Naloxone hydrochloride occurs as a white to slightly off-white powder, and is soluble in water, in dilute acids, and in strong alkali; slightly soluble in alcohol; practically insoluble in ether and in chloroform.
Naloxone hydrochloride injection is available as a sterile solution for intravenous, intramuscular, and subcutaneous administration. Each mL contains 0.4 mg of Naloxone hydrochloride. Each mL contains 8.9 mg of sodium chloride. The pH is adjusted between 3.0 to 6.5 with  or sodium hydroxide. The air in the cartridges has been displaced by nitrogen gas.
The most common side effects reported with naltrexone are gastrointestinal complaints such as diarrhea and abdominal cramping.
These adverse effects are analogous to the symptoms of withdrawal, as the mu receptor blockade will increase GI motility.