Abstract

In a recent article¹ we discussed an experimental preparation of tetracosactrin (a synthetic corticotrophin-like substance) combined with an inorganic zinc complex to prolong its action (Synacthen Depot - Ciba; Cortrosyn Depot - Organon). Synacthen Depot is now generally available. After an injection of this preparation or of corticotrophin in gel, plasma corticosteroids increase to a maximum in about 8 hours. They decline more rapidly after corticotrophin in gel than after depot tetracosactrin. Unlike porcine and bovine corticotrophin preparations Synacthen Depot can be chemically standardised and prescribed by weight. Loss of response to porcine corticotrophin occurs in a few of the patients who develop antibodies to it, and for these Synacthen Depot might be indicated since the development of antibodies to Synacthen Depot and associated loss of activity has not so far been found and is unlikely. The preparation is worth trying in patients allergic to corticotrophin. One mg Synacthen Depot seems to be roughly equivalent to 80 international units of corticotrophin in gel.