When I looked for usage examples, I found that 'normative' documents are closely tied to the idea of 'regulatory' because they are usually a set of documents that by regulation must meet certain document control standards.
I found this explanation in a document explaining the requirements for a laboratory to be accredited under a particular ISO/IEC standard:
Normative documents are those that provide rules, guidelines or characteristics for activities or their results. It is a generic term that covers such documents as standards, technical specifications, codes of practice and regulations. (Source)
At first, I thought that these two terms were not interchangeable, but then I found some examples of usage that would suggest otherwise:
Essential documents are commonly referred to as regulatory documents. ICH GCP guidance defines essential documents as “those documents which individually and collectively permit evaluation of the conduct of the clinical trial and the quality of the data produced. These documents serve to demonstrate the compliance of the investigator, sponsor, and monitor with the standards of Good Clinical Practice and with all applicable regulatory requirements.” (Source)
It seems that there is an overlap between two senses of the word "regulatory". When I read "regulatory" my first impression involves government oversight and laws intended to regulate or 'to adjust to a particular specification or requirement'. The co-location I'm most familiar with is "regulatory agency", but government is not the only thing that can regulate. Thermostats regulate temperature and could be called "regulatory devices" (although I don't believe that's common). It is not incorrect to say "regulatory documents", it just may cause a layperson to confuse the term with documents published by the government or required by the government, because that's the context where we most frequently see the word regulatory.
I would use normative documents when I was referring to a set of documents that are intended to make sure a process is consistent and repeatable.
I might use regulatory documents when I was referring to a set of documents intended to make sure that something meets a certain specification of performance, or that are required by law.
The senses of those phrases are so close that I think they are interchangeable for audiences that work in the field. If the audience is the general public, I would avoid regulatory unless you're talking about government rules and laws. The word normative is a less common word and signals to me that there is some technical distinction I should pay attention to.
And, to actually answer the question at hand:
3) draft normative documentation or normative document for the medicinal product or reference to a relevant pharmacopeia monograph;
I would write that with 'normative' but adding the article as TRomano mentioned in a comment:
3) draft normative documentation or a normative document for the medicinal product or reference to a relevant pharmacopeia monograph;
However because it can be argued that there is a slight difference between normative and regulatory in this context, it might be better to include both types of documents/documentation in the list for completeness:
3) draft normative documentation or a regulatory document for the medicinal product or reference to a relevant pharmacopeia monograph;