Heparin sodium is available from various manufacturers in concentration ranging from 1000 to 20000 units/mL,packaged in sizes ranging from 0.5-to 1 –mL ampuls,vials, or prefilled syringes to 30-mL multiple dose vials.Benzyl alcohol or parabens may also be present as preservatives,and hydrochloric acid and/or sodium hydroxide may have been added to adjust pH.Sodium chloride may have been added to some products for isotonicity.In addition,dulute solutions of 10 and 100 units/mL in 1-to 5-mL disposable syringes and 1-to 30- mL vial are available for use in flushing heparin locks.