Excipient cellulose derivatives used

Sakellariou P, Rowe RC, White EFT. The thermomechanical properties and glass transition temperatures of some cellulose derivatives used in film coating. Int J Pharm 1985 27 267-277. Callahan JG, Cleary GW, Elefant M, et al. Equilibrium moisture content of pharmaceutical excipients. Drug Dev Ind Pharm 1982 8 355-369. 

Polyelectrolytes (most notably ionic cellulose derivatives and crosslinked polyacid powders) are also commonly used as matrices, binders and excipients in oral controlled release compositions. In these applications, the polyelectrolytes provide hydrophilicity and pH sensitivity to tablet dosage forms. Acidic polyelectrolytes dissociate and swell (or dissolve) at high pH values whereas basic polyelectrolytes (for instance, polyamines) become protonated and swell at low pH. In either case, swelling results in increased permeability [290], thereby allowing an incorporated drug to be released. 

Research on nasal powder drug delivery has employed polymers such as starch, dextrans, polyacrylic acid derivatives (e.g., carbopol, polycarbophil), cellulose derivatives (microcrystalline cellulose, semicrystalline cellulose, hydroxypropylmethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose), chitosan, sodium alginate, hyaluronans, and polyanhydrides such as poly(methyl vinyl ether-co-maleic anhydride) (PVM/MA). Many of these polymers have already been used as excipients in pharmaceutical formulations and are often referred to as first-generation bioadhesives [38-45], In nasal dry powder a single bioadhesive polymer or a... 

Solid formulations for sustained drug release may contain mesogenic polymers as excipients. The mesogenic polymers form a matrix, which is usually compressed into tablets. Some of the most frequently used excipients for sustained release matrices include cellulose derivatives, which behave like lyotropic liquid crystals when they are gradually dissolved in aqueous media. Cellulose derivatives such as hydroxy-propyl cellulose or hydroxy-propylmethyl cellulose form gel-like lyotropic mesophases in contact with water, through which diffusion takes place relatively slowly. Increasing dilution of the mesophase with water transforms the mesophase to a highly viscous slime and then to a colloidal polymer solution. 

Similar analyses of moisture uptake data available in the literature for other cellulose and starch derivatives used as pharmaceutical excipients are presented in Table 5. Considering the uncertainties associated with the estimated moisture uptake values from published graphs, the values of are all quite consistent with each other and with a stoichiometry of one water molecule per anhydroglucose unit. It is interesting to note that the two samples derived from cellulose, sodium carboxymethylcellulose and sodium croscar-mellose, did not require any correction for degree of crystallinity to conform to close to a 1 1 stoichiometry. It appears quite likely, therefore, that the change in chemical structure and the processing of these materials essentially eliminates the crystallinity of cellulose. 

Subsequently, the BPI provides a Ust of all active substances and excipients, in a way that defines their identity and quality unambiguously. For example, it should be clear if the free active substance has to be used or the salt form, or, when multiple hydrates exist, which hydrated form is required (see Sect. 23.1).To define the quality of the raw materials it is advisable to use their pharmacopoeial names wherever possible. Preferably, additional specifications (Functional related characteristics, FRCs) which are not mentioned in the monograph that distinguish between different qualities, are added to the name of the raw material. Examples are the particle size of a solid material, the viscosity of a liquid or a cellulose derivative, or the concentration of a solution. Sometimes a brand name reflects the quality better (e.g. Witepsol H15 instead of Adeps solidus). If confusion may stiU be possible (crystal water, salt forms), addition of the chemical formula might be useful. 

SEPIFILM 003 and 752 The association of cellulose with a film coating agent was originally patented by SEPPIC. Microcrystalline cellulose is probably one of the most extensively used excipients in pharmaceutical and nutritional products. Unlike other fillers, such as lactose, cellulose is inert, vegetable derived, and accepted worldwide and its shelf life is unlimited. Figure 31 shows the advantage of cellulose microcrystalline in film coating. 

Due to their large surface area for adsorption, porous materials are useful excipients for solid dispersions. For example, 2-naphthoic acid (2-NPA) solid dispersion with porous crystalline cellulose (PCC) has been successfully prepared by heat treatment of 2-NPA and PCC mixture. " PCC is derived from MCC, but with a larger surface area. Different from 2-NPA mixed with PCC, 2-NPA mixed with MCC still maintained a crystalline form under the same mixing and heating conditions. Various experimental data such as X-ray powder diffraction, Fourier transform infrared (FT-IR) spectroscopy, and solid-state fluorescence measurements suggest that 2-NPA is adsorbed onto the surface of PCC and becomes molecularly dispersed into the system. 

Cellulose is the most abundant organic material found in nature (13). It is the primary component of plant cell walls and is therefore a large constituent of fruits and vegetables. Since cellulose is safe for human consumption, it is commonly used as an additive in food products. Cellulose and chemical derivatives of cellulose are also widely used as excipients in pharmaceutical applications. The biocompatibility of cellulose coupled with a molecular structure that is conducive to chemical modification, has made cellulose a staple of pharmaceutical formulations. Each anhydroglucose unit of the cellulose backbone contains three hydroxyl groups that provide reactive sites for chemical substitution. Thereby, cellulose can be chemically modified in a variety of ways to yield materials with differing properties useful for diverse pharmaceutical applications. 

Cellulosic membranes are developed as a novel dmg delivery system, which is expressed to use on the skin and used as a mucus membrane of stomach, ear, nose, eye, rectum, and vagina. The goal excipients of these preparations are adhesive and film-former polymers. Modified cellulose, especially cellulose ethers, are extensively applied in bio-adhesives such as nasal, vaginal, ocular, buccal, and transdermal inventions only or by blend with additional polymers. Further newly applied ethers of cellulose in bio-adhesives contain anionic ether derivatives such as sodium carboxy-methyl cellulose (NaCMC) and non-ionic cellulose ethers such as hydoxypropyl cellulose (HPC), carboxymethyl cellulose (CMC), hydroxyethyl cellulose, ethyl cellulose (EC), hydroxylpropylmethyl cellulose (HPMC), or methyl cellulose (MC). Capability of polymer to absorb water from mucus and pH of objective area are main features defining the adhesive power of polymers. One benefit of cellulose ethers, such as HPC and NaCMC, is smaller dependence of adhesion period and their adhesion strength to pH of medium than thiolated bio-adhesive polymers and polyacrylate... 

---