Diseases which affect gastric motility and emptying are predominantly diseases of the gastrointestinal tract itself, disorders involving smooth muscle and extraintestinal diseases. Some diseases only affect one of the phases of gastric emptying. Generally duodenal ulcer produces accelerated emptying, while gastric ulcer reduces antral motility, producing normal emptying of liquids but delayed emptying of solids50. Emptying of a solid meal is slowed in patients with pernicious anaemia51 and atrophic gastritis52, but in achlorhydric patients liquids empty rapidly53.
Gastro-oesophageal reflux is a common disease affecting between 10 and 20% of the general population54, although the true magnitude of the condition is not known since a large proportion of sufferers self-medicate55. It is therefore likely that within a given patient group a significant proportion will be suffering from this disease to some extent. The effect of this disease on gastric emptying is unclear since some studies report no effect on the emptying of liquids56 or mixed meals57, whilst others demonstrate a delay58-60. It is possible that the emptying of solids in a mixed meal is selectively delayed61 suggesting impaired antral motility. This would lead to a greater difference in emptying between liquids, pellets and tablets than in normal subjects.
Migraine is frequently associated with nausea (95%) and vomiting (20%) and there is some evidence that gastric emptying is delayed during migraine attacks.
The eating disorders bulimia nervosa and anorexia nervosa are believed to affect between 5 and 10% of adolescent females and young women in the western world. Bulimia does not affect gastric emptying, but anorexia produces both delayed solid and liquid emptying62.
The most commonly used type of dosage form is the conventional compressed tablet. Despite the use of scintigraphy to evaluate more sophisticated dose forms63, there has been surprisingly little study of the behaviour of ordinary tablets. Most workers assume that tablets will disintegrate rapidly in vivo due to the use of superdisintegrants and the evidence
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