What is the appropriate lisinopril dosing for an Addison’s disease patient on furosemide and alprazolam who has a blood pressure of 188/112 mmHg and a pulse of 94 bpm?

Lisinopril Dosing in Addison's Disease with Severe Hypertension

In this Addison's disease patient with severe hypertension (188/112 mmHg), start lisinopril at 5 mg once daily, optimize glucocorticoid replacement first, reduce or discontinue furosemide, and avoid combining ACE inhibitors with aldosterone antagonists or potassium-sparing diuretics. 1, 2

Critical First Step: Optimize Glucocorticoid Replacement

Before adjusting antihypertensive therapy, the priority is to assess and optimize glucocorticoid replacement, as excessive dosing can cause hypertension in Addison's disease. 2

• Review current hydrocortisone dose - excessive glucocorticoid replacement is a common cause of hypertension in Addison's patients 2
• Assess for signs of mineralocorticoid excess - check for edema, hypokalemia, or suppressed renin 2
• Consider reducing fludrocortisone if there are clinical or biochemical signs of mineralocorticoid excess 2

Lisinopril Dosing Strategy

Initial Dose

Start with 5 mg once daily - this is the recommended starting dose for patients on diuretics or those at higher risk for hypotension. 1

• The standard initial dose of 10 mg daily 1 should be reduced to 5 mg in this patient because:
  • Patient is currently on furosemide (a diuretic) 1
  • Addison's disease patients have altered renin-angiotensin-aldosterone axis dynamics 2
  • Risk of excessive hypotension is higher 1

Titration Approach

• Monitor blood pressure closely after initiation, checking within 1-2 weeks 3
• Titrate upward gradually based on response, increasing to 10 mg, then 20 mg, up to a maximum of 40 mg daily 1
• Target blood pressure <140/90 mmHg initially, with consideration for <130/80 mmHg if tolerated 4
• Achieve target within 3 months to ensure adherence and reduce cardiovascular risk 5

Management of Concurrent Furosemide

Furosemide should be reduced or discontinued in this Addison's patient with hypertension. 2

• Loop diuretics like furosemide should be avoided in Addison's disease with hypertension unless there is concurrent heart failure with volume overload 2
• Diuretics can exacerbate volume depletion and electrolyte abnormalities in Addison's disease 2
• If the patient has no signs of heart failure or volume overload, discontinue furosemide 2
• The fludrocortisone dose should be reviewed and potentially reduced if there are signs of mineralocorticoid excess 2

Alprazolam Considerations

Alprazolam does not require dose adjustment with lisinopril, but monitor for:

• Potential additive hypotensive effects, though this is not a major concern 1
• Alprazolam may mask symptoms of hypoglycemia in Addison's patients during adrenal crisis
• No significant drug-drug interaction between alprazolam and lisinopril 6

Monitoring Parameters

Initial Phase (First 1-2 Weeks)

• Blood pressure - check within 1-2 weeks after initiation 3
• Serum creatinine and potassium - monitor 1-2 weeks after starting lisinopril 7, 3
• Renin levels - if renin is toward upper end of normal or elevated, continue ACE inhibitor without changing fludrocortisone 2
• Signs of adrenal crisis - ensure patient is educated on stress dosing of glucocorticoids 8, 9

Ongoing Monitoring

• Blood pressure - every 4 months when stable 3
• Renal function and electrolytes - every 4 months when stable 7, 3
• Watch for hyperkalemia - ACE inhibitors increase potassium, which is particularly important in Addison's disease 7, 1

Additional Antihypertensive Options if Needed

If blood pressure remains uncontrolled on lisinopril alone:

Second-Line Agent

Add a dihydropyridine calcium channel blocker (e.g., amlodipine 2.5-5 mg daily) 4, 2

• Calcium channel blockers are clinically useful as second-line agents in Addison's disease 2
• Preferred over increasing diuretics 2

Third-Line Combination

Add a thiazide-like diuretic (e.g., chlorthalidone 12.5-25 mg daily) only if volume status is appropriate 4

• Use with extreme caution in Addison's disease 2
• Monitor electrolytes closely 7

Agents to Avoid

Do NOT use:

• Aldosterone antagonists (spironolactone, eplerenone) - contraindicated in Addison's disease due to existing mineralocorticoid deficiency 2
• Potassium-sparing diuretics (amiloride, triamterene) - risk of severe hyperkalemia when combined with ACE inhibitors 10, 2
• Combination of two RAS blockers (ACE inhibitor + ARB) - not recommended 5

Critical Safety Considerations

Hyperkalemia Risk

• Maximum accepted creatinine rise is 50% or up to 266 μmol/L from baseline 3
• Discontinue lisinopril if:
  • Creatinine increases by 100% or more 3
  • Potassium exceeds 5.5 mmol/L 3
  • eGFR drops below 20 mL/min/1.73 m² 3

Adrenal Crisis Prevention

• Patient must be educated on stress dosing - double to triple hydrocortisone during illness 8, 9
• Parenteral hydrocortisone needed for vomiting, diarrhea, or acute hypotension 8
• Lisinopril-induced hypotension could precipitate adrenal crisis if glucocorticoid coverage is inadequate 2

Renal Dosing

If creatinine clearance is 10-30 mL/min, start with 2.5 mg daily and titrate cautiously 1

Twice-Daily Dosing Consideration

If blood pressure control is inadequate with once-daily dosing at maximum dose (40 mg), consider splitting to twice-daily administration (e.g., 20 mg twice daily). 11

• Twice-daily lisinopril dosing achieved 10.2/4.3 mmHg greater blood pressure reduction compared to the same total daily dose given once daily 11
• This approach may be particularly useful in resistant hypertension 11

7, 4, 3, 4, 12, 5, 1, 2, 11