A method of producing a batch of a tetracycline-class component HPMC extended release pharmaceutical product having a desired dissolution profile, comprising: selecting a dissolution rate-controlling polymer comprising an HPMC component, the HPMC component having a selected % HP value; validating that the % HP in the selected HPMC component is such that a mean sample of the product complies with the desired dissolution profile over each time point in the dissolution profile, and preparing the product by preparing a formulation comprising a pharmaceutically effective amount of the tetracycline-class chemical and the selected HPMC component with the % HP value. There is also provided a method of predicting the dissolution rate profile over a number of dosage forms.