Dr Reddy’s Laboratories (UK) Limited v Boehringer Ingelheim International GmbH

In an application for an interim injunction in pharmaceutical patent litigation, the court must apply the American Cyanamid principles to the evidence in the particular case. Market-specific factors do not create rebuttable presumptions. Where future market conditions are unusually uncertain, the court should assess irreparable harm under each realistic hypothesis, including further generic entry, rather than attempt to assign precise probabilities. A generic company’s failure to clear the path by progressing revocation proceedings may weigh in favour of preserving the status quo. The court may grant an injunction where damages are inadequate for both parties and preservation of the status quo, together with the generic company’s litigation conduct, makes an injunction more likely to produce a just result.

The claimant sought to launch generic empagliflozin products in the United Kingdom under skinny-label marketing authorisations. The defendant held patents and a supplementary protection certificate relating to empagliflozin and applied for an interim injunction preventing sale or supply pending the trial of the claimant’s revocation claim and the subsequent form of order hearing.

The application concerned the adequacy of damages, the likely effects of generic dapagliflozin entry on the empagliflozin market, the possibility of further generic competition, and whether the claimant had delayed clearing the way. The central issue was whether the balance of the risk of injustice favoured preserving the existing market position until judgment after trial.

1. Interim injunction principles. The court applied the four-stage guidelines in American Cyanamid v Ethicon [1975] AC 396, as explained in Dapa II CA [2025] EWCA Civ 480. There were serious issues to be tried concerning the validity and infringement of the relevant rights.
2. No presumptions from market type. Pharmaceutical patent cases should be decided on the evidence in the particular case. The usual features of generic entry were relevant, but did not operate as rebuttable presumptions. The substantial uncertainty surrounding the future empagliflozin market made it inappropriate to treat the claimant’s forecast of a 90% market loss within three to nine months as established.
3. Adequacy of damages. Damages were not an adequate remedy for either party. If further generic competitors entered, price erosion, possible recategorisation under the Drug Tariff, switching pressure and difficulty restoring prices would make the defendant’s loss difficult to quantify. Conversely, an injunction could deprive the claimant of first-mover advantages and make its lost sales difficult to assess, particularly if further entry occurred or the scope of any patent infringement differed from the injunction’s scope.
4. Further generic entry. It was unnecessary to conclude that further entry was more likely than not. A real risk of further entry was sufficient to require the court to consider the consequences under that hypothesis. The court should assess whether either course was likely to cause irreparable prejudice, rather than attempt to quantify the percentage chances of each possible outcome.
5. Clearing the path and outcome. The claimant had not explained why it had issued and progressed its revocation proceedings so slowly, accepted a trial in October 2026, and only altered its launch plans after the dapagliflozin market became generic. That failure to take effective steps to clear the path, together with the status quo, favoured an injunction. The injunction was granted until the form of order hearing following judgment after trial.