Drug in Focus May 2006: Finasteride

Later this year several US patents covering the active ingredient Finasteride (Proscar, Propecia) will expire in the US, whereas equivalent patents in Europe will expire 12 months from now.  Based on information contained in the GenericsWeb Pipeline Selector report for Finasteride, this month’s Drug In Focus analyses the patent landscape surrounding this product with a view to launching generic equivalents.

The Finasteride General Information (Table 1) shows that Finasteride-containing products are generally indicated for treatment of Male Pattern Baldness/Androgenic Alopecia (Propecia) and of Benign Prostatic Hyperplasia (Proscar).  These different branded products account for the oral dosage forms containing 1mg and 5mg respectively of the Finasteride base compound.

Table 1: Finasteride General Information

 

The Key Patent Indicator (Table 2) for Finasteride shows that a number of patent families protect the Merck branded products making development of non-infringing generic equivalents a complex task for those companies eager to launch immediately following molecule patent expiry.

Table 2: Finasteride Key Patent Indicator

The molecule patent family for Finasteride is very complex, however the Key Patent Indicator expiry analysis for this family distils the array of patents into a concise summary that confirms which patents are directly relevant to Finasteride and when they expire.  Analysis shows that this family affords two levels of patent protection in each territory, one covering the molecule per se and the other covering its use in the treatment of Androgenic Alopecia.  In the US and Europe, we can confirm that the Androgenic Alopecia indication benefits from longer protection, implying that early generics will only be in the form of 5mg tablets indicated for BPH; whereas the molecule patent has the longer protection in Canadian and Australian territories.

The Key Patent Indicator also highlights that the Propecia product benefits from further protection of the dosing regimen until 2013 or 2014, which is likely to see non-authorised 1mg generic products constrained until much later than expiry of patents found in the molecule patent family.  This, of course, is subject to any litigation that may ensue in regard these patents and the terms of subsequent settlements with generic competitors.

The Key Patent Indicator identifies a family relating to polymorphic forms of Finasteride. Analysis of these patents reveals that Merck have so far been unsuccessful in patenting the polymorphic forms I and II ‘per se’ across Europe, but an application is still pending with claims to this effect.  However, certain polymorphic forms are already protected by US and Australian patents.  The Patent Category Distribution graph (Figure 1) demonstrates that generic competitors are circumventing these polymorphic form protection issues by developing and patenting their own molecular forms.  These patents represent nearly 15% of the total number of patents relevant to development of generic Finasteride products.

Figure 1: Finasteride Patent Category Distribution 

The Patent Category Distribution graph combined with the Patent Filing Trends graph (Figure 2) further shows that the problems in developing generic Finasteride products will not stop at molecular form and indications for use.  Process patent applications represent nearly half of all filings for this product, a significant portion of which are filed in the last five years.  Sourcing API that is manufactured by a non-infringing route is therefore a task that should involve careful consideration of these patents and applications, resulting from comprehensive searching, at an early stage in the negotiations.

Figure 2: Finasteride Patent Filing Trends