Drug Interactions between cosyntropin and hydrochlorothiazide / spironolactone

MONITOR: The concomitant use of corticosteroids and agents that deplete potassium (e.g., potassium-wasting diuretics, amphotericin B, cation exchange resins) may result in increased risk of hypokalemia. Corticosteroids can produce hypokalemia and other electrolyte disturbances via mineralocorticoid effects, the degree of which varies with the agent (from most to least potent: fludrocortisone - cortisone/hydrocortisone - prednisolone/prednisone - other glucocorticoids) and route of administration (i.e. systemic vs. local). However, large systemic doses of any corticosteroid can demonstrate these effects, particularly if given for longer than brief periods. When used pharmacologically, adrenocorticotropic agents such as corticotropin have similar mineralocorticoid activities as cortisone and hydrocortisone.

MANAGEMENT: Patients receiving potassium-depleting agents with corticosteroids should be monitored closely for development of hypokalemia, particularly if fludrocortisone or large doses of another corticosteroid or adrenocorticotropic agent is given. Potassium supplementation may be necessary. Patients should be advised to notify their physician if they experience signs of electrolyte disturbances such as weakness, lethargy, and muscle pains or cramps.

ADJUST DOSING INTERVAL: The accuracy of cosyntropin as a diagnostic agent in the screening of adrenocortical insufficiency may be impaired by the concomitant use of spironolactone. Spironolactone may falsely elevate plasma cortisol levels, which may lead to inaccurate results following the administration of cosyntropin.

MONITOR: Cosyntropin may antagonize the effects of spironolactone by inducing sodium and fluid retention.

MANAGEMENT: Clinicians should be aware of the potential for inaccurate results when administering a cosyntropin test to patients on concomitant therapy with spironolactone. Some authorities recommend withholding spironolactone on the day of testing. In addition, patients receiving spironolactone and prolonged cosyntropin therapy should have blood pressure, electrolyte levels, and body weight monitored regularly, and be observed for the development of edema and congestive heart failure. The dosage of spironolactone may require adjustment.