Menarini’s Priligy (Dapoxetine HCl) Use Patent held Not Valid as being Obvious

Menarini launched Priligy in Korea. Dapoxetine HCl is the active ingredient in Priligy tablets. Korean patent No. 719, 977 covers the branded products and is listed in Green List of KFDA. The patented invention is “Methods of Using Rapid-Onset Selective Serotonin Reuptake Inhibitors for Treating Sexual Dysfunction.” The patent at issue is not for a compound invention but for the second use invention. The Korean patent for the second use invention will expire on June 5, 2021. Several Korean generic companies filed invalidity proceedings to challenge the second use patent. Menarini will face generic companies’ challenges soon.

On August 23, 2013, the IPT of KIPO held that the patent in issue is not valid because the compound and its use have been disclosed in the prior art. There has been no challenge to the compound patent so far. The key issue for the second use patent was a new limitation of “on as as-needed basis” in claim language. The patentee argued that such a new limitation was not found in the prior art and made the claimed use invention being novel and nonobvious over the prior art. However, the IPT rejected the argument on the ground that such limitation is related to a method of administering a drug and thus such limitation may not be regarded as an element for a patent claim under Korean patent law.

The patentee appealed the IPT decision to the Patent Court and the case is pending.

Low Dose Entecavir Formulation in Korean Patent held as being Obvious by the IPT of KIPO

Entecavir is the active ingredient in Baraclude tablets of BMS. The drug has been sold for the treatment of chronic hepatitis B virus infection in Korea. When Korean generic companies noticed that a US district court found that entecavir would have been obvious in light of the prior art, they filed an invalidity trial to challenge the validity of the corresponding Korean compound patent, too. The invalidity case is pending in the IPT of KIPO.

On the other hand, Baraclude is covered by another patent for low dose formulation of entecavir. Several companies including those want to launch generic versions of Baraclude after expiry of extecavir compound patent, filed separate proceedings to challenge non-obviousness of law dose formulation over the prior art. The subject Korean patent is No. 757,155 that claims low dose entecavir formulations of 0.5mg or 1.0 mg for the treatment of chronic hepatitis B virus infection. The prior art discloses enetcavir compound, its use, a range of doses and animal test data, but did not disclose claimed doses.

On April 30, 2013, the IPT held that low dose entecavir formulations of 0.5mg or 1.0 mg should be regarded being obvious over the prior art. To the IPT decision, the patentee BMS appealed to the Patent Court and argued that a person of ordinary skill could have neither anticipated nor determined the claimed low dose formulations of 0.5mg or 1.0 mg entecavir from the prior art. Oral hearings were held two days for expert witness examination and BMS’s expert argued at the Patent Court that determining specific doses for human required numerous trials. The panel of 3 judges in the Patent Court will decide the case on March 14, 2014.