Despite advances made in drug delivery technologies, current oral drug administration methods have only limited use for a variety of important drugs that are mainly absorbed in the upper part of the small intestine, hence  are known to have a “narrow absorption window”.

Drugs that pass their absorption window will not be absorbed. For such drugs, existing controlled-release dosage forms do not provide an answer, as they do not keep the drug near its absorption site. Only retaining the drug in the stomach (gastric retention), above and near the absorption site, for prolonged period of time, could significantly improve the pharmacokinetics and the pharmacodynamics of these drugs.

Drugs that are relevant for gastric retention, meet one or more of the following criteria:

• Absorbed mainly in the upper GI tract
  
  
• Absorbed through active transport mechanisms
  
  
• Significant ADR are due to fluctuations in plasma levels
   
• Acting locally in the GI tract
  
  
• Possess a pharmacological rationale to reduce exposure  in the distal GI region