GlaxoSmithKline is seeing strong growth from sales in emerging markets, offsetting declines in the U.S. and Europe from competition by generic drugs, Chief Executive Andrew Witty told CNBC Tuesday. Glaxo [GSK 43.14 -0.04 (-0.09%) ] came through a period “where we’ve seen a lot of our historic portfolio exposed to generic competition, and business has gone away over the last several years,” he said. “We’re now seeing really an emergence from that period.” Sales in Europe and the U.S. have been stabilizing, with very strong growth in the emerging markets in Glaxo’s pharmaceuticals business. He said emerging-markets growth has been at a “20% rate in both our pharma and consumer businesses,” amounting to one-third of the company’s total business.