Swiss drugmaker Novartis will focus on its debts before undertaking any big purchases following its acquisition of eyecare group Alcon, Novartis's chairman was quoted as saying on Saturday.

The Basel-based firm spent much of last year trying to clinch 100% ownership of Alcon and has finally sealed its $50.9 billion buy by paying Alcon's minority shareholders an extra $463 million in cash.

"Now it's about cutting back on the debt burden somewhat before we can undertake new big buys," Chairman Daniel Vasella told Swiss newspaper Blick. "But smaller bolt-ons are surely still possible in the near future."

Vasella, who previously served as the firm's chief executive, also said the Alcon buy was expected to yield synergies of more than $300 million in the next three years.