Tablet characterization

PHARMACEUTICAL PREFORMULATION PHYSICOCHEMICAL PROPERTIES OF EXCIPIENTS AND POWDERS AND TABLET CHARACTERIZATION... 

Nilsson M, Mihranyan A, Valizadeh S, et al. Mesopore structure of microcrystalline cellulose tablets characterized by nitrogen adsorption and SEM the influence on water-induced ionic conduction. J Phys Chem B 2006 110 15776-15781. 

The main objectives in tablet characterization are to identify drug-excipients interactions, quantitation of the amount of active substance per tablet, to identify the solid form present and to observe changes with storage conditions (stability). All of these findings, taking into account that in tablet formulations the API concentration can be very low and the signals of excipients usually dominate the spectrum, make SSNMR characterization a challenge. 

Gordon RE, Rosanske TW, Fonner DE, Anderson NR, Banker GS. Granulation technology and tablet characterization. Lieberman HA, Lachman L, Schwartz JB, eds. Pharmaceutical Dosage Forms Tablets. New York Marcel Dekker, 1990. 

Kumar, V., de la Luz Reus-Medina, M. Yang, D. (2002). Preparation, characterization, and tabletting properties of a new cellulose-based pharmaceutical aid. International Journal of Pharmaceutics, Vol. 235,1-2, (March 2002), pp. (129-140), ISSN 0378-5173... 

Nunthanid, J., Laungtana-Anan, M., Sriamornsak, R, Limmatvapirat, S., Puttipipatkhachorn, S., Lim, L. Y. Khor, E. (2004). Characterization of chitosan acetate as a binder for sustained release tablets. Journal of Controlled Release, Vol. 99, 1, (September 2004), pp. (15-26), ISSN 0168-3659... 

To evalnate whether some foods contain true vitamin B,2 or inactive vitamin B,2 analogs, some vitamin B[2 compoimds were purified and characterized using silica gel 60 TLC [11-15]. An algal health food, spirulina tablets, contained considerable amounts of a vitamin Bjj analog (pseudovitamin Bjj) inactive for humans (Figure 10.6) [11]. 

In a four-part article, Porter [130] provided a comprehensive review of tablet coating technology, with emphasis on contemporary practice. More specifically, a recent review [131] discusses characterization techniques for the aqueous film coating process and provides a useful influence matrix between process variables and final product attributes. 

Although a number of methods are available to characterize the interstitial voids of a solid, the most useful of these is mercury intrusion porosimetry [52], This method is widely used to determine the pore-size distribution of a porous material, and the void size of tablets and compacts. The method is based on the capillary rise phenomenon, in which excess pressure is required to force a nonwetting liquid into a narrow volume. 

The majority of active pharmaceutical agents are administered as tablets, and as a result the characterization of compact species is of great interest to formulators. During the compression step, a variety of particle-particle interactions take place, which ultimately lead to the formation of a stable entity. One may envision that the compaction process results in such consolidation of the input solids that the final density of the tablet approaches the true density of the component materials. 

An initial use of reflectance spectroscopy in the characterization of pharmaceutical solids concerned studies of the stability of coloring agents in tablet formulations. With the description of a device that enabled the surface of intact tablets to be studied [14], the photostability of various dyes and lakes in tablets was followed [15,16]. Exposure of formulations to both normal and exaggerated light conditions was investigated, and the kinetics of the photodegradation evaluated. In most cases, the photoreactions appeared to follow first-order kinetics. 

As an example of this work, the reflectance spectra of tablets formulated with FD C Blue No. 1 and exposed to various light intensities are shown in Fig. 3. Under normal illumination (45 foot-candles), the decomposition kinetics are modest. When exposed to higher levels of illumination (550 foot-candles), complicated kinetics characterized by at least three different reaction pathways were observed [15]. 

Although UV/VIS diffuse reflectance spectroscopy has not been used extensively in the study of pharmaceutical solids, its applications have been sufficiently numerous that the power of the technique is evident. The full reflectance spectra, or the derived colorimetry parameters, can be very useful in the study of solids that are characterized by color detectable by the human eye. It is evident that questions pertaining to the colorants used for identification purposes in tablet formulations can be fully answered through the use of appropriately designed diffuse reflectance spectral experiments. With the advent of newer, computer-controlled instrumentation, the utility of UV/VIS diffuse reflectance as a characterization tool for solids of pharmaceutical interest should continue to be amply demonstrated. 

Tablets 13C, 31P Drug-excipient interaction studies, (pseudo)-polymorphic characterization at the qualitative and quantitative levels...

Methods for characterizing the elastic, plastic, and brittle properties of compacts of organic materials have been developed by Hiestand and coworkers [29-33]. These indices of tableting performance measure the mechanical properties of compacted materials. 

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