Pradaxa

How does Pradaxa work?

• Pradaxa capsules contain the active ingredient dabigatran etexilate, which is a type of medicine called a direct thrombin inhibitor. It is used to stop blood clots forming within the blood vessels.
• Blood clots usually only form to stop bleeding that has occurred as a result of injury to tissue in the body. However, after hip or knee replacement surgery there is a risk of blood clots forming in the blood vessels. This risk is increased by being immobile for long periods of time following the surgery, as a result of slowed blood flow in the leg and pelvic veins. A clot that forms in the veins of the leg is called a deep vein thrombosis. These dangerous blood clots can travel to the lungs, causing a serious condition called a pulmonary embolism.
• People with a type of fast irregular heartbeat called atrial fibrillation (AF) are also at risk of blood clots forming, both within the heart and in the blood vessels. This is because the abnormal heart rhythm disrupts blood flow in the blood vessels. Clots in the heart can detach and travel to the brain, causing a stroke. Clots can also travel in and block other blood vessels around the body.
• The blood clotting process is complicated. When blood begins to clot, a cascade of chemicals is activated within the body, resulting in the formation of an enzyme called thrombin. Thrombin is central to the complete process of blood clotting. It causes a protein called fibrinogen to be converted into another called fibrin. Fibrin binds blood cells called platelets together, and this forms the blood clot.
• Dabigatran works by binding to thrombin in the clotting process described above and blocking its action. This stops the formation of fibrin, the essential component of blood clots. Dabigatran can therefore prevent blood clots from developing.

How do I take Pradaxa?

• Pradaxa capsules can be taken either with or without food.
• The capsules should be swallowed whole with a glass of water. They must not be opened or chewed because this dramatically increases the absorption of dabigatran into the body and thus increases the risk of bleeding (see warning section below).
• The dose prescribed and how often dabigatran needs to be taken depends on the reason for taking the medicine. It is important to follow the instructions given by your doctor. These will be printed on the dispensing label that your pharmacist has put on the packet of medicine.
• If dabigatran is being used to prevent blood clots following hip or knee replacement surgery, treatment should be started within one to four hours after the surgery, though this may be delayed if there are any complications with bleeding after surgery. The capsules are taken once daily for 10 days following a knee replacement and for 28 to 35 days following a hip replacement.
• If you forget to take a dose of Pradaxa you should take it as soon as you remember, unless there are less than six hours before your next dose is due. In this case, leave out the missed dose and take your next dose as usual when it is due. Do not take a double dose to make up for a missed dose.
• Do not stop taking Pradaxa until you have been advised to by your doctor.

Pradaxa should be used with caution in

• Elderly people.
• People who weigh less than 50kg or more than 110kg.
• People with kidney or liver problems.
• People with diabetes.
• People with heart disease.
• People with an increased tendency to bleed, for example due to blood clotting disorders such as haemophilia, or the conditions listed below.
• People with low numbers of blood cells called platelets in their blood (thrombocytopenia).
• People with inflammation in the stomach (gastritis), inflammation of the foodpipe (oesophagitis) or gastro-oesophageal reflux.
• People with bacterial infection of the heart valves and the lining surrounding the heart (bacterial endocarditis).
• People who have recently had a biopsy.
• People who have recently had a major injury.
• People having spinal or epidural anaesthesia or injection into the spine (lumbar puncture).
• People who have an indwelling catheter in their spine for pain relief after surgery.
• People taking medicines that may increase the risk of bleeding, for example non-steroidal anti-inflammatory drugs (NSAIDs, eg diclofenac), SSRI antidepressants, eg fluoxetine, or antiplatelet medicines such as low dose aspirin or clopidogrel (see last section of factsheet for more examples).

Who should not take Pradaxa?

• People with active severe or dangerous bleeding.
• People with a disease or condition in an organ that significantly increases the risk of major bleeding, for example, ulcerative diseases of the intestines such as peptic ulcer or ulcerative colitis, or cancers at high risk of bleeding.
• People with known or suspected oesophageal varices, which are dilated veins in the foodpipe that are usually a complication of liver cirrhosis.
• People with malformations or abnormalities of the blood vessels.
• People who have recently had any bleeding inside the skull.
• People who have recently had brain, spinal or eye surgery.
• People who have recently had a brain or spinal injury.
• People taking other anticoagulant medicines to treat or prevent blood clots, such as warfarin or heparin (except when switching treatment to or from Pradaxa).
• People with severely decreased kidney function.
• People with decreased liver function or liver disease that may be life-threatening.
• People with an artificial heart valve.
• This medicine is not recommended for people having surgery for a hip fracture.
• This medicine is not recommended for children and adolescents less than 18 years of age, as its safety and efficacy have not been established in this age group.
• This medicine should not be used if you are allergic to one or any of its ingredients. If you feel you have experienced an allergic reaction, inform your doctor or pharmacist immediately.

Can I take Pradaxa while pregnant or breastfeeding?

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

• The safety of dabigatran for use during pregnancy has not been established. For this reason, Pradaxa should not be used in pregnancy unless considered essential by your doctor, and then only if the benefit of its use outweighs the risk to the unborn child. Women who could get pregnant should use a reliable method of contraception to avoid getting pregnant while taking Pradaxa. Seek further medical advice from your doctor.
• It is not known if dabigatran passes into breast milk. The manufacturer states that women who need treatment with dabigatran should not breastfeed while taking it. Seek further medical advice from your doctor.

What are the possible side effects of Pradaxa?

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with dabigatran. Just because a side effect is stated here does not mean that all people using Pradaxa will experience that or any side effect.

Common side effects (affect between 1 in 10 and 1 in 100 people)

• Low red blood cell count (anaemia).
• Nosebleeds.
• Bleeding in the gut.
• Abdominal pain.
• Diarrhoea.
• Indigestion.
• Feeling sick.
• Bruising of the skin.
• Abnormal results in liver function tests.

Uncommon side effects (affect between 1 in 100 and 1 in 1000 people)

• Weeping of a surgical wound.
• Blood clots which form a solid swelling at the injection site (haematoma).
• Coughing up blood.
• Bleeding from the rectum.
• Bleeding from piles (haemorrhoids).
• Ulceration in the gut.
• Acid reflux.
• Vomiting.
• Difficulty or pain when swallowing.
• Blood in the urine (haematuria).
• Bleeding into a joint (haemarthrosis).
• Bleeding inside the skull.
• Bleeding underneath the skin.
• Bleeding after an operation or injury.
• Decrease in the number of platelets in the blood (thrombocytopenia).
• Rash or itching.

Rare (affect between 1 in 1000 and 1 in 10,000 people)

• Bleeding from an injection site.
• Bleeding from a catheter site.
• Nettle-type rash (urticaria).

The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.

For more information about any other possible risks associated with dabigatran, please read the information provided with the medicine or consult your doctor or pharmacist.

Can I take Pradaxa with other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to make sure that the combination is safe.

Dabigatran must not be used in combination with the following medicines:

• ciclosporin
• dronedarone
• itraconazole
• ketoconazole
• tacrolimus.

Dabigatran is not recommended for people taking protease inhibitors for HIV infection such as ritonavir.

Dabigatran will enhance the effect of other anticoagulant medicines used to treat and prevent blood clots, such as those listed below. For this reason, it should not be used in combination with these medicines (except if treatment is being switched to or from Pradaxa):

• acenocoumarol
• apixaban
• argatroban
• bivalirudin
• danaparoid
• fondaparinux
• heparins (unless this is being used to stop blood clots forming in a central line)
• low-molecular weight heparins, eg dalteparin, enoxaparin, tinzaparin
• lepirudin
• phenindione
• rivaroxaban
• warfarin.

There may be an increased risk of bleeding if dabigatran is used in combination with other medicines that can affect blood clotting, such as those listed below:

• aspirin (including low-dose aspirin to 'thin the blood')
• clopidogrel
• dextran
• dipyridamole
• duloxetine
• glycoprotein IIb/IIIa receptor antagonists, eg abciximab, eptifibatide and tirofiban
• non-steroidal anti-inflammatory drugs (painkillers such as diclofenac, ibuprofen, naproxen) - while you are taking this medicine you should only take these types of painkillers on the advice of a doctor
• prasugrel
• SSRI antidepressants such as fluoxetine, fluvoxamine, paroxetine, citalopram
• sulfinpyrazone
• thrombolytic agents (clot-busters), eg alteplase, streptokinase
• ticagrelor
• venlafaxine.

The following medicines may increase the amount of dabigatran in the blood and so could increase the risk of side effects such as bleeding:

• amiodarone
• clarithromycin
• posaconazole
• quinidine
• rilpivirine
• telaprevir
• ticagrelor
• verapamil.

If you are taking any of these medicines in combination with dabigatran your doctor may need to prescribe you a lower than normal dose of dabigatran. They will also monitor you more closely, particularly for any signs of bleeding or anaemia.

The following medicines may reduce the amount of dabigatran in the blood and as a result could make it less effective. These should be avoided while you are taking dabigatran:

• carbamazepine
• phenytoin
• rifampicin
• the herbal remedy St John's wort (Hypericum perforatum).

References:

http://www.netdoctor.co.uk/medicines/heart-and-blood/a8679/pradaxa-dabigatran/

https://www.pradaxa.com

https://www.drugs.com/pradaxa.html

https://en.wikipedia.org/wiki/Dabigatran

https://www.drugwatch.com/pradaxa/

http://www.rxlist.com/pradaxa-side-effects-drug-center.htm

https://www.medicines.org.uk/emc/medicine/20760