What is the role of IV phentolamine in the treatment of complex regional pain syndrome (CRPS)?

Updated: Jun 20, 2018
  • Author: Gaurav Gupta, MD; Chief Editor: Stephen A Berman, MD, PhD, MBA  more...
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Answer

Phentolamine’s primary mechanism of activity is believed to occur via α-1 adrenergic antagonism, although the drug also has serotonergic, histaminergic, and cholinergic activities [86] , along with local anesthetic properties. [123] Controlled clinical trials showed mixed results and poor methodology. [37, 124] One study reported that phentolamine infusion was less sensitive but more specific than stellate ganglion block for the diagnosis of SMP. [109] An uncontrolled report observed that some patients with CRPS experience days or weeks of pain relief after 1 phentolamine infusion, although some of those reported that peak pain relief did not arrive until several days after phentolamine infusion. [125]

Phentolamine infusion has several advantages over sympathetic blockades—it is minimally invasive, not operator-dependent, and has systemic activity that allows for the simultaneous treatment of multiple body regions with SMP. Whether phentolamine has a dose-response relationship is unclear; therefore, some patients may need higher doses to see an effect. [126]


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