In response to Wilbert's request I will attempt to briefly explain the
patent issues that I understand and hopefully not confuse anyone. In
nearly all countries patent life starts at the date of filing of the patent
and runs for 20 years. Patents can be issued for the product itself, the
process by which the product is made and the use to which the product is
put. There can also be more than a single patent on a product and these
patents are not necessarily filed at the same time. Therefore, it may take
more than 20 years before a generic equivalent can be marketed. In Canada,
for example, 75 products have 2 patents, 55 have 3-5 patnets, 10 have 6-10
patents.
In the USA, EC and Japan there is also something known as patent life
restoration or extension which means that companies can get an extra period
of patent protection to make up for some of the time that a drug spends in
the regulatory approval process. In each of these three countries this
period is up to 5 years. According to figures from the pharmaceutical
industry the effective patent life (i.e. the length of time for which a
product is in a monopoly position once it is on the market) is 14 years in
the USA, and 15 years in the EC and Japan. (I suspect that these figures
are an underestimate.) Companies also engage in what is called
"evergreening" their patents. This is an attempt to extend the effective
patent life on their products. There are a number of strategies for this:
1) New Dosage Form-changing the doage form of the original product from
say standard release to modified release. The new dosage form gets a new
patent.
2) Processes and Intermediates-Taking out patents which cover the
synthesis of intermediates of a particular active ingredient. These
patents on the intermediates expire after the patent on the final product.
3) Polymorphs-The company takes out a patent on a polymorph-the same drug
but in a different crystal form. A well known example of this is ranitidine
which can be made in two forms, Form 1 and Form 2. The patents for the
different forms expire at different times.
4) Metabolites-A brand name company first discovers the molecule then
later discovers that it is acutually a metabolite which has therapeutic
activity in the body. The company may then seek a patent on the
metabolite.
Hope this is helpful.
Joel
Joel Lexchin MD
121 Walmer Rd.
Toronto, Ontario
CANADA M5R 2X8
Phone: (416)-964-7186
Fax: (416)-923-9515
E-mail: joel.lexchin@utoronto.ca
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