Contact information
Type
Scientific
Primary contact
Prof Pierre Blier
ORCID ID
Contact details
1145 Carling Avenue
Room LG2043
Ottawa
K1Z 7K4
Canada
+1 613 722 6521 (6908)
pblier@rohcg.on.ca
Additional identifiers
EudraCT number
ClinicalTrials.gov number
Protocol/serial number
N/A
Study information
Scientific title
Acronym
Study hypothesis
Tyramine is well known by clinicians for its capacity to increase blood pressure, typically in patients treated with monoamine oxidase inhibitors. The finding that pretreatment with reserpine, which induces a depletion of catecholamines, abolishes the effect of Tyramine on blood pressure suggests that Tyramine acts indirectly as a sympathomimetic agent. It has been shown that Tyramine is taken up in NE neurons by the NE transporter and that by stochiometric displacement, it then releases NE from intraneuronal stores (Hoffman and Lefkowitz 1990). Blood pressure is increased by the release of NE; therefore, blood pressure serves as a simple and reliable index of the action of Tyramine. The Tyramine test (Ghose and Turner 1975) consists of measuring the transient increase in the blood pressure of patients after a Tyramine load. It can be carried out either by determining the dose of Tyramine required to induce a fixed increase in systolic blood pressure (SBP) (for example, 30 mmHg,) or by measuring the effect of a fixed dose of Tyramine. Pretreatment with Tomoxetine (now called Atomoxetine), a relatively potent and selective inhibitor of NE uptake, has been reported to decrease the transient elevation in blood pressure produced by Tyramine administration (Zerbe et al. 1985). In recent work, we have demonstrated that transient blood pressure elevation in response to Tyramine is reduced by pretreating subjects with Desipramine, Nortriptyline, Clomipramine and Reboxetine, three NE uptake inhibitors, but not by pretreating with Paroxetine, a selective 5-HT uptake inhibitor (Blier et al. 1997; Slater et al. 2000; Turcotte et al. 2001). In the proposed study, if treated subjects decrease their pressor response to Tyramine, it will be interpreted as evidence of NE uptake inhibition.
In this study, the 5-HT content of the whole blood will be used as an index of 5-HT uptake in depressed patients and will be measured before and after each week of treatment. Since more than 90% of the 5-HT in the blood is in platelets, it is not necessary to correct this value for the platelet count. Notably, Flament et al. (1987) found that the mean level of 5-HT did not change significantly after 5 weeks of placebo whereas it dropped by 95% after 5 weeks of treatment with clomipramine. In this study, the use of each subject as his own control will allow the use of covariance analysis, increasing the likelihood of detecting a statistically significant difference between the different groups at the end of the treatments.
Ethics approval
Not provided at time of registration
Study design
Randomised controlled trial
Primary study design
Interventional
Secondary study design
Randomised controlled trial
Trial setting
Not specified
Trial type
Treatment
Patient information sheet
Condition
Major Depression
Intervention
This is a three-arm, randomized, parallel study designed to assess the inhibition of NE and 5-HT uptake by Venlafaxine, Paroxetine and Atomoxetine. Approximately 40 depressed patients will be randomized to one of three treatment groups with the goal of having at least 10 subjects complete the study in each group. The investigators involved in the Tyramine test or the collecting of biochemical data will be blind to the medications used by patients. This study will be conducted on an outpatient basis.
Intervention type
Drug
Phase
Not Specified
Drug names
Venlafaxine, Paroxetine and Atomoxetine
Primary outcome measure
The primary objective of this study is to find evidence of a dose-dependent inhibition of NE reuptake starting of Venlafaxine at 150 mg/day.
Secondary outcome measures
A secondary objective of this study is to show a lack of effect of Paroxetine on NE reuptake at doses of up to 50 mg/day. Another secondary objective is to show a lack of effect of Atomoxetine on 5-HT reuptake and a similar action of higher doses of Venlafaxine and Atomoxetine on NE reuptake. A third secondary objective is to show a marked effect of Paroxetine and Venlafaxine on 5-HT reuptake starting at low doses.
Overall trial start date
01/08/2004
Overall trial end date
30/04/2005
Reason abandoned (if study stopped)
Eligibility
Participant inclusion criteria
1. Male or female patients between 18 and 65 years of age
2. Diagnosis of major depression according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) (American Psychiatry Association, 1994) using the Structured Clinical Interview for Depression (SCID) (Spitzer 1992)
3. Initial global score 18 on the 17-item Hamilton depression rating scale
4. Written informed consent signed by the patient
Participant type
Patient
Age group
Adult
Gender
Both
Target number of participants
40
Participant exclusion criteria
1. Evidence of significant physical illness contraindicating the use of Venlafaxine, Paroxetine or Atomoxetine found on physical or in the laboratory data obtained during the first week of the study
2. Evidence of suicidality or severity of depression precluding safe participation in the study
3. Mental retardation (IQ lower than 80) rendering the response to investigators unreliable
4. Pregnancy, or absence of adequate contraceptive method in women with childbearing potential
5. Concurrent use of psychotropic medication such as antipsychotics, mood stabilizers or regular use of high doses of benzodiazepines
6. Lack of response or intolerance to optimal doses of Paroxetine, Venlafaxine or Atomoxetine
7. Participation in another clinical trial within 30 days of entry into the current study
Recruitment start date
01/08/2004
Recruitment end date
30/04/2005
Locations
Countries of recruitment
Canada
Trial participating centre
1145 Carling Avenue
Ottawa
K1Z 7K4
Canada
Sponsor information
Organisation
Wyeth Pharmaceuticals (Canada)
Sponsor details
50 Minthorn Boulevard
Markham
Ontario
L3T 7Y2
Canada
Sponsor type
Industry
Website
Funders
Funder type
Industry
Funder name
Wyeth Pharmaceuticals
Alternative name(s)
Funding Body Type
Funding Body Subtype
Location
Results and Publications
Publication and dissemination plan
Not provided at time of registration
Intention to publish date
Participant level data
Not provided at time of registration
Basic results (scientific)
Publication list