California Rocket Fuel: Mirtazapine Plus Venlafaxine
"California Rocket Fuel" refers to the combination of mirtazapine (a noradrenergic and specific serotonergic antidepressant, NaSSA) and venlafaxine (a serotonin-norepinephrine reuptake inhibitor, SNRI), used for treatment-resistant depression. 1
The Two Medications
- Venlafaxine: An SNRI that inhibits reuptake of both serotonin and norepinephrine 2
- Mirtazapine: A NaSSA (not an SSRI) that enhances noradrenergic and serotonergic neurotransmission through alpha-2 antagonism 1
Rationale for This Combination
The combination targets multiple neurotransmitter systems simultaneously, which theoretically provides enhanced antidepressant efficacy compared to single-agent therapy. 1
Dual-acting antidepressants (those affecting both norepinephrine and serotonin) have demonstrated superiority over SSRIs in severe depression, with tertiary amine tricyclics like amitriptyline and clomipramine showing particular advantage in hospitalized or severely depressed patients. 3
SNRIs like venlafaxine provide marginally superior remission rates compared to SSRIs (49% vs. 42%) in major depressive disorder, with additional benefits for patients with comorbid pain disorders. 3
Clinical Application
This combination is specifically indicated for treatment-resistant depression—patients who have failed to respond to initial adequate trials of standard antidepressants. 1
Preclinical studies demonstrate that sub-effective doses of mirtazapine (5 mg/kg) combined with venlafaxine (7.5 mg/kg) reduced immobility in forced swim tests without affecting motor activity or causing sexual dysfunction. 1
Important Caveats
Risk of hypomanic switching: This combination carries significant risk of inducing profound alterations in mental state, including drug-induced hypomania, and should be reserved for carefully selected patients with close monitoring. 4
The combination should only be used after failure of first-line treatments, as second-generation antidepressants (SSRIs and SNRIs) are considered equally effective for treatment-naïve patients. 3