Method of producing an oral osmotic pharmaceutical delivery system and a pharmaceutical batch produced using the same

A method of producing a pharmaceutical batch of a controlled release pharmaceutical solid dosage form comprising a core comprising an active pharmaceutical ingredient, said core surrounded by a semi-permeable membrane comprising cellulose acetate, the method comprising:

• (a) selecting an amount of the active pharmaceutical ingredient for a solid dosage form;
• (b) producing a batch of cores, each comprising the active pharmaceutical ingredient in the selected amount;
• (c) obtaining a lot of cellulose acetate;
• (d) determining a content of acetyl in the obtained lot;
• (e) determining an effective coating amount based on the selected amount of the active pharmaceutical ingredient and the determined content of acetyl from statistical data for previously produced pharmaceutical batches for the selected amount of the active ingredient;
• and (f) for each core of the batch of cores, forming around the core a semi-permeable membrane coating using the effective coating amount determined in step (e).