There is a study "Update: Pharmacologic Vitreolysis" in the January 2011 Review of Ophthalmology page 38-40. It is an EXPERIMENTAL study that used a chemical injected in to the vitreous to liquify it. The study was to relieve vitreo-retinal traction and treatment of macular holes and it was usefull for that. However it was not used for regular annoying floaters, indeed floaters and flashes sometimes increased after injection.
The use of medication to get rid of regular floaters by injection of chemicals into the back of the eye in not at all likely to occur in the next few years due to costs and risks.
For other reasons it is likely treatment will become available in the future.
JCH MD