Frontloading is the taking, initially, of a drug at a higher dosage than will be the case on an ongoing basis, for the purpose of more quickly getting blood levels to where they would eventually stabilize at with the ongoing dosage.
With drugs that have a long half-life, simply taking the ongoing dosage results in it taking quite some time for blood levels to get where they should be.
For example, 20 mg/day of Nolvadex on an ongoing basis will get blood levels to where they are effective for PCT.
But, on an ongoing basis, when taking a 20 mg tab you don’t just have in your system that 20 mg that you just took. You also have the great majority of yesterday’s dose, most of the day-before-yesterday’s dose, etc.
Users had found simply using 20 mg/day Nolvadex from the start to be slow, yet continuous 40 mg/day use was too much. The idea was thought up of using 40 mg/day for the first week – as a completely arbitrary time value – and then switching to 20 mg/day. Pharmacokinetics were likely not worked out.
So you are frontloading by taking the 40 mg/day.
An entire week overshoots what is needed.
Ordinarily, prior to taking a scheduled ongoing dose, one has in the system an entire half-life’s worth of dosing.
If we figure tamoxifen’s half-life as six days, then with ongoing dosing of 20 mg/day, then at steady-state (drug levels having stabilized) there will be about 120 mg in the system prior to taking a dose.
If a person takes 40 mg per day for the first three days and then switches to 20 mg/day, this has them a little short, as while they did take in 120 mg, some of it has metabolized.
I calculated the exact value some while back but don’t remember it, but I think 4 days was a slight overshoot. Anyway the value required for accurate frontloading, if never using more than double-dosing, is about 3-4 days.
(Alternately one can complete the frontload on the first day and get levels where they should be almost immediately. In this case, with 150 mg on the first day, for example as 40 mg three times across the day, and final dose of 20 mg. That is just extra information, as that doesn’t remain an option for you on this cycle.)
In your case, switching to the 20 mg/day ongoing dose level would be appropriate at this time, rather than going for an entire week at 40 mg/day, which unnecessarily overshoots the level of drug.