Elan is buying AOP Orphan Pharmaceuticals, which has a minority stake in Shield Therapeutics, a Switzerland-based specialty pharmaceutical company.

Elan, a US-listed drugs maker, has agreed to pay up to $693m for a bio-tech company focused on rare diseases as part of a wider series of dealmaking.

Elan is buying AOP Orphan Pharmaceuticals, which has a minority stake in Shield Therapeutics, a Switzerland-based specialty pharmaceutical company treating iron deficiency in the blood also backed by chocolate company Nestle’s corporate venturing unit, for $342.5m in cash and stock with up to another $351m in performance-related payments.

Separately, Elan has spun…