A Cochrane review (abstract , review ) included 22 studies with a total of 1 099 patients (11 were crossover trials). The studied adrenergic drugs included phenylpropanolamine (11 trials), midodrine (2 trials), norepinephrine (3 trials), clenbuterol (3 trials), terbutaline, eskornade and Ro-115-1240 (1 trial each). The limited evidence suggested that an adrenergic agonist drug is better than placebo in reducing the number of pad changes and incontinence episodes, as well as improving subjective symptoms. In two small trials, the drugs also appeared to be better than pelvic floor muscle training, possibly reflecting relative acceptability of the treatments to women but perhaps due to differential withdrawal of women from the trial groups. There was not enough evidence to evaluate the use of higher compared to lower doses of adrenergic agonists nor the relative merits of an adrenergic agonist drug compared with oestrogen, whether used alone or in combination. Over a quarter of women reported adverse effects. There were similar numbers of adverse effects with adrenergics, placebo or alternative drug treatment. However, when these were due to recognised adrenergic stimulation (insomnia, restlessness and vasomotor stimulation) they were only severe enough to stop treatment in 4% of women.
Comment: The quality of evidence is downgraded by study quality (inadequate or unclear allocation concealment) and by indirectness (problems of generalizability due to studied interventions).