Randomized controlled trial of topical phenylephrine in the treatment of faecal incontinence

Anal incontinence due to internal sphincter dysfunction is not amenable to simple surgical repair. The alpha-adrenergic agonist phenylephrine produces contraction of the internal sphincter and raises resting pressure when applied topically in healthy volunteers. The effect of topical phenylephrine in the treatment of faecal incontinence due to internal sphincter dysfunction was investigated.

Thirty-six patients (22 women) aged 28-81 (mean 58) years with faecal incontinence and ultrasonographically structurally normal anal sphincter muscles were treated with topical 10 per cent phenylephrine and placebo gels, allocated in random order in a double-blind crossover study. Maximum resting anal sphincter pressure and anodermal blood flow were measured. A symptom questionnaire was completed and incontinence score determined using a validated scale.

There were no significant differences in incontinence score, resting anal pressure and anodermal blood flow between the active and placebo treatments. Six patients on active treatment and two on placebo experienced more than 75 per cent subjective improvement. Three patients developed allergic dermatitis to phenylephrine.

This is the first study of the use of a topical pharmacological agent to treat faecal incontinence. This concentration of topical phenylephrine did not produce a significant improvement in symptoms or function. A subgroup of patients may respond. Further studies are required with increased concentrations.