Prosyma Research Ltd report to Hoechst-Roussel Ltd

S F Bush

Introduction

In 1990-91 Roussel established a process at Rouvex in Northern Ireland for producing toroidal rings of around 56 mm diameter.

The rings consist of a core of diameter d_c surrounded by a sheath of thickness h. In the 1990 process d_c was 2 mm and h was 3.75 mm. The core contains 5 mg of particles of the drug levonorgestrel embedded or dissolved in a mixture of N-propyl silicate and a siloxane polymer (silastic X7-3099) with 0.5% stannous octoate catalyst and 2% barium sulphate. The sheath consists of the same mixture minus the drug and the barium sulphate and acts as a controlled release diffusion barrier. The rings are made in a sequence of three injection mouldings. The writer provided advice on optimizing the process at Rouvex (November 1990) and gave a review of alternative methods of manufacture to Roussel staff at Swindon (August 1990).