Adnan Badwan - Academia.edu (original) (raw)

Papers by Adnan Badwan

Marine Drugs, Sep 25, 2017

Acta Crystallographica, Dec 1, 2017

Calcium carbonate must be processed before it can be compressed into tablets. This study examined... more Calcium carbonate must be processed before it can be compressed into tablets. This study examined the compression behavior of calcium carbonate powder when granulated with different binders. Hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC) and sodium alginate (Na-Alg), were chosen at different concentrations as binding agents. Data analysis and optimization were carried out using load-displacement curves and the Kawakita model of powder compression. The viscosity of the binder solutions, the specific surface area of the granulated CaCO3 and the contact angle of the binder solutions on CaCO3 compact surfaces were used to interpret granulation behavior. Each binder interacted differently with CaCO3 with respect to powder and tablet properties. Optimum tablet processing was found to be strongly dependent on the compression pressure and concentration of the binder used. A 3% binder concentration gave the most desirable outcomes with respect to the area under the load-...

Pharmaceutics, 2019

The subject of our research is the optimization of direct compression (DC), controlled release dr... more The subject of our research is the optimization of direct compression (DC), controlled release drug matrices comprising chitosan/xanthan gum. The foregoing is considered from two main perspectives; the use of low molecular weight chitosan (LCS) with xanthan gum (XG) and the determination of important attributes for direct compression of the mixtures of the two polymers. Powder flow, deformation behaviour, and work of compression parameters were used to characterize powder and tableting properties. Compression pressure and LCS content within the matrix were investigated for their influence on the crushing strength of the tablets produced. Response surface methodology (RSM) was applied to determine the optimum parameters required for DC of the matrices investigated. Results confirm the positive contribution of LCS in enhancing powder compressibility and crushing strength of the resultant compacts. Compactibility of the XG/LCS mixtures was found to be more sensitive to applied compress...

ACS Biomaterials Science & Engineering, 2019

The development and evaluation of a controlled-release (CR) pharmaceutical solid dosage form comp... more The development and evaluation of a controlled-release (CR) pharmaceutical solid dosage form comprising xanthan gum (XG), low molecular weight chitosan (LCS) and metoprolol succinate (MS) is reported. The research is, partly, based upon the utilization of computational tools; in this case molecular dynamics simulations (MDs) and response surface method (RSM), in order to underpin the design/prediction and to minimize the experimental work required to achieve the desired pharmaceutical outcomes. The capability of the system to control the release of MS was studied as a function of LCS (% w/w) and total polymer (LCS and XG) to drug ratio (P:D) at different tablet tensile strengths. MDs trajectories, obtained by using different ratios of XG:LCS as well as XG and high molecular weight CS (HCS), showed that the driving force for the interaction between XG and LCS is electrostatic in nature, the most favourable complex is formed when LCS is used at 15 % (w/w) and, importantly, that the interaction between XG and LCS is more favourable than that between XG and HCS. RSM outputs revealed that the release of the drug from the LCS/XG matrix is highly dependent on both the % LCS and the P:D ratio and that the required CR effect can be achieved when using weight fractions of LCS ≤ 20% and P:D ratios ≥ 2.6:1. Results obtained from in-vitro drug release and swelling studies on the prepared tablets showed that using LCS at the weight fractions suggested by MDs and RSM data plays a major role in overcoming the high sensitivity of the controlled drug release effect of XG on ionic strength and pH changes of the dissolution media. In addition, it was found that polymer relaxation is the major contributor to the release of MS from LCS-XG tablets. Using Raman spectroscopy, MS was shown to be localized more in the core of the tablets at the initial stages of dissolution due to film formation between LCS and XG on the tablet surface which prevents excess water penetration into the matrix. In the later stages of the dissolution process, the film starts to dissolve/erode allowing full tablet hydration and a uniform drug distribution in the swollen tablet.

Marine Drugs, 2016

An increasing interest has recently been shown to use chitin/chitosan oligomers (chito-oligomers)... more An increasing interest has recently been shown to use chitin/chitosan oligomers (chito-oligomers) in medicine and food fields because they are not only water-soluble, nontoxic, and biocompatible materials, but they also exhibit numerous biological properties, including antibacterial, antifungal, and antitumor activities, as well as immuno-enhancing effects on animals. Conventional depolymerization methods of chitosan to chito-oligomers are either chemical by acid-hydrolysis under harsh conditions or by enzymatic degradation. In this work, hydrolysis of chitosan to chito-oligomers has been achieved by applying adsorption-separation technique using diluted HCl in the presence of different types of zeolite as adsorbents. The chito-oligomers were retrieved from adsorbents and characterized by differential scanning calorimetry (DSC), liquid chromatography/mass spectroscopy (LC/MS), and ninhydrin test.

Profiles of Drug Substances, Excipients and Related Methodology, 2016

SECTION 2: Hazard(s) identification 2.1. Classification of the substance or mixture GHS-US classi... more SECTION 2: Hazard(s) identification 2.1. Classification of the substance or mixture GHS-US classification Not classified 2.2. GHS Label elements, including precautionary statements GHS-US labeling No labeling applicable 2.3. Other hazards which do not result in classification No additional information available 2.4. Unknown acute toxicity (GHS US) Not applicable SECTION 3: Composition/Information on ingredients 3.1. Substances Substance type : Mono-constituent Name Product identifier % GHS-US classification Calcium Carbonate (Main constituent) (CAS-No.) 471-34-1 100 Not classified Full text of hazard classes and H-statements: see section 16 3.2. Mixtures Not applicable SECTION 4: First-aid measures 4.1. Description of first aid measures First-aid measures general : Check the vital functions. Unconscious: maintain adequate airway and respiration. Respiratory arrest: artificial respiration or oxygen. Cardiac arrest: perform resuscitation. Victim conscious with labored breathing: half-seated. Victim in shock: on his back with legs slightly raised. Vomiting: prevent asphyxia/aspiration pneumonia. Prevent cooling by covering the victim (no warming up). Keep watching the victim. Give psychological aid. Keep the victim calm, avoid physical strain. Depending on the victim's condition: doctor/hospital. First-aid measures after inhalation : Remove person to fresh air and keep comfortable for breathing. Remove the victim into fresh air. Respiratory problems: consult a doctor/medical service.

International Journal of Pharmaceutics, 2000

An anti-hapten IgG was covalently immobilized on glutaraldehyde-activated alginate-chitosan gel b... more An anti-hapten IgG was covalently immobilized on glutaraldehyde-activated alginate-chitosan gel beads. The antibody immobilization efficiency was influenced by glutaraldehyde-bead reaction time, IgG concentration and pH. In addition, immobilization conditions such as glutaraldehyde and antibody concentrations influenced antibody hapten binding affinity. The immobilized IgG on the beads was stable and no reduction in the percent binding to hapten was noticed following 25 days of storage. It was concluded that antibodies could be successfully immobilized on alginate-chitosan gel beads. Such a system can be applied for the development of immunoaffinity purification and immunoassays.

Profiles of Drug Substances, Excipients and Related Methodology, 2015

Sudan Journal of Medical Sciences, 2010

Objectives: To formulate chitosan nanoparticles with specific combinations of molecular weight an... more Objectives: To formulate chitosan nanoparticles with specific combinations of molecular weight and degree of deacetylation (DDA) that could be developed into an oral insulin delivery system. Methods: This study was conducted at Jordanian Pharmaceutical Manufacturing Company (JPM), Jordan in the period 2006-2009. Nanoparticles were prepared by polyelectrolyte complexation method (PEC). The physicochemical characteristics of the nanoparticles were evaluated. The role of nanoparticles in stabilization of insulin at high temperature and protecting insulin from pancreatic degradation was investigated. Results: The PEC formation process is influenced by a variety of parameters, including the system pH, chitosan molecular weight and DDA. The most important factor appears to be the system pH. All insulin-chitosan complexes displayed positive zeta potential. PECs protect insulin from pancreatin and the protective ability affected by DDA of chitosan. The results of insulin stability indicate that insulin-chitosan PEC protects insulin from degradation for at least 24 h. Conclusions: Molecular parameters of chitosan nanoparticles play an important role in stabilization of insulin in the GIT. So we can modulate relative parameters to develop an oral insulin delivery system.

Journal of Pharmaceutical Sciences, 2015

Paracetamol has an extensive first-pass metabolism that highly affects its bioavailability (BA); ... more Paracetamol has an extensive first-pass metabolism that highly affects its bioavailability (BA); thus, dose may be repeated several times a day in order to have longer efficacy. However, hepatotoxicity may arise because of paracetamol metabolism. Therefore, this project aimed to increase paracetamol BA in rats by glucosamine (GlcN). At GlcN-paracetamol racemic mixture ratio of 4:1 and paracetamol dose of 10 mg/kg, paracetamol area under the curve (AUC) and maximum concentration (Cmax ) were significantly increased by 99% and 66%, respectively (p < 0.05). Furthermore, paracetamol AUC and Cmax levels were increased by 165% and 88% in rats prefed with GlcN for 2 days (p < 0.001). Moreover, GlcN significantly reduced phase Ι and phase I/ΙΙ metabolic reactions in liver homogenate by 48% and 54%, respectively. Furthermore, GlcN molecule was found to possess a good in silico binding mode into the CYP2E1 active site-forming bidentate hydrogen bonding with the Thr303 side chain. Finally, serum ALT and AST levels of rats-administered high doses of paracetamol were significantly reduced when rats were prefed with GlcN (p < 0.01). In conclusion, GlcN can increase the relative BA of paracetamol through reducing its metabolism. This phenomenon is associated with reduction in hepatocytes injury following ingestion of high doses of paracetamol.

Powder Technology, 2010

The influence of the lubricant magnesium stearate (MgSt) on the powder and tablet properties of c... more The influence of the lubricant magnesium stearate (MgSt) on the powder and tablet properties of chitin-Mg silicate coprecipitate was examined and compared with lubricated Avicel® 200 and Avicel-Mg silicate coprecipitate. Crushing strength and disintegration time studies were conducted in order to evaluate tablet properties at different compression pressures. Lubrication of chitin-Mg silicate powder with MgSt was evaluated using a high speed rotary tablet press. The compactability and disintegration time of chitin-Mg silicate are unaffected by the possible deleterious action of up to 2% (w/w) MgSt. The deleterious effect of MgSt on Avicel® 200 compaction was found to be minimized when magnesium silicate was coprecipitated onto Avicel® 200. Lubrication of chitin-Mg silicate with MgSt does not enhance particle agglomeration, whereas the opposite is the case for Avicel® 200; the foregoing was ascertained by measurements of the fixed bulk density, constant powder porosity using Kawakita analysis and by the absence of variation in particle size distribution in the presence of up to 5% (w/w) MgSt. In the case of chitin-Mg silicate tablets the ejection force was greatly reduced at a compression speed of 150,000 tablet/h at a MgSt concentration of 0.5% (w/w). The physical properties and drug dissolution profile of ibuprofen tablets were found to be unaffected when chitin-Mg silicate was lubricated up to 5% (w/w) with MgSt. Optimal drug dissolution was attained for gemfibrozil tablets using 3% (w/w) MgSt when compared to a reference (Lopid tablets).

International Journal of Pharmaceutics, 2011

A directly compressible excipient has been developed by co-processing starch with magnesium silic... more A directly compressible excipient has been developed by co-processing starch with magnesium silicate. The foregoing was achieved either by co-precipitation of magnesium silicate onto different types of starch or by dry granulation of maize starch with magnesium silicate. A variety of techniques (permeability, water retention/swelling, compression analysis, scanning electron microscopy, tensile strength and disintegration/dissolution studies) were used to characterize these systems. The permeability of the formulations produced using the two methods was evaluated experimentally using Darcy's permeability law. Magnesium silicate, as an anti-adhering agent, increases the permeability of both maize and partially pregelatinized starch, resulting in compacts of high mechanical strength, short disintegration time and low lubricant sensitivity. Such advantages are evident when the properties of the physical mixture of maize starch with magnesium silicate are compared with the co-precipitation and dry granulation techniques. Formulation with this novel excipient system, using paracetamol as a model drug, indicated its suitability as a single multifunctional excipient.

Supramolecular Chemistry, 2009

Pharmaceutical Development and Technology, 1998

Journal of Pharmaceutical and Biomedical Analysis, 2006

Guest-host interactions of sildenafil (Sild) with cyclodextrins (CyDs) have been investigated usi... more Guest-host interactions of sildenafil (Sild) with cyclodextrins (CyDs) have been investigated using several techniques including phase solubility diagrams (PSD), differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD), proton nuclear magnetic resonance (1 H NMR) and molecular mechanical modeling (MM +). Estimates of the complex formation constant (K 11) show that the tendency of Sild to complex with CyDs follows the order: ␤-CyD > HP-␤-CyD > ␥-CyD, ␣-CyD, where K 11 values at pH 8.7 and 30 • C were 150, 68 and 46, 43 M −1 , respectively. Ionization of Sild reduces its tendency to complex with ␤-CyD, where protonated (at pH 3.6) and anionic Sild (at pH 12.1) species have K 11 values of 17 and 42 M −1 , respectively, compared with 150 M −1 for neutral Sild (at pH 8.7). The hydrophobic character of Sild was found to provide 39% of the driving force for complex stability, while other factors including specific interactions contribute −7.9 kJ/mol. Complex formation of Sild with ␤-CyD (G • = −22.9 kJ/mol) is largely driven by enthalpy (H • = −19.8 kJ/mol) and slight entropy (S • = 10.3 J/mol K) changes. 1 H NMR and MM + studies indicate formation of two isomeric 1:1 complexes: one involving complete inclusion of the phenyl-moiety into the ␤-CyD cavity while the other pertaining to partial inclusion of the pyrimidinone moiety. The dominant driving force for complexation is evidently van der Waals with very little electrostatic contribution. DSC, XRPD and 1 H NMR studies proved the formation of inclusion complex in solution and the solid state.

Marine Drugs, Sep 25, 2017

Acta Crystallographica, Dec 1, 2017

Calcium carbonate must be processed before it can be compressed into tablets. This study examined... more Calcium carbonate must be processed before it can be compressed into tablets. This study examined the compression behavior of calcium carbonate powder when granulated with different binders. Hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC) and sodium alginate (Na-Alg), were chosen at different concentrations as binding agents. Data analysis and optimization were carried out using load-displacement curves and the Kawakita model of powder compression. The viscosity of the binder solutions, the specific surface area of the granulated CaCO3 and the contact angle of the binder solutions on CaCO3 compact surfaces were used to interpret granulation behavior. Each binder interacted differently with CaCO3 with respect to powder and tablet properties. Optimum tablet processing was found to be strongly dependent on the compression pressure and concentration of the binder used. A 3% binder concentration gave the most desirable outcomes with respect to the area under the load-...

Pharmaceutics, 2019

The subject of our research is the optimization of direct compression (DC), controlled release dr... more The subject of our research is the optimization of direct compression (DC), controlled release drug matrices comprising chitosan/xanthan gum. The foregoing is considered from two main perspectives; the use of low molecular weight chitosan (LCS) with xanthan gum (XG) and the determination of important attributes for direct compression of the mixtures of the two polymers. Powder flow, deformation behaviour, and work of compression parameters were used to characterize powder and tableting properties. Compression pressure and LCS content within the matrix were investigated for their influence on the crushing strength of the tablets produced. Response surface methodology (RSM) was applied to determine the optimum parameters required for DC of the matrices investigated. Results confirm the positive contribution of LCS in enhancing powder compressibility and crushing strength of the resultant compacts. Compactibility of the XG/LCS mixtures was found to be more sensitive to applied compress...

ACS Biomaterials Science & Engineering, 2019

The development and evaluation of a controlled-release (CR) pharmaceutical solid dosage form comp... more The development and evaluation of a controlled-release (CR) pharmaceutical solid dosage form comprising xanthan gum (XG), low molecular weight chitosan (LCS) and metoprolol succinate (MS) is reported. The research is, partly, based upon the utilization of computational tools; in this case molecular dynamics simulations (MDs) and response surface method (RSM), in order to underpin the design/prediction and to minimize the experimental work required to achieve the desired pharmaceutical outcomes. The capability of the system to control the release of MS was studied as a function of LCS (% w/w) and total polymer (LCS and XG) to drug ratio (P:D) at different tablet tensile strengths. MDs trajectories, obtained by using different ratios of XG:LCS as well as XG and high molecular weight CS (HCS), showed that the driving force for the interaction between XG and LCS is electrostatic in nature, the most favourable complex is formed when LCS is used at 15 % (w/w) and, importantly, that the interaction between XG and LCS is more favourable than that between XG and HCS. RSM outputs revealed that the release of the drug from the LCS/XG matrix is highly dependent on both the % LCS and the P:D ratio and that the required CR effect can be achieved when using weight fractions of LCS ≤ 20% and P:D ratios ≥ 2.6:1. Results obtained from in-vitro drug release and swelling studies on the prepared tablets showed that using LCS at the weight fractions suggested by MDs and RSM data plays a major role in overcoming the high sensitivity of the controlled drug release effect of XG on ionic strength and pH changes of the dissolution media. In addition, it was found that polymer relaxation is the major contributor to the release of MS from LCS-XG tablets. Using Raman spectroscopy, MS was shown to be localized more in the core of the tablets at the initial stages of dissolution due to film formation between LCS and XG on the tablet surface which prevents excess water penetration into the matrix. In the later stages of the dissolution process, the film starts to dissolve/erode allowing full tablet hydration and a uniform drug distribution in the swollen tablet.

Marine Drugs, 2016

An increasing interest has recently been shown to use chitin/chitosan oligomers (chito-oligomers)... more An increasing interest has recently been shown to use chitin/chitosan oligomers (chito-oligomers) in medicine and food fields because they are not only water-soluble, nontoxic, and biocompatible materials, but they also exhibit numerous biological properties, including antibacterial, antifungal, and antitumor activities, as well as immuno-enhancing effects on animals. Conventional depolymerization methods of chitosan to chito-oligomers are either chemical by acid-hydrolysis under harsh conditions or by enzymatic degradation. In this work, hydrolysis of chitosan to chito-oligomers has been achieved by applying adsorption-separation technique using diluted HCl in the presence of different types of zeolite as adsorbents. The chito-oligomers were retrieved from adsorbents and characterized by differential scanning calorimetry (DSC), liquid chromatography/mass spectroscopy (LC/MS), and ninhydrin test.

Profiles of Drug Substances, Excipients and Related Methodology, 2016

SECTION 2: Hazard(s) identification 2.1. Classification of the substance or mixture GHS-US classi... more SECTION 2: Hazard(s) identification 2.1. Classification of the substance or mixture GHS-US classification Not classified 2.2. GHS Label elements, including precautionary statements GHS-US labeling No labeling applicable 2.3. Other hazards which do not result in classification No additional information available 2.4. Unknown acute toxicity (GHS US) Not applicable SECTION 3: Composition/Information on ingredients 3.1. Substances Substance type : Mono-constituent Name Product identifier % GHS-US classification Calcium Carbonate (Main constituent) (CAS-No.) 471-34-1 100 Not classified Full text of hazard classes and H-statements: see section 16 3.2. Mixtures Not applicable SECTION 4: First-aid measures 4.1. Description of first aid measures First-aid measures general : Check the vital functions. Unconscious: maintain adequate airway and respiration. Respiratory arrest: artificial respiration or oxygen. Cardiac arrest: perform resuscitation. Victim conscious with labored breathing: half-seated. Victim in shock: on his back with legs slightly raised. Vomiting: prevent asphyxia/aspiration pneumonia. Prevent cooling by covering the victim (no warming up). Keep watching the victim. Give psychological aid. Keep the victim calm, avoid physical strain. Depending on the victim's condition: doctor/hospital. First-aid measures after inhalation : Remove person to fresh air and keep comfortable for breathing. Remove the victim into fresh air. Respiratory problems: consult a doctor/medical service.

International Journal of Pharmaceutics, 2000

An anti-hapten IgG was covalently immobilized on glutaraldehyde-activated alginate-chitosan gel b... more An anti-hapten IgG was covalently immobilized on glutaraldehyde-activated alginate-chitosan gel beads. The antibody immobilization efficiency was influenced by glutaraldehyde-bead reaction time, IgG concentration and pH. In addition, immobilization conditions such as glutaraldehyde and antibody concentrations influenced antibody hapten binding affinity. The immobilized IgG on the beads was stable and no reduction in the percent binding to hapten was noticed following 25 days of storage. It was concluded that antibodies could be successfully immobilized on alginate-chitosan gel beads. Such a system can be applied for the development of immunoaffinity purification and immunoassays.

Profiles of Drug Substances, Excipients and Related Methodology, 2015

Sudan Journal of Medical Sciences, 2010

Objectives: To formulate chitosan nanoparticles with specific combinations of molecular weight an... more Objectives: To formulate chitosan nanoparticles with specific combinations of molecular weight and degree of deacetylation (DDA) that could be developed into an oral insulin delivery system. Methods: This study was conducted at Jordanian Pharmaceutical Manufacturing Company (JPM), Jordan in the period 2006-2009. Nanoparticles were prepared by polyelectrolyte complexation method (PEC). The physicochemical characteristics of the nanoparticles were evaluated. The role of nanoparticles in stabilization of insulin at high temperature and protecting insulin from pancreatic degradation was investigated. Results: The PEC formation process is influenced by a variety of parameters, including the system pH, chitosan molecular weight and DDA. The most important factor appears to be the system pH. All insulin-chitosan complexes displayed positive zeta potential. PECs protect insulin from pancreatin and the protective ability affected by DDA of chitosan. The results of insulin stability indicate that insulin-chitosan PEC protects insulin from degradation for at least 24 h. Conclusions: Molecular parameters of chitosan nanoparticles play an important role in stabilization of insulin in the GIT. So we can modulate relative parameters to develop an oral insulin delivery system.

Journal of Pharmaceutical Sciences, 2015

Paracetamol has an extensive first-pass metabolism that highly affects its bioavailability (BA); ... more Paracetamol has an extensive first-pass metabolism that highly affects its bioavailability (BA); thus, dose may be repeated several times a day in order to have longer efficacy. However, hepatotoxicity may arise because of paracetamol metabolism. Therefore, this project aimed to increase paracetamol BA in rats by glucosamine (GlcN). At GlcN-paracetamol racemic mixture ratio of 4:1 and paracetamol dose of 10 mg/kg, paracetamol area under the curve (AUC) and maximum concentration (Cmax ) were significantly increased by 99% and 66%, respectively (p < 0.05). Furthermore, paracetamol AUC and Cmax levels were increased by 165% and 88% in rats prefed with GlcN for 2 days (p < 0.001). Moreover, GlcN significantly reduced phase Ι and phase I/ΙΙ metabolic reactions in liver homogenate by 48% and 54%, respectively. Furthermore, GlcN molecule was found to possess a good in silico binding mode into the CYP2E1 active site-forming bidentate hydrogen bonding with the Thr303 side chain. Finally, serum ALT and AST levels of rats-administered high doses of paracetamol were significantly reduced when rats were prefed with GlcN (p < 0.01). In conclusion, GlcN can increase the relative BA of paracetamol through reducing its metabolism. This phenomenon is associated with reduction in hepatocytes injury following ingestion of high doses of paracetamol.

Powder Technology, 2010

The influence of the lubricant magnesium stearate (MgSt) on the powder and tablet properties of c... more The influence of the lubricant magnesium stearate (MgSt) on the powder and tablet properties of chitin-Mg silicate coprecipitate was examined and compared with lubricated Avicel® 200 and Avicel-Mg silicate coprecipitate. Crushing strength and disintegration time studies were conducted in order to evaluate tablet properties at different compression pressures. Lubrication of chitin-Mg silicate powder with MgSt was evaluated using a high speed rotary tablet press. The compactability and disintegration time of chitin-Mg silicate are unaffected by the possible deleterious action of up to 2% (w/w) MgSt. The deleterious effect of MgSt on Avicel® 200 compaction was found to be minimized when magnesium silicate was coprecipitated onto Avicel® 200. Lubrication of chitin-Mg silicate with MgSt does not enhance particle agglomeration, whereas the opposite is the case for Avicel® 200; the foregoing was ascertained by measurements of the fixed bulk density, constant powder porosity using Kawakita analysis and by the absence of variation in particle size distribution in the presence of up to 5% (w/w) MgSt. In the case of chitin-Mg silicate tablets the ejection force was greatly reduced at a compression speed of 150,000 tablet/h at a MgSt concentration of 0.5% (w/w). The physical properties and drug dissolution profile of ibuprofen tablets were found to be unaffected when chitin-Mg silicate was lubricated up to 5% (w/w) with MgSt. Optimal drug dissolution was attained for gemfibrozil tablets using 3% (w/w) MgSt when compared to a reference (Lopid tablets).

International Journal of Pharmaceutics, 2011

A directly compressible excipient has been developed by co-processing starch with magnesium silic... more A directly compressible excipient has been developed by co-processing starch with magnesium silicate. The foregoing was achieved either by co-precipitation of magnesium silicate onto different types of starch or by dry granulation of maize starch with magnesium silicate. A variety of techniques (permeability, water retention/swelling, compression analysis, scanning electron microscopy, tensile strength and disintegration/dissolution studies) were used to characterize these systems. The permeability of the formulations produced using the two methods was evaluated experimentally using Darcy's permeability law. Magnesium silicate, as an anti-adhering agent, increases the permeability of both maize and partially pregelatinized starch, resulting in compacts of high mechanical strength, short disintegration time and low lubricant sensitivity. Such advantages are evident when the properties of the physical mixture of maize starch with magnesium silicate are compared with the co-precipitation and dry granulation techniques. Formulation with this novel excipient system, using paracetamol as a model drug, indicated its suitability as a single multifunctional excipient.

Supramolecular Chemistry, 2009

Pharmaceutical Development and Technology, 1998

Journal of Pharmaceutical and Biomedical Analysis, 2006

Guest-host interactions of sildenafil (Sild) with cyclodextrins (CyDs) have been investigated usi... more Guest-host interactions of sildenafil (Sild) with cyclodextrins (CyDs) have been investigated using several techniques including phase solubility diagrams (PSD), differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD), proton nuclear magnetic resonance (1 H NMR) and molecular mechanical modeling (MM +). Estimates of the complex formation constant (K 11) show that the tendency of Sild to complex with CyDs follows the order: ␤-CyD > HP-␤-CyD > ␥-CyD, ␣-CyD, where K 11 values at pH 8.7 and 30 • C were 150, 68 and 46, 43 M −1 , respectively. Ionization of Sild reduces its tendency to complex with ␤-CyD, where protonated (at pH 3.6) and anionic Sild (at pH 12.1) species have K 11 values of 17 and 42 M −1 , respectively, compared with 150 M −1 for neutral Sild (at pH 8.7). The hydrophobic character of Sild was found to provide 39% of the driving force for complex stability, while other factors including specific interactions contribute −7.9 kJ/mol. Complex formation of Sild with ␤-CyD (G • = −22.9 kJ/mol) is largely driven by enthalpy (H • = −19.8 kJ/mol) and slight entropy (S • = 10.3 J/mol K) changes. 1 H NMR and MM + studies indicate formation of two isomeric 1:1 complexes: one involving complete inclusion of the phenyl-moiety into the ␤-CyD cavity while the other pertaining to partial inclusion of the pyrimidinone moiety. The dominant driving force for complexation is evidently van der Waals with very little electrostatic contribution. DSC, XRPD and 1 H NMR studies proved the formation of inclusion complex in solution and the solid state.