GlaxoSmithKline is to pay a record $3bn (£1.9bn; €2.2bn) to settle longstanding disputes with the US government over marketing of some of its best known drugs.

The disputes, some of which go back to 1997, include an investigation by the US Justice Department into the marketing of the antidiabetes drug rosiglitazone (marketed as Avandia) and GSK’s alleged attempts to market the antidepressant bupropion (Wellbutrin) as a slimming aid. The settlement also includes the alleged misuse of “nominal pricing” arrangements to overcharge the Medicaid programme.

Comparison with other large fines levied by the US authorities is difficult, because so many different drugs are involved in the GSK case, but the amount it is prepared to pay exceeds the previous highest levied at one …