Semicontinuous biooxidation of high-sulfur concentrates: Relationship between volume or mass dissolution rate and pulp density

2018 ◽  
Vol 35 (4) ◽  
pp. 202-214
Author(s):  
Y. Song ◽  
H.Y. Yang ◽  
L.L. Tong ◽  
W. Sand
Keyword(s):  
Dissolution Rate ◽  
Pulp Density

Cementation of Lead From Lead Sulfate Slurries. I. Kinetics With Zinc Precipitant

1988 ◽  
Vol 41 (12) ◽  
pp. 1857
Author(s):  
IJ Bear ◽  
RCA Flann ◽  
R Woods ◽  
JR Gardner
Keyword(s):  
Dissolution Rate ◽  
Lead Sulfate ◽  
The Other ◽  
Pulp Density ◽  
Metallic Lead ◽  
Initial Rise ◽  
Steady Rate ◽  
Two Samples ◽  
Rate Of Reaction ◽  
Rate Profile

The cementation of metallic lead from two samples of lead sulfate powders with zinc precipitant has been studied in stirred aqueous slurries. The reaction proceeded by dissolution of the lead sulfate and precipitation of the lead from solution. The kinetics were characterized by two alternative reaction profiles; in profile No. 1, the extent of reaction rose steeply during the first 15-60 min to a gently sloping incline or plateau, while in profile No. 2 the initial rise was less sharp but the reaction continued to completion at a steady rate. Profile No. 1 was observed under all conditions studied with the lead sulfate sample that had the faster dissolution rate. The other sample gave rise to profile No. 2 when the initial partial pulp density (IPPD) of lead sulfate was 100 g/l. or higher, and to mixed No. 1 and No. 2 kinetics at lower values. The rate of reaction increased with decrease in the IPPD of lead sulfate when the kinetics followed profile No. 1, whereas the reverse condition was evident when profile No. 2 was operative.

Solubility Enhancement of Poorly Soluble Drug Simvastatin by Solid Dispersion Technique

2016 ◽  
Vol 2 (2) ◽  
pp. 91-95
Author(s):  
Neelima Rani T ◽  
Pavani A ◽  
Sobhita Rani P ◽  
Srilakshmi N
Keyword(s):  
Dissolution Rate ◽  
Drug Carrier ◽  
Solid Dispersions ◽  
Aqueous Solubility ◽  
Onset Of Action ◽  
Kneading Method ◽  
Wetting Property ◽  
Poorly Soluble ◽  
Dispersion Technique ◽  
Low Solubility

This study aims to formulate solid dispersions (SDs) of Simvastatin (SIM) to improve the aqueous solubility, dissolution rate and to facilitate faster onset of action. Simvastatin is a BCS class II drug having low solubility & therefore low oral bioavailability. In the present study, SDs of simvastatin different drug-carrier ratios were prepared by kneading method. The results showed that simvastatin solubility & dissolution rate enhanced with polymer SSG in the ratio 1:7 due to increase in wetting property or possibly may be due to change in crystallinity of the drug.

Dissolution Rate of Copper in Lead and Aluminum Melts

1994 ◽  
Vol 80 (4) ◽  
pp. 294-299
Author(s):  
Katsumi MORI ◽  
Toshiro KITAHARA ◽  
Kunihiko NAKASHIMA
Keyword(s):  
Dissolution Rate

Studies on the Preparation, Characterization and Solubility of -Cyclodextrin-Roxythromycin Inclusion Complexes

2009 ◽  
Vol 2 (2) ◽  
pp. 523-530
Author(s):  
D. Nagasamy Venkatesh ◽  
S. Karthick ◽  
M. Umesh ◽  
G. Vivek ◽  
R.M. Valliappan ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Inclusion Complexes ◽  
Phase Solubility ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Ir Studies ◽  
Poorly Soluble ◽  
Poorly Soluble Drug

Roxythromycin/ β-cyclodextrin (Roxy/ β-CD) dispersions were prepared with a view to study the influence of β-CD on the solubility and dissolution rate of this poorly soluble drug. Phase-solubility profile indicated that the solubility of roxythromycin was significantly increased in the presence of β-cyclodextrin and was classified as AL-type, indicating the 1:1 stoichiometric inclusion complexes. Physical characterization of the prepared systems was carried out by differential scanning calorimetry (DSC), X-ray diffraction studies (XRD) and IR studies. Solid state characterization of the drug β-CD binary system using XRD, FTIR and DSC revealed distinct loss of drug crystallinity in the formulation, ostensibly accounting for enhancement of dissolution rate.

Influence of β-Cyclodextrin and Hydroxypropyl-β-Cyclodextrin on Enhancement of Solubility and Dissolution of Isradipine

2017 ◽  
Vol 10 (3) ◽  
pp. 3752-3757
Author(s):  
Narendar D ◽  
Ettireddy S
Keyword(s):  
Inclusion Complex ◽  
Dissolution Rate ◽  
Solid Dispersions ◽  
Physical Stability ◽  
Molecular Complexes ◽  
In Vitro Dissolution ◽  
Molar Ratio ◽  
Phase Solubility ◽  
Cyclodextrin Complexation

The content of this investigation was to study the influence of β-cyclodextrin and hydroxy propyl-β-cyclodextrin complexation on enhancement of solubility and dissolution rate of isradipine. Based on preliminary phase solubility studies, solid complexes prepared by freeze drying method in 1:1 molar ratio were selected and characterized by DSC for confirmation of complex formation. Prepared solid dispersions were evaluated for drug content, solubility and in vitro dissolution. The physical stability of optimized formulation was studied at refrigerated and room temperature for 2 months. Solid state characterization of optimized complex performed by DSC and XRD studies.  Dissolution rate of isradipine was increased compared with pure drug and more with HP-β-CD inclusion complex than β-CD. DSC and XRD analyzes that drug was in amorphous form, when the drug was incorporated as isradipine β-CD and HP-β-CD inclusion complex. Stability studies resulted in low or no variations in the percentage of complexation efficiency suggesting good stability of molecular complexes. The results conclusively demonstrated that the enhancement of solubility and dissolution rate of isradipine by drug-cyclodextrin complexation was achieved.   

The Effect of Superdisintegrants on the Dissolution of Promethazine. HCl Fast Dissolving Tablets

2010 ◽  
Vol 3 (1) ◽  
pp. 867-871
Author(s):  
Ganesh kumar Gudas ◽  
Manasa B ◽  
Senthil Kumaran K ◽  
Rajesham V V ◽  
Kiran Kumar S ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Angle Of Repose ◽  
Content Uniformity ◽  
Disintegration Time ◽  
Enhanced Dissolution ◽  
Weight Variation ◽  
Compressibility Index ◽  
Chemoreceptor Trigger Zone ◽  
Trigger Zone ◽  
Standard Limit

Promethazine.HCl is a potent anti-emetic. The central antimuscarinic actions of antihistamines are probably responsible for their anti-emetic effects. Promethazine is also believed to inhibit the medullary chemoreceptor trigger zone, and antagonize apomorphine -induced vomiting. Fast dissolving tablets of Promethazine.HCl were prepared using five superdisintegrants viz; sodium starch glycolate, crospovidone, croscarmellose, L-HPC and pregelatinised starch. The precompression blend was tested for angle of repose, bulk density, tapped density, compressibility index and Hausner’s ratio. The tablets were evaluated for weight variation, hardness, friability, disintegration time (1 min), dissolution rate, content uniformity, and were found to be within standard limit. It was concluded that the fast dissolving tablets with proper hardness, rapidly disintegrating with enhanced dissolution can be made using selected superdisintegrants. Among the different formulations of Promethazine.HCl was prepared and studied and the formulation S2 containing crospovidone, mannitol and microcrystalline cellulose combination was found to be the fast dissolving formulation. In the present study an attempt has been made to prepare fast dissolving tablets of Promethazine.HCl, by using different superdisintegrants with enhanced disintegration and dissolution rate. 

Solubility Enhancement of the Poorly Water-Soluble Antiulcer Drug Famotidine by Inclusion Complexation

2013 ◽  
Vol 6 (1) ◽  
pp. 1983-1989 ◽  
Author(s):  
Shabnam Ain ◽  
V Gupta ◽  
Babita K ◽  
Q Ain ◽  
J Dahiya
Keyword(s):  
Inclusion Complex ◽  
Dissolution Rate ◽  
Phosphate Buffer ◽  
Physical Mixture ◽  
Water Soluble ◽  
Molar Ratio ◽  
Phase Solubility ◽  
Distilled Water ◽  
Physicochemical Interaction ◽  
Mixture Phase

Aqueous solubility is a critical factor for optimum drug delivery. In the present study, we investigated the potential of drug-cyclodextrin complexation as an approach for improving the solubility and bioavailability of famotidine, an H2-receptor antagonist and acid reducing drug which has poor solubility and bioavailability. Solubility improvement of drug by β-cyclodextrin was done by simple complexation approach using physical, kneading and co-precipitation methods and compared with physical mixture. Phase solubility profile indicated that the solubility of famotidine was significantly increased in presence of β-cyclodextrin and shows a linear graph with β-cyclodextrin indicating formation of inclusion complexes in a 1:1 molar ratio. β-Cyclodextrin-famotidine mixture have maximum stability constant 1477.6 M-1. The inclusion complex ratio 1:1 of kneading mixture was selected based on drug release profile and compared with physical mixture. Further characterization was done by  using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) to identify the physicochemical interaction between drug and carrier and its effect on dissolution. Dissolution rate studies for selected inclusion complex was performed in 0.1 N HCl (pH 1.2), phosphate buffer (pH 7.5) and distilled water (pH 6.8) and compared these to pure drug profile which was found to be 2.34 fold increase in distilled water, 1.83 fold in HCl and 2.01 fold in phosphate buffer (pH 7.5). These results suggest that the kneaded complex of famotidine with β-cyclodextrin as hydrophilic complexation agent can substantially enhance the solubility and dissolution rate. Such complex has promising potential to improve the bioavailability of famotidine.  

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