Vial Sizes and Concentrations

Updated April 15, 2024

We want to determine what vial sizes and concentrations are a good fit, maximizing both. As we’ve said in other places, the official recommendation from USP/FDA etc is that vials be discarded 28 days after puncture. But, we’re going to call 12 weeks a rough good cutoff point for vials considering that any official number will be highly conservative.

For estradiol, assuming a 5mg dose and a 0.035mL dead space:

Concentration	Dose Vol.	With Dead Space	Vial Size	Doses
20mg/mL	0.25mL	0.285mL	3mL	10
20mg/mL			5mL	17
40mg/mL	0.125mL	0.16mL	3mL	18
40mg/mL			5mL	31

For testosterone, assuming a 50mg dose and a 0.035mL dead space:

Concentration	Dose Vol.	With Dead Space	Vial Size	Doses
200mg/mL	0.25mL	0.285mL	3mL	10
200mg/mL			5mL	17

For Estradiol, we recommend using 20mg/mL in a 3mL vial in order to create a vial that lasts for about 10 doses (or about 10 weeks).

For Testosterone, we recommend using 200mg/mL in a 3mL vial in order to create a vial that lasts for about 10 doses (or about 10 weeks).

Until we are able to conduct some experiments to determine how long these vials can last without contamination, being punctured regularly or even after a single puncture and being left around, then we think it’s best to hug closer to official guidelines.

We believe 3 times the official guideline is still okay seeing as many folks are putting 40mg/mL into 10mL vials, and using it for over a year. They are hopefully using extra benzyl alcohol (but not a toxic amount), but without further research that’s not something we’re willing to do or advocate for.

Now, most homebrewers will brew at a 40mg/mL concentration, and often distribute a 10mL vial, effectively containing a years worth of HRT in a single vial. This is a bad idea. The FDA requires that all vials are discarded 28 days after first puncture. And like, yeah sure, ACAB, and truly the FDA is probably way conservative, but also… they’re probably not that wrong here. Another issue to consider is coring. If you puncture your vial every week for a year eventually you run the risk of causing some rubber to fall into your meds and also compromising the integrity of the seal. We’ve seen vials core in under 8 weeks due to poor puncturing technique.