Phenoxybenzamine overdose:

There is no antidote
Supportive treatment indicated
Avoid ephedrine as may increase hypotension

Methylene Blue in septic shock:

A release of nitric oxide has been incriminated in the cardiovascular alterations of septic shock. Since guanylate cyclase is the target enzyme in the endothelium dependent relaxation mediated by nitric oxide, Methylene blue- a potent inhibitor of guanylate cyclase has been found very effective in improving the arterial pressure and cardiac function in septic shock.

Studies have found improvement in mean arterial pressure (MAP) and systemic vascular resistance (SVR) while decreasing vasopressor requirements in septic shock.