Pharmaceutical Technology: Controlled Drug Release, Volume 2
Pharmaceutical Technology: Controlled Drug Release, Volume 2
Pharmaceutical Technology: Controlled Drug Release, Volume 2
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13<br />
A comparison of dissolution properties from matrix tablets<br />
prepared from microcapsules and mixtures containing<br />
phenobarbitone and poly(DL-lactic acid)<br />
Biljana Oraceska, Reza Ul Jalil and J.R.Nixon<br />
Chelsea Department of Pharmacy, King’s College London, Manresa Road, London SW3<br />
6LX, UK<br />
SUMMARY<br />
Microcapsules for use in the preparation of sustained release formulations have been under<br />
investigation for a number of years without any great success. There is an initially rapid release,<br />
due to the porosity of the wall coupled with the effect of wall saturation, which builds up during<br />
long storage. Compression has provided formulations with better sustained release characteristics.<br />
The materials traditionally used for the walls have been non-biodegradable and this meant that<br />
only the oral route has been available.<br />
The present study investigates a biodegradable polymer, poly(DL-lactic acid) (DL-PLA), as the<br />
microcapsule wall. Tablets of microcapsules prepared with this method should be capable of use as<br />
subcutaneous implants. Three different compression forces, 2, 5 and 10 kN, were used, with<br />
core:wall ratios of 1:1 and 2:1. For comparison, the same proportions of drug and coating polymer<br />
were compressed without prior microencapsulation.<br />
The release of the drug phenobarbitone (PB) from tablets prepared using simple mixtures of DL-<br />
PLA and PB, as well as from the corresponding tablets from microencapsulated PB, is reported.<br />
These results are compared with release from the original microcapsules.<br />
INTRODUCTION<br />
Oral administration is a relatively safe route for sustained action drug delivery. Oral delivery<br />
allows the use of either tablets or capsules [1]. A wide range of techniques is available for their<br />
preparation.