Patent Status

The naturally occurring Cyclodextrins have been in the public domain for many years as products of nature. They would not ordinarily be considered patentable subject matter. However; there are many unexpired patents claiming specific complexes of the natural Cyclodextrins with drugs, particularly ß-Cyclodextrin/drug complexes. Given the volume of prior art now existing, the likelihood of finding a new, useful and unobvious - in other words, patentable - natural Cyclodextrin/drug complex is not great.

Although numerous CMCyclodextrins are now known, the possibility of synthesizing new, patentable CMCyclodextrins certainly exists. The patent situation varies for known derivatives and complexes. In the cases of HPB and other hydroxyalkylated derivatives of ß-Cyclodextrin, the derivatives themselves have been known for nearly twenty years and the basic patents have expired. Potentially patentable complexes of HPB and related derivatives with drugs have been developed much more recently, however.

In the USA, the HPB patent scene is dominated by US Patent No 4,727,064 granted to the US Department of Health and Human Services on 23 February 1988. This patent claims compositions containing an amorphous complex of Cyclodextrin and a drug, and a method of producing such a complex from amorphous Cyclodextrins. HPB appears to be the most promising of the amorphous cyclodextrins described in the patent.

Outside the USA and especially in Europe, the dominant patent position with respect to HPB belongs to Janssen Pharmaceutical Co. of Beerse, Belgium. Based on the work of Müller and Brauns, the Janssen European application relates to pharmaceutical compositions containing drugs which are unstable or sparingly soluble in water, complexed with HPB or a related BCyclodextrin derivative. A European patent was issued to Janssen in 1990 with claims narrowed in the light of earlier work by Pitha. An opposition to the Janssen Cyclodextrin patent by at least one European manufacturer of Cyclodextrins was filed but later abandoned.

At the end of 1999, CTD Inc. had more than 4000 patents in its Cyclodextrin Patent database. New patents describing uses for Cyclodextrins enter the literature at about 30 per month. Procter & Gamble has filed and received between 1996 and 1999 at least 100 patents related to the use of Cyclodextrins in laundry and deodorizing applications.

In response to some unreasonable licensing terms regarding HPBCyclodextrin offered by another pharmaceutical company, Pfizer undertook, in the mid 90's to obtain patent protection for another chemical modification of ß-Cyclodextrin (sulfobutylether) for its own use. Patents regarding this derivative have been licensed by Pfizer, but their validity is sure to be tested legally as chemically modified Cyclodextrin's become standard formulation ingredients.