Modern psychopharmacology is largely the story of chemical neurotransmission. One must be fluent in the language and principles of chemical neurotransmission to:
Understand the actions of drugs on the brain.
Grasp the impact of diseases upon the central nervous system.
Interpret the behavioral consequences of psychiatric medicines.
After studying Module 2: Lecture Materials & Resources, discuss the following:
Choose an FDA-approved medication currently used in psychiatry.
Explain the concept of that drug’s half-life.
How long would it take for that drug to reach a steady state?
How frequently should the medication be dosed based on the half-life?
Full Answer Section
Reaching Steady State:
It takes several half-lives for a medication to reach a steady state in the bloodstream. This means the amount of drug entering the body through each dose is balanced by the amount being eliminated. For fluoxetine, with a half-life of 1-3 days, it can take 4-9 days to reach a steady state concentration.
Dosing Frequency:
Fluoxetine's long half-life allows for once-daily dosing. Because it takes several days to reach steady state, it may take a few weeks before the full therapeutic effects of the medication are noticeable.
Additional Points:
- Individual factors like metabolism and liver function can influence fluoxetine's half-life.
- Some patients may require adjustments in dosage based on their response and potential side effects.
By understanding the concept of half-life, we can predict how long it takes for a medication to reach therapeutic levels and how often it should be dosed for optimal effect.
Sample Answer
Fluoxetine (Prozac) and Understanding Half-Life
Chosen Medication: Fluoxetine (Brand Name: Prozac) is a selective serotonin reuptake inhibitor (SSRI) commonly used to treat depression, anxiety disorders, and obsessive-compulsive disorder (OCD).
Half-Life Explained:
The half-life of a drug refers to the time it takes for the amount of the drug in the body to decrease by half. For fluoxetine, the half-life is approximately 48-72 hours (1-3 days).