Multiple dosing kinetics - Dr. K

What does the principle of superposition explain in the context of multiple dosing regimens?

• The interaction of two drugs when administered together.

• The additive effect of multiple doses of a drug on the plasma concentration.

• • The change in drug metabolism over time.

• The fluctuation between peak and trough levels of a drug.

• The impact of renal clearance on drug levels.

Answer explanation

The principle of superposition states that the total plasma concentration at any time is the sum of concentrations that would have been present if each dose had been given alone.

What is the primary clinical significance of maintaining a steady state concentration of a drug administered intravascularly?

• To decrease the frequency of dosing.

• To ensure the drug reaches therapeutic levels quickly.

• To avoid toxicity while maintaining efficacy.

• To allow for easier administration of the drug.

• To reduce the cost of treatment.

Answer explanation

Maintaining a steady state concentration helps balance the drug's efficacy with minimal toxicity, ensuring effective and safe therapy.

A patient is prescribed a medication that follows first-order kinetics with a volume of distribution of 40 L and an elimination rate constant of 0.03 hr-1. Calculate the elimination half-life of the medication and provide your answer in hours (do NOT include units)

Which of the following are independent of dose administered (SATA)

• Systemic clearnace

• AUC

• Volume of distribution

• Elimination constant

• Peak plasma concentration

Answer explanation

The dose independent parameters are : Systemic clearance, Elimination half life, Elimination rate constant, volume of distribution, and renal clearance

Given a drug with a bioavailability (F) of 0.8 and an oral dose of 100 mg that achieves an AUC of 500 hr*mg/L, calculate the clearance of the drug. Round your answer to two decimal places. (Do not include units)

Calculate the loading dose of a drug where the max plasma concentration is 50 mg/L and the volume of distribution is 30 L. (Do not include units)

What is the significance of using a loading dose in pharmacotherapy?

• To decrease the overall cost of treatment

• To reduce the frequency of drug administration

• To achieve therapeutic drug concentrations rapidly

• To decrease the drug's side effects

• To simplify the formulation of the drug

Answer explanation

A loading dose is often used to rapidly achieve therapeutic concentrations of a drug in the plasma, especially when it would take a long time to reach these concentrations with regular dosing alone due to the drug's pharmacokinetics.

A drug administered every 6 hours reaches a steady state with a dose of 200 mg, a volume of distribution of 40 L, and a half-life of 4 hours. Calculate the peak plasma concentration at steady state (Cp max ss).

A drug used in the treatment of chronic pain is administered at a dose of 500 mg every 12 hours. The drug has a volume of distribution of 50 L and a half-life of 10 hours. Calculate the steady-state peak concentration (Cp max ss) using the given pharmacokinetic parameters. Assume the elimination process follows first-order kinetics. Round your answer to two decimal places and do not include units

Tags

NGSS.HS-PS3-1

A patient is prescribed an antibiotic with a narrow therapeutic window. The drug is administered at 250 mg every 6 hours. Given that the half-life of the drug is 3 hours and the volume of distribution is 20 L, calculate the steady-state minimum concentration (Cp min ss). Assume perfect adherence to the dosing schedule and that the drug follows first-order kinetics. Round your answer to two decimal places and do not include units. (Hint: you need to solve for Cpmax first)