The authors are using the term pharmacological to refer to plasma concentrations that are only achievable by IV administration.

Per the authors, the body regulates Vitamin C to 80-100uM so you can't just consume more of it. IV administration however gets around the natural intestinal absorption limits.

So unless you plan to shoot up your supplements, this doesn't seem applicable to typical person just yet. Though I must say I'm imagining a funny skit where we see what appears to be a drug den of people shooting up and it's a bunch of natural herbalist types cooking up and injecting vitamin c from a pile of oranges.