Registered Practical Nurse (RPN) Practice Test

How long before a blood draw should a client take their last dose of imipramine (Tofranil) to ensure accurate medication level monitoring?

1. 6 hours

2. 12 hours

3. 24 hours

4. 1 hour

The correct answer is: 12 hours

For accurate monitoring of imipramine (Tofranil) levels in the blood, it is essential to consider the drug's pharmacokinetics, including its half-life and the time it takes for the drug to reach a stable steady state in the body. Imipramine is a tricyclic antidepressant that has a relatively long half-life, typically ranging from 10 to 20 hours. When monitoring for therapeutic drug levels, it is generally recommended to allow adequate time between the last dose and the blood draw for the drug levels to stabilize. Taking the last dose approximately 12 hours prior to the blood draw is a widely accepted practice. This timing allows the medication to reach a peak concentration in the system and then begin to decline, providing a more accurate representation of the levels the client is experiencing without being affected by the immediate influence of the recent dose. This approach helps ensure that the healthcare provider receives a laboratory result that accurately reflects the medication's effectiveness and the client’s adherence to the regimen, facilitating informed clinical decisions regarding treatment adjustments.