DHEA has a half-life in blood of about 1−3 hrs, while DHEA-S has a half-life of 10−20 hrs, Taking this half-life of 20hrs x 5 cycles = 100hrs so in 4-5 days you should have cleared the exogenous DHEA effect on DHEA-S.
The following is from the attached article:
The abundant circulating concentrations of DHEA-S are due in part to the clearance of DHEA from the blood at a rate of approximately 2000 L/day, whereas DHEA-S clearance is about 13 L/day (
Lephart et al., 1987). Therefore, DHEA has a half-life in blood of about 1−3 hrs, while DHEA-S has a half-life of 10−20 hrs (
Rosenfeld et al., 1975). Clearance rate is defined as the volume of plasma that would contain the amount of drug excreted per unit volume. Therefore, clearance expresses the rate of drug removal from the plasma, but not the amount of compound eliminated. The clearance rates of DHEA and its sulfate are also influenced by their protein-binding characteristics. For example, DHEA is weakly bound to albumin, while DHEA-S is strongly bound to albumin.
or
Pharmacokinetics
Oral absorption of DHEA is excellent. The volume of distribution is 17.0-38.5 L for DHEA and 8.5-9.3 L for DHEAS. DHEA and DHEAS are converted into several active metabolites, including androstenedione, testosterone, estrone, estradiol, and estriol (Figure 1). The elimination half-life of DHEA is 15-38 minutes, whereas the half-life of DHEAS is 7-22 hours. Renal excretion accounts for 51-73% of the elimination of DHEAS and its metabolites.
Then half-life is 22 hours so for DHEA, 5 days should be fine.
The attached research paper on Pregnenolone says the sufate metabolite clears from the blood in 120 minutes so again you will be fine in theory with a 5 days waiting period. But this is clearance and not half-life, the only mention of Pregnenolone half-life in an article was 40hours, I could not find something quickly on this. But if it is 40 x5 = 200hours, you will be clear of both after 10 days.
I found the last added researchpaper while looking for the pregnenolone half-life, I think its interresting as it shows that taking Pregnenolone on its own would convert into its metabolite and then quickly into DHEA, so is there a real need to take DHEA seperate or in a combi with Pregnenolone?