Coating level

In pharmaceuticals, NIR is used for, of course, moisture, polymorphic (drug) forms, percent crystallinity, isomer purity, tablet/capsule assay, coating levels, evaluation of dissolution times, and numerous process tests. It is a rapid means for the Food and Drug Administration to check for counterfeit drugs, and for the Drug Enforcement Agency to ascertain what type of materials are impounded in drug raids. ... 

Prior work related with shutdown separators also involved application of waxes on membranes." " In these cases, the wax or low melting polymers were coated on the polyolefin separator. The disadvantage of this technique is that the coating can block the pores of the separator and thus can affect the performance by increasing separator resistance. Moreover, the coating level has to be very high to get complete shutdown. 

In this context, diffuse reflectance FTIR spectroscopy has been applied to analyze the influence of mixing variables (i.e. treatment concentration, time and temperature of mixing) on both the ultimate flller coating level and possible reaction between the treatment and flller surface [127]. 

It is critical, during initial process development, to give serious consideration to the amount of material that will be applied (especially for processes involving drug layering or those involved with the application of modified-release coatings to fine particle products, where required coating levels in excess of 50% are not uncommon). Key factors to be established are ... 

When you consider the different columns that can be produced by controlling hydration, bonding agent, coating levels, and end-capping, it is not hard to understand the variations in C18 columns coming from different manufacturers. 

FIGURE 5-27. Effect of column surface upon retention of organic amines ( ) separation on a fully coated C]8 column, (b) Separation on a column with 50% coating level of C18. (c) Separation on a column of silica. The mobile phase is acetonitrile/ water (60 40) with 4 mM dibasic ammonium phosphate (pH 7.8). The sample components are (1) benzocaine, (2) lidocaine, (3) etidocaine, and (4) tetracaine. (Reprinted from reference 4 with permission.)... 

Fig. 6 Pulsatile drug delivery system based on coated effervescent cores—influence of the coating level (7% and 15%w/w) and hardness (50 and 100N) on the drug release/ lag time (coating, EC/DBS core, 30%w/w, effervescent agents, microcrystalline cellulose). (From Ref...

Tang, L. Schwartz, J.B. Porter, S.C. Schnaare, R.L. Wigent, R.J. Drug release from film-coated chlorpheniramine maleate nonpareil beads effect of water-soluble polymer, coating level, and soluble core material. Pharm. Dev. Technol. 2000, 5 (3), 383-390. 

Dredin, J. Zelkb, R. Antal, I. Bihari, E. Ricz, I. Effect of particle size and coating level on the diffuse reflectance of wax matrices. J. Pharm. Pharmacol. 1998, 50, 139-142. 

FIGURE 4 Effects of the plasticizer level and curing conditions (indicated in the figure) on theophylline release from pellets coated with HPMCAS in O.IM HCI (20% coating level). Ahhreviation HPMCAS, hydroxypropyl ntethylcellu-lose acetate succinate. Source From Ref. 46. 

FIGURE 10 Effect of (A) plasticizers and (B) curing on the propranolol HCl release in 0.1 N HCI from Kollicoat SR 30 D-coaied pellets (15% coating level). Source From Ref. 78. 

Results published by Kirsch and Drennen in 1995 [87] suggest that valuable information about the tablet core can be obtained through the film coat, permitting nondestructive analysis of coated dosage forms for potency, hardness, and other parameters. Likewise, the NIR method provided an accurate measure of coating levels. 

The initial coating levels are based on the binding capacity of the microtiter plate (1, 2, 5, and lOpg/mL). 

In summary, in the DS process titania particles are exposed to an increasing concentration of monomeric silica species, and, depending on the coating level required (i.e., the total amount of silica added) this... 

However, there are inherent disadvantages due to additional raw materials and extra process costs. Furthermore process control is more difficult and the total wash coat deposit feasible on a unit basis is much reduced. In consequence this provides an artificial and undesirable limitation on activity, durability and poison resistance. In response to these limitations, a new process has been developed which minimises surface interactions without resort to precoats. The data shown in Fig. 9 indicate that this technology enables the benefits of stabilised high wash coat levels to be achieved without adverse impact on thermal shock characteristics. 

For a 100 pm core particle (1.6 g/cc core density) with a 10 pm thick coating (1.0 g/cc coat density), the coating would be 42.1% of the final particle by volume and 31.3% of the final particle by weight. These relationships can be rearranged to estimate the coat thickness for a given coat level and particle size. 

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