In a conference call, GlaxoSmithKline’s top executive is asked if he would consider “pairing up” with another drug company. Back in May, an analyst started talk of a “PfizerKline” merger.

GSK’s (NYSE: GSK) CEO Andrew Witty noted a merger would be a “big issue to cross.”

Not only is GSK still dealing with the challenges of its three-part asset swap and partnership with Novartis, it also continues to face sales challenges. A Reuters report on GSK’s earnings announced Wednesday clearly stated that Witty is under growing pressure to deliver better results.

GSK also underwent a major restructuring this year, leading to 900 job cuts in the Triangle alone. In fact, GSK’s earnings weren’t as bad as expected, triggering a jump in shares when the earnings were disclosed.

So Witty could have hardly been surprised by the potential merger question from Timothy Anderson of Sanford C. Berstein & Co.

“In terms of the company, obviously we’re a product of mergers, and we’ve been through these things before, and we’re in the middle of a significant integration in two of our biggest divisions,” Witty responded, as the GlaxoSmithKline name indicates.

Witty insisted that management feels “very, very good about the capability of the company to deal with the environment that we’re engaged in. I mean, I completely accept that I have a different view or at least I’ve elucidated a different view to perhaps some other people.”

The ongoing impact of Witty’s reorganization would have to be a factor in any possible deal, he added.

“The extent to which then you want to complicate or to create even greater company scale than the scale we have today is a big – that’s a big question, right? That’s a big issue to cross, and I’d say it has a very high pain threshold, not because you can’t read a banker’s book and imagine all sorts of synergies and everything else, but just the scale of the company, the complexity of the company, all of those very practical realities of how you actually run a business of that kind of scale, when you’re already dealing with corporations which are very, very large. So I think the threshold of that next step is very big.”

Mergers and acquisitions in the life science business certainly continue at a remarkable rate. Look at North Carolina-based LabCorp’s purchase of Covance – and Quintiles’ response in forming a new subsidiary with Quest. And in crop science, Monsanto wants Syngenta. Then there was the sale of Raleigh-based Salix.

The list goes on.

All the action led to a rarity from a CEO in a conference call: Witty offered to “hypothecate.”

“I would hypothecate, Tim, at least to some extent, what we’re seeing at the moment is M&A in the sector – largely driven, I think, for the same analysis we’ve elucidated, which everybody can feel the pressure in the system – people are trying to acquire assets or they’re trying to acquire businesses to give themselves synergy pools or growth opportunities to ready themselves for the threats which are emerging around us,” Witty explained/

“But they’re doing it in, let’s call it, the easy M&A space. So as long as you have a checkbook, you can buy the small companies, you can buy the biotechs, you can buy the midcaps, and you can leverage the cheap money to acquire it.

“What we haven’t seen so far is the big transactions, I think for some reasons I’ve just outlined, which is they have a very high pain threshold, they’re not easy to pull off, and they bring with them a fair amount of risk. So where we net out on all this is, at least for now, we’ve just done one of the biggest transactions, one of the most complicated transactions to pull off. It gives us a tremendous chance to build up global leadership in Vaccine and Consumer without massively distracting our Pharma business, which focus on R&D launches. We think we should be really fixated and focused on that.”

Read the full transcript at: