I've a bit of input here which might be of help, as I worked for a company that was involved in drug testing equipment for 20 years
If company A discovered the cure for the common cold, it would have to enter a period of testing to prove that the drug, amongst other tests, was stable for use across the entire world. It is well known that drugs can change their characteristics depending on what temperatures and humidities they are exposed to and therefore may become dangerous. This could mean drugs used in a temperate climate such as ours may be safe, but the same drug stored / used in tropical climates may be dangerous.
I was told that only 10% of drugs in development make it through all of the tests they have to complete before they get to market because the other 90% fail for one reason or another. Therefore the 10% of drugs that make it through to production have to recoup not only their own development costs but also the development costs of the 90% of drugs that failed somewhere along the line.
In addition to this, company A has to state how long its cure for the common cold will last in your medicine cabinet at home. Obviously company A will want it to be as long as possible especially as company B is probably working on the same cure. So a clock starts ticking and it lasts for eight years. Now, assuming you claim that you drug is safe for five years, then you have to provide test results over five years to prove your drug is safe no matter where it is used / stored throughout the world. Until you provide this proof, you will not be given a licence to sell your drug.
So. after five years of testing, you finally have a drug that you can sell and can make you loads of money. Unfortunately, that only means you have three years to 'cash in' before the licence expires. Now your drug becomes GENERIC meaning yo have to release all of the technical data so that anyone can make the drug.
Paracetamol, may have been a clever drug when it was first produced, but now you can get 100 tablets in Tesco for 20p if you see what I mean