Background & Rationale: Major Depressive Disorder (MDD) is a common and debilitating illness
that that commonly does not respond to conventional treatments. Transcranial magnetic
stimulation (TMS) and intermittent theta-burst stimulation (iTBS) are non-invasive
neurostimulation treatments for depression that are Health Canada approved. These work by
generating magnetic fields outside of the body to change the activity of brain cells to
change how the brain works. They have a very favorable profile, with many patients
experiencing improvement with minimal side effects.
The investigators recently completed a study pairing iTBS with an FDA approved medication
that was chosen because it might enhance iTBS improvements. This medication is called
D-cycloserine, an old antibiotic that is rarely used in modern times. Years after it stopped
being useful as an antibiotic, scientists recognized other properties that the molecule has,
and it is some of these that make it interesting to pair with iTBS. When the investigators
did so, they found that compared to iTBS with a placebo, participants who received
iTBS+D-cycloserine were more likely to benefit from treatment.
In this original study, all participants received a fixed dose of 100mg daily. This means
that people of very different sizes could have had different drug levels, and the
investigators do not know how that impacted outcomes. With this study, there will be no
placebo condition because the purpose is to understand whether dosing according to weight
matters.
Research Question and Objectives: To describe the pharmacokinetic profile of 100mg oral
D-cycloserine and weight-based oral D-cycloserine dosed 25mg/17.5kg among individuals with
depression undergoing non-invasive intermittent theta-burst stimulation to the left
dorsolateral prefrontal cortex (DLPFC) in Major Depressive Disorder.