Enteric coated systems differ from conventional preparations, which disintegrate and release their drug loads in the stomach, so the time to onset for an enteric coated dosage form is longer, and dependent on its gastric residence time. This parameter varies widely, depending on the nature of the dosage form, the stomach contents, and any concomitant medication the patient may be receiving. Dosage form size has a major influence on emptying rate. Particles less than 1-2 mm in diameter are emptied rapidly during a meal, with the liquid phase. They also empty rapidly on an empty stomach with the liquid used to ingest the dose. Larger particles are retained during digestion, and empty during Phase 3 of the interdigestive period. Examination of the literature suggests that to overcome the variability in onset times, large tablets should be taken at least one or two hours before a meal, with a small amount of water, and pellet formulations should be taken with a large volume of water or a meal, unless food adversely affects the bioavailability of the drug.