Capitalized Fees paid to a Related Party

3 Months Ended

Mar. 31, 2015

Capitalized Fees paid to a Related Party

Capitalized Fees paid to a Related Party

5. Capitalized Fees paid to a Related Party

Capitalized fees paid to a related party, which consist of registrational and launch-related milestone fees paid to GSK, were as follows:

March 31, 2015

December 31, 2014

Weighted

Average

Remaining

Amortization

Gross

Net

Gross

Net

Period

Carrying

Accumulated

Carrying

Carrying

Accumulated

Carrying

(In thousands)

(Years)

Value

Amortization

Value

Value

Amortization

Value

Approval and launch related milestone payments under the LABA Collaboration

14.8

$

220,000

(15,265

)

$

204,735

$

220,000

(11,809

)

$

208,191

These milestone fees are being amortized over their estimated useful lives commencing upon the commercial launch of the product in their respective regions with the amortization expense recorded as a reduction in revenue from collaborative arrangements. Additional information regarding these milestone fees is included in Note 3, “Collaborative Arrangements.” Amortization expense for the three months ended March 31, 2015 and 2014 was $3.5 million and $1.8 million, respectively. The remaining estimated amortization expense is $10.4 million for 2015, $13.8 million for each of the years from 2016 to 2020, and $125.3 million thereafter.