How Long Is A Drug Patent Good For?

by on August 26, 2012

The answer to the question is deceptively simple.

Drug patents are good for 20 years in the United States. There you have it.

But really the matter is far more complex than it would seem.

patent protectionPatents are good for 20 years after the invention of a drug--not after the drug comes to market. It can easily take eight years for the pharmaceutical companies to gather enough data to get approval for their new invention from the U.S. Food and Drug Administration. Meanwhile the FDA can send the drug company back for more clinical studies  (experiments using humans as subjects to test the drugs’ efficacy and side effects) and more data, and all the while the patent clock is ticking.

That's why the name of the game for pharmaceutical companies is working to extend those patents for a top-selling drug.

Why, you might ask, is extending patent such an important maneuver for pharmaceutical companies? Why don't they just 'go gently into that good night' of generics, as Dylan Thomas might have advised?

Well, money for one thing. Lots of it.

Biggest selling medicine ever, Lipitor (atorvastatin)the anti-cholesterol heart medicine, lost patent last fall.  Pfizer, the drug's maker, noted a 19% decline in the first quarter after the patent ended, almost solely due to falling Lipitor sales.

After Eli Lilly's Prozac (flouoxetine) went off patent in 2002, sales fell a sharp 9% for Lilly in the second quarter, mainly due to loss of Prozac income.

When Lilly (again) lost patent on its antipsychotic Zyprexa (olanzapine) in October of 2011, it was hit hard. Sales plummeted 73%, mainly due to the loss of Zyprexa sales, and, as FiercePharma puts it, "[t]hat dramatic drop was blamed for every negative in Lilly's Q2 report, from margin shrinkage to earnings per share pain."

The Journal of Pharmacy and BioAllied Sciences notes that when Merck lost patent protection in 2000 for Pepcid (famotidine) to treat ulcers and gastric reflux, its bottom line changed radically. Pre-patent expiration Merck earned $755 million in US sales. Following patent expiration, sales plummeted to $110 million.

Is it any wonder that companies would like to do whatever is in their power to keep the patents running as long as possible?

How Drug Patents May be Extended

There are ways to extend the original 20-year patent, much of which got eaten up with clinical trials--a variety of ways.

The Hatch-Waxman Act

Legislation was passed in 1984 to try to even the patent playing field for drugs that got unfairly held up by the FDA regulatory process.  The Drug Price Competition and Patent Term Restoration Act of 1984 (a.k.a. the “Hatch-Waxman” Act), allows for patent extensions to compensate for the delays in the approval process as the FDA is working to grant permission to bring the drug to market.  There are, however, some limits.

The entire patent extension is limited 5 years, no matter how long drug development was held up. And the remaining amount of protected years following FDA approval is capped at 14.

Other means of extending patents exist, and pharmaceutical companies, after investing over a billion in each drug, work to make use of them.

Additional Research

One of the simplest, most straightforward techniques for extension of patent involves research on children. Any drug company can get an extra 6 months of patent protection by testing its medication on children to determine the best doses for them. And this 'pediatric exclusivity' extension can be used not just once but twice.

Other Techniques and Strategies to Maximize Patent Life

But, as often as the pediatric exclusivity extension is taken advantage of, it only gets the company a year at most. So the pharmaceutical industry uses a variety of other techniques to keep their branded drugs exclusively on the market--and the generics away--for as long as possible.

These strategies are sometimes referred to as "evergreening."  Some such strategies for extending patent include:

1. New formulations

A simple way for a drug company to extend patent production on a medication is to get new patents for new formulations of a drug.  This often revolves around simplifying dosing and administering of the pill, so extended-releaseformulations, where a patient need take, say, only 1 dose a day, or a week, instead of multiple doses a day, of the medicine, usually prolongs patent protection. Both extended-release formulations SeroquelXR (quetiapine) and Glucophage XR (metformin) added on years to the life of the drug patents. Even though Seroquel went generic early this year, maker AstraZeneca is able to hold on to their expensive exclusivity for the XR formulation through 2017.

Anti-diabetes drug Glocophage, after having extended patent for 6 months due to pediatric testing, was still earning over $3 billion in sales, and Bristol Myers Squibb was loathe to say goodbye. Part of their strategy to keep the drug branded was developing the XR version, which bought them 3 years of patent extension.

2. New means of administering the drug 

If the drug is delivered in an alternative fashion than when it received original patent, it might be up for extension.

Migraine treatment drug Imitrex (sumatriptan) made over $1 billion in annual sales for GlaxoSmithKline, and thus the company was mightily motivated to hold on to the patent, set to expire in 2006. To do so they developed an intranasal spray, which received FDA approval, and let them keep hold of the drug--and profits--for 5 more years.

Most recently Intermezzo, designed to treat middle-of-the-night awakening, earned a new patent, even though it's a form of the generic zolpidem, or brand AmbienBecause Intermezzo dissolves under the tongue and isn't in pill form, it was granted approval as a new chemical entity last November by the FDA.

Even though Intermezzo has the same active formula as Ambien, the fact that is has a different dosage and different means of taking it earned Transcept Pharmaceuticals 5 years of patent protection for selling the new drug.

Johnson and Johnson's antipsychotic Risperdal (risperidone) went off patent in 2008, but, repackaged as a long-acting intramuscular injection, and named Rispderdal Consta, the patent protection extended until 2013.

3. New Uses for the Drug

A drug can earn three years extension under the three year new use/new clinical exclusivity FDA rule. The name of the game here is not to re-work the medication or re-formulate it, but merely to find a new use for it.

A 2006 article in Biopharm International notes how well this worked for pharmaceutical giant Eli Lilly. Lilly patented atomexitine in the early 1980s to treat depression. But further research indicated that the compound could treat attention deficient hyperactivity disorder. So Lilly received new patent protection for atomexetine as an ADHD drug, which it marketed as Strattera. This held patent protection until the end of 2010, long after doctors had stopped using amotexitine as an antidepressant.

4. Purifying of the isomers and re-branding

Perhaps the most famous recent case of this is the re-branding of the older, off-patent anti-depressant Celexa (citalopram) as the new Lexapro (escitalopram).

Celexa--like many drugs--is made of two isomers (this harks back to college chemistry, I know, but isomers are basically chemicals that have the same number of atoms of the same elements but differ in structure) and, as is frequently the case, only one of them is actually effective. Forest Pharmaceuticals knew as long as it had its Celexa that only one isomer was active, but it won patent for the double-isomer drug.

However, Forest, like many other companies, when it came time for Celexa to lose its patent, reformulated the drug by removing the inactive isomer, yielding a medication with only the active chemical compound.

Although in essence and efficacy it's basically Celexa, officially Lexapro is a new drug, earning its own patent and exclusive marketing rights.

[Forest was not the first to think up this creative solution. Remember the allergy pill Seldane (terfenadine)? Same two-isomer issue, so when Sanofi-Aventis wanted a first-rate allergy drug without having to create a compound from scratch, they merely developed a single-isomer version of Seldane, and earned themselves a first-rate patent on Allegra (fexofenadine).]

5. New combinations of drugs

Lilly had an active patent on antipsychotic Zyprexa, a name you might remember from above, while its patent on anti-depressant Prozac had expired. In a move that would extend the patent on Zyprexa and keep Prozac profitable, despite the emergence of a generic, Lilly developed and patented a new drug that was a combination of both, called Symbyax, one of very few drugs FDA-approved for treating bipolar depression—and they've got patent protection on that specific combination of drugs locked up until 2017.

Glucovance, approved as the first "combination oral antihyperglycemic [or diabetes] agent," is also simply a combination of two previous medications.  Remember that Bristol Myers Squibb's top-selling diabetes drug Glucophage was set to lose patent in 2000. So first Bristol Myers utilized their pediatric patent extension, which brought them into 2001. Then they combined Glucophage with already-generic glyburide, another diabetes medication--and earned a new patent--for another 3 years--just as they were losing one on one of their best-selling drugs.

Between the two pills that make up its composition, Glucovance lowers blood glucose by helping the body make better use of insulin and by increasing the amount of insulin the pancreas produces. It was the first pill to combine the mechanisms of the two other pills into one--and it thus earned itself new years of patent protection.

6. Seven-year orphan drug exclusivity extension

Under the U.S. Orphan Drug Act, in order to promote drug development for rare, or 'orphan,' diseases, this protection is given to medications used to treat diseases affecting 200,000 or fewer people in the U.S.

Research and development for drugs for rare disorders was lagging in the U.S. when Congress passed the 1983 act, which provided a number of incentives for companies to develop drugs that would never have a wide market. One of those was a 7-year monopoly on drug sales. And that only applied to the first approved use. The company was able to apply for a different use for the drug, and it could obtain exclusive rights for that, as well.

This exclusivity blocks the FDA from approving any competing generics for the orphan use during this time. The drugs get special consideration under the rule, since it is assumed that drug-makers could not recoup the cost of developing and marketing the drug through sales under normal patenting restrictions.

As an example Avonex (Interferon beta-1a)for treating relapse in patients with multiple sclerosis, won market exclusivity for 7 years, ending in 2003, under the Orphan Drug Act.

7. 30-Month Stays of FDA Approval

 This has less to do with any reformulation of a medication, and more about just holding on tight to a patent, fighting off threats to a drug's exclusivity status.

Sometimes a generic company, instead of waiting for the patent to expire and being in direct competition with multiple other drug makers, will apply for approval anyway, claiming either that the original patent is invalid, or that the new generic product doesn't infringe upon that patent.

This almost without fail leads to the developing company suing the generic for patent infringement. The lawsuit triggers an automatic 30-month stay. During that time the FDA may not respond to the generic company's drug application--and the holders of the patent have earned themselves nearly 3 years of extension.

Take GlaxoSmithKline's efforts to keep antidepressant Paxil (paroxetine) safe from generic competition. Canadian drug-maker Apotex filed to patent a generic version of Paxil in March 1998. GSK duly sued, which yielded that 30-month stay, expiring in November 2000.

But GSK, knowing they had a good thing going, didn't stop there. As the Paxil patent expired, GSK took option #2, developing a new formulation that patients could take just once a day, as opposed to twice. They went for option #1, as well, gaining new FDA approval and extending the patent by finding use for Paxil in eating disorders and premenstrual syndrome.

Those new patents entitled GSK to bring more infringement lawsuits against Apotex, and, by the end, they had forced an automatic stay of FDA approval on APotex's version for over 5 years.

[Apotex was less than amused.  Bernard Sherman, chief executive of Apotex, claimed that GSK had "repatented every conceivable form" of Paxil to block the competition. "It's an absurdity," he said.]

Another big pharmaceutical company to utilize more than one technique to keep the life of the patent long is Eli Lilly.  Lilly doubled its efforts to keep its earnings from Prozac strong by both developing a pill to be taken only once a week and getting new FDA approval for its use in treating premenstrual dysphoric disorder.

GSK reformulated antidepressant Wellbutrin (buproprion) into a sustained-release form and got an additional patent when studies showed the drug helped smokers quit. The company marketed the smoking cessation drug under the name Zyban.

But sometimes even the most ingenious efforts don't always pay off.

With the patenting of Prozac Weekly, Eli Lilly thought they could staunch what was bound to be a flood of losses due to generic flouxetine entering the market. But the drug never sold all that well and certainly didn't come close to bringing in the profits that the original Prozac did. A $2 billion a year money-maker for Lilly before it lost patent in 2001, Prozac was the drug of a lifetime. Prozac Weekly never came close, as in 2004 all the Prozac products made $184 million, less even than the much-cheaper generic.

And despite all of a company's best efforts to keep the patent game alive, the day will come when even a drug-maker's best-selling product will go off patent. They'd best have a number of other drug options in the pipeline by then, to stay financially sound.

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4 Responses

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  1. Adam C

    Just a suggestion...In the sentance, "Patents are good for 20 years after the invention of a drug--not after the drug comes to market," this should actually be worded more specific, stating that the patent would actually begin when the patent is applied for.

    Just stating, "after the invention of a drug" is too wide-open. This could imply when the patent is applied for or when the patent is approved.

    Thank you,

    Adam C.

  2. Вы попали в самую точку.
    Я думаю, что это отличная мысль.

  3. Eric Z

    Should simplify to one 5 year extension for any of the exceptions to extend patents.
    Albuterol inhalers were generic until we started worrying about the ozone layer. Not against this but breathing seems to be a social "good" also.
    The propellant had to be changed, which let big pharma to repatent the drug delivery system and drive the price up 700%.
    What a country!!
    You can still however, get it in Canada and Bahamas with original formulation for origial price.

  4. Tricia

    Just wanted to say thank you for this extremely informative article.....I was assigned an "extra assignment" for pharmacology because I missed 2 more days than allowed and have to write a paper about 5 new medications, including why drug companies really push these meds...... I paraphrased in my notes just about every paragraph in here....(yes, my work will be sited"..... but you pretty much described in great detail EVERYTHING I was strugging to understand about the FDA New Medication Approval Process and how the patents for these drugs actually work....
    Thanks so Much for all your hard work....this really was very interesting and insanely informative ...

    thanks again!

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