The “p” is recognizable as the first letter of the second word after “poxleber.”
I have an excerpt here. You can clearly see how the “p” was written downward, and at the end, the point where the quill turned. Since the body of the ‘p’ also matches all the other “p”s in the text, we must assume that this glyph is also a “p.”
This provides further support for the spelling “pinen” = “torment” or “pain.”
“poxleber pinen putrifer” is an alliteration that is likely intended as a mnemonic:
poxleber for pain / bloating.
As Hildegard von Bingen wrote at the 12th century, Poxleber is a remedy for stomach pain and intestinal problems.
I quote from the text of Hildegard von Bingen below:
Frequent consumption of it (the male goat) heals the intestines and strengthens the stomach. [...]
Those suffering from stomach ailments should eat dried Bocksleber [male goat’s liver] frequently until August.