From the Guidelines
Escitalopram is absorbed into the body relatively quickly, with maximum plasma concentration reached within 0.5 to 4 hours after administration. This rapid absorption is due to its good absorption from the gastrointestinal tract, as stated in the study by 1. The time to reach maximum plasma concentration (tmax) is approximately 0.5 to 4 hours, indicating a relatively fast absorption rate.
Key Points
- The absorption of Escitalopram is not significantly affected by food intake, as it has a high bioavailability of around 80% 1.
- The drug's high distribution volume and fast distribution from plasma to the central nervous system also contribute to its rapid onset of action.
- However, it is essential to note that while Escitalopram is absorbed quickly, its full therapeutic effect in treating depression or anxiety typically takes 2-4 weeks of regular use to manifest, as it involves long-term modulation of the brain's serotonin system.
Pharmacokinetics
The study by 1 provides detailed information on the pharmacokinetic properties of Escitalopram, including its absorption, distribution, metabolism, and elimination. The drug's high first-pass metabolism and genetic polymorphisms affecting its metabolism should be considered when prescribing, as they may influence the drug's efficacy and safety.
Clinical Implications
In clinical practice, the rapid absorption of Escitalopram should be taken into account when monitoring patients for potential side effects or adjusting dosages. However, the delayed onset of its therapeutic effects should also be considered, and patients should be advised to continue treatment for an adequate duration to experience the full benefits of the medication.
From the FDA Drug Label
Following a single oral dose (20 mg tablet or solution) of escitalopram, peak blood levels occur at about 5 hours. The absorption of Escitalopram (Cipralex) into the body is relatively quick, with peak blood levels occurring at about 5 hours after a single oral dose 2.
From the Research
Absorption of Escitalopram
- Escitalopram is rapidly absorbed into the body, with maximum plasma concentrations reached in approximately 3-4 hours after oral administration 3, 4.
- The absorption of escitalopram is not affected by food 3, 4.
- Escitalopram has a high absolute bioavailability, with a mean systemic clearance and volume of distribution of 31 L/h and 1,100 L, respectively 4.
Pharmacokinetics of Escitalopram
- The mean half-lives of escitalopram are 27 and 33 hours, respectively, with steady state attained within 7-10 days 3 and 10 days 4.
- The area under the plasma or serum concentration time curve from time zero to 24 hours and C(max) is both linear and proportional to the dose 4.
- Escitalopram is metabolised by the cytochrome P450 (CYP) isoenzymes CYP2C19, CYP2D6 and CYP3A4 3.
- Escitalopram has negligible inhibitory effects on CYP isoenzymes and P-glycoprotein, suggesting that escitalopram is unlikely to cause clinically significant drug-drug interactions 3.
Comparison with Other Studies
- Other studies have also reported that escitalopram is well tolerated and effective in treating depressive symptoms 5.
- A study on the pharmacokinetics of selective serotonin reuptake inhibitors reported that gastrointestinal absorption of the SSRIs is generally good, with peak plasma concentrations observed after approximately 4 to 6h 6.
- A recent study on pharmacokinetic correlates of clinical response in a naturalistic sample of escitalopram-treated patients found that patients with low clearance of escitalopram may be less likely to respond to escitalopram 7.