I will not spend time here explaining how a tincture is made.
What is important for the moment is to know if there are any kashrut problems on Pesach.
The last year-if I remember well- I sent you a kashrut ishur.
Until now, I have not received an ishur from the pharmacies/importer.

Of course, the problem is not the herb but the kind of alcohol used to make the concentrated extract [in England], and this is not known to me.
The tincture made from the concentrated extract imported from England, here in Israel by the 2 pharmacies[Gilo-French Pharmacy and Many] is made with alcohol which is kosher for Pesach, so it is no problem.
During all the years, I have told my patients that if they have to take medicine in a fluid form where the kashrut status is not known, to “spoil” the taste of the medicine with something bitter[I will write with what] and then even for Pesach, there should be no problem.!
I asked the Rav in Gilo again for all certainty, and he confirmed that this was all right.
I also asked the Rav of Beit Knesset Aderet Eliyahu in Gilo -Rav Asaf Harnoy -and he confirmed what I wrote above.

How can you “spoil” the taste of the drops you will use for Pesach?
Add anything you really dislike or are bitter [for example, the herb shiba] or buy some tincture of Gentiana [which is very bitter] and add some drops to the bottle you prepare.
Do this BEFORE Pesach!
As portulaca has been shown now for years to be extremely important -even if only in my opinion-[other doctors seem not interested to know about it] I would urge you not to stop it on Pesach
We have not seen any patient who took/takes Portulaca now for more than 2 years being very sick or hospitalised, Bauch Ha-Shem. May this have a chazaka for whatever may come.
Pesach sameach ve-kasher.

P.s The same principle is true for all tinctures in case you really need them and where the kashrut status is not known.