ROCHE DIAZEPAM PETITION: FIVE STUDIES WILL BE CONDUCTED

ROCHE DIAZEPAM PETITION: FIVE STUDIES WILL BE CONDUCTED to address the bioequivalence issues raised by the company in relation to generic diazepam, Roche outside counsel William Vodra (Arnold & Porter) told FDA in an April 9 letter. In February, Roche petitioned FDA to revise its bioequivalence requirements for generic versions of Valium to include pharmacodynamic studies of the availability of diazepam at the site of action. The firm further petitioned that FDA delay approvals of diazepam ANDAs and paper NDAs until adequate criteria for determining bioequivalence of diazepam products are established ("The Pink Sheet" March 4, p. 3). The five studies are: "A multiple dose steady state diazepam bioavailability study"; "bioavailability of two oral diazepam products in 24 subjects over 264 hours (Valium and Anksiyolin)"; "evaluation of receptor binding of Valium compared to two diazepam products in rodents"; "bioavailability following single oral doses of two diazepam products relative to Valium in patients with generalized anxiety disorder using both standard plasma levels and computer analyzed EEG measurements"; and "relative bioavailability of diazepam in normal volunteers following single oral doses of two diazepam products relative to Valium using both standard plasma levels and computer analyzed EEG measurements." The new studies were recommended to Roche by a group of 11 experts convened by Roche in early March to discuss the "pharmaco-EEG" study (by Itil, et al) of Valium which found a bioinequivalence problem with two generic diazepam products, Vodra explained. The members of the scientific panel included: George Simpson, MD, Medical College of Pennsylvania; Hank Yamamura, PhD, University of Arizona; Professor Rokus DeZeeuw, State University (Groningen, The Netherlands), David Greenblatt, MD, Tufts University; Bernard Cabana, PhD, President Internatl. Drug Registration, Steven Paul, MD, Natl. Institute of Medical Health. A "general consensus" agreed that the Itil study methodology and findings "were valid and more sensitive than conventional methods of bioavailability testing because [the study] assessed the drug effects on the target site of action," he continued. "Most importantly, the experts agreed that the data demonstrated bioinequivalence exists among the tested diazepam products, which could have serious clinical repercussions."