Hi, Ravenclaw,

I am not a doctor, but I have studied physiology and biochemistry, and I use a blood thinner for a prothrombin gene mutation. This is my understanding, but you should ask a pharmacist to be sure.

The citrate anticoagulates work by binding calcium to prevent clotting, and calcium is necessary for normal muscle contractions. Anything that changes the available calcium would have an effect on muscle strength and stamina, and it makes sense that citrate anticoagulates would be contraindicated for people with MG.

Heparin works by activating antithrombin, which is a protein in the blood that prevents thrombin from forming clots, and it therefore should not have any effect on muscle strength or stamina. I have used Lovenox, which is a low-molecular weight heparin with fewer side effects, since 2001, and it has not had any effect on my muscle strength or stamina.

The vitamin K antagonists reduce the amount of active vitamin K in the body, and vitamin K is necessary to produce prothrombin, which is a protein in the blood that is activated to form thrombin, which is necessary for a clot to form. Again, there should be no effect on muscles if you take this.

I use Lovenox because I don't have to get blood drawn every 3 weeks to test my clotting factors, and I don't have as many dietary restrictions as I would with a vitamin K antagonist, although there are still a lot of foods and supplements that affect blood clotting. Read more about them here under the heading Interactions: https://en.wikipedia.org/wiki/Anticoagulant

Lovenox is only available by daily subcutaneous injection, so if needles bother you, then you may be stuck with a vitamin K antagonist. However, if you are on a lot of other medications, it may mean the vitamin K antagonist is not a realistic option. It's complicated, and you need someone with a solid medical background to advise you.

Please ask your pharmacist to verify all of the above, and help you determine the best and safest option for you, based on your medications and medical conditions. They are usually pretty good about being able to figure out whether I can take a medication or not.

Good luck to you!

Rose