A drug that is structurally very similar to already known drugs, with only minor differences. The term "me-too" carries a negative connotation. However, me-too products may create competition and drive prices down1.

The majority of the new products the industry puts out, are "me-too" drugs, which are almost identical to current treatments but "no better than drugs already on the market to treat the same condition." Around 75 percent of new drugs approved by the FDA are me-too drugs. They can be less effective than current drugs, but as long as they're more effective than a placebo, they can get the regulatory green light2.

This isn't surprising at all, as someone who works in the field, but these so-called "me-too" drugs, which are reportedly better than their forebears, is driving costs. A "me-too" drug is a drug that has its origins in another drug. Probably the most famous example of this is Prilosec ("The Purple Pill") and Nexium ("Today's Purple Pill"). Prilosec's active ingredient is omeprazole. Nexium's active ingredient is called esomeprazole. The difference is that Nexium is the left-handed version of omeprazole. In chemistry, S stands for sinister, which means the molecular conformation has a left-handed orientation. (D would be right handed.) So this S-omeprazole is one half of the mixture that comprises its predecessor. By specifically picking only the S conformation, the drug is made more potent. This sounds great, but its efficacy is only marginally better than Prilosec-, which has a generic version, and costs about a third less than Nexium. Some other "me-too" drugs are: Claritin (loratidine) and Clarinex (desloratidine), Celexa (citalopram) and Lexapro (escitalopram)3.

What are "Me-Too" drugs?

Ever since the advent of modern chemotherapy, when drugs were discovered and developed through the process of screening thousands of molecules for a variety of disease conditions, using animal models, there has been a growing criticism that too many molecules were developed with similar chemical structure and the same pharmacological profile, with very little to distinguish them from each other in terms of their therapeutic utility. In other words, once the first breakthrough discovery is made of a new pharmacological activity for a new molecule, subsequent years saw the emergence of a host of new molecules or "me-too" drugs from the same chemical class and possessing the same pharmacological profile.

Such follow-up drugs have been termed molecular modifications, molecular roulettes or copycats, the development of which are alleged to be motivated by purely commercial considerations. They are also deemed to involve lower levels of innovation, compared to the original molecule. It is important to analyze in a historical perspective the end results of such efforts in different therapeutic areas of developing new molecular entities, as later generation products, after an initial breakthrough discovery has been made and the technical, medical and commercial merits of developing such drugs.

Development of "Me-Too" drugs

The success rate in the discovery of new chemical entities with fundamentally new chemical and biological profiles of activity are very low. In fact, even chemical entities within the same structural class of an approved drug are becoming rare now, compared to the period of sixties to eighties. In 2001, $ 26 billion was spent on developing new drugs and the U.S. FDA approved only 9 new chemical entities. At the same time, two thirds of the drugs approved from 1989 to 2000 were modified versions of existing drugs or even identical to those, in newer forms and formulations4.

Of the 1,035 drugs approved by FDA during 1989 to 2000, only 361 or 35% contained new active ingredients. Of these, only fewer than half were granted priority review status by the FDA. One impression is that these drugs are slightly altered versions of existing drugs, with little to offer in terms of better activity or tolerance, let alone new pharmacological profiles. The implication is that such drugs are developed, as patents on top-selling original drugs run out and not many truly new medicines are discovered. The indication that many of these drugs do not offer any major advantages over existing drugs is given by FDA's unwillingness to grant priority review for most of them.

On the other hand, conventionally, the Regulatory Agencies, including the FDA, are not obliged to consider better efficacy over existing drugs as a criterion for approval; rather, they require only the establishment of efficacy and safety of the new drug over a placebo.

How good are they?

Notwithstanding such perceptions, historically, many "me-too" drugs have proved to be considerably better than their original counterparts. Examples are a series of generations of beta-blockers, which came up after the original drug Propanalol was discovered by ICI, with most of them having merits in terms of better efficacy, cardio-selectivity and safety. Ranitidine, the first follow-up drug after the introduction of the first H-2 receptor antagonist, Cimetidine, was followed by Famotidine and in each case these "me-too" drugs had notable merits over the original drug.

Apart from the major breakthrough in the development of orally active beta lactam antibiotics of the Penicillin and Cephalosporin class, within the same oral derivatives, there have been considerable improvements brought about by change in the side chains incorporated by condensation of specific agents with 6-APA, 7-ADCA and 7-ACA. A whole new range of broad-spectrum antibiotics of these structural classes could thus be developed. In each of the major classes of antibiotics, classified according to the mechanisms of their action, namely inhibition of cell wall synthesis (Beta Lactams, Vancomycin), inhibition of bacterial protein synthesis (Erythromycin, Tetracycline, Streptomycin), inhibitors of DNA or RNA replication (Quinolones, Rifamycins), inhibition of Folate Coenzyme biosynthesis (Sulfa drugs, Trimethoprim), there have been several "me-too" drugs marketed.

An important recent example to show that 'me-too" drugs need to be developed is the case of the oral hypoglycemic drug Troglitazone, approved as an anti-diabetic drug in 1997. The drug was withdrawn from the market following reports of unacceptable hepato-toxicity. The follow-up "me-too" drugs, Rosiglitazone and Pioglitazone are much less toxic and are today widely used. If these drugs were not developed, the withdrawal of Troglitazone would have left a major therapeutic gap in anti-diabetic therapy.

"Me-Too" drugs: Strategies for New Drug Research for Indian Companies

Breakthrough innovations in pharmaceutical industry, of new drugs, such as the first beta blocker, the first NSAID, the first of each class of Antibiotics, Calcium Channel blockers, ACE inhibitors, Sulfonyl Ureas, Biguanides, Insulin, Glitazones, Glinides, Tricyclic Anti Depressants,major and minor Traquillisers, Selective Serotonin Receptor inhibitors, H-1 and H-2 Receptor antagonists, Proton Pump inhibitors etc are relatively rare and even though a few of the original drugs under these classes are still very much in use, they have been superceded in most cases, by later generation products, many of them "me-too". The newer drugs are discovered both through incremental innovations on the original drugs as well as through new research.

Generally the original discovery leads to feverish activity both within the innovator company as well as in Competitors' laboratories, to develop better products in the same therapeutic category. The essential caveat for commercial success, however, is that the newly discovered molecules should meet the minimum standards of patentability. For example within three years of the discovery of the highly successful Sildinafil Citrate (Viagra), three more new versions for the same indications have been patented and developed5.

Me-too drugs also provide therapeutic advantage6. For the practicing physicians, there's the benefit of established drug MoA with a "me-too" medication, coupled with clinical studies that - hopefully - show patient-centered benefits such as better adverse events profiles, less frequent dosing, less bothersome potential for drug/drug interactions, and so forth. A "me-too" drug is a helluva lot easier to incorporate in practice than a totally novel medication7.

"Me-Too" drugs: The hidden dynamics

The most common criticism of drug development centers on the so-called "me-too" drugs that employ the same biological mechanism as pioneer brands. This involves a lot more than such high-profile targets as the anti-ulcer drug Nexium. We should be thinking about antidepressants, cholesterol-reducing drugs, diabetes treatments, anti-psychotics, and other therapeutic categories that have seen both blockbuster sales and rapid innovation. There is quite a bit of evidence that follow-on drugs do a lot of patients a lot of good. The newer statins, for example, often out-perform the older ones in clinical trials where the endpoints are the number of heart attacks and deaths prevented.

Me-too drugs are also a powerful tool for cutting health care costs. We should be glad that our research industry does not target only brand new biological mechanisms. That would be a very expensive business model indeed. Fortunately, the industry also works on marginal improvements, exploiting opportunities to make drug therapy better and sometimes opening the door to really radical improvements that happen to lie more or less next-door, scientifically speaking. In the meantime, we get price competition as a by-product. Me-too's almost always undercut the prices of the pioneer drugs.

Another part of the me-too story gets almost completely ignored even though it is extraordinary important. For me-too manufacturers, advancing the science is a way to gain a competitive advantage. The classic example is the statin class of cholesterol drugs. Research on one of the follow-on drugs (Pravachol) demonstrated for the first time that using a statin to reduce cholesterol would actually prevent deaths from heart attacks, something that had previously been assumed without proof. Additional trials for several statins, including Lipitor, the formidable challenger to Zocor and Pravachol, have demonstrated that serum cholesterol is far more important than almost anyone thought (for preventing strokes, for example).

There are lots of other stories about the benefits of new research from me-too drugs, but they are part of a larger story: new uses for old drugs. The data showing a slowdown in new drug approvals exclude essential information: discoveries of new uses for old drugs. This kind of discovery has become so common that it amounts to a "new-use" revolution. One of the scientific ironies of the new era of pharmaceutical research is that as drugs become more tightly targeted on biological mechanisms, their uses actually become more diverse. This is because the body typically uses specific mechanisms over and over again, sometimes in what appear to be completely unrelated ways.

Consider the SSRI antidepressants. A recent Science article on the diverse and unexpected applications of drugs that fiddle with serotonin reuptake which is what the SSRIs do concluded that the very term "antidepressant" is misleading because there is no scientific reason to think of this drug as being just for depression. Fighting depression just happened to be the first really useful condition that was explored for this very interesting class of drugs.

Another example is the Cox-2 inhibitors like Celebrex (and Vioxx, which is important in this story and may return to the market partly for this reason). These were invented to relieve arthritis pain. But the Cox-2 enzyme turns out to be important for lots of things including cancer and Alzheimer's. Clinical trials to exploit these leads have been underway for years. Celebrex has already been approved for reducing the risk of colorectal cancer, and Vioxx has also achieved promising results. Of course, the big news recently has been that these drugs may cause heart attacks. But even here, me-too economics is of surpassing importance. The traditional NSAIDS (non-steroidal anti-inflammatory drugs) like Alleve and Advil may have the same heart attack risks. The potential risk has been there for decades, but only the new drugs-the Cox-2s-have been put through large-scale long-term clinical trials because those are the only ones still under patent. This is an example of how me-too drug development adds importantly to the research base. Thanks to the me-too's, we are learning about NSAIDs, heart attacks, cancer and probably much more.

Also dominated by new uses are the new-targeted cancer drugs, which attack such specific biological mechanisms that they avoid killing every fast-growing cell in sight (as traditional chemotherapy tends to do).

The implications are clear. The annual count of new drug approvals will only show a tick when a new cancer drug or a new statin gets its very first approval. But a new use for an old drug can be as valuable as an entirely new drug, or even more valuable when you consider that we know more about the safety profile of old drugs and one drug will sometimes do the work of two (preventing both heart attacks and strokes, for example)8.

Me-too products can sometimes have important advantages on tolerability or dosing. It could help create more competition and lower the price. If you have five me-toos, possibly the sixth is something that is a little better. That is for the plans to decide on behalf of their patients. And even if it has the same mechanism of action, more competition could help drive down the price of the entire class. That's an important influence, with potentially an improvement in health from greater access.

How bad are they?

Even though the major problem of antibiotic therapy, namely drug resistance cannot be addressed by the development of "me-too" drugs, due to the propensity of the same class to develop cross resistance; in most cases, the new semi-synthetic derivatives had distinct advantages over the earlier ones. Thus, for example, the first generation Cephalosporins are useful for gram-positive infections, while the second-generation drugs cover a broader spectrum including gram-negative organisms. The third generation drugs provide resistance against the beta lactamase enzyme, as well as acting against some of the most intractable infections, such as those caused by Pseudomonas and Klebsiella strains.

Even while the pharmaceutical industry turns out families of me-too drugs for relatively mild conditions in affluent people, it pays almost no attention to serious diseases, such as malaria, affecting impoverished people. It also gives short shrift to less profitable drugs, so there now are shortages of some vaccines and life-saving drugs9.

The big problem with me-too drugs is that they are chemically very similar to other drugs already available, yet they are marketed as if they were important new breakthroughs, with very high prices. Many new, expensive me-too drugs are not necessarily better than older and less expensive drugs. Most of the time they are compared with placebos and not older drug comparisons.

"Me-too" drugs are responsible for 80% of increased spending in recent years, and on average they are four times more expensive than the comparable, older alternatives10. By Patented Medicines Pricing Review Board's (PMPRB) definitions, at the time of their introduction "me-too" drugs were judged to provide moderate, little or no improvement - in terms of effectiveness and safety - compared to older alternatives. However, on average, "me-too" drugs cost about 2.5 times as much per prescription as comparable older drugs. The question is whether the perceived or real differences justify the increased costs. New drugs do have a role in some situations and for some patients. However, it makes sense to use the older equally effective drugs whenever possible11.

Changing FDA rules to discourage me-too drug approvals would make R&D far more expensive, would discourage competition and therefore raise healthcare costs, and would forestall the wave of new research that has revolutionized our scientific understanding of the therapeutic categories where competition has been most intense.

Conclusion

New drugs are not required to improve on old ones, and there's usually no way to know whether they do. Although the FDA must test drugs before they are marketed, they don't need to be compared with similar drugs already on the market. The FDA only requires they be reasonably safe and better than nothing-a low standard indeed. This loophole in FDA regulations opens the door for an unlimited number of me-too drugs, which are easier to develop than innovative drugs.

Given everything, it should come as no surprise that these more expensive "me-too" drugs cost the medical industry money. The prevalence of the me-too's really says an awful lot about the lack of innovation within the pharmaceutical industry. If you look at the new drugs marketed over the last six years, 78 percent weren't even new chemical compounds. They were just new combinations or different formulations of old drugs. And 68 percent were classified by the F.D.A. as unlikely to be improvements over drugs already on pharmacy shelves.

At the same time, there are shortages of some important drugs that the pharmaceutical companies aren't much interested in making because they are not as profitable as the me-too's. But the companies don't have to turn out needed drugs, if they are not lucrative. And they don't.

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