Effects of different doses of venlafaxine on serotonin and norepinephrine reuptake in healthy volunteers.
Venlafaxine is generally considered to be a dual 5-HT and NE reuptake inhibitor when it is used at doses above 75 mg/d in humans. While its 5-HT reuptake-inhibiting property has been demonstrated, some controversy still exists regarding the doses of venlafaxine required to inhibit NE reuptake. Healthy male volunteers received, on a double-blind basis, paroxetine (20 mg/d), desipramine (100 mg/d), nefazodone (300 mg/d), or venlafaxine (150 or 300 mg/d) in the last 5 d of a 7-d period of administration. Inhibition of 5-HT reuptake was estimated by determining the degree of depletion of whole-blood 5-HT, while that of NE was assessed by measuring the attenuation of the systolic blood pressure increases produced by intravenous injections of tyramine. Paroxetine, both regimens of venlafaxine, and to a lesser extent desipramine significantly decreased whole-blood 5-HT content. Nefazodone failed to produce any significant change. Desipramine abolished the tyramine pressor response, whereas all other drug regimens left this parameter unaltered. Venlafaxine and paroxetine acted as potent 5-HT reuptake inhibitors in the present study. In contrast, neither the moderate nor the high dose of venlafaxine displayed any significant inhibiting activity in this model assessing NE reuptake in peripheral NE terminals. The validity of the model was confirmed by the potent inhibitory action of desipramine on NE reuptake. While the reasons for this unexpected lack of action remain unclear, venlafaxine appeared to be an effective NE reuptake agent in depressed patients using the same approach.
Blier
Pierre
P
Department of Psychiatry, McGill University, Montréal, QC, Canada. pblier@rohcg.on.ca
Saint-André
Elise
E
Hébert
Chantal
C
de Montigny
Claude
C
Lavoie
Normand
N
Debonnel
Guy
G
D018759:Adrenergic Uptake Inhibitors / Q000008:administration & dosage; D000328:Adult; D018687:Antidepressive Agents, Second-Generation / Q000008:administration & dosage*; D000929:Antidepressive Agents, Tricyclic / Q000008:administration & dosage; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D001794:Blood Pressure / Q000187:drug effects; D003511:Cyclohexanols / Q000008:administration & dosage*; D003891:Desipramine / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D050484:Norepinephrine Plasma Membrane Transport Proteins / Q000187:drug effects* / Q000378:metabolism; D017374:Paroxetine / Q000008:administration & dosage; D010879:Piperazines; D012016:Reference Values; D015203:Reproducibility of Results; D012701:Serotonin / Q000097:blood; D050486:Serotonin Plasma Membrane Transport Proteins / Q000187:drug effects* / Q000378:metabolism; D017367:Selective Serotonin Reuptake Inhibitors / Q000008:administration & dosage*; D013997:Time Factors; D014230:Triazoles / Q000008:administration & dosage; D014439:Tyramine / Q000494:pharmacology; D000069470:Venlafaxine Hydrochloride
D018759:Adrenergic Uptake Inhibitors; D018687:Antidepressive Agents, Second-Generation; D000929:Antidepressive Agents, Tricyclic; D003511:Cyclohexanols; D003891:Desipramine; D009638:Norepinephrine; D050484:Norepinephrine Plasma Membrane Transport Proteins; D017374:Paroxetine; D010879:Piperazines; D012701:Serotonin; D050486:Serotonin Plasma Membrane Transport Proteins; D017367:Selective Serotonin Reuptake Inhibitors; D014230:Triazoles; D014439:Tyramine; D000069470:Venlafaxine Hydrochloride; C493230:SLC6A4 protein, human; C051752:nefazodone