Which medication should be taken on an empty stomach according to the provided mnemonics?

Taking penicillin on an empty stomach is essential because it enhances the absorption of the medication. When penicillin is ingested with food, particularly dairy products and high-fiber foods, its absorption can be significantly diminished. This is particularly important for penicillin V, the oral form, as optimal blood levels need to be achieved for effective treatment of infections.

The other medications listed may have different administration guidelines. For instance, tetracyclines are also recommended to be taken on an empty stomach for better absorption, but they can also have interactions with certain foods and supplements, making their administration slightly more complex. Azithromycin and metoprolol, on the other hand, can generally be taken with or without food, and taking them on an empty stomach does not provide the same level of critical absorption necessity as seen with penicillin.

Therefore, the correct understanding of penicillin highlights why it is emphasized in the mnemonics for administration on an empty stomach.