Tablet advantages

Table 11.14 Manufacturing and formulating tablets-advantages and disadvantages. ...

This reaction is first conducted on a chromium-promoted iron oxide catalyst in the high temperature shift (HTS) reactor at about 370°C at the inlet. This catalyst is usually in the form of 6 x 6-mm or 9.5 x 9.5-mm tablets, SV about 4000 h . Converted gases are cooled outside of the HTS by producing steam or heating boiler feed water and are sent to the low temperature shift (LTS) converter at about 200—215°C to complete the water gas shift reaction. The LTS catalyst is a copper—zinc oxide catalyst supported on alumina. CO content of the effluent gas is usually 0.1—0.25% on a dry gas basis and has a 14°C approach to equihbrium, ie, an equihbrium temperature 14°C higher than actual, and SV about 4000 h . Operating at as low a temperature as possible is advantageous because of the more favorable equihbrium constants. The product gas from this section contains about 77% H2, 18% CO2, 0.30% CO, and 4.7% CH. ... 

The advantages of this type of system are that the release rates are independent of the dmg properties, macromolecules and ionic species may be dehvered, fluxes may be high, and release rates are not dependent upon environmental conditions such as pH. The disadvantages are that the system is subject to dose-dumping if it is chewed. It is also more expensive to formulate than coating tablets, and there is a possibiUty of hole plugging. 

The results will also be influenced by the concentration of NaCl solution sprayed —some metals are affected more by one concentration than another — for example, zinc is corroded most by a concentrated brine (20%), while iron is corroded most by a dilute brine (3%) synthetic sea-water is less corrosive to these metals than either brine. In view of the many other ways by which the conditions within a salt-spray box differ from those of exposure to a natural sea-coast environment, there seems to be no great advantage in making-up complicated synthetic sea-waters for use in salt-spray testing. However, tablets for this purpose are commercially available. 

Similar methods with modifications such as the one by Schutz et al.8 have been in use for over 20 years. In 1968, Ferren and Shane9 published a paper on the differential spectrometric determination of caffeine in soluble coffee and drug combinations. It had the advantage of eliminating a preliminary separation that was required by the earlier method. While the method was successful for coffee, it was not as successful in the determination of caffeine in acetaminophen/phenacetin/caffeine tablets. They proposed that phenacetin was a limiting factor. The official AOAC methods for these methylxanthines in coffee and tea still involve similar methods.10... 

Latices and pseudolatices are widely used for the coating of solid pharmaceutical dosage forms such as tablets, capsules, and pellets. The major advantage compared to conventional coating techniques is the avoidance of organic solvents. 

Liquid paraffins, particularly those of low viscosity, have been used and are said to be of value for colored tablets, and even the use of modified vegetables has been attempted. However, they appear, in general, to offer little advantage over solid lubricants, and their incorporation into the precompression mixture is more difficult, requiring solution in a volatile liquid that is then sprayed onto the unlubricated material. Due to handling and EPA requirements, these materials are often rejected in the preformulation stage. 

The convective diffusion equations presented above have been used to model tablet dissolution in flowing fluids and the penetration of targeted macro-molecular drugs into solid tumors [5], In comparison with the nonequilibrium thermodynamics approach described below, the convective diffusion equations have the advantage of theoretical rigor. However, their mathematical complexity dictates a numerical solution in all but the simplest cases. 

Consumer relevant characteristics of tablets are easiness of dispensing and convenience in handling, i.e., no dosing and dispensing aids are needed. Other advantages include precise dosing and smaller packages compared to powder products, due to their concentration. 

This technology can also be applied for pre-dosed detergents like tablets [79], which offer the advantage of an easier determination of detergent already fed into the washing tub. 

These advantages can only be significant if the tablets are considerably stable and hard. They must be hard enough to withstand mechanical stress by packag-... 

Laser ablation ICP-AES and LA-ICP-MS were also proposed for rapid, direct analysis of tablets containing metallic species.194 Compendial heavy metal tests based on wet chemistry are among the most labor-intensive tasks in pharmaceutical laboratories. Both ICP-MS and ICP-OES have been proposed as alternatives for compendial methods and have the advantages of smaller sample size, element-specific information, quantitation, rapid sample throughput, and significantly improved accuracy.195-198... 

---