Final answer:
In a uremic patient, a decreased ability to bind drugs to plasma proteins indicates that a higher proportion of Phenytoin would be unbound and thus active. As a result, the free drug concentration in the plasma would likely be higher, which requires vigilant monitoring to avoid toxicity, especially due to Phenytoin's narrow therapeutic range.
Step-by-step explanation:
The question focuses on the effect of a uremic patient's decreased ability to bind drugs to plasma proteins on the drug concentration in their blood. Phenytoin is used as the example drug, which is known to be 90% bound to plasma proteins in normal individuals. The therapeutic range of Phenytoin is 10-20 µg/mL.
In a uremic patient, the ability to bind drugs to plasma proteins is diminished. Because of this condition, there would be a higher proportion of the free (unbound) form of Phenytoin in the bloodstream. As only the free drug is available to cross membrane barriers and exert pharmacological effects, the lower protein binding in uremic patients would mean that careful monitoring is required to avoid drug toxicity while still achieving therapeutic effects. This is essential given the narrow therapeutic range of Phenytoin.
The precise concentration of Phenytoin that would be free in the plasma cannot be determined without additional information. However, it can be deduced that with a decrease in binding, the free concentration of Phenytoin would likely be higher than in individuals with normal renal function, provided that the total plasma concentration of Phenytoin was the same.