How does Humira work?

[EthanPSU]

I am not very medically knowledgeable I guess and don't really know the extent of how medicine works. So how does Humira like "get in you" and make you better? I know im injecting it in my body but not in the blood stream where I thought all medicine needed to go. So what happens to the medicine once I inject it into my belly fat?

 

[Dunbar]

Everything taken in our bodies either by skin, fat, blood is absorbed. Sunscreen to Humira. Humira is formulated to a cellular level to highjack the TNFa. If you want the medical jargon and incidentally the correct answers, I'd wait for David or Judith to weigh in, they know what they are talking about. I'm guessing with my limited understanding of this stuff. I'd like to know too. lol

 

[Patricia56]

Humira is subcutaneously injected. This means it is injected into the tissues just below the skin layers.

This tissue has blood vessels running through it. They aren't very big but they are there. The medicine is absorbed by the cells of the tissues where it is injected and then passed on into the blood stream by those cells.

Since the blood goes everywhere, it carries the medicine to the rest of your body.

Injecting the medicine helps make sure that it is fully absorbed in a controlled way - better than if it was taken by mouth. Injecting it into the subcutaneous tissues instead of into the muscle is done as a way of further refining the speed and way that the medicine is absorbed. Muscle tissue is more active and usually has more blood vessels and so would absorb and distribute the medicine faster.

Does that answer your question?

Humira "works" by interfering with the chain of events that lead to inflammation in your body. If you think of the way inflammation works in the body as a web of links all hooked together, then Humira works by disconnecting part of that web from the other parts. It doesn't completely break the web but it stops one part of it from connecting to all the rest.

This helps reduce the total amount of inflammation.

For some people - those who respond really well to biologics - this particular link in the web was a really important link.

For other people who don't respond well, then it seems likely that that particular link isn't as important a reason for their inflammation. Either that or the biologic they tried wasn't a good fit to unlock their particular version of the link.

 

[Judith]

Thanks for the props Dunbar, I cant really add too much jargonwize except that Humira is a "humanized" antibody directed against TNFa. Humanized means that certain areas of the antibody look like the human form of antibody. Whereas some earlier antibody-resembling biologics resembled the mouse form (also called murine). The fact that Humira is humanized is important in that it is less likely to stimulate your immune system to respond against it as a foreign invader.

Humira is an IgG type of antibody which is important because the IgG antibody type is very small relative to other types of antibody. Since it is so small it can diffuse throughout your body faster than something larger. (The ability for something to diffuse throughout your body is also affected by multiple other factors such as charge and how well it diffuses in water, etc. so size isnt the only thing affecting this)

When people inject Humira subcutaneously, an injection dosage of around 40mg of antibody (Humira active ingredient) will result in a maximum concentration that can be recovered in the blood of 4.7 micrograms/mL (+ or - 1.6 micrograms/mL).

Scientific Jargon Term: Cmax = maximum serum concentration

Cmax - tells you the maximum serum concentration of a drug (whether taken orally or injected) on those super fine print Drug Monograph sheets.
Your Cmax may be higher because most patients get a "Loading Dose" of Humira which is higher than 40mg (Maintainence doses are usually 40mg though).

Scientific Jargon Term: Tmax = Time taken to reach Cmax

The Tmax for Humira is 131 hours post-injection (but can range = or - 56 hours depending on the individual).