Abstract: The present invention relates to an improved oral pharmaceutical composition containing at least one poorly water soluble active agent, the active agent containing at least one of an endothelin conversion enzyme (ECE) inhibitor and a neutral endopeptidase (NEP) inhibitor in an amount greater than 10% w/w of the composition, and an alkali system comprising a mixture of at least two alkaline compounds in a ratio of from 1:20 to 20:1. The present invention also relates to an improved oral pharmaceutical composition containing, SLV-306 or at least one pharmaceutically acceptable salt, ester, hydrate, solvate, isomer or derivative thereof, as an active agent, and an alkali system in an amount greater than 10% w/w of the composition comprising a mixture of at least two alkaline compounds and optionally at least one pharmaceutically acceptable excipient. The present invention further relates to a process for preparation of such improved compositions and methods for treatment using such compositions.