Sometimes Oliver Cowdery (or perhaps even Joseph Smith in his reading off of the text) replaced unfamiliar words with familiar ones that sound alike and semantically work, more or less. For a list of examples, see the discussion regarding “the pleasing bar of God” under Jacob 6:13.
Here in Alma 40:26, the infrequent word dregs was misheard (or perhaps misread) as the much more frequent word drugs. The 1830 typesetter caught this error since he knew that with the noun cup the expected word was dregs, not drugs. The correct dregs is, in fact, found twice elsewhere in the Book of Mormon, namely, in two quotations from the King James Bible:
The text is invariant for both instances of dregs in 2 Nephi 8 (although 𝓞 is not extant for these two occurrences of dregs). The word drug is not otherwise found in any of the scriptures. The critical text will accept the 1830 emendation of drugs to dregs here in Alma 40:26.
Summary: Accept in Alma 40:26 the 1830 typesetter’s decision to emend drugs (the reading of both manuscripts) to dregs; either Oliver Cowdery or Joseph Smith in the early transmission of the text replaced the less frequent dregs with the more frequent drugs.