what is the equivalent in mg to 400,000 U i medicine
what is the equivalent in mg to 400,000 U i medicine/what is 400,000 U of penicilina equal to in mg?
International Units are a measure of a drug's efficacy (or rather a standardized measurement of expected biological effect), not its mass, so strictly speaking, the two terms do not describe measurements that are interchangeable by a simple formulaic conversion across chemical classes. That is, you should not expect to find a single uniform answer to fit across the entire spectrum of drug classes.
According to this source, one International Unit of penicillin G refers to the expected activity of 0.6μg of penicillin G (or 6 x 10 ^ -4 mg). Assuming this information is valid, it should be a simple matter to convert 400,000 I.U. of penicillin G to milligrams.
While the word "penicilina," and the abbreviation "U.I." are Spanish, this is probably not the forum to be asking such questions. I would suggest, instead, that you search out resources such as this one