For 57 years, patients have been receiving Coumadin to reduce the risk of blood clots. What most of them don’t know is that their “drug” really rat poison- warfarin. That is not really the problem (other than the “yech” factor)- it’s that the effective dosage is difficult to ascertain and maintain. Too low a dose- and the potential for bleeding out exists; too much warfarin- and the patient’s blood congeals, precluding blood flow. Certain foods (broccoli, spinach, among other Vitamin K laden vegetables) interact with the drug, and each patient has a different response to warfarin; women with menstrual cycles, obviously, have a more difficult time maintaining the optimal dosage. Basically, the only way to determine the effective dosage is to monitor the blood clotting time (which is not performed daily or weekly)- it’s “hit or miss”.
Obviously, creating a new, replacement drug to preclude blood clots is not an easy task- or we would not be using rat poison for so many years. The blood clotting system is a veritable balancing act- blood must circulate, yet congeal in an instant should a vessel be injured and start to leak. Platelets in the blood morph from disks to stars and interlock at the damaged site; clotting factors and thrombin [an enzyme] develop a ‘sticky mesh’ to ensnare the red blood cells, forming a patch on the spot. As if that ballet were not difficult enough, the veins rely on one pathway (thrombin), while the platelet process dominates in the arteries.
Then, we get into the costs of the “drug”. It only costs about $ 160 for year’s dosage of Coumadin. Of course, that does not include the blood testing costs, but you can see the price is pretty cheap. As a point in fact, the CDC (Centers for Disease Control and Prevention) states that problems with warfarin are the most common reason older adults are rushed to the emergency room.
The market size comprises some 2.3 million people, who undergo dialysis or suffer from atrial fibrillation (most common form of abnormal heart rhythm) and venous clots. Treating those patients means the total market size may range from $ 4 to 12 billion by 2020. Couple that market with those people undergoing hip and/or knee replacement or folks who have artificial heart valves (like my step-daughter)- and the market is larger still.
Last year, Boehringer Ingelheim received FDA approval (20 September 2010) to sell dabigatran (Pradaxa) for dialysis and atrial fibrillation; they have approval for hip and knee replacement only in Europe. The drug demonstrated that it reduced stroke risk by 2/3, which is equivalent to warfarin; but the potential for fatal hemorrhage was also identical to that of warfarin. Right now, dabigatran has about 5% of the total clot control market (warfarin has the rest), but 16% of the smaller atrial fibrillation sub-market. And, it’s monthly cost (which may be covered by insurance) is $ 230- or some 18X that of warfarin.
Now, yet two other new drugs may receive approval. Normally, the third or fourth entrants fail to win in the marketplace. But, one of these two may break that common wisdom.
Bayer/Johnson & Johnson’s new drug, rivaroxaban (Xarelto), only needs to be taken once daily, just like warfarin. But, rivaroxaban is just equivalent in efficacy (prevention of strokes) and safety (likeliness of the patient to bleed out), when compared to warfarin. [Note: This drug was just approved on 1 July 2011; its monthly cost is $ 200 or so.] Apixiban (Eliquis), developed by Bristol-Myers Squibb and Pfizer, requires twice daily dosage, as does dibigatran. But, testing on apixiban has proved it to be superior in efficacy and safety to warfarin.
This data has actually cause a drop in the valuation of Bayer and J&J stock prices. But, before you sell off those stocks, you should know that rivaroxaban will be useful for post-orthopedic surgery; that is not in the cards for apixiban.
All of the new drugs have defined dosages; the “hit or miss” of warfarin is not a factor for the patients. As long as money is not an issue, the one thing that is certain is that patient care and safety is bound to improve!
A topic somewhat over my head Roy but an interesting read nonetheless.
In agreement with your concluding comments about patient care and safety improving with unlimited resources. I guess the question that raises is how to channel the required money and resources into those areas of medicine which need them…
Sorry about that, Jym.
So many people are on warfarin (rat poison). Patients with heart and clot problems. And, because it is not a drug, the dosage is guestimated. And, it changes (especially for women who still have their periods.) And, they have to avoid things like broccoli, which upsets their apple cart.
These new drugs will make that better. But, more expensive. (Yet, probably not when one considers the hospitalization that is often associated with wrong doses…)
This is, indeed, a WordPress blog. I started out on WordPress’ site and was convinced to move it to my corporate site for crass, commercial purposes. After all, we write these blogs to inform and entertain- and to let potential clients know how much we know, how we think, and why we really have their interests at heart.
Thanks for the question- and the ability to reiterate why I do what I do.
Roy