Rastamon mentioned "Coumadin". That is a brand, similar to "Maravan". Both contain the ingredient 'warfarin' or 'warfrin'. This ingredient is also known colloquially as "rat-poison".
Warfarin makes the blood thinner, preventing clots, but if one takes too much warfarin, then even a small bleeding is hard to stop, and in theory one could bleed to death. In fact that's how mice/rats get killed. An overdose of warfarin can be reversed relatively easily in a hospital setting.
Patients are on this kind of medication for a variety of reasons, main one being cardiac. When patients are on warfarin, a regular check of the 'thinness' of the blood needs to be done. This is called INR check. There are now available small handheld, battery
operated machines available for this purpose.
When a patient is on this medication for a number of months or years, INR levels would have stabilised, and a check every few months is all that is required, although a change of diet or lifestyle can and will affect the INR number. It is all about the therapeutic INR level that the doctor has set for the patient. If it is too low, than the medication did not give the desired effect and bloodclots can form in your bloodstream. If the INR is too high, then you have increased chance of bleeding.
Some posters mentioned "NOAC": New Oral Anti Coagulant. These are allegedly safer medications, with the same desired result as warfarin, but without the need to check the thinness of the blood. In Australia
there are, as far as I know, three of this kind of NOACs approved.
Back to the OP: I am pretty sure that warfarin/Coumadin is available virtually anywhere at fairly low prices, while the NOACs may still demand a premium price
(as the patents are still valid).
INR checking can be done by any doctor, in any hospital, and in some chemists. But the need for checking will be greatly reduced if your lifestyle and diet are stable.