Drug Truths

A site devoted to teaching about drug discovery and development.

Better Antihistamines? Don’t Count On It

with 8 comments

A recent headline in FierceBiotech Research proclaimed: “Scientists crack histamine code that could lead to better allergy relief.”  The article goes on to describe how an international research team studied how doxepin, an old drug used to treat allergic reactions and other conditions, binds to the human histamine receptor protein, thereby easing allergy symptoms.  The team did this by solving the complex 3-D structure of the human histamine H1 receptor protein.  Dr. Simone Weyland, one of the investigators, commented on the importance of this finding, stating, “First generation antihistamines such as doxepin are effective, but not very selective, and because of penetration across the blood-brain barrier, they can cause side-effects such as sedation, dry mouth and arrhythmia.  By showing exactly how histamines bind to the H1 receptor at the molecular level, we can design and develop much more targeted treatments.”

Based on this pronouncement, allergy sufferers might assume they will have new, superior medicines to treat their symptoms.  Well, this scenario is highly unlikely.

Antihistamines, like diphenhydramine (the active ingredient of Benadryl),  have been available for over 60 years.  While effective in treating hives, runny nose, itchy eyes, etc., they do cause toleration issues including sleepiness.  In the 1980s, pharmaceutical companies sought to come up with better antihistamines that produced less drowsiness.  This pursuit led to the so-called second-generation agents such as loratidine (brand name: Claritin) and cetirizine (brand name: Zyrtec).  These antihistamines have proven to be safe; they are so broadly used that they are now available over-the-counter at any pharmacy and supermarket.

Perhaps loratidine and cetirizine can be improved upon.  The research that’s been done to get a better understanding of the biological interaction between the drug and the site of action in the body would be a good starting point to begin such a drug discovery program.  But it would be surprising to find a company willing to make the investment to do this.  The current antihistamines on the market work well enough.  To do the research to devise a new generation of agents from lab bench through clinical trials and to FDA approval would require 12 – 15 years and hundreds of millions of dollars.  Is it really economically responsible for a drug company to go down such a path?  Wouldn’t it be better for patients if the time and effort needed to get a third-generation antihistamine be invested in areas of major medical need?

Critics of the pharmaceutical industry have justifiably been concerned that not enough R&D is being devoted to discovering new treatments for Alzheimer’s Disease, diabetes, cancer, drug-resistant infections, etc.  In fact, back in the late 1990s, companies may have indeed capitalized on this new scientific breakthrough and looked for a third generation antihistamine.  But economics in today’s world of medicine won’t support such a research program.  The science done in “cracking the histamine” code is of academic interest, and, in theory, it could lead to a new drug that works slightly better than what’s already available.  But if the R&D dollars are instead invested in areas of more critical need, we’ll all eventually be better off.

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Written by johnlamattina

June 30, 2011 at 4:25 pm

Posted in Uncategorized

8 Responses

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  1. I am in full agreement with this article. Discovery of new human histamines receptor may add to the scientific data base but with no practical implications from the commercial point of view. With so many generic anti-histamine around, where is the incentive? I foresee similar thing happening in the CV and diabetic franchise as well, should a ground breaking discovery comes along. As the article correctly says everything also need to be looked at from the prism of regulatory and economic forces. Dollars are better spent for cancer and AD.

    musings

    July 1, 2011 at 2:04 pm

  2. Dr. LaMattina: Congrats on the blog. Good comment on the difficult economics around developing a third-generation antihistamine. I agree that the odds are pretty long.

    Owen Hughes

    July 1, 2011 at 2:50 pm

  3. i’m happy to see that you are blogging John. I’ll be a regular reader.
    God is good
    jpu

    John Umland

    July 3, 2011 at 12:44 am

  4. I suffer from all over body itch without a rash – doctors have yet to find a reason or a treatment. My life is a living hell . . . 24 hour itching with no relief is just about a recipe for suicide. Since I started this itching 14 years ago, I have met on-line a lot of people just like me . . . some do suffer from diseases like kidney failure, Primary Biliary Cirrhosis, Aquagenic Pruritus, Polycythemia Vera, etc . . . We all have one thing in common: the current antihistamines don’t work all that well, especially when we have to take them around the clock and hold down a job. I whole-heartedly disagree with this article – people like me deserve to have people researching better methods to help us live a life either free from suffering or at least with the suffering greatly reduced.

    Stephanie

    April 10, 2012 at 5:27 pm

  5. […] drugs on the market, with loratidine and cetirizine so-called second generation drugs.  Dr. LaMattina makes a clear point why drug companies are reluctant to developing new anti-histamines: Perhaps loratidine and […]

  6. Anthistamines are really necessary if you have perenial rhinitis and urticaria. ”

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    Marshall Vogle

    October 31, 2012 at 3:34 am

  7. For the most part, antihistamines are safe. Having said that, antihistamines can have side effects which, if the antihistamine is not properly administered, can be serious. The truth is, all medications have side effects. Some are mild, as in the case of an aspirin, unless you have stomach ulcers or aspirin sensitivity and others are more serious such as the side effects from chemotherapy, but for the most part, antihistamine side effects are fairly mild. The newest antihistamines are probably about the safest medications that there are. But there are differences between the various antihistamines and their side effects.’

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    Louvenia Cazeau

    February 10, 2013 at 8:40 am

  8. Antihistamines are most commonly used to control the symptoms of allergies such as hay fever.In these conditions they work by preventing the actions of histamine, which is a substance produced by the body as part of its natural defences.`

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    Darla Usry

    February 19, 2013 at 1:07 pm


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