Switching Lexapro from Nighttime to Daytime Dosing
Give the next dose of Lexapro tomorrow morning, approximately 12 hours after the last nighttime dose, then continue with morning dosing thereafter.
Rationale for Timing
The FDA-approved prescribing information for escitalopram explicitly states that it "should be administered once daily, in the morning or evening, with or without food," indicating flexibility in timing without specific transition protocols 1. Given escitalopram's pharmacokinetic profile, a simple transition is both safe and practical:
- Escitalopram has a long elimination half-life of 27-33 hours, which provides substantial overlap in drug levels during the transition 2
- Steady-state concentrations are achieved within 7-10 days, meaning minor timing adjustments do not significantly disrupt therapeutic levels 2
- The drug exhibits linear pharmacokinetics with predictable plasma levels, making dose timing changes straightforward 3, 2
Practical Transition Approach
For your patient who took Lexapro last night:
- Skip tonight's dose completely
- Give the first morning dose tomorrow (approximately 12 hours after the last nighttime dose)
- Continue with morning administration daily thereafter 1
This approach avoids:
- Taking two doses too close together (which could occur if giving both tonight and tomorrow morning)
- Creating an unnecessarily long gap in medication coverage
- Any risk of withdrawal symptoms, given the long half-life 2
Clinical Considerations
The timing change itself has minimal clinical impact because:
- Escitalopram absorption is not affected by food or time of day 2
- Maximum plasma concentrations occur 3-4 hours post-dose regardless of administration time 2
- The 27-33 hour half-life ensures continuous therapeutic coverage during the transition 3, 2
Patient tolerance may guide optimal long-term timing:
- Some patients experience activation/insomnia with SSRIs and prefer morning dosing 4
- Others experience sedation and prefer nighttime dosing 4
- The FDA label supports either timing as equally valid 1
Common Pitfall to Avoid
Do not have the patient take doses both tonight and tomorrow morning in an attempt to "not miss a dose." With escitalopram's long half-life, this creates unnecessary overlap and potential for increased side effects without therapeutic benefit 2.