There isn't an easy answer for this, even though it's a common area of disagreement between providers and auditors. To start with, though, I'd point out that prescription of anything, drug or otherwise, is listed in the table of risk, which is only one component of MDM - it's not sufficient by itself to meet moderate MDM. Assessment of MDM really requires looking at the totality of the documentation, and the notes would also have to meet a component of number of diagnoses/management options or amount/complexity of data in addition to risk to qualify for moderate MDM. But even if the disagreement is just about the risk element, I'd make a reminder that the guidelines state that the entries in the table of risk are 'common clinical examples rather than absolute measures of risk' so it's more complex than just saying a prescription automatically qualifies or does not.
In my experience, assessment of risk in E&M is an area that's best approached with providers as an open discussion item rather that as a right vs. wrong audit outcome because the providers are really the only ones qualified to know what the patient's true level of risk is. As coders/auditors, we can explain that risk is a component of MDM, and remind the providers that documentation needs to be sufficient such that one of their peers would agree that the level of risk is there, but if the provider feels that a particular diagnosis and the nature of treatment associated with it qualifies as moderate risk, then I'm usually inclined to their word for it. So rather than telling a provider that something does or doesn't qualify as moderate risk, I'd take the approach of working with the provider to make sure they document thoroughly their clinical impression, orders and rationales so that there is clarity in the medical record about the patient's condition and treatment plan.
Another good tool for discussing E&M levels in context of patient problems and treatment options is to look at the clinical examples in the Appendix of the CPT book. If you can find examples there that are comparable to the types of problems your providers are dealing with, that gives additional support and context to the E&M levels that the coder or provider is selecting.
Hope this helps a little!