CONJUGATED ESTROGENS BIOEQUIVALENCY ISSUES

CONJUGATED ESTROGENS BIOEQUIVALENCY ISSUES will be discussed by FDA's Fertility and Maternal Health Drug Products Advisory Committee at its Jan. 5-6 meeting, FDA said. The agency will ask the committee to consider whether urinary excretion studies are adequate to determine the bioequivalency of generic estrogens in lieu of blood level studies. The issue is ripe for committee review because FDA recently rejected an estrogen ANDA from Barr Labs that was based on urinary excretion studies. Barr Labs recently filed a request for an FDA administrative hearing on the agency's refusal to approve the ANDA. The agency has not yet made a decision on whether to grant the hearing request. FDA Center for Drug Evaluation and Research (CDER) Director Carl Peck, MD, denied Barr's application because the bioequivalence data was based on urinary excretion studies and did not show the rate of absorption of the estrogens through blood level studies. The company had a meeting with Peck on Sept. 19 to discuss the urinary excretion data ("The Pink Sheet" Sept. 26, T&G-10). Earlier this summer, FDA indicated to generic companies that it had decided to accept only blood level studies in support of estrogen ANDA approvals with AB(therapeutically interchangeable) ratings. Barr made an appeal to FDA Commissioner Young, at an Oct. 14 meeting, to overturn Peck's denial of the application. Reportedly, Barr is appealing to the commissioner on the grounds that the firm's ANDA complies with earlier CDER testing guide-lines. The company conducted urinary excretion studies based on a protocol guidance that FDA issued in December 1986 for determining bioequivalency of conjugated estrogens. Young has not yet made a decision on the appeal. Other FDAers in attendance at the Oct. 14 meeting were: Acting Deputy Commissioner James Benson; Office of Executive Operations Deputy Director Henry Dausch; Associate Commissioner for Legislative Affairs Hugh Cannon; Office of Drug Standards Deputy Director James Morrison; division of Metabolism and Endocrine Drug Products Solomon Sobel, MD; and General Counsel David Adams. The other participants were: Nancy Taylor, a health aide to Senator Orrin Hatch; Barr scientific consultant Gary Hodgen, PhD, Jones Institute for Reproductive Medicine; Barr attorneys Joseph diGenova of Bishop, Purcell & Reynolds and Tom Parry of Parry Romani Associates. The Hatch aide attended the meeting, according to FDA, in order to observe the appeal process between Barr and Young and did not express the Utah Senator's position on the issue. Reportedly, however, Hatch sent a letter to FDA about a year ago in support of urinary excretion studies as a basis for approving ANDAs. Able Labs also received a non-approval letter for its ANDA application for conjugated estrogens. Like Barr, Able had also based its application on urinary excretion studies.