1.1 Oral Drug Delivery System:
Oral route is the most common route of drug administration. Modern drug delivery strategies try to improve oral drug delivery.1 When a new drug is discovered, a pharmaceutical industry asks one of the first questions is whether the drug can be effectively administered for its intended effect by the oral route or not. If patient self administration cannot be achieved, the sale of drug constitute only small fraction of what the market would be otherwise. Tablets and capsules represent unit dosage forms in which one usual dose of drug has been accurately placed. By comparison, liquid oral dosage forms such as syrups, suspensions, emulsions, solutions and elixirs are usually designed to contain one …show more content…
Pellets reduce variation in gastric emptying time.
4. They provide tremendous flexibility in development of oral dosage form.
5. It allows combined delivery of two or more bioactive agents that may not be compatible, at same site or at different site in gastrointestinal tract.
6. It also permit combination of pellets of different release rates of same drug in single dosage form.
7. It is easy to obtain uniform and reproducible fill weights in capsules.
8. Pellets can also be made attractive due to various shades of color that can be imparted.
1.9.2 THEORY OF PELLET FORMATION AND GROWTH 38,39 Different theories have been postulated related to the mechanism of formation and growth of pellets. Some of these theories are derived from experimental results while others are confined to visual observations. As the conventional granulation, the most thoroughly studied, most classified pelletization process, which involves a rotating drum, a pan or a disc, has been divided into three consecutive regions: nucleation, transition and ball growth. However, based on the experiments carried on the mechanism of pellet formation and growth, the following steps were proposed: nucleation, coalescence, layering and abrasion …show more content…
Coating pans are less expensive than most other types of pelletization equipment. They are also extremely versatile in that both layering and pellet coating. Coating pans are available in a wide variety of shapes and sizes. Pear, hexagonal, angular, spherical, elliptical, and donut-shaped. Pellet movement is best described as cascading, with maximum turbulence in the centre of the load. Conventional coating pans, however, have significant limitation as pelletization equipment. The degree of mixing is very poor, and the drying is not efficient. Mixing is a function of the pan shape, the tilt angle, the baffle arrangement, and the rotational speed of the pan itself. These parameters must be optimized to provide uniform drying and sufficient particle movement to eliminate the potential formation of dead spots during the operation and to maximize yield. For instance, during pelletization elliptical pans tend to have fewer stagnant spot than do cylindrical pans and, consequently the equipment of choice. Reducing the tilt angle can also minimize formation of dead spots. If the rotational speed of the pan is too slow, segregation may occur owing to percolation and induce the preferential layering of the drug onto larger