The company had been anticipating a Class 1 designation for its resubmission of its BVF-033 bupropion compound, which would have meant a shorter review period of around two months.

Yesterday's confirmation that the US Food and Drug Administration (FDA) believes the submission worthy of Class 2 status adds a further four months to the review period, with the FDA's decision now due on 23 April 2008.

At the start of the year Biovail was confident that its BVF-033 candidate would be launched during the final quarter of 2007, but recent FDA decisions have scuppered the drug delivery specialist's plans.

Back in July the company was issued a Non Approval letter by the regulators regarding the BVF-033 bupropion salt antidepressant. Disappointed by the decision, Biovail sought to reassure its investors and met with the FDA to discuss its concerns about the drug.

The FDA was of the opinion that pharmacokinetic (PK) studies carried out by Biovail were inappropriate, and requested that a specific PK study design be followed before the product could be considered for approval.

Biovail disputed this decision, believing its existing PK data to be sufficient, and after meeting with the FDA in August submitted a complete response letter to the agency in October, which contained new analyses of existing information, but no new clinical data.

As of less than two weeks ago, the company was still positive and expected a response form the FDA "in the near term."

Unfortunately, a six month wait was not the response that Biovail had wanted or anticipated.

"Biovail is surprised and disappointed by the FDA's decision with respect to the status of our Complete Response," Biovail CEO Douglas Squires said in a statement yesterday.

"Biovail remains fully committed to securing the approval of BVF-033."

Should the FDA decide that Biovail still needs to carry out additional PK studies to the agency's specific design, it is likely to take the Canadian firm another eight weeks to complete the extra study, even with the expertise of its in-house contract research organisation.

Missed opportunity?

The company had hoped to take advantage of a settlement entered into with a number of generic manufacturers that delays the launch of generic competition for its Wellbutrin XL (bupropion) 150g dose until the end of May 2008.

The deal would have provided a convenient window of opportunity in which Biovail hoped to maximise the market potential of BVF-033 - had it kept to the anticipated timeline and made it to market by the end of 2007.

With an FDA decision now not due until the end of April 2008, Biovail has lost out on gaining this edge in the market.

On top of this, BVF-033 is also intended as a platform for another of Biovail's drug candidates, a bupropion combination product, BVF-045.

BVF-045 combines two antidepressants which between them target serotonin, dopamine and norepinephrine, and according to the company could offer faster onset of action, better efficacy at lower doses, and an improved side effect profile.

However, plans for BVF-045 necessarily hinge on approval of BVF-033, and as such the 045 compound will also have been delayed by the FDA decision.

In its third quarter results a few weeks ago, Biovail still believed it was on track to launch BVF-033 in early 2008, and mentioned that the firm was in late-stage partnership discussions.

The firm was not available to comment on how these discussions may have been affected following confirmation of the FDA's Class 2 designation.

Yesterday's news hit the company's shares hard, dropping over 11 per cent to an eight year low.