Levothyroxine sodium is available as a lyophilized powder in single-dose amber vials containing 100, 200, or 500 mcg of drug.2883 Also present in the vials are dibasic sodium phosphate heptahydrate, mannitol, and sodium hydroxide.2883 The contents of each vial should be reconstituted by adding 5 mL of sodium chloride 0.9%, resulting in solutions containing levothyroxine sodium 20, 40, and 100 mcg/mL, respectively.2883 Shake well to ensure complete dissolution.2883
Levothyroxine sodium also is available as an injection solution.2847; 3131
Levothyroxine sodium injection solution formulated with tromethamine (Fresenius Kabi) is available as a 20-, 40-, or 100-mcg/mL injection solution in 5-mL single-dose clear glass vials containing 100, 200, or 500 mcg •of drug.2847 Each mL also contains tromethamine 10 mg, sodium iodide 0.14 mg, sodium chloride 6.48 mg, and water for injection.2847 Sodium hydroxide and/or hydrochloric acid may have been added for pH adjustment.2847
Levothyroxine sodium injection solution (Hikma) formulated with arginine and betadex sulfobutyl ether sodium is available as a 100-mcg/mL injection solution in 1-mL single-dose clear glass vials.3131 Each mL also contains arginine 0.05 mg, betadex sulfobutyl ether sodium 80 mg, edetate disodium 0.05 mg, and water for injection with sodium chloride to adjust tonicity.3131 Hydrochloric acid and/or sodium hydroxide may have been added for pH adjustment.3131
pH
Injection solution (Fresenius Kabi): 9.5 to 10.8.2847
Levothyroxine sodium injection may be administered undiluted by intravenous injection.2847; 2883; 3131 Product labeling for the injection solution formulated with tromethamine (Fresenius Kabi) states the intravenous injection rate should not exceed 100 mcg per minute.2847 The drug also has been administered by intramuscular injection;2885 however, current US product labeling no longer includes this information.2847; 2883; 3131
Levothyroxine sodium injection (Fresenius Kabi) is a clear colorless solution.2847 Levothyroxine sodium injection (Hikma) is a clear, colorless to slightly yellow solution.3131
Intact vials of the lyophilized powder or injection solution should be stored at controlled room temperature and protected from light.2847; 2883; 3131 Product labeling for levothyroxine sodium injection solution (Fresenius Kabi) states intact vials may be stored for up to 24 hours exposed to indoor lighting outside of the carton.2847
Reconstituted solutions are stated to be stable for 4 hours.2883 Unused portions of reconstituted solutions or injection solutions should be discarded2847; 2883; 3131
Product labeling states that levothyroxine sodium injection solution and reconstituted solutions should not be added to intravenous solutions.2847; 2883; 3131
Syringes
Levothyroxine sodium 0.1 mg/mL in sodium chloride 0.9% was packaged as 5 mL in 6-mL polypropylene syringes (Monoject). No loss of drug was found after 7 days at 5°C.2354
Sorption
In a study of levothyroxine sodium stability in glass, polyolefin, and PVC containers for continuous infusion, delivery of the drug through PVC tubing resulted in 13% loss of drug in glass and polyolefin containers and 18% loss of drug in PVC containers over 1 hour as a result of sorption to the PVC materials.2884 Levothyroxine sodium concentrations returned to greater than 90% of the initial concentration by 3 hours in all 3 container types and thereafter remained above 90% for the duration of the 24-hour study period.2884 The use of polyolefin tubing or flushing of a PVC line with levothyroxine solution prior to administration has been suggested to minimize such sorption.2884
For a list of references cited in the text of this monograph, search the monograph titled References.