Beyond the typical alpha adrenergic and botulinum toxin approaches to improving bladder emptying, other pharmaceutical interventions have been explored. While these approaches still are few in number, this section describes primarily the use of 4-Aminopyridine (Grijalva et al. 2010) and isosorbide dinitrate (Reitz et al. 2004). 4-Aminopyridine prepared in various commercial formulations for the treatment of MS-related walking difficulties is also known as fampridine [ampyra, fampyra]. Most SCI specific studies involving 4-Aminopyridine assess bladder sensation and/ or control with respect to outcomes relevant to bladder management; often conducting more global assessments of function following treatment. This section reports only on bladder specific outcomes.
4-Aminopyridine is a potassium channel blocker, prolonging action potentials and increasing neurotransmitter release at the neuromuscular junction. Only one study to date, Grijalva et al. (2010), has explicitly commented on bladder function following administration of fampridine. During the open-label portion of the study where dosage levels of fampridine peaked, 3 of 12 participants regained both sensation and control of the bladder sphincter, and 1 of 12 regained sensation only. The paucity of literature in this area does not yet warrant fampridine as a primary treatment of bladder management in SCI.
Isosorbide dinitrate is a drug typically used to prevent angina attacks. However, it has been studied for the use of improving bladder function among 12 males post SCI (Reitz et al. 2004). In this single pre-post study, it was found that isosorbide dinitrate reduced external urethral sphincter pressure along with dyssynergic contraction; however, bladder pressures remained unchanged.
There is level 4 evidence (from one pre-post study: Reitz et al. 2004) that isosorbide dinitrate may be effective in reducing eternal urethral pressure and dyssynergic contraction.
There is level 4 evidence (from one pre-post study: Griljava et al. 2010) that 4-aminopyridine, at sufficient dosage, may be effective in restoring sensation and/ or control of the bladder sphincter.