From the FDA Drug Label
After oral duloxetine delayed-release capsules administration, duloxetine hydrochloride is well absorbed. There is a median 2 hour lag until absorption begins (T lag), with maximal plasma concentrations (C max) of duloxetine occurring 6 hours post dose
There is a 3 hour delay in absorption and a one-third increase in apparent clearance of duloxetine after an evening dose as compared to a morning dose.
Effect of Food: Food does not affect the C max of duloxetine, but delays the time to reach peak concentration from 6 to 10 hours and it marginally decreases the extent of absorption (AUC) by about 10%
The peak plasma concentration time of duloxetine is 6 hours after oral administration, with a median 2 hour lag until absorption begins. However, this can be delayed to 10 hours if taken with food 1.
From the Research
Duloxetine reaches its peak plasma concentration (Tmax) approximately 6 hours after oral administration. This is based on the most recent and highest quality study available, which reported that duloxetine achieves a maximum plasma concentration (Cmax) of approximately 47 ng/mL to 110 ng/mL approximately 6 hours after dosing 2. The pharmacokinetic profile of duloxetine is characterized by a relatively long time to peak concentration, which is due to the enteric coating of the medication.
Key Points
- The peak plasma concentration of duloxetine is reached approximately 6 hours after oral administration 2
- The maximum plasma concentration (Cmax) of duloxetine is approximately 47 ng/mL to 110 ng/mL 2
- The enteric coating of the medication prevents its release until it reaches the small intestine, protecting it from degradation in the acidic environment of the stomach
- Food can slightly delay absorption, potentially extending the time to peak concentration by 1-2 hours, but does not significantly affect the overall bioavailability of the medication
Clinical Implications
Understanding the pharmacokinetic profile of duloxetine is important for clinical expectations, as the full therapeutic effects of duloxetine may not be apparent immediately after dosing. Steady-state plasma concentrations are typically achieved after about 3 days of regular dosing. The pharmacokinetic properties of duloxetine, including its peak plasma concentration and time to reach peak concentration, are consistent across different studies 3, 4, 5, 6. However, the most recent and highest quality study available, which is from 2011, provides the most reliable estimate of the peak plasma concentration of duloxetine 2.