Formulation and Evaluation of Sustained Release Tablets of Timolol Maleate

Abstract

Timolol maleate tablets were prepared by wet granulation method to study the effect of method of manufacture on the drug release. Drug and the diluent (MCC or Lactose) were sifted and mixed well to ensure the uniformity of premix blend. Most conventional oral drug products, such as tablets and capsules, are formulated to release the active drug immediately after oral administration, to obtain rapid and complete systemic drug absorption. Such immediate-release products result in relatively rapid drug absorption and onset of accompanying pharmacodynamic effects. However, after absorption of the drug from the dosage form is complete, plasma drug concentrations decline according to the drug's pharmacokinetic profile. Eventually, plasma drug concentrations fall below the minimum effective plasma concentration (MEC), resulting in loss of therapeutic activity. Before this point is reached, another dose is usually given if a sustained therapeutic effect is desired. An alternative to administering another dose is to use a dosage form that will provide sustained drug release, and therefore maintain plasma drug concentrations, beyond what is typically seen using immediate-release dosage forms. In recent years, various modified-release drug products have been developed to control the release rate of the drug and the time for drug release.
Keywords: Minimum effective plasma concentration (MEC), Drug release, Wet granulation method, Lactose, Therapeutic effect.