 80 was used as the droplet stabilizer and n-hexane was added to harden the microspheres. The prepared microspheres were characterized for their micromeritic properties, drug content, loading efficiency, production yield, and particle size. Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray powder diffractometry and scanning electron microscopy were used to characterize microparticles. The in vitro release studies were performed in pH 1.2 and 7.4. The prepared microspheres were spherical in shape. The drug-loaded microspheres showed near to the theoretical of entrapment and release was extended up to 24. The X-ray diffractogram and differential scanning thermographs showed amorphous state of the drug in the microspheres. It was shown that the drug: polymer ratio, stirring rate, volume of dispersing medium and surfactant influenced the drug loading, particle size and drug release behavior of the formed microparticles. The results showed that, generally, an increase in the ratio of drug: polymer (0.5:1) resulted in a reduction in the release rate of the drug which may be attributed to the hydrophobic nature of the polymer. The in vitro release profile could be modified by changing various processing and formulation parameters to give a controlled release of drug from the microparticules. The release of tolmetin was influenced by the drug to polymer ratio and particle size and was found to be diffusion and erosion controlled. The best-fit release kinetic was achieved with Peppas model.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Effects of process variables on micromeritic properties and drug release of non-degradable microparticles

Advanced Pharmaceutical Bulletin, 2011

The purpose of this investigation was to evaluate microencapsulated controlled release preparatio... more The purpose of this investigation was to evaluate microencapsulated controlled release preparation of theophylline using Eudragit RS 100 as the retardant material with high entrapment efficiency. Microspheres were prepared by the emulsion-solvent evaporation method. A mixed solvent system consisting of methanol and acetone and light liquid paraffin as oily phase were chosen. Sucrose stearate was used as the surfactant to stabilize the emulsification process. The prepared microspheres were characterized by drug loading, Fourier-transform infrared spectroscopy (FTIR), differential scanning colorimetry (DSC) and scanning electron microscopy (SEM). The in vitro release studies were performed at pH 1.2 and 7.4 aqueous medium. Increasing the concentration of emulsifier, sucrose fatty acid ester F-70, decreased the particle size which contributed to increased drug release rate. The drug loading microparticle Eudragit RS100(1:6) showed 60-75% of entrapment and mean particle size 205.93-352.76 μm.The results showed that, an increase in the ratio of polymer: drug (F5, 6: 1) resulted in a reduction in the release rate of the drug which may be attributed to the hydrophobic nature of the polymer. The release of theophylline is influenced by the drug to polymer ratio and particle size. Drug release is controlled by diffusion and the best-fit release kinetic is Higuchi model.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Propranolol hydrochloride osmotic capsule with controlled onset of release

Drug Delivery, Oct 1, 2007

Hard gelatin capsule was coated by a cellulose acetate as a semipermeable membrane with or withou... more Hard gelatin capsule was coated by a cellulose acetate as a semipermeable membrane with or without castor oil and filled with propranolol hydrochloride and sorbitol as an osmotic agent. After sealing the capsule with white bees wax plug, the onset of release and dissolution rate of the drug were studied. Water penetration into the capsule from the dissolution medium increases simultaneously the osmotic and hydrostatic pressures of its content. When the hydrostatic pressure is high enough to overweigh the gravity and frictional forces of the plug, the expulsion of the plug occurs and drug release starts. The effects of thicknesses of the membrane and plug as well as the concentrations of cellulose acetate and castor oil on the onset of drug release were presented by a polynomial model. We found that the effect of plug thickness on the onset of release is more important when the membrane is thicker. The results showed that the presence of caster oil in coating formulation (cellulose acetate 10% or 15%) increased the onset of release (t(o) values). The onset of release varied from 0.6 to 10.5 hr among which the onset times of 4.2, 4.8, 5.9, 5.5, 7.5, 5.0, 7.8 and 10.5 hr could be of use for either chronotherapeutic purposes in protection of patients against heart attacks and strokes during early morning hours or reducing daily frequency of dosage.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The microsponge delivery system of benzoyl peroxide: Preparation, characterization and release studies

International Journal of Pharmaceutics, Feb 3, 2006

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The dissolution and solid-state behaviours of coground ibuprofen–glucosamine HCl

Http Dx Doi Org 10 3109 03639045 2014 991401, Dec 11, 2014

Bookmarks Related papers MentionsView impact