Veterinary Medicine - February 2008 - (Page 116) Hyperadrenocorticism and trilostane PEER-REVIEWED TABLE 7 CONCLUSION Dogs with hyperadrenocorticism that do not respond to mitotane or other forms of medical therapy may bene t from trilostane therapy. Any practitioner using trilostane should be familiar with the likely side effects and be able to adequately monitor patients during therapy. Prompt recognition of potentially life-threatening complications is imperative, and appropriate supportive care must be available. Clients must be informed that trilostane is not approved in the United States, educated on the warning signs of adrenal insuf ciency, and given clear instructions about when to discontinue therapy and seek veterinary care. Editors’ note: Dr. Cook is an educational and marketing consultant for Dechra Pharmaceuticals, PLC. Monitoring and Dose Adjustment for Dogs Receiving Trilostane Each evaluation should include a physical examination, a serum chemistry profile with electrolytes, and an ACTH stimulation test. • Evaluate the patient 10 to 14 days after starting trilostane therapy. • Repeat within two to three weeks if the dose is changed. • Repeat every three to six months if the patient is stable. Post-ACTH Stimulation Cortisol Concentration 9 µg/dl Dose Adjustment Stop the trilostane therapy. Do not restart it unless signs of hyperadrenocorticism are noted. Stop the trilostane therapy for 48 hours, then restart the therapy at 50% of the previous dose. Continue the present dose. Consider a 50% increase in the dose if the patient shows clinical signs of hyperadrenocorticism. Increase the dose 50% to 100%. REFERENCES 1. Behrend EN, Kemppainen RJ, Bruyette DS, et al. Intramuscular administration of a low dose of ACTH for ACTH stimulation testing in dogs. J Am Vet Med Assoc 2006;229(4):528-530. 2. Feldman EC, Nelson RW. Canine hyperadrenocorticism (Cushing’s syndrome). In: Canine and feline endocrinology and reproduction. 3rd ed. St. Louis, Mo: Elsevier Saunders, 2004;252-357. 3. Peterson ME. Diagnosis of hyperadrenocorticism in dogs. Clin Tech Small Anim Pract 2007;22(1):2-11. 4. Hanson JM, van ‘t HM, Voorhout G, et al. Ef cacy of transsphenoidal hypophysectomy in treatment of dogs with pituitary-dependent hyperadrenocorticism. J Vet Intern Med 2005;19(5):687-694. 5. Peterson ME. Medical treatment of canine pituitary-dependent hyperadrenocorticism (Cushing’s disease). Vet Clin North Am Small Anim Pract 2001;31(5):1005-1014. 6. Potts GO, Creange JE, Hardomg HR, et al. Trilostane, an orally active inhibitor of steroid biosynthesis. Steroids 1978;32(2):257-267. 7. Wenger M, Sieber-Ruckstuhl NS, Müller C, et al. Effect of trilostane on serum concentrations of aldosterone, cortisol, and potassium in dogs with pituitary-dependent hyperadrenocorticism. Am J Vet Res 2004;65(9):1245-1250. 8. Plumb DC. Plumb’s veterinary drug handbook. 5th ed. Ames, Iowa: Blackwell Publishing, 2005;778-779. 9. Vetoryl Package Insert. Shrewsbury, Shropshire: Arnolds Veterinary Products/Dechra Veterinary Products. 10. Neiger R, Ramsey IK. Trilostane therapy of canine hyperadrenocorticism, in Proceedings. Am Coll Vet Intern Med Forum 2002. 11. Neiger R, Ramsey I, O’Connor J, et al. Trilostane treatment of 78 dogs with pituitary-dependent hyperadrenocorticism. Vet Rec 2002;150(26):799-804. 12. Reusch CE. New treatment options in canine Cushing’s syndrome, in Proceedings. World Small Anim Vet Assoc Congress 2002. 13. Braddock JA, Church DB, Robertson ID, et al. Trilostane treatment in dogs with pituitary-dependent hyperadrenocorticism. Aust Vet J 2003;81(10):600-607. 14. Alenza DP, Arenas C, Lopez ML, et al. Long-term ef cacy of trilostane administered twice daily in dogs with pituitarydependent hyperadrenocorticism. J Am Anim Hosp Assoc 2006;42(4):269-276. 15. Barker EN, Campbell S, Tebb AJ, et al. A comparison of the survival times of dogs treated with mitotane or trilostane for pituitarydependent hyperadrenocorticism. J Vet Intern Med 2005;19(6):810-815. 16. Chapman PS, Kelly DF, Archer A, et al. Adrenal necrosis in a of Tennessee College of Veterinary Medicine Clinical Endocrinology Service adrenal panel: cortisol, estradiol, androstenedione, 17-hydroxyprogesterone, progesterone, and aldosterone), affected patients have abnormal resting and post-ACTH concentrations of one or more of the cortisol precursors or adrenal androgens or estrogens. Many of these patients have adrenal tumors, so abdominal ultrasonography is always warranted before starting medical therapy. A detailed discussion of these cases is beyond the scope of this review. However, depending on the particular steroid deregulation identi ed, trilostane may be an appropriate choice for some of these cases unless a surgical lesion is identied. A thorough understanding of the adrenocortical biochemical pathways is necessary to make an appropriate medical plan (Figure 1), and consultation with an endocrinologist may be helpful. If either mitotane or trilostane is used, careful monitoring for signs of hypocortisolemia is still warranted. 116 February 2008 VETERINARY MEDICINE http://www.stokespharmacy.com http://www.stokespharmacy.com
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