Evergreen or nevergreen: that is the question

Guy Selby-Lowndes is the IPKat's friend -- and one of his oldest readers in both senses of the word. A greatly experienced patent attorney, he also possesses a curiosity and liveliness of intellect that this Kat very much respects. Guy has written to the IPKat as follows:
"The daily tablets I consume purportedly produce favourable effects within my body but two of them also exercise my mind; perindopril and valsartan.

The product called generically PERINDOPRIL was for some years protected by a patent owned by Les Laboratoires Servier (LLS). While they had the patent monopoly they sold the product as the tert-butylamine salt [also referred to as the erbumine salt] using the trade mark COVERSYL. After litigation around the world it was established, at least in the UK, that the patent coverage had ceased [see earlier IPKat posts here and here and PatLit here]. LLS continue to market PERINDOPRIL as the tert-butylamine salt but under its generic name only. However they have obtained European patent 1 354 873 for the arginine salt of perindopril. They are now using the COVERSYL trade mark on this product which has potential patent protection until at least 2023. The European patent is currently in force in the UK. The change evergreens the COVERSYL trade mark.

Work carried out by the Australian government has concluded that there is no clinical advantage in prescribing the arginine salt rather that the tert-butylamine salt. The alleged improvement in using the different salt relates to storage under extreme conditions. However there is a cost difference. The BNF price for a packet of 30 PERINDOPRIL tert-butylamine 4 mg tablets is £2.74 whereas the cost for the equivalent arginine salt is £10.22 [Due to molecular weight differences the equivalent arginine salt tablets are 5 mg.] The price differential follows all sizes of tablets.

Doctors are not adept at noticing things like patent expiries and frequently prescribe by trade mark name rather than generic name. If COVERSYL tablets are prescribed it is likely that most pharmacists will dispense the more expensive perindopril arginine salt at a higher cost but of no higher benefit to the patient. In Australia their robust system has insisted the two salts of perindopril are sold at the same price!

Doctors' adhesion to trade marks is exemplified by the fact that many advise PANADOL for headaches and other minor afflictions. The relevant patent has long expired and generic paracetamol is widely widely available and costs less. However the word of a doctor is so revered by many that they insist on purchasing PANADOL rather that the less expensive equivalent.

Valsartan, marketed in the UK as DIOVAN, has not featured in any of your blogs so far. Its SPC expires next year and there has already been a spat in the US between the patentee and an Indian generic manufacturer".
Says the IPKat, this is a provocative little piece: I can almost hear the hiss of steam billowing out of some readers' ears as they seethe with indignation at these attempts to preserve protection beyond what might be regarded as its reasonable limits. Well, says Merpel, I expect that other readers will be nodding vigorously with approval at the fact that some well-run and highly focused companies have sought, within the limits of the law, to maximise the value of their investments in a market which is increasingly competitive and dominated by manufacturers of sure-profit generic products.

Evergreening here (per Wikipedia) and here (per European Generic Medicines Association)
How to play the Evergreen Game here