I recently started using Imitrex for migraines, using one of those auto-inject pens. The directions said to do it on a “fatty area” like your thigh.
If I’m injecting this medicine into a fatty area, rather than directly into a vein, how does it work?
I know when you receive medicine through an IV, the IV is in a vein, so the drug goes right into the vein and therefore into the bloodstream. That makes sense to me.
But how does just getting this stuff dispersed into the flesh make it work? Do diabetics inject the insulin into a vein or just anywhere?
Does it matter?
If I tried to inject this stuff right over a vein, would it work faster?
There are many ways to introduce medication to the body through the skin.
It all depends on what the drug is and how it is absorbed and how quicly you want it to be absorbed.
‘Normal’ injections are into muscle bulk and are taken up by the body fairly quickly (less than half an hour).
Injections may be made just under the skin (sub-cutaneously) often used for immunizations, or into the fatty layer beloew the skin (intra-dermally)- this slows down absorption a little and is good for drugs whose carrier is a fatty substance. Insulin is often introduced this way.
If it says ‘into fat’, then into fat it should go.
Other routes are
intra-venous (into a vein)
into the spinal column
into a body cavity
etc.etc. but you don’t really need or want to think about that.
IANAMD, but I am a juvenile-onset diabetic, and I have given myself several thousand insulin injections over the years.
If your medication’s directions say to inject in a “fatty area”, that means it is appropriate only for subcutaneous injection, not intravenous injection. The most common subcutaneous areas used by diabetics are the abdomen, the thighs, the buttocks, and the backs of the arms.
If you would like to speed up the absorption of the medication, you may want to use your abdomen. I’ve read that this area absorbs insulin more quickly than other areas. You might also try injecting prior to a hot bath or shower, as this will improve circulation and speed up absorption.
Thanks for both of your answers, but I’m not sure I got the answer I was looking for.
Maybe I didn’t phrase my question quite right.
What I am wondering is: how does the medicine get throughout my body when I inject it into the fatty part of my thigh? As opposed to injecting it directly into a vein?
In my way of thinking (which is obviously wrong), injecting something into a fatty area would just make it just sort of dissipate (?) in that area, not move throughout my system and take effect. Injecting a drug right into a vein gets it directly into the bloodstream, and therefore working faster. Right?
Since I am not getting this drug directly into the bloodstream, how does it work? How does my body get the effects of the drug?
When a substance is injected into the “fatty” tissue, it is absorbed by blood cells and such, since some areas of fat tissue are highly vascular, and contain lots of blood vessels. The medicine is absorbed into the areas into which it is injected, and is absorbed by the blood vessels in the area, where it is then transported to it’s proper location.
You have to think of the skin and muscle as not just one construction apart from veins etc.
Muscle consists of cells and they are surrounded by what is called inter-stitial fluid- bathing them with the appropriate medium in which to thrive. Within this muscle bulk are arterioles and venules- which meet each other to allow return from the arterial system to the vascular system.
Fat (known formally as adipose tissue)is a layer of non cellular material which stores energy and acts as protection. Interstitial fluid passes into this layer from the muscle bulk and from the skin above.
The skin (derma) is one of the most complex organs in the body, and is well perfused with arterioles and venules and laso has interstitial fluid.
All these media act in concert to make sure that everything is kept running smoothly (this is called homestasis) and this involves perfusion with oxygen, nutrients and fluids.
Injections piggy-back on this system to allow delivery of drugs.
Very few injections involve intra-venous routes- the drug tends to travel in a small concentrated ball (a bolus) and hits organs in high concentrations. Most drugs need to be delivered slowly. Injection into fat achieves this- slow release of a controlled amount over a period of time. SOmetimes high concentrations and quick release is just undesirable. In fact some injections (usually of psychiatric or birth control drugs) are chemically attached to fatty substances (usually oils like linseed or peanut oils) and injected into muscle bulk. The body takes some 2-3 weeks to break down all of this fatty bolus, achieving slow slow release- this is a depot injection.
Do not (repeat do not) try to achieve quick onset by IV injection- the reason you are asked to inject into fat is to give a long lasting effect to the drug. Sudden high concentrations are just not as effective.
Unless your MD tells you to do something stupid (like jumping out a window or referring you to a psychiatrist ;)), follow the instructions after questioning them directly- they will tell you more effectively (usually) than even this message board.
If it says “inject into fatty area” then only inject it into fatty areas!
Some medications, particularly those with blood-pressure altering effect (like Imitrex, if I recall correctly) can have SEVERE complications if injected into a vein. The dose needs to be absorbed gradually to avoid sudden and potentially harmfull changes in blood pressure, pulse, or other bodily processes. By injecting into fat, absorbtion is slowed to a pace that avoids unnecessary complications.
As an example - the Epi-Pens used in life-threatening allergic reactions state that failure to inject properly (the large muscle of the thigh is the recommended spot) can have all sorts of unpleasent consequences like heart attack, stroke, tissue damage that may require amputation, or death. Which is a heck of a side effect. It’s pretty strong stuff even administered properly, put it directly into a vein you’ll probably kill the patient.
So, to repeat - If it says inject into a fatty area, ONLY inject it into a fatty area
To clarify: Of course I follow the directions; it was really a hypothetical question. I should have said that. Sorry.
I just needed a little Anatomy 101. (All my medical knowledge comes from watching ER. )
I just didn’t understand how the drug would be absorbed from the fatty area into my bloodstream. I tend to think of various systems (skin, fat, veins) as separate from each other. I know (but usually forget) that it’s all connected and related.
You would do well to take what you see on ER with a large grain of salt. Despite the efforts to make it all look and feel authentic, they still manage to get some of the medical detail wrong. (My wife banned me from watching ER when she did - she got sick of me criticizing the errors).
If you want to find out about anatomy, look it up in Encarta or an equivalent encyclopedia. Usually this is enough to satisfy most lay people. Then there is always the internet to dig around for more detailed info if you need it. And if all else fails, try SDMB.
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