Reboxetine increases anal pressure substantially in healthy women: a double-blind, randomized, placebo-controlled crossover study

Christoffersen T1, Riis T1, Kornholt J1, Sonne J1, Sonne D1, Klarskov N2

Research Type


Abstract Category

Anorectal / Bowel Dysfunction

Abstract 395
Bowel Dysfunction
Scientific Podium Short Oral Session 24
Friday 9th September 2022
15:30 - 15:37
Hall D
Anal Incontinence Pharmacology Clinical Trial Female
1. Department of Clinical Pharmacology, Bispebjerg and Frederiksberg, University of Copenhagen, 2. Department of Obstetrics and Gynaecology, Herlev and Gentofte Hospital, University of Copenhagen

Thea Christoffersen



Hypothesis / aims of study
Fecal incontinence, defined as the involuntary discharge of liquid or solid stool, is a prevalent and debilitating condition with limited treatment options. Anal sphincter dysfunction, accompanied by decreased anal pressure, is an important cause of fecal incontinence in women. Therefore, drugs that increase the tone of the anal sphincters constitute potential pharmacological treatments of fecal incontinence. On the other hand, drugs that decrease the anal pressure may contribute to fecal incontinence. While an observational study suggests that selective serotonin reuptake inhibitors (SSRI) are associated with urinary incontinence [1], clinical studies indicate that reboxetine, a noradrenaline reuptake inhibitor (NaRI), increases the urethral pressure and alleviates urinary incontinence symptoms [2,3]. Because the physiology of fecal continence resembles the corresponding urinary continence process, we hypothesized that reboxetine increases and citalopram decreases the anal pressure. This study aimed to evaluate the effect of reboxetine and citalopram on anal opening pressure (AOP) in healthy women.
Study design, materials and methods
We recruited healthy women (age 18–55 years, body mass index 18.5–30 kg/m2) for this single-site, randomized, double-blind, placebo- and active-controlled crossover study. At three clinic visits, the participants received single oral doses of 40 mg citalopram (and reboxetine-matched placebo), 8 mg reboxetine (and citalopram-matched placebo), and two placebos, respectively. We measured AOP at rest and under voluntary contraction (squeeze)  using anal acoustic reflectometry at the reported time of peak plasma drug concentrations (tmax). The administration of study drugs was split into two timepoints due to a one-hour difference in reported tmax. The washout period between clinic visits was a minimum of eight days. Randomization of participants to one of six possible treatment sequences was balanced for period, and sequence allocation was concealed to participants, investigators, and outcome assessors. Adverse events were collected at the end of each visit, by phone one day after each visit, and eight days after last visit.
We screened and randomized 24 women and had no dropouts. Compared to placebo, reboxetine increased AOP with 23.4 cmH2O (95% confidence interval [CI] 16.5-30.2, p<0.001) in resting condition and 22.5 cmH2O (95% CI 15.2-29.8, p<0.001) in squeezing condition. Citalopram did not change AOP statistically significantly compared to placebo (resting: 4.2 cmH2O [95% CI -2.7-11.1, p=0.2]; squeezing: 3.0 cmH2O [95% CI -4.3-10.3, p=0.4]) (Figure 1). Adverse drug reactions (ADRs) were more common with reboxetine and citalopram vs. placebo, (nausea: 11% vs. 17% vs. 0%; insomnia: 11% vs. 6% vs. 2%; dizziness: 9% vs. 6%  vs. 0%; and headache: 2% vs. 8% vs. 2% of total ADRs). No serious adverse events were reported.
Interpretation of results
This is the first randomized, placebo-controlled study evaluating the effect of reboxetine and citalopram on anal pressure in humans using anal acoustic reflectometry. We found that reboxetine induced a substantial increase in both resting and squeezing AOP, suggesting that reboxetine enhances the tone of both the internal and external anal sphincter. An effect of this magnitude is likely to be clinically relevant for the prevention of fecal incontinence, however, clinical studies in women with fecal incontinence are needed to elucidate the potential role of reboxetine in the management of fecal incontinence. Citalopram did not cause any statistically significant change in AOP, suggesting that SSRI treatment will not influence fecal incontinence pathophysiology.
Concluding message
Single dose 8 mg reboxetine increased the placebo-corrected AOP significantly, suggesting that reboxetine or other NaRIs may be efficacious in the treatment of fecal incontinence. Clinical trials in patients with fecal incontinence are needed to evaluate the potential clinical benefit of this treatment approach.
Figure 1 Figure 1. The figure shows the mean opening anal pressure at tmax corrected for the placebo value (mean AOP, cmH2O [95%CI]).
  1. Felde G, Engeland A, Hunskaar S. Urinary incontinence associated with anxiety and depression: the impact of psychotropic drugs in a cross-sectional study from the Norwegian HUNT study. BMC Psychiatry. 2. november 2020;20:521.
  2. Klarskov N, Cerneus D, Sawyer W, Newgreen D, van Till O, Lose G. The effect of single oral doses of duloxetine, reboxetine, and midodrine on the urethral pressure in healthy female subjects, using urethral pressure reflectometry. Neurourology and Urodynamics. januar 2018;37(1):244–9.
  3. Klarskov N, Scholfield D, Soma K, Darekar A, Mills I, Lose G. Measurement of Urethral Closure Function in Women With Stress Urinary Incontinence. Journal of Urology. juni 2009;181(6):2628–33.
Funding None Clinical Trial Yes Registration Number (Identifier: NCT04097288), EudraCT (Identifier: 2019-000059-14) RCT Yes Subjects Human Ethics Committee Regional Ethics Committee of The Capital Region of Denmark Helsinki Yes Informed Consent Yes

Continence 2S2 (2022) 100369
DOI: 10.1016/j.cont.2022.100369

22/06/2024 14:50:42