How long would a single dose of T gel stay in my system?

[KayXo]

the lack of T (except occasionally) for the 3+ years since surgery has stimulated my adrenals to pick up the slack.

It doesn't work that way. ACTH isn't increased by the lack of T, only LH and FSH. My adrenals certainly haven't picked up the slack since my surgery in 2005 and I needed to eventually add some T.

With T-Gel, the absorption will stop when you wash it off by sweating too much or taking a shower.

I believe absorption mostly stops when the alcohol totally evaporates which in the case of Androgel takes a few seconds. Taking a shower within the hour may still remove some of the T lying in the outer surfaces of the skin though

[suzifrommd]

I believe absorption mostly stops when the alcohol totally evaporates which in the case of Androgel takes a few seconds. Taking a shower within the hour may still remove some of the T lying in the outer surfaces of the skin though

With T-Gel, the absorption will stop when you wash it off by sweating too much or taking a shower. Within 5 half lives, there should be no testosterone left in your blood system. 

That's not how I understand it works. According to an article posted on the NIH website:

The skin serves as a reservoir for the sustained release of testosterone into the systemic circulation.

Later in the article, that mechanism is described in more detail:

The patient should avoid showering, swimming, or washing the site for at least 3 hours after application to allow adequate absorption of the drug into the subcutaneous tissue where it remains stored for continuous release into the systemic circulation.

My interpretation of this article is that the T remains in the skin long after it has evaporated or been washed from the surface. That it remains in the subcutaneous tissue where it is absorbed steadily.

[KayXo]

I may have misconstrued my message. After the alcohol evaporates, there is no more T that will absorb into the superficial layers of skin from where during the following hours, it will migrate into the dermis and subcutaneous tissue where it absorbs into the blood slowly over the course of many hours. At least, this is my understanding from everything I read.

In any case, if stopped, I highly doubt that anything remains in the subcutaneous tissue after 1 week.

[Dani]

My interpretation of this article is that the T remains in the skin long after it has evaporated or been washed from the surface. That it remains in the subcutaneous tissue where it is absorbed steadily.

Even though a portion of the testosterone stays in the skin acting like a reservoir for longer absorption , there is a half-life for that application. Applying a second dose renews and extends that half-life. This effect is well documented in the science of Pharmacokinetics. Some timed release drugs use a deposit or reservoir of medication and others use a slowly dissolving coating over active medication to release a second dose some hours after the first dose. Regardless all drug delivery methods have a half-life after a single dose. Even if the drug in question uses a reservoir to continue  drug release, the reservoir will eventually become depleted and that is where the half-life becomes noticeable.