[e-drug] Cost of enantiopure medicines

e-drug
1

E-DRUG: Cost of enantiopure medicines
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[I do not expect you will get a (true) answer to this but has posted it. Enantiomers are often included in the term 'greening of patents', i.e. small investment for a new medicines with few, if any, benefits. But much higher cost. Moderator]

Dear All,

I would appreciate if some one could provide me information on the
pricing/cost details on racemic switches (racemic therapeutics redeveloped
as single enantiomers). For instance cetrizine and levocitrizine.

I am looking for a comparative analysis.

Thanks for your time.

valliappan

--
*Valliappan, K. M.Pharm., Ph.D.
Professor
Department of Pharmacy
Annamalai University
Annamalainagar*
TN 608 002, INDIA

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E-DRUG: st of enantiopure medicines (3)
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Dear all,

please allow me to strongly disagree with the concept of "small investment
for a new medicines with few, if any, benefits". [that was moderator's comment]

There are several reasons and advantages in developing a single enantiomer:

- From a safety perspective you should only administer as a drug what is
necessary and not additional components.
- Enantiomers are distinct molecular entities with different properties. - Often there is a misbelieve that one of two enantiomers is active and the other is inert, but this is "true" only for what has been tested during research activities.
- Even in the event that one enantiomer is inactive, still I would consider
that the human body would have to interact with from a pharmacokinetic and
metabolic point of view causing unnecessary work to the metabolizing
machinery and potentially alteration drug metabolism of other concurrent
treatments (drug-drug interaction).
- In addition to this, for oral drugs smaller pills or tablets would reduce
cost of manufacturing and could enhance where appropriate the
bioavailability as it is easier to formulate and there are more options
available for smaller doses.

From the perspective of cost of good including enantioselective synthesis of a single enantiomer, today the option available are such that, apart from some exception, the difference should be marginal. In particular in the case discussed below I do not see clear reasons that could justify much higher cost of manufacturing, but higher cost and new patent on the enantiomer are justified by the advantages (not obvious) cited

above that are not predictable but must be discovered case by case.

Stefano Biondi
Medicinal Chemist
yrnbion@yahoo.it

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E-DRUG: Cost of enantiopure medicines (2)
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Valliappan,

To decide if costs are worthwhile you need to know if there are
benefits. The single enantiomer drugs that colleagues and I have
looked at several years ago have not had significant benefits.

Let me know if you think the following articles may be useful for you.

Svensson S, Mansfield PR. Escitalopram: Superior to citalopram or
chiral chimera? Psychother Psychosom. 2004;73(1):10-6.
Mansfield PR, Henry D, Tonkin A. Single-Enantiomer Drugs: Elegant
Science, Disappointing Effects. Clin Pharmacokinet 2004;43(5):287-90.

--
regards,

Peter

Dr Peter R Mansfield OAM BMBS
GP
Director, Healthy Skepticism Inc
www.healthyskepticism.org
Visiting Research Fellow, University of Adelaide
www.adelaide.edu.au/directory/peter.mansfield