or by rupturing due to the application of ultrasonic forces many of the current applications for microcapsules require them to be easily ruptured under pressure as in the case of carbonless copy paper typically the microcapsules would be on the order of from 2 to 100 microns in diameter the drug within the microcapsule will typically be in solution or otherwise dispersed throughout the polymer of the microcapsule however since it is possible to microencapsulate crystals drug crystals may be employed in such cases the microcapsule may present sharp angles which will easily become embedded and fixed to the artery wall when the balloon is inflated when referred to herein 34 microcapsule 34 shall include microspheres the release mechanisms from the microcapsules may include any of the existing release mechanisms such as those described by robert langer in 34 new methods of drug delivery 34 science vol 249 28 sep 1990 pp 1527 1533 the viscous matrix material of the present invention can be any viscous tacky material which is biocompatible and may be bioabsorbable or bioerodeable and which provides a chemically compatible carrier for the chosen drugs or drug containing microcapsule bioabsorbable waxes pastes or gels could be made from materials such as polyvinyl pyrrolidone proteins e g albumin fibrinogen fibrin gelatin fats carbohydrates e.