Dissolution properties

Acetone, methyl ethyl ketone, methyl isobutyl ketone, dimethylformamide, ethyl acetate, and tetrahydrofuran are solvents for vinyhdene chloride polymers used in lacquer coatings methyl ethyl ketone and tetrahydrofuran are most extensively employed. Toluene is used as a diluent for either. Lacquers prepared at 10—20 wt % polymer sohds in a solvent blend of two parts ketone and one part toluene have a viscosity of 20—1000 mPa-s (=cP). Lacquers can be prepared from polymers of very high vinyhdene chloride content in tetrahydrofuran—toluene mixtures and stored at room temperature. Methyl ethyl ketone lacquers must be prepared and maintained at 60—70°C or the lacquer forms a sohd gel. It is critical in the manufacture of polymers for a lacquer apphcation to maintain a fairly narrow compositional distribution in the polymer to achieve good dissolution properties. 

Traditional octanol-water distribuhon coefficients are shll widely used in quan-titahve structure-achvity relationship (QSAR) and in ADM E/PK studies. However, alternahve solvent systems have been proposed [80]. To cover the variabihty in biophysical characterishcs of different membrane types a set of four solvents has been suggested, somehmes called the critical quartet [81]. The 1,2-dichloroeth-ane-water system has been promoted as a good alternative to alkane-water due to its far better dissolution properties [82, 83], but may find little applicahon because of its carcinogenic properties. 

Wingstrand, K., Abrahamsson, B., Edgar, B., Bioavailability from felodipine extended-release tablets with different dissolution properties, Int.J. Pharm. 1990, 60, 151—156. 

Fluoride ions considerably change the physico-chemical properties of apatites and particularly their dissolution properties. 

A comparison of dissolution properties from matrix tablets prepared from 141... 

Biodegradable polymers Effect of thermal treatment on the physicomechanical and dissolution properties of compacts... 

The aim of the example was to compare tablets with respect to good and bad dissolution properties using IR imaging and to identify the root causes of bad dissolution [24]. 

This PCA image study showed the differences between the two data sets, that is, it separated the good and bad dissolution samples. The main differences were due to the distribution of magnesium stearate and the API. No differences were observed in the spatial distribution of poloxamer or Avicel. Magnesium stearate is hydrophobic, thus protecting the tablet core from moisture and hence slowing dissolution. When a sample had more active ingredient on the surface, the dissolution properties were increased. 

The two main online applications of hyperspectral imaging are blending endpoint determination (Figure 19) and capsule control (Figure 20). Other applications may be possible, such as content uniformity, determination of dissolution properties, and water quantification, but are not described in this chapter. 

Eudragit (Rohm/Pharma Polymers, Darmstadt, Germany) is a class of polymer that will dissolve at specific pH values. Eudragit polymers are members of the poly(alkyl methacrylate) family of polymers. This family of polymers has a wide degree of properties due to the many modifications used in the formation of the polymers. The dissolution properties are based on the modification of the carboxylic moieties of methacrylic acid. The degree of modification and the specific modification determine at what pH and how quickly the polymers dissolve. 

Kislaligglu MS, Khan MS, Blount C, Goettsch RW, Bolton S. Physical characterization and dissolution properties of ibuprofen eudragit copreciptates. J Pharm Sci 1991 80(8) 799-804. 

Portero A, Remunanlopez C, Vilajato JL. Effects of chitosan and chitosan glutamate enhancing the dissolution properties of the poorly water soluble drug nifedipine. Int J Pharm 1998 175 75-84. 

The preferred dissolution apparatus is 1 ISP apparatus 1 (basket) or 11 (paddle), used at compendially recognized rotation speeds (e.g., 100 rpm for the basket and 50-75 rpm for the paddle). In other cases, the dissolution properties of some ER formulations may be detennined with USP apparatus 111 (reciprocating cylinder) or IV (flow through cell). 

Mura, P, Bettinetti, G. P, Cirri, M., Maestrelli, F., Sorrenti, M., and Catenacci, L. 2005. Solid-state characterization and dissolution properties of naproxen-arginine-hydroxyptjbtnylelodextrin ternary system. 

Patel, R. R, Sawant, K. K., Patel, M. M., and Patel, N. R. 2005. Enhancement of the dissolution properties of furosemide by inclusion complexation wipshcyclodextrin.Drug Delivery Technol. 5 62-66. 

In an ideal solution, the maximum solubility of a drug substance is a function of the solid phase in equilibrium with a speciLed solvent system at a given temperature and pressure. Solubility is an equilibrium constant for the dissolution of the solid into the solvent, and thus depends on the strengths of solute solvent interactions and solute solute interactions. Alteration of the solid phase of the drug substance can inLuence its solubility and dissolution properties by affecting the solute solutc molecular interactions. 

Following oral administration, dissolution of the drug molecule in the intestinal milieu is a prerequisite for the absorption process. According to the Biopharmaceutical Classification System (BCS) [2], poor water-soluble compounds (i.e., aqueous solubility less than 100 pg/ mL) are class 2 or class 4 compounds. For class 2 compounds, the absorption level is dictated by the dissolution properties of the molecule in the gastrointestinal (GI) fluids. BCS class 4 compounds, which are characterized by both low solubility and poor intestinal wall permeability, are generally poor drug candidates (unless the dose is very low). 

In applications such as the preparation of tableting feeds and the manufacture of detergent powders, the aim is to produce small agglomerates (usually 2 mm diameter and less) with improved flow, wetting, dispersing or dissolution properties. This is accomplished by superficially wetting the feed powder, often with less than 5% of bridging liquid in the form of a... 

Ionic liquids — A class of preferably organic salts that are liquid at room temperature and may be simultaneously used as both solvents and supporting electrolytes for electrochemical reactions. Their unconventional properties include a negligible vapor pressure, a high thermal and electrochemical stability, and exceptional dissolution properties for both organic and inorganic systems. 

Oral Powders Appearance, color, odor, moisture content of powder, and, if intended for reconstitution, appearance, pH, and dispersibility/dissolution properties. 

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