Perhaps this info will answer your question. It looks like Synacthen Depot can only be administered as a shot in muscle, so Synacthen is what is used in the IV for the stimulation test:SYNACTHEN®
Tetracosactide Hexaacetate
250 micrograms/mL Solution for Injection or Infusion.
Qualitative and quantitative composition
250 micrograms tetracosactide (beta1-24-corticotrophin) per ampoule (as hexaacetate).
For excipients, see List of excipients
Pharmaceutical form
A clear colourless aqueous solution for intramuscular injection or intravenous infusion in a 1 mL ampoule.
Clinical particulars
Therapeutic indications
Diagnostic use: for the investigation of adrenocortical insufficiency.
Therapeutic use: alternative to Synacthen Depot in cases where i.v. injection or infusion of tetracosactide is preferable to i.m. injection. (see Synacthen Depot data sheet)
Unlike Synacthen Depot, Synacthen has a short duration of action and can be administered both i.m. and i.v.
Dosage and method of administration
Diagnostic use:
30-minute Synacthen test: Plasma cortisol is measured immediately before and exactly 30 minutes after an injection of 250 micrograms Synacthen i.m. or i.v. If plasma cortisol increases by >200 nmol/L (70 micrograms/L), i.e. if the value 30 minutes after injection is >500 nmol/L (180 micrograms/L), adrenocortical function is regarded as normal.
If the 30-minute test gives inconclusive results, or if the aim is to determine the functional reserve of the adrenal cortex, the 5-hour test may be performed using Synacthen Depot (see Synacthen Depot BPI).
