Comparison of serum cortisol concentrations in clinically normal dogs after administration of freshly reconstituted versus reconstituted and stored frozen cosyntropin.

OBJECTIVE To evaluate the biological stability of reconstituted cosyntropin after storage at -20 C for 2, 4, and 6 months. DESIGN Prospective study. ANIMALS 10 clinically normal dogs. PROCEDURE Serum cortisol concentrations in dogs were determined before and 1 hour after administration of freshly reconstituted cosyntropin (synthetic ACTH) or cosyntropin that had been reconstituted and stored frozen at -20 C in plastic syringes for 2, 4, and 6 months. Cosyntropin was administered at 5 micrograms/kg (2.3 micrograms/lb) of body weight, i.v. RESULTS Baseline serum cortisol concentrations were similar at each sampling time. Compared with the effects of freshly reconstituted cosyntropin, administration of cosyntropin that had been frozen did not have a significantly different effect on serum cortisol concentrations. CLINICAL IMPLICATIONS Cosyntropin can be reconstituted and stored frozen at -20 C in plastic syringes for 6 months with no adverse effects on bioactivity of the polypeptide.