Posted 7/26/2013 5:06 PM (GMT 0)
6MP and Imuran aren't exactly the same drug, but they're in the same class of drugs and work in the same way.
Quick biology lesson: most of the cells in your body divide very infrequently, and the majority of differentiated cells don't divide at all. Cells that DO divide frequently are blood and intestinal stem cells, in order to constantly replenish blood and intestinal epithelium.
Mercaptopurine (6MP is mercaptopurine, and Imuran is metabolized to mercaptopurine) is an analog of purine nucleotides. The body thinks it's adenine or guanine, but it can't use mercaptopurine to synthesize new DNA. If your cells can't synthesize new DNA, they won't divide (they won't DIE, they just won't divide).
Mercaptopurine therefore suppresses your immune system by lowering the number of white blood cells that are necessary to carry out an immune response. However, it takes time to build up enough mercaptopurine in the body to have an effect. It can take a minimum of 2-3 months to see an effect from 6MP or Imuran, and sometimes it can take longer.
Humira and Remicade are proteins that are designed to bind to specific inflammatory molecules in the body. The molecule they target is TNF-alpha (tumor necrosis factor alpha), which is a very well-known molecule in the immune response. By binding to TNFa, Humira and Remicade prevent it from binding to receptors on cells and carrying out that immune response. Humira can be administered at home, and Remicade has to be given at a hospital or infusion center.
The advantages of 6MP or Imuran is that you just take the medication in pill form every day, and it's easy to adjust the dosage of medication if you're either not seeing an effect, or if the side effects become bothersome. The disadvantages of these drugs is that they're very non-specific (they slow down cell replication throughout the body), and they can take months to work. You also will need to have blood tests done frequently when you start the medication, and often when you change the dosage. You are not supposed to drink alcohol on these drugs. My doctor has not been clear about WHY, but I think it's because drinking can do some damage to your liver, which is usually repaired by cell replication (liver cells are able to divide even after differentiation, which is really cool).
The advantages of Humira and Remicade are that they often start working very quickly (Remicade began working for me within a few days of my first infusion), and they are incredibly specific. They only reduce levels of TNFa, which means they don't impair all cell replication throughout the body. You also don't have to take a pill every single day, which for some people is nice. The disadvantages are that you have to inject Humira yourself, which can be painful. Remicade must be administered at an infusion center or hospital, which can eat a huge chunk of time out of your day every 6-8 weeks. A lot of people eventually build up a resistance to Remicade, since the protein is not 100% human. That means that people typically stay on Remicade forever, until they develop resistance. You can switch to Humira after using Remicade, if necessary, and there are other anti-TNFa biologics that are on the market, or that are being developed.
Both types of medications are immunosuppressants, which means that you are much more likely to get sick. If you are sick, and you have a Remicade infusion scheduled, you have to reschedule it. The side effects of both types of medications are mostly serious, but they're very rare (whereas prednisone side effects are both very serious and very, very common).
My doctor put me on both 6MP and Remicade, since 6MP has been known to boost the effectiveness of Remicade. I haven't noticed the 6MP being terribly effective for me; between Remicade infusions, I would just get sicker again, even after we bumped up the frequency and dosage of Remicade. Remicade + hydrocortisone enemas has helped me the most. I highly recommend trying Remicade.