Sinthrome tablets contain the active ingredient acenocoumarol (previously known as nicoumalone in the UK), which is a type of medicine called an oral anticoagulant. It is used to stop blood clots forming within the blood vessels.
Blood clots normally only form to stop bleeding that has occurred as a result of injury to the tissues. The clotting process is complicated and begins when blood cells called platelets clump together at the site of damage and produce chemicals that activate clotting factors in the blood. Clotting factors are proteins that are produced by the liver. Vitamin K is essential for their production. The activated clotting factors cause a protein called fibrinogen to be converted into another called fibrin. Fibrin binds the platelets together, forming a blood clot. This is the bodys natural way of repairing itself.
Sometimes, however, a blood clot can form abnormally within the blood vessels. This is known as a thrombus and can be dangerous because the clot may detach and travel in the bloodstream, where it becomes known as an embolus. The clot may eventually get lodged in a blood vessel, thereby blocking the blood supply to a vital organ such as the heart, brain or lungs. This is known as a thromboembolism.
Some people have an increased tendency for blood clots to form within the blood vessels. This is usually due to a disturbance in the blood flow within the blood vessels. For example, fatty deposits on the walls of the blood vessels (atherosclerosis) can disrupt the blood flow, giving a tendency for platelets to clump together and start off the clotting process. Slow blood flow in the leg and pelvic veins can also result in clots forming (deep vein thrombosis). These clots can break off and travel to the lungs (pulmonary embolism). A type of fast irregular heartbeat called atrial fibrillation can also disrupt blood flow and may lead to blood clots forming in the heart. Heart valve disease can have the same effect, particularly if artificial heart valves have been fitted. Clots in the heart can detach and travel to the brain, causing a stroke. Acenocoumarol is used to reduce the risk of blood clots forming inside the blood vessels in conditions such as these.
Acenocoumarol works by preventing the vitamin K dependent production of the clotting factors described above. Acenocoumarol prevents the production of these clotting factors by inhibiting the action of vitamin K. Without these clotting factors fibrinogen cannot be converted into fibrin and blood clots are therefore less likely to occur.
Acenocoumarol takes about three days to produce its full anticoagulant effect because, while it prevents the production of new clotting factors, it takes about this long for clotting factors that have already been produced to be used up. For this reason, when treating blood clots such as deep vein thrombosis (DVT) or pulmonary embolism, a faster acting injectable anticoagulant, such as a heparin, is often used as well to begin with.
The anticoagulant effect of acenocoumarol is measured in terms of the prothombin time, which is the time taken for blood clotting to occur in a sample of blood to which calcium and a substance known as thromboplastin have been added. This time is expressed as the International Normalised Ratio (INR). Your doctor will take regular blood samples and adjust your dose of acenocoumarol as necessary to make your INR fall into the range that has been shown to be effective at preventing blood clots in your particular condition.
Treating and preventing blood clots in the blood vessels, for example in the following cases:
This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.
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.
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 this medicine. Because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.
The side effects listed above may not include all of the side effects reported by the drug's manufacturer.For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.
The anticoagulant effect of acenocoumarol can be affected by many 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 ensure that the combination is safe.
The following medicines may enhance the effect of acenocoumarol (increased INR; acenocoumarol dose may need reducing):
The following medicines may reduce the effect of acenocoumarol (decreased INR; acenocoumarol dose may need increasing):
The following medicines may also alter the effect of acenocoumarol and the dose of acenocoumarol may need to be adjusted up or down (as INR may be increased or reduced by the following medicines):
This medicine may enhance the blood sugar lowering effect of antidiabetic tablets such as glibenclamide. Antidiabetic tablets may also enhance the anti-blood-clotting effect of this medicine. Combined use should be well monitored.
There may be an increased risk of bleeding if acenocoumarol is taken in combination with any of the following medicines.
There are currently no other medicines available in the UK that contain acenocoumarol as the active ingredient.