The problems arise in treating specific diseases and pathophysiological conditions that alter the regular physiology in ways we have yet to determine. The most common confounding states being ARDS, MOSD, Sepsis, Multiple Trauma, Sickle Cell and many types of cancers. If it were easy, I would be selling popcorn in St. Martin. Keep up the good work ladies and gentlemen. We need you, the patients need us.
All population models are like yesterday's newspaper.
Even if your patient was an adult, the use of population models alone is usually NOT enough, because of the diversity in the population. But they are all one has. That is the whole purpose of getting feedback. That is what Bayes' theorem is all about. Put in the dosage regimen.