Raw material and technology to dissolution of solid preparations II

Writer： admin Time：2020-04-24 11:07 Browse：℃

 3.Material powdering
Medicine powdering technologies refer to the methods of mechanical grinding, supercritical fluid process and low temperature spraying to narrow medicine size distribution and increase its specific surface area. These technologies can not only reduce complexity of tableting technique, but also greatly increase dissolution rate and bioavailability of insoluble medicine preparation.
 
Roxithromycin dispersing tablets are produced through ball grinding. Roxithromycin is of strong hydrophobicity. Therefore, lactose, soluble auxiliary material is added into powdered materials and they are ground together in order to help dissolution medium permeate into granules and ground roxithromycin disperse completely. The result shows that the mixture of rodithromycin and lactose has the minimum size of 0.1μm and the prepared dispersing tablets has better dissolution rate.
 
When carrying out glimepiride tablets formulation and technique sifting and dissolution rate evaluation, the researcher applies ball grinding to decrease glimepiride size from D50:20.2μm to D50:2.7μm. The other auxiliary materials are selected according to leaflet of original product to prepare generic glimepiride tablets. The result shows: The generic preparation is similar to the reference preparation in its dissolution curves when dissolved in four solvents of different pH.
 
In another research on glimepiride, the researcher applies jet grinding method to increase its dissolution rate. After the comparison of granule size between glimepiride material and powdered glimepiride material and dissolution curve between generic preparation and reference preparation, it can be found that size of material before powdering is about D50:20.2μm and ranges 0.3-90.0μm. The dissolution curve is also not similar to that of reference preparation. However, size of powdered material reduced to D50:1μm and ranges to 0.1-4.8μm. The dissolution curve is also similar to that of reference preparation. However, the reference preparation in this research is a local product, which disobey requirements of Guidance for the Selection and Determination of Reference Preparation for General Solid Preparation. Consistency of localized product to the original product is not evaluated.
 
A research studied on dissolution rate of cefdinir granules prepared by powdered material. In the research, vibrating grinding method is applied to prepare powdered cefdinir material. When dissolved in three solvent of different pH, cefdinir granules made from powdered materials have higher dissolution rate than preparation made from materials without powdering.
 
Also, in a research on the influence of powdering on properties and dissolution of berberine hydrochloride, result shows that after vibrating grinding, berberine hydrochloride granule size can reach D90: 38.78μm. Granules’ specific surface area and porosity will change as grinding continues. In the first four minutes, specific surface area and pore volume increase. Afterwards, they tend to decrease as grinding continues. After repeated tests, when ground for 4min and the size of berberine hydrochloride is 38.84μm, the specific surface area and pore volume are the max and the granule dissolution effect is the best.
 
Actually, during polymorphic crystal medicine evaluation, importance should be attached to possible crystal transformation and crystallinity reduction caused by powdering, since these factors will challenge preparation stability.
 
4.Material preparing and tablet pressing techniques
Preparing techniques of tablets are classified into direct table pressing and granulation tablet pressing. The latter is commoner. Granulation is also classified into wet granulation and dry granulation. Influence of preparing technique on tablet dissolution should be analyzed on the basis of specific tablet type.
 
After research on the influential factors to medical release of doxofylline HPMC matrix tablets, it can be found that matrix tablets made by direct tablet pressing release more quickly than the tablets made by wet granulation. The reason is that the adhesive of wet granulation increases viscosity of gel layer and decreases matrix dissolution speed. Therefore, medicine release speed is slower.
 
The result of research on influence of granule size and granulation technique on aspirin tablet dissolution, shows that wet granulation tablet pressing is better than direct tablet pressing. Insoluble material surface can obtain hydrophilicity during wet granulation so that dissolution rate is medicine is heightened. When the mixture of 0.5% SDS and dry starch is disintegrant and grounded material pass through 100 mesh screen, i.e. wet granulation tablet pressing, the preparation dissolution rate is obviously higher than the rate of tablets made by direct tablet pressing.