Nifedipine (Adalat, Procardia)
Nifedipine is commonly used as a pharmacological option for the acute management of autonomic dysreflexia when non-pharmacological measures are insufficient. As a calcium ion influx inhibitor (Ca-channel blocker), it reduces peripheral vascular resistance by inhibiting calcium influx in vascular smooth muscle, resulting in a rapid decrease in systolic and diastolic pressure (5-10mm Hg systolic although sometimes larger). When used in acute settings, nifedipine is typically administered using the “bite and swallow” method at a dose of 10 mg to help safely lower elevated blood pressure.
Discussion
Five studies (Steinberger et al. 1990; Lindan et al. 1985; Thyberg et al. 1994; Kabalin et al. 1993; Dykstra et al. 1987) have evaluated the effects of Nifedipine. Four of these five studies saw a reduction or alleviation of AD with nifedipine (Steinberger et al. 1990; Thyberg et al. 1994; Kabalin et al. 1993; Dykstra et al. 1987. Steinberger and co-investigators (1990) reported that sublingual nifedipine decreased peak systolic, diastolic, and mean blood pressure in individuals with SCI undergoing electroejaculation. Braddom and Rocco (1991) surveyed 86 physicians with an average of 16.8 years of experience in managing AD in individuals with SCI. They found that while pharmacologic treatment of AD varied greatly from physician to physician, antihypertensive medications were the most frequently used medications, with Nifedipine being a drug of choice in minor AD cases for 48% of physicians and in severe symptomatic cases for 58% of physicians. Although nifedipine has been the most commonly used agent for management of AD in individuals with SCI (Thyberg et al. 1994; Dykstra et al. 1987; Esmail et al. 2002; Braddom & Rocco 1991), its use has declined recently (Frost, 2002; Anton & Townson 2004). There have been no reported adverse events from the use of nifedipine in the treatment of AD (Blackmer, 2003), although all studies had a very small sample size. However, a review of nifedipine for the management of hypertensive emergencies not specific to SCI found serious adverse effects such as stroke, acute myocardial infarction, death and numerous instances of severe hypotension (Grossman et al. 1996). Due to several reports of serious adverse reactions occurring after administration of immediate-release nifedipine, the Joint National Committee on Detection, Evaluation and Treatment of High Blood Pressure (1997) has discouraged use of this drug.
Conclusion
There is level 2 evidence (from 2 prospective controlled trials) (Steinberger et al. 1990; Lindan et al. 1985) that Nifedipine may be useful to prevent dangerous blood pressure reactions, e.g. during cystoscopy and other diagnostic or therapeutic procedures in SCI injured patients with AD.
There is level 5 evidence (from clinical consensus) (Joint National Committee on Detection, Evaluation and Treatment of High Blood Pressure, 1997), that serious adverse effects from Nifedipine may occur and these have been reported in other populations.
