Some people say that there are "pernicious myths" circulating about patents, pharmaceutical patents in particular, and that a "demystification" needs to take place. We couldn't agree more. In this chapter we will present some of the issues that most commonly arise on the subject of pharmaceutical patents. The general theme to bear in mind is diversity: different countries have the flexibility to adopt different options in designing their patent systems to best suit their own needs. What works for an OECD country may not work for a least developed country. A patent may be granted for an invention in one country, yet it may be perfectly legally rejected in another. A patent that has been granted in a country may be revoked if it turns out the patent office should not have granted it.

The way a patent is constructed is examined in Annex B with the help of a practical example: a patent for stavudine, a drug used in AIDS combination therapy.