As shown in the per protocol analysis of a recent randomized, controlled trial, when tolerated, Desipramine is effective over placebo in treating moderate-to-severe functional bowel disorders.
Clinical experience suggests that the benefit from tricyclic antidepressants in functional bowel disorders can be achieved at doses lower than those used to treat major depression.
Within psychiatry, when using higher dosage of tricyclic antidepressants, plasma levels can be used to adjust daily dosage to optimize a treatment response.
However, in functional bowel disorders, it is not known whether plasma levels at the lower dosage are similarly related to a clinical response.
Dr Halpert and colleagues from Canada determined whether Desipramine blood levels or dose taken can predict a clinical response in treating functional bowel disorders.
The researchers included 431 patients with functional bowel disorder that were part of a study of 12 weeks of antidepressant and psychological treatment at the University of North Carolina and the University of Toronto.
| There was a modest correlation between mean Desipramine dose and Desipramine blood level at week 6|
|American Journal of Gastroenterology|
The research team studied those participants who completed treatment (per protocol analysis) taking Desipramine (N = 97, dose 50,150 mg/day) or pill placebo (N = 5,513 pills/day).
The primary outcome measure was defined by the investigators as a composite score (Satisfaction with Treatment, McGill Pain Questionnaire, Global Well-being, and Irritable Bowel Syndrome-Quality of Life).
The composite score was correlated with Desipramine plasma levels at week 6, and the number of pills taken over the duration of the 12 week treatment period.
In addition, the reasearchers also compared Desipramine dose with Desipramine plasma levels.
The team reported a modest correlation between mean Desipramine dose at weeks 5 and 6 and Desipramine blood level at week 6.
However, the research team noted no significant correlations between the composite score either with Desipramine dose or with Desipramine blood levels.
Dr Halpert concludes, “Detectible blood levels of Desipramine are associated with a clinical response in functional bowel disorders.”
“However, with dosages up to 150 mg, there is no relationship between total dose or plasma level and the clinical response."