<prompt> All of the following drugs are useful in detrussor instability except aEURSolefenacinTolterodineFlavoxateDuloxetine  <response>: Duloxetine Detrusor instability Detrusor is a smooth muscle which forms the body of the bladder. Its contraction causes micturition. The other smooth muscle that plays an impoant role in micturition is the internal sphincter. Internal sphincter is a concentraction of smooth muscle at the bladder neck. It is well developed only in males and its principal function is to prevent retrograde.flow of semen during ejaculation. When detrusor relaxes and the sphincters close urine is stored. Whereas voiding requires contraction of destrusor accompanied by relaxation of sphincters. Detrusor is innervated mainly by parasympathetic nerves which are excitatory and cause the muscle to contract where as internal sphincter is rich in al adrenoreceptor sympathetic nerves. Thus the mechanisms of urine voiding involves :? - Increased parasympathetic drive Contracts the detrusor - Decreased sympathetic drive --- Relax the sphincter Detrusor instability or unstable bladder is characterized by uninhibited, unstable contractions of the detrusor which may be of unknown etiology or secondary to an upper motor neuron lesion or bladder neck obstruction. Since detrusor contracts under parasympathetic influence, Anticholinergic specifically antimuscarinic drugs are used to treat overactive bladder disease or detrusor instability. These agents lower intravesical pressure, increase capacity and reduce the .frequency of contractions by antagonizing parasympathetic control of bladder. These agents include : -Darifenacin -Solefenacin - Tolterodine -Trospium chloride -Oxybutynin - -Solifenacin - Flavoxate Duloxetine is used in stress incontinence. It is a dual norepinephrine and serotonin reuptake inhibitor. Its mechanism of action is thought to be centrally, by increasing urethral sphincter tone and contractility. It can be used in mixed incontinence. Comparison of different drugs used for treatment of Detrusor instability Drug Benefits Weaknesses Generic - Cheap Poorly tolerated oxybutynin - Recommended by NICE well established Slow release - Improved side-effect profile More expensive than oxybutynin - Escalating does regimen possible immediate release Oxybutynin - Reduced side - effect profile Patches may cause skin patches Irritation limiting use Flavo xate - Less side effects than Less offecting Oxybutinin Tolterodine - First of newer anticholinergics Trial suggests not as - Robust trial evidence effective as solifenacin Trosplum - Does not cross blood- brain harrier Broad spectrum - May have benefits in the elderly or anticholinergic side patients with polypharrnacy effects Propiverine - Calcium antagonist action Recommended for frequency but not urge incontinence Solifenacin - STAR study suggests some benefits Commonest side effect over tolterodine at normal does - dry mouth Darifenacin - M3 selective Limited direct clinical experience outside of trials 