Excipient properties

In solid dosage forms, granulation is frequently used to improve excipient properties such as flowability, compactibility, bulk density, granule strength, dissolution rates, and so The granulation process... 

The resulting measurement of a compression force is highly correlated with a variety of tablet properties. As compression increases, so does tablet hardness and weight (at constant thickness and true density), along with a force required to eject a tablet. Many variables affect the force of compression press settings, press speed, punch length variation, punch wear, and damage, formulation and excipient properties. 

It should be noted that aluminum stearate can also refer to the distearate (CAS number [300-92-5]) and the monostearate (CAS number [7047-84-9]) in addition to the tristearate. The distearate exhibits the same excipient properties as the tristearate and is used in similar pharmaceutical applications. However, the monostearate is more widely used in cosmetics as a colorant. 

The series mission was expanded some time ago to include profiles of excipient materials, reflecting that these materials require the full degree of scrutiny historically associated with drug compounds. These highly detailed compilations of excipient properties and analytical methods have been well received by workers in the field, and such profiles will continue to be sought. In the present volume, the series mission is further expanded to include a profile of a natural product which has been used as a precursor material in the synthesis of new drug candidates. If this information proves to be of interest to the pharmaceutical community, additional chapters of this type will be developed. 

The monographs include pharmacopoeial information, non-proprietary names and synonyms, chemical name, CAS Registry number, empirical formula, molecular weight, functional category, applications and incompatibilities, material description and typical excipient properties, safety, stability, storage and handling precautions. 

Bioavailability, Bioequivalence, and Pharmacokinetics. Bioavailabihty can be defined as the amount and rate of absorption of a dmg into the body from an adrninistered dmg product. It is affected by the excipient ingredients in the product, the manufacturing technologies employed, and physical and chemical properties of the dmg itself, eg, particle size and polymorphic form. Two dmg products of the same type, eg, compressed tablets, that contain the same amount of the same dmg are pharmaceutical equivalents, but may have different degrees of bioavailabihty. These are chemical equivalents but are not necessarily bioequivalents. For two pharmaceutically equivalent dmg products to be bioequivalent, they must achieve the same plasma concentration in the same amount of time, ie, have equivalent bioavadabihties. 

The different salts, esters, ethers, isomers, mixtures of isomers, complexes or derivatives of an active substance shall be considered to be the same active substance, unless they differ significantly in properties with regard to safety and/or efficacy, in which case additional safety and efficacy data are required. The same qualitative and quantitative composition only applies to the active ingredients. Differences in excipients will be accepted unless there is concern that they may substantially alter the safety or efficacy. The same pharmaceutical form must take into account both the form in which it is presented and the form in which it is administered. Various immediate-release oral forms, which would include tablets, capsules, oral solutions and suspensions, shall be considered the same pharmaceutical form for this purpose. 

By choosing the excipient type and concentration, and by varying the spray-drying parameters, control was achieved over the physical properties of the dry chitosan powders. The in vitro release of betamethasone showed a dose-dependent burst followed by a slower release phase that was proportional to the drug concentration in the range 14-44% w/w [200]. 

The Cadila system [13] has been designed to formulate tablets for drugs based on their physical (solubility, hydroscopicity, etc), chemical (functional groups), and biologically interrelated (dissolution rate) properties. The system first identifies the desirable properties for optimum compatibility with the drug, selects those excipients that have the required properties, and then recommends proportions based on the assumption that all tablet formulations comprise at least one binder, one disintegrant, and one lubricant. Other... 

The portal of drug entry The physical form of the drug product The design and formulation of the product The method of manufacture of the drug product Various physicochemical properties of the drug and excipients... 

It may sometimes by necessary to supplement the properties of the drug so that it compresses more easily, and these needs have been realized by several manufacturers of excipients. Materials described as compression aids are now commercially available. Ideally, such adjuvants should develop mechanical strength while improving, or at least not adversely affecting, release characteristics. Among the most successful at meeting both these needs have been the microcrystalline celluloses (partially acid-hydrolyzed forms of cellulose). A number of grades are available based upon particle size and distribution. 

As a generalization, increasing compressional force will retard dispersion on administration, and therefore, levels should be kept as low as possible, consistent with achieving acceptable mechanical properties. With some excipients there is a critical compressional force range required to achieve minimum disintegration times. 

Factors affecting the mix of active ingredients and excipients should be discussed. These should include particle size and shape, rugosity, charge, flow properties, and water content. Since the dose delivery for these products is dependent on air flow characteristics, an attempt should be made to establish an in vivo-in vitro correlation. 

To produce tablets that are uniform in weight and content and exhibit a certain degree of mechanical strength, one needs a mixture of powders with (a) good flow properties (b) a minimum tendency for segregation, and (c) the ability to be compressed. To achieve these ends, granulation with other excipients is often necessary. 

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