For the newly bred and nearly dead dosing is heavily dependent on rate of metabolism. This is why kidney and liver function are so important to dosage. If a person can’t metabolize and clear out metabolites at a steady rate then it increases the bioavailability of a drug in the person’s system and can lead to overdoses. I used to tell my lab students that there’s no guaranteed way to tell how young kids are going to react to a medication just because their little systems are doing so much at wildly different rates.
Yea the science is making the dosage ranges and the art is the caregivers administering the medicine and monitoring the patient. I like the science part but the art part is too stressful for me.