How accurate is IM dosing?

[mako9802]

Anyone ever thought that no matter how accuate you get the dosage in your syringe how do you know you are gettng your precribed dosage everytime.  I wondered can the estradiol settle in the vial?  This might be a odd or silly question but oh well.

[AnneK]

Generally, if medication can settle, you're advised to shake before using.  However, you can always ask your pharmacist, to be sure.

[KayXo]

There's always gonna be a very little amount left in the syringe that can't make it out of the needle.

[SadieBlake]

There's always gonna be a very little amount left in the syringe that can't make it out of the needle.

The delivered dose is exactly how many CCs you inject (i.e. plunger start minus plunger stop). What's contained in the luer lock fitting is called dead volume and is disposed of with the syringe & needle.

Op, estradiol does not settle in the vial, it's thoroughly mixed with the diluting oil (castor or similar).

The main error would be the accuracy of your syringe.  Using a 3cc syringe, accuracy should be +/- 5-10% or better.

My dosage happens to be very small, only 0.0625 cc and so I use a smaller 1cc syringe and usually err a bit on the high side, 0.07 to 0.08cc to ensure I'm not dosing below the prescription amount.

[Dani]

Variations in syringes and what is left in the syringe are real but small losses. In fact there is a manufacturing range of allowable medication per unit volume. The USP standard is usually + or - 5%. Also, the older a drug is, the more it degrades and loses potency. Another source of variable doses.

Injectable estradiol is a solution, so there is no settling out like a suspension does.

[KayXo]

The delivered dose is exactly how many CCs you inject (i.e. plunger start minus plunger stop). What's contained in the luer lock fitting is called dead volume and is disposed of with the syringe & needle.

Agreed.

Using a 3cc syringe, accuracy should be +/- 5-10% or better.

I think an overestimation. I use a 3 cc syringe and I'd say accuracy is closer to 1% or less.

My dosage happens to be very small, only 0.0625 cc

Are you sure you don't mean 0.625? That is infinitesimally small. I inject 1 cc at a time.

[SadieBlake]

Absolutely positive, I started at a standard weekly dosage and got E readings of 700 pg/ml, and blood work showed my albumin levels too high. We cut it in half, exactly halving the mid-week measure to 350 and then in half again to get down to the low 200s which is a number both I and my endocrinologist like ok.

For accuracy, ISO 7886-1:1993  dictates that accuracy should be +/-5% for volumes greater than half the syringe capacity, however as a 3 ml is probably being used to deliver 1/2 - 1cc for most im injections, the accuracy is probably less.

Again, it really doesn't matter, 10% accuracy is more than good enough for estradiol. And I agree one can do better than "standard" but then I'm a scientist/engineer and prefer to state accuracy conservatively.

[KayXo]

Do you take spironolactone by any chance? What were your albumin levels and have they decreased since?

I've had levels between 1,000 and 4,000 pg/ml and albumin levels remained normal. Just goes to show you everyone reacts differently.

[SadieBlake]

Never needed spironolactone -- I think I just threw our the original bottle, 90% full, the estrogen fully suppresses my T to below 25.

And I misremembered, at an E measure of 700 my albumin was low, 3.2 against a normal range of 3.4 - 5.0.

[KayXo]

at an E measure of 700 my albumin was low, 3.2 against a normal range of 3.4 - 5.0.

And now, what are your albumin levels since you're taking less E?

[SadieBlake]

3.7 in August and 3.8 in April (pre-op), my E, T measurements were 225, 17 and 210, 20 respectively.

[KayXo]

Just went through my previous blood tests and noticed my albumin levels are indeed lower since switching to injections three years ago but remain in normal range except for this one time when they were measured at another hospital and were under the normal range (lower limit 3.8, my level was 3.6) but my endocrinologist didn't see any reason to lower my dose of estradiol injections. Before injections, levels were around 4.3-4.8. After injections, consistently at 4.1 except for that one time. So far, after reading a couple of studies, it seems estrogen can indeed lower albumin synthesis in the liver. Serum albumin levels are also, apparently, typically lower during pregnancy. Interesting...

[KayXo]

With IM, it is not uncommon for estradiol levels to reach pregnancy levels. As a result, other hormones, proteins, electrolytes may change and to compare those levels to normal range could be misleading. For instance, it's quite normal for TSH and total T4, T3, prolactin or total cortisol to increase and albumin levels to decrease, following a significant increase in estrogen levels during pregnancy.

See this link http://www.babymed.com/laboratory-values/serum-albumin-during-pregnancy

Thus, given Sadie's estrogen values came close to what is seen during pregnancy during IM, her albumin levels were indeed normal if we compare those values to that seen during pregnancy (3.1 - 5.1 during first trimester). Hence, nothing abnormal and I believe this is why my doctors didn't budge since this is to be expected. Same with my cortisol or prolactin values or even TSH, all of which significantly increased while on injections due to high levels of estradiol. Although in excess of normal values, they remain within the norm for pregnancy values. So, all is good.

[SadieBlake]

It wasn't "while I was on IM" I'm still administering via IM, simply at a lower dose. I see no value in being at pregnancy levels of estrogen (I've been around pregnant women). Also pregnancy is quite hazardous, just because it's natural doesn't make it a good idea.

Anyhow, this is pretty well drifting away from the OP's topic.