There are currently drugs in development that have one of the above various modes of action. These drugs are in various stages of development from pre-clinical laboratory testing through to clinical evaluation. The most advanced microbicide therapy that is in the final stage (Phase 3) of clinical testing is Carraguard. This drug acts by blocking the attachment of the HIV virus to the host target cells. Microbicide therapies that are one stage back in the development process (Phase 2/3) are BufferGel, a acid buffering agent that maintains a low virucidal pH in the vagina, and Pro-2000, which like Carraguard, blocks the attachment of HIV to host target cells. It is predicted that there may be some microbicides available for use by the end of this decade.

Apart from the challenge of developing a microbicide that scientifically is effective there are other ongoing challenges in actually getting a microbicide to the market and to the people who need them. These challenges include overcoming major constraints in development costs as microbicides must be:

• cheap rather than expensive,

• able to be manufactured in sufficient quantity,

• must be stable over a certain range of temperatures and pH

• must be usable i.e. convenient and socially acceptable

One thing is clear and that is that there is an urgent need for microbicides and that getting an effective microbicide to market involves a huge amount of effort and cost from both scientists and drug developers.