SERM Half-Lives & Front Loading
TL:DR SERMs have half-lives, which could impact your choice of compound and dose depending on need.
We cover what SERMs (& AI) are here, and list out those common for our needs, their sides, and dose suitable for your brommunity. There’s a key omission which this article will address: half-life.
A half-life is defined as the duration of action of a drug. It is the period of time required for the concentration or amount of drug in the body to be reduced by one-half. 5 half-lifes means that the the compound has been effectively cleared from the body (97% cleared, but close enough). The reverse is also true - it will take 5 half-lifes for the drug to accumulate to maximal concentration if one were to take a dose every 1 half life (i.e. once every 12 hours for a drug that has a half-life of every 12 hours). This is not to say that a drug is not effective until it has reached that steady state point, but that it will not be maximally effective until it has reached that steady state.
To make it more confusing, SERMs have metabolite half-lifes, separate from the drug which are an active component.
Half-life may influence what SERM you choose to use, depending on where you are in your cycle. Let’s take the classic nolva PCT of 4 weeks. Only at 4.2 weeks in is nolva at steady state. Even worse, the metabolite does not reach steady state until 10 weeks in - long after the individual has discontinued use.
These numbers are interesting for me most in the concept of utilizing a SERM alongside a SARM. As always, let me preface this concept by saying a SERM PCT on a SARM only cycle doesn’t make sense, but running it alongside from early in the cycle seemingly does. The 6 day half-life would mean that nolva (for example) is at a steady state midway through your cycle, when you are anecdotally experiencing the greatest suppression symptoms, with the metabolite almost peaking before you finish up at 8 weeks.
Updated SERM Table
- Nolva is not significantly active until metabolized.
- Clomid (or rather enclomiphene) causes rapid improvement to LH, likely due to the short metabolite half-life
- Torems metabolites are not as active as the parent, so metabolites half-life not as relevant
Compensating for the delayed steady state is certainly possible by front loading, or running compounds initially at higher than normal doses. This effectively increases the amount of compound circulating, putting it a level that would ordinarily take the 5 half-lives to achieve. Example, front loading 50mg of nolvadex in the first week would achieve the same steady state as running it at 10mg for 5 weeks.
Every compound has its side effects, which tend to become increasingly common at high doses. Front loading may increase risk of these presenting. To many, this is an acceptable risk.
A Word On Timing
PCT using a compound with a long half-life is not going to reach its maximum concentration in your blood until the end of the therapy. That’s not to say that the compound is not effective prior to steady state, as gene expression is not wholly reliant on having a steady state and it’s not always a linear relationship between time and response. Some parts of your body are highly responsive, more so than the concept of a steady state might otherwise imply. That gives us some subjectivity as it applies to what is the best compound for PCT, or treatment of gyno. We know that nolva and ralox are effective in most cases in reducing gyno, and we know clomid is effective in preserving LH alongside otherwise suppressive compounds, quicker than it takes to achieve a steady state.
That said, what if you end up in the sticky situation of gyno on cycle, and you have no SERM on hand? What should you do? In that instance, I would opt for a SERM with a short half-life, one that will accumulate rapidly. Fortunately, ralox would be an option, and is well tolerated at higher doses: 120mg a day for 3 months in 15 health male 60-70 year olds had no reported side effects. Frontloading at 120mg a day would achieve the same steady state as 60mg in 1 day the same steady that would otherwise take 5 to achieve. (The calculators online for this don’t seem to be geared to allow for comparison against front loaded doses, or are otherwise just explanations on the math, so I built a quick model in excel to determine steady based on dose available for download here - just change the doses. If there’s interest I’ll turn this into a proper calculator and host it on pedsr.com).
When considering adding in a SERM to your cycle, consider also its half-life and that of its metabolites. Front loading is a valid option, and one not to be dismissed easily from fear of side effects, especially if dealing with significant sides.