Switching antidepressant (tricyclic antidepressants (TCA) to serotonin reuptake inhibitors (SSRIs)) in adults

Switching antidepressant (tricyclic antidepressants (TCA) to serotonin reuptake inhibitors (SSRIs))

From all except clomipramine

Cross-taper

Cross-tapering can usually be undertaken cautiously over 2 to 4 weeks, the speed is determined by individual tolerability. It could include:

• halving the dose of the TCA
• then adding the SSRI at the usual starting dose
• then slowly reducing and stopping the TCA over 5 to 7 days

Additional caution when switching to fluoxetine, fluvoxamine and paroxetine

• if switching to fluoxetine, fluvoxamine or paroxetine, caution is required because fluvoxamine is a potent inhibitor of the liver enzyme CYP1A2 and fluoxetine and paroxetine are potent inhibitors of the liver enzyme CYP2D6; these enzymes are involved in the metabolism of TCAs
  • note that though the TCA is being withdrawn, you should still be aware of the risk of raised TCA levels in the body when they are administered together

From clomipramine

Taper, stop and switch

• gradually reduce the dose of clomipramine and stop. Start low dose SSRI the following day. If switching to fluoxetine it should be started at 10mg daily
  
  
• cross-tapering is not recommended and should only be undertaken if specialist advice is in place, this is because clomipramine is a potent serotonin reuptake inhibitor so there is a high risk of serotonin syndrome

Reference:

• NHS Specialist Pharmacy Service (February 2023). Tricyclics to other antidepressants: switching in adults