What is anticoagulation?
Anticoagulation is the thinning of blood with medications. It employs medications which block parts of the complex blood clotting system, which includes about 2 dozen different clotting proteins found in the blood and blood vessel walls. These numerous proteins promote clotting of blood, while other natural blood and blood vessel proteins encourage blood thinning; the body maintains a tight balance in healthy blood vessels.

Anticoagulants are much stronger in blood thinning effects than aspirin or plavix ®, which work differently by blocking platelet clotting cells. Alternatively, thrombolytic drugs are much stronger medications that break down clots, while anticoagulants prevent them from forming to begin with.

Anticoagulants that have been used for vein clots include Heparin, Low Molecular weight Heparins (‘LMWH,’ including Lovenox ®, Fragmin ®, Arixtra ®, & others), Warfarin (generic name for Coumadin ® & others), and Pradaxa ®. Heparin is typically used in the hospital as a continuous IV drip for immediate blood thinning. LMWH such as Lovenox ® are special versions of standard heparin that have fewer side effects and are given as injections under the skin 1-2 times a day, allowing patients to treat themselves at home. Warfarin has been used for 70 years as an oral blood thinning pill taken once a day. Pradaxa is a very new oral blood thinner.

How and why are anticoagulants used in venous disease?
Anticoagulants are used to treat or prevent blood clots (‘thrombosis’) of veins, which include superficial vein clots (‘superficial venous thrombosis’ or ‘SVT’) and deep vein clots (‘deep venous thrombosis’ or ‘DVT’), or the extension of SVT or DVT clots into the lungs (‘pulmonary embolism’). Some are FDA approved for both treatment and prevention of clots, some for only prevention or treatment. Prevention is employed in patients at high risk of DVT or pulmonary embolism, due to surgery, trauma, or medical conditions. Sometimes, vein specialists will prescribe lovenox ® to prevent clots after vein procedures when the patient has a history of blood clots, or an extensive family history. Or, they may use lovenox ® by itself or followed by warfarin if a vein procedure results in SVT or DVT as a side effect.

What are the benefits of anticoagulation therapy?
There are extensive studies performed over decades documenting that anticoagulant drugs improve the outcome of patients with blood clots, either SVT, DVT, &/or pulmonary embolism, including prevention of recurrent clots, pulmonary embolism, and death, and improvement of symptoms. Other studies show that these drugs help prevent clots in patients at high risk. But the drugs are far from 100% effective, spurring constant interest in improved medicationis. Also, we do not have studies addressing outcomes in every scenario, including in use for preventing or treating clots after vein procedures. Aspirin has been shown to have weak but real benefits in preventing DVT or pulmonary embolism after orthopedic surgery, but no studies have been reported for plavix ® to date to our knowledge for vein clots.

It is even more vital than for most medications to not skip doses of anticoagulants, given the risks of clots and of bleeding if intake is erratic. Also, unlike most medications, the effects and dosing of some anticoagulants such as warfarin can be monitored precisely with routine blood monitoring, which you should always comply with per your provider’s instructions.

What are the side effects?
Blood thinners by their very nature may cause bleeding since they tip the body’s natural balancing act of clotting and bleeding. Bleeding can range from minimal nuisance bleeding like oozing of a cut to deadly bleeding such as hemorrhage into the brain or profuse intestinal bleeding. Studies of long term blood thinners are surprisingly safe and cause serious bleeding in approximately 1% of patients per year, not significantly higher than the rate in patients not on blood thinners. However, study patients are often healthier than real live patients, so that in the ‘real world’ bleeding rates are a bit higher. Short term injected blood thinners cause serious bleeding in approximately 3% of patients over the first 1-4 weeks.

Non bleeding side effects vary with the exact medication. Heparin and LMWH drugs can occasionally cause hair loss, rash, skin blistering, liver inflammation, thinning of bones, elevated potassium level, or a dangerous drop in platelet cell counts that can ironically cause massive clotting. Warfarin can rarely cause hair loss, rash, or skin blistering. Pradaxa can cause stomach upset, the dosing varies from person to person and over time, and it can interact with virtually any medication, food, alcohol, and supplements.

Each blood thinner, except for Pradax ®, has specific antidote drugs in case of overdosage or need to reverse the blood thinning effect during bleeding or before urgent surgery.

What new drugs are available & soon to be available?
Pradaxa ® is an oral drug that is unique in that it blocks the clotting protein thrombin. It is FDA approved only for preventing artery clots & stroke in patients with the irregular heartbeat called atrial fibrillation. However, it has been shown to be effective for treating and preventing DVT vein clots and pulmonary embolism.

Rivaroxaban is an oral drug that is unique in that it block the clotting protein factor X. It was just FDA approved this month for preventing DVT and pulmonary embolism after hip or knee replacement.

The next few years will bring about another dozen new and often unique anticoagulants to the market as the search for medications with improved safety and effectiveness continues. We are currently in a golden age for anticoagulant discovery and development.