European Journal of Clinical Pharmacology

, Volume 28, Issue 5, pp 553–557 | Cite as

Relationship between clinical effects, serum drug concentration and serotonin uptake inhibition in depressed patients treated with citalopram

A double-blind comparison of three dose levels
  • L. Bjerkenstedt
  • L. Flyckt
  • K. Fredricson Overø
  • O. Lingjærde


Three dose levels (5, 25, and 50 mg once daily) of the selective serotonin uptake inhibitor citalopram were compared in a four-week, double-blind trial in depressed patients. Serum levels of citalopram and desmethylcitalopram, and the inhibitory effect of serum on serotonin uptake by fresh platelets, were assessed once weekly during the trial. The serum concentrations of citalopram were highly correlated with inhibition of serotonin uptake. Less of the metabolite was found, it being detected only in the higher dose groups. Steady state levels of citalopram, attained after 1 week, were linearly related to dose. The relationship between improvement (percentage reduction in total score on the Montgomery-Åsberg Depression Rating Scale) and serum level of citalopram indicated a lower limit of effect in endogenous depression at about 100 nM, corresponding to an average dose of 15 mg. Marked improvement was seen in ten patients with steady state levels in the range 70 to 335 nM. The ten nonendogenously depressed patients had steady state levels from 15 to 620 nM; complete remission was seen in the three with the lowest levels (15–25 nM). No significant correlation was found between serum drug level and the few reported side effects.

Key words

citalopram serotonin uptake inhibition depressed patients steady state levels clinical effect desmethylcitalopram platelets side-effects dose-response relationship 


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Copyright information

© Springer-Verlag 1985

Authors and Affiliations

  • L. Bjerkenstedt
    • 1
  • L. Flyckt
    • 1
  • K. Fredricson Overø
    • 2
  • O. Lingjærde
    • 3
  1. 1.Dept. of Psychiatry and PsychologyKarolinska InstituteStockholmSweden
  2. 2.Biochemical DepartmentH. Lundbeck A/SCopenhagenDenmark
  3. 3.Section of Clinical PsychiatryUniversity of TromsøNorway

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