Allergan Plc (AGN.N) CEO Brent Saunders calls them “stepping stones” – small, bolt-on acquisitions, as opposed to the mega-deals common in the drug industry. And they’re expected to boost dealmaking in sectors ranging from neurology to skin care.

Allergan’s agreement on Tuesday to acquire liver drug developer Tobira Therapeutics Inc (TBRA.O) for $1.7 billion may seem trivial compared to the proposed $160 billion deal Allergan crafted last year to sell itself to Pfizer Inc (PFE.N).

But that deal was torpedoed in April by the U.S. Treasury’s latest curbs on tax inversions. Now the company, domiciled in Ireland, is taking a new tack, preparing to spend a war chest of more than $20 billion on stepping-stone deals.

The small deals are aimed at filling gaps in its core therapeutic areas, which range from the central nervous system and gastrointestinal diseases, to dermatology and eye care.