Neurim Pharmaceuticals v Generics UK (EWCA, [2020] EWCA Civ 793, 2020)

Dhenne Avocats · 11 October 2026

Our analysis

Summary

The Court of Appeal upheld the refusal of an interim injunction sought by Neurim and its exclusive licensee Flynn against Mylan’s launch of a generic version of Circadin (prolonged release melatonin). The patent, which claims a therapeutic use in Swiss form, had been held invalid by the EPO Opposition Division, a decision under appeal and therefore suspended. With a trial fixed just over four months away, damages were an adequate remedy for the claimants: the losses alleged could be calculated and entry by other generics before trial was not established. For practitioners, the judgment shows the weight of an expedited timetable and of critical scrutiny of loss evidence in the American Cyanamid analysis.

Facts and procedure

EP(UK) 1 441 702 B1, expiring on 12 August 2022, claims the use of a prolonged release melatonin formulation for improving the restorative quality of sleep in patients with primary insomnia (paras 1, 3 and 4). By a decision of 2 January 2020, the Opposition Division held it invalid; the appeal suspends that effect (para 3). Mylan obtained a marketing authorisation around December 2019 for a generic with the same label (para 10). On 3 June 2020 Marcus Smith J refused the interim injunction; an expedited trial had meanwhile been fixed from 26 October 2020 (paras 1 and 11).

The applicable law

The court may grant an interim injunction where it is « just and convenient » to do so (section 37(1) of the Senior Courts Act 1981), following the four-stage approach in American Cyanamid v Ethicon: serious question to be tried, adequacy of damages for the claimant, then for the defendant, and finally the balance of convenience (para 15). Damages need not be a perfect remedy to be adequate (para 16).

Question

Are damages an adequate remedy for a patentee exposed to generic competition for four months before trial, where it alleges a price spiral and consequential losses to its business?

Decision

Floyd LJ first identified an error by the judge: at stages 2 to 4, the court must do the best it can on the available written evidence rather than merely look for a serious question; the error was immaterial, as the Court of Appeal could decide on the same material (paras 18 and 19). The consequential losses relied on (research, clinical trials, redundancies) were not made out: the witness statements predated the order for an expedited trial, and Neurim’s reserves were sufficient to maintain those activities (paras 38 to 41 and 49). The period to trial is very short, 53% of prescriptions are written by brand and the reimbursement price was unlikely to change before trial (para 43). Entry by a second generic was not likely, Teva being bound by a settlement agreement (paras 44 to 47); this was therefore not a price spiral case (para 50). The claimants’ sales forecasts and Flynn’s and Mylan’s actual figures would allow the loss to be calculated, including by extrapolation after trial, damages being assessed liberally (paras 51 and 52). The Court stated that it decided no principle of general application (para 54). Damages being adequate, the appeal was dismissed without considering the balance of convenience (para 55).

Key points for practice

• At stages 2 to 4 of American Cyanamid, the court decides the facts as best it can on the written evidence (para 18).
• An expedited trial greatly reduces the scope of alleged harm and calls for critical reading of evidence prepared beforehand (paras 38 and 40).
• Practical point: a patentee seeking an interim injunction must update its evidence of harm to the actual procedural timetable and show concretely that other generic entry is likely.

Provisions applied

National law

Senior Courts Act 1981, section 37(1)

Case law cited

American Cyanamid v Ethicon [1975] AC 396; National Commercial Bank of Jamaica v Olint [2009] UKPC 16; Livingstone v Rawyards Coal Company; Pneumatic Tyre Co v Puncture Proof Pneumatic Tyre Co (1899) 16 RPC 209

Prepared by Dhenne Avocats from the text of the decision (National Archives, Find Case Law), consulted on 11 October 2026. Only the official text is authoritative.