In the US, this is called a "package insert". In Europe, particularly the UK, this is called a "patient information leaflet". However, my main central European client insists on using the more literal "instructions for medical use" - a phrase that generally only appears in documents translated from Russian. ("medical use" here is really "human use", in contrast to "veterinary use")

Лекарственный препарат can be medication, medicinal product, drug, drug product. "Medication package insert" or "drug package insert" or "package insert for a drug product" are all in use in the US, for instance.

Again, this is a case where it is best to ask your client for their preference, but absent a preference, I would call it a package insert for a US-based client and a patient information leaflet for everyone else.

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Note added at 10 hrs (2019-04-02 15:56:43 GMT)
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Yes, I would use package insert for that as well.

It looks like the terms are used more or less interchangeably in Russian (инструкция для пациентов is another variant), though as Elena noted in the discussion above, инструкция по применению can also be more general, i.e., instructions for use that are just printed out, and not included specifically as a package insert.