Replies to post #351658 on Innovation Pharmaceuticals Inc (IPIX)

[Lemoncat]

I wouldn't stress over the selectivity index too much. A high SI does not necessarily mean we're going to have great efficacy.

Question for our Pharma docs on the board: There seems to be a pretty high obsession on SI the past couple days. I'm reading up on it...how accurate is my understanding of the following:

SI = Selectivity Index
AVA = Antiviral Activity
TOX = Cytotoxicity

SI = AVA/TOX

Brilacidin is considerably safer than most of the drugs on this list from a cytotoxicity perspective. Therefore it has a relatively (very) low TOX value compared to many of these other drugs.

Take some possible numbers:

Remdesivir AVA = 1032
Remdesivir TOX = 8

Brilacidin AVA = 213
Brilacidin TOX = 0.5

Remdesivir SI = 1032/8 = 129
Brilacidin SI = 213/0.5 = 426

So there is a potential set of numbers where Brilacidin has a much higher SI while having a much lower AVA because the TOX value is extremely low comparatively. Brilacidin dosage is limited by systemic blood pressure effects rather than cytotoxicity. Therefore it seems like the truth about how valuable SI is depends on what the underlying variables actually are.

The question the trial will answer is does Brilacidin have ample effect on COVID at dosages below the problematic ones of the Polymedix trial. If so, we have a hit, If not, the situation becomes more precarious. SI is the same in either case.

I'm not sure how useful SI is for Brilacidin. I think Brilacidin will kill the patient through systemic damage (Polymedix+ SAEs) long before it has a cytotoxic (cell damage) dosage.

Obviously all things equal a higher SI is better than a lower one but in the case of Brilacidin isn't our dosage limitation based on systemic SAE constraints rather than cytotoxicity?

Go IPIX!