ah. polyestradiol phosphate. Ouch, the pharmacokinetics of that...

You do understand that word, right?

Pharmacokinetics See also: Pharmacokinetics of estradiol PEP has a very long duration and is given by intramuscular injection once every 4 weeks.[35] In men, an initial intramuscular injection of PEP results in a rapid rise in estradiol levels measured at 24 hours followed by a slow and gradual further increase in levels up until at least day 28 (the time of the next injection).[35] Subsequent injections result in a progressive and considerable accumulation in estradiol levels up to at least 6 months.[35] The mean elimination half-life of PEP has been found to be 70 days (10 weeks) with a single 320 mg intramuscular dose of the medication.[7] The tmax (time to maximal concentrations) for estradiol was about 16 days.[7] PEP has a duration of approximately 1 month with a single dose of 40 mg, 2 months with 80 mg, and 4 months with 160 mg.[60][61][62][63][39]

PEP reaches the bloodstream within hours after an injection (90% after 24 hours), where it circulates, and is accumulated in the reticuloendothelial system.[52] Estradiol is then cleaved from the polymer by phosphatases, although very slowly.[64] Levels of estradiol in men with intramuscular injections of PEP once every 4 weeks were about 350 pg/mL with 160 mg, 450 pg/mL with 240 mg, and almost 700 pg/mL with 320 mg, all measured after 6 months of treatment.[35] With monthly injections, steady-state estradiol concentrations are reached after 6 to 12 months.[52] Estradiol is metabolized primarily in the liver by CYP3A4 and other cytochrome P450 enzymes, and is metabolized to a lesser extent in extrahepatic tissues.[20][1] The metabolites are mainly excreted in urine via the kidneys.[1]

Early studies found that a dosage of 80 mg PEP every 4 weeks rapidly produced relatively high mean estradiol levels of about 400 to 800 pg/mL.[65] These levels are similar to those of 100 mg estradiol undecylate every month, which has been found to produce estradiol levels of around 500 to 600 pg/mL.[66][67] As a result, it has previously been said that 80 mg PEP per month and 100 mg estradiol undecylate per month are roughly equivalent.[68][69][7] However, subsequent studies showed that this dosage of PEP actually achieves much lower estradiol levels than originally demonstrated.[35]

source: https://en.wikipedia.org/wiki/Polyestradiol_phosphate#:~:text=The%20mean%20elimination%20half%2Dlife,estradiol%20was%20about%2016%20days.

hmm. nice for the bubs. that good long term build up of female sex hormones with a half life 100x times that of the 17h of estradiol itself. must be why its use is contraindicated in..... breastfeeding