GSK Plc shares surged after the UK pharma company agreed to pay as much as $2.2 billion to resolve about 80,000 US court cases alleging that its old reflux medication Zantac was contaminated with a suspected carcinogen.

GSK has agreed to pay $2.2bn to settle about 80,000 Zantac lawsuits in the US. In a statement released after the close of markets on Wednesday, the pharmaceuticals firm said it had reached an agreement with 10 firms who represent 93% of the Zantac (ranitidine) state court product liability cases pending against it in the US.

GSK has settled lawsuits in the US that alleged the drugmaker’s now-discontinued heartburn drug Zantac triggered cancer