Liquid-suspension controlled-release pharmaceutical composition

A method of ensuring naproxen plasma levels higher than 18 .mu.g/ml for at least 24 hours in a patient in need of such treatment, comprising administering to said patient once daily a controlled-release pharmaceutical dosage form, wherein said dosage form comprises:

• a multiplicity of microgranules containing naproxen as an active ingredient and at least one excipient, said microgranules having substantially no controlled-release properties prior to coating,
• a series of successive polymeric coatings that coat said microgranules, comprising:
• a first coating applied directly to the microgranules, at least said first coating imparting controlled-release properties to said microgranules, said coating comprising polyethylene glycol as one ingredient thereof;
• a second coating with hydrophilic characteristics;
• a third applied coating with lipophilic characteristics;
• and
• an outermost coating with hydrophilic characteristics, at least said outermost coating imparting resistance of said microgranules to dissolution in gastric fluids;
• said microgranules after coating having sizes ranging from 50 to 500 .mu.m.