I have dissolved Furanyl Fentanyl HCl and regurlar fentanyl HCl many times in water with no problems. However I currently have Furanyl Fentanyl HCl sitting in a cloudy solution and I cannot get it to dissolve. I have tried heating it and shaking it vigorously but nothing is working. I have dissolved this same batch in the water before without any problems, but the most recent solution I made has been sitting in a saline nasal spray for days. Whenever I let it sit for a while, most of the fentnyl just sinks to the bottom. I really dont want to use this the way it is now because I know there are hot spots and that is obviously very dangerous. But I am already withdrawing and I dont think I can force myself to wait mcuh longer. Will someone please tell me what would cause a water soluble salt, that you have previously dissolved with no problem, to all of the sudden not dissolve the next time you tried to mix it with the same solvent it dissolved in previously.