11 DESCRIPTION
Fentanyl Citrate Injection is an opioid agonist. Fentanyl Citrate Injection, is a sterile, nonpyrogenic solution of fentanyl citrate in water for injection, available as 50 mcg (0.05 mg) per mL which is administered only by the intravenous or intramuscular routes of injection. The chemical name is N-(1-phenethyl-4-piperidyl) propionanilide citrate (1:1). The molecular weight is 528.60. Its molecular formula is C22H28N2O∙C6H8O7 , and it has the following chemical structure.

Fentanyl citrate, a white powder which is sparingly soluble in water. Each milliliter contains fentanyl (as the citrate) 50 mcg (0.05 mg). May contain sodium hydroxide and/or hydrochloric acid for pH adjustment. pH 4.7 (4.0 to 7.5).
The solution contains no bacteriostat, antimicrobial agent or added buffer and is intended only for use as a single-dose injection. When smaller doses are required, the unused portion should be discarded in an appropriate manner.