House Calls: What to know about using blood thinners

By Christopher B. Cutter April 22, 2014 07:25 am

House Calls runs every two weeks. Today’s column is written by Christopher B. Cutter, a physician at Sutter Coast Community Clinic.

Physicians are using various types of blood thinners with increasing regularity to prevent serious disease.

In the last decade or so the use of these drugs has skyrocketed so much that your family doctor is having to become an expert in this therapy. There are several things that  patients and their families need to know about this type of therapy. Let’s look at the three types of drugs being used and the most common reason to use them:

The most familiar one of all is aspirin. This is in fact a bit of a wonder drug. It blocks the effects of platelets, which are tiny cells that form part of a clot inside blood vessels. Its effects start very soon after ingesting the pill and last for 6–8 days. It has now been well proven to lower the risk of strokes and heart attacks in patients who have prior events by about 20 percent — a pretty good deal for a few pennies a day.

The real cost, however, is in the risk of the drug. Bleeding from the stomach can occur with aspirin and can be serious. People who smoke, drink alcohol or have had prior stomach ulcers are at much more risk for complications. Therefore, doctors like to weigh the risks carefully in low-risk patients before advising to use aspirin. However, in patients who have had a stroke, the benefit is usually quite clear, and worth risk in most cases. The best dose has been studied extensively, and most experts accept the 81 mg dose as sufficient and safe. 

Clopidogrel (Plavix), Effient (prasugrel) and Aggrenox (aspirin and dipyrimadole) are  other drugs that block the effectiveness of platelets. They are sometimes used in combinations — especially right after a cardiologist has put a special kind of stent in your heart arteries (coronaries). Patients on combination therapy have to be especially careful about watching for signs of bleeding.

The other very common blood thinner is Warfarin (Coumadin). This drug blocks the effect of vitamin K and prevents the production of the protein factors that makes blood form clots. It is used in high-risk patients with atrial fibrillation to prevent strokes and cuts the stroke risk by half or more.

It is also used in patients with certain kinds of heart valves, patients with hearts that don’t pump strongly enough and in patient who have had blood clots in their legs and even gone into the lung circulation (pulmonary embolus).

Warfarin is very potent and its effect must be monitored by a blood test, (the Pro Time or INR). This is usually done every week until it is in the proper range, and then every month. If a patient eats foods containing vitamin K (green vegetables, broccoli, cucumbers, dried herbs and so on), then the INR will be affected. 

The best approach is to have a steady and healthy amount of vegetables everyday, don’t binge in either direction, and let your provider adjust the Warfarin accordingly.

The last type of blood thinner is newer and is referred to as a “direct thrombin inhibitors” (Pradaxa, Xaralto). This class of drugs appears to be quite effective and at least as safe as Warfarin. These drugs are much more expensive and they do not require blood monitoring, which is convenient. However, they have no simple antidote and therefore bleeding episodes have to be treated accordingly in the hospital. I suspect we will all be hearing more about these drugs in the future.

The most important thing I ask you to take away from this article is the understanding that you should never stop your blood thinning therapy without the clear recommendation from the doctor who knows you best. When in doubt, ask the cardiologist if you have to.

All too often patients are told to stop their medicines in order to have elective procedures such as dental and skin surgeries, and the results could be very serious. In one study of 289 patients sitting in a hospital with a serious stroke, 13 had stopped their medicine prior to the event (mostly aspirin).

We now know that six days after you stop the aspirin, the effectiveness is gone and some studies suggest the stroke risk is significantly increased (rebound effect) by stopping the medicine. Warfarin begins losing its effectiveness after missing one dose, as do the other meds we discussed.

No elective surgery is worth a stroke, heart attack, or blood clot to your lung! A prepared surgeon can do complex surgery on most parts of the body safely (exception — spine, brain, back of the eye). We have special ways to change blood thinning prior to and after a surgery using injectable thinners (“bridging”) which we can arrange when the need is there. 

Modern medicine is becoming more and more of a team effort. Your provider, here in Crescent City, is only a phone call away from your specialist and we can make sure your care is coordinated so that no unnecessary risks come your way. Just ask us.

And remember — take those medicines as directed, get tested when asked, and know your drug dosages and names of your meds.