Functional excipients

The use of capillary electrophoresis (CE) during the synthetic drug development is described from the preclinical development phase to the final marketed stage. The chapter comprises the determination of physicochemical properties, such as acid—base dissociation constants (pKJ, octanol—water distribution coefficients (logP), and analysis of pharmaceutical counterions and functional excipients. 

In principle, the same separation systems can be used to determine functional excipients like small organic acids or amines. 

Sherwood BE, Becker JW. A new class of high functionality excipients silicified microcrystalline cellulose. Pharm Tech 1998 22(10) 78—88. 

Bansal AK, Nachaegari SK. High-functionality excipients for solid dosage forms. Business Briefing Pharmagenerics 2002 38-44. 

Joshi AA, Duriez X. Added functionality excipients an answer to challenging formulations. Pharm Technol (Excipients and Solid Dosage Forms) 2004 12-19. 

Several good surfactants in terms of solubility, compatibility, and toxicity can be selected for prototype formulation development. In general, one surfactant can be used as the primary solubilizer in a prototype formulation. Functional excipients, such as antioxidants, tonicity agents for parenteral products and sweeteners, and taste masking agents for oral products, may be added to the prototyp formulation. 

Thus, the amount of drug released is proportional to the square root oftjiBe ndCs. In some cases, diffusion is not the only pathway by which a drug is released from the delivery system. The erosion of the delivery matrix following relaxation of the polymer and other functional excipient(s) contributes to the overall drug release as well. Discussed below are examples of the diffusion- and erosion-controlled matrix delivery systems. 

Chang CA, Kumar K, Tweedle MF Eur Patent 0454078 Dual functioning excipients for metal contrast agents... 

Cohesiveness Make the material more cohesive by adding water, oil, or other functional excipients. One of the prerequisites for segregation is inter-particle motion. Increasing cohesiveness causes the particles to stick together and reduces this motion. 

Castellanos Gil, E., Bataille, B., Iraizoz Colarte, A., Delarbre, J. L., El Ghzaoui, A., and Durand, D. (2008), A sugar cane native dextran as an innovative functional excipient for the development of pharmaceutical tablets. Eur. J. Pharm. Biopharm 68 (2), 319-329. 

If the sensitivity is still not sufficient, then a different detection techniques or analytical technique may need to be employed (for example, LC-MS and fluorescence detection, capillary electrophoresis, ion mobility spectrometry, etc.). These alternate methods and/or detection techniques may have higher sensitivity than HPLC with UV detection. Since the new method will be a simple method (peaks from APl(s) and/or functional excipients), development of these methods should be simple and fast. MS is generally more... 

Hot-melt extruded dosage forms are complex mixtures of active medicaments and functional excipients. The functional excipients may be broadly classified as matrix carriers, release modifying agents, bulking agents, and miscellaneous additives. The selection and use of various excipients can impart specific properties to hot-melt extruded pharmaceuticals in a manner similar to those in traditional dosage forms. 

Foldvari M, Bagonluri M. Carbon nanotubes as functional excipients for nanomedicines I Pharmaceutical properties. Nanomedicine 2008 4 173-182. 

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