Neonatal Nurse Practitioner Practice Exam

What factor does NOT influence the length of a drug's half-life?

1. Dosage of the drug given

2. Glomerular filtration rate

3. Volume of distribution

4. Patient's age

The correct answer is: Patient's age

The length of a drug's half-life is primarily determined by factors such as the drug’s clearance from the body and its volume of distribution. Specifically, factors that significantly influence drug half-life include the dosage of the drug given, the glomerular filtration rate (a key component of renal function), and the volume of distribution, which affects how extensively the drug is distributed throughout the body. While the patient's age can affect pharmacokinetics overall, such as possibly altering metabolism and excretion, it does not directly influence the calculation of a drug's half-life. This is important because age-related physiological changes may impact various organ functions that in turn can affect how long a drug stays in the body, but age itself is not a determinant in calculating half-life. Thus, when considering the intrinsic pharmacokinetic properties of a drug, age is not a direct factor influencing half-life compared to the other variables mentioned.