For the benefit of those who don't read Blackletter, here is my translation.
One Saturday, summoned to the Chief Rabbi, [Luzzatto] requested a quill, ink and paper so he could write a prescription; but neither the rabbi nor anyone in his family would give these to him, because he was only a little inconvenienced, and he had his office nearby1. But he had quill and ink in his bag, and tore out a page from his book and wrote something like this:1 I assume this meant that Dr. Luzzatto could have gone to his office and gotten the medication, rather than write out a prescription. Alternatively, maybe they wanted him to go to the office and get the ink, etc. himself rather than handle it for him. Or maybe it means that the rabbi's illness was itself only an inconvenience and not life-threatening, therefore no prescription should have been written at all?
"Today on this holy Sabbath day, in the month of Shevat, in the year 5500 (ie, 1740) , [when the weekly reading containing the verse, Ex. 21.19, Parshas Mishpatim) וְרַפֹּא יְרַפֵּא, healing for the perfect haham, the distinguished judge, the pious, the modest, etc. "greater than the title 'rabbi' is the name," his honor, the rabbi . . . the Lord will send him healing . . . "
Then came the prescription in Latin, followed by four satirical lines in Hebrew, which could no longer be recalled by the person who told me about this. This was rude and callous to play with the patient's feelings and beliefs. I hope this anecdote is not true and question it's authenticity, especially because of the well-known saying de mortuis nihil nisi bene, which מליצים have given with the same truth and more wit: אחרי מות קדושים אמור.2
2 On the one hand this is surprising. It would seem to indicate that the story was true. After all, if אחרי מות קדושים אמור holds water then would the story be said if it weren't true, despite that tendency? On the other hand, I suppose it depends on why the story was being told. It certainly seems to bolster Luzzatto's quick wit and way with a pen, thus in that sense it could be a case of inflating his reputation after death. In addition, it is worth having a look at what Rashi comments on those two words (see here). Razor sharp! In any case, at least one detail of the story is obviously wrong, the date. In 1740 Ephraim Luzzatto was all of 11 years old. In addition, the overly flowery prose in the rabbi's title raises questions (גדול מרבן שמו כמהו"רר ? You've gotta be kidding me.) Indeed, one scholar identified the rabbi as Moses Cohen d'Azevedo (which would place the story after 1761) on the basis of the poor esteem which he was held as a scholar (which even caused a distinguished dayan to resign when d'Azevedo was appointed to the Bet Din).