What are the potential side effects of ACE (Angiotensin-Converting Enzyme) inhibitors, such as lisinopril, in geriatric patients with hypertension, heart failure, or diabetes, and how can they be managed?

Side Effects of ACE Inhibitors in Geriatric Patients

ACE inhibitors cause several important side effects in elderly patients that require careful monitoring, with the most clinically significant being hypotension (especially first-dose and orthostatic), hyperkalemia, renal dysfunction, dry cough, and angioedema. 1, 2

Common and Serious Adverse Effects

Hypotension

• First-dose hypotension is the most critical concern when initiating ACE inhibitors in elderly patients, particularly those on diuretics, with heart failure, or who are volume-depleted 1, 3, 4
• Orthostatic hypotension occurs more frequently in the elderly due to impaired cardiovascular reflexes and decreased baroreceptor response that accompanies aging 1, 5, 3
• The risk is substantially increased when ACE inhibitors are combined with diuretics, requiring either temporary discontinuation of the diuretic or dose reduction before starting the ACE inhibitor 2, 3

Renal Dysfunction

• ACE inhibitors can cause acute deterioration of renal function, particularly in elderly patients with pre-existing chronic kidney disease, volume depletion, or bilateral renal artery stenosis 1, 2, 4
• A modest, reversible decline in glomerular filtration rate at treatment onset is expected and may actually predict better long-term renal protection 4
• However, acute renal failure can occur when glomerular filtration is critically dependent on angiotensin II-mediated efferent arteriolar tone 4
• Monitor renal function within 1-2 weeks of initiation and with each dose increase 6, 4

Hyperkalemia

• Potassium retention is a significant risk, especially when ACE inhibitors are combined with potassium-sparing diuretics, potassium supplements, or NSAIDs 1, 2
• Check serum potassium within 1-2 weeks of starting therapy, as hyperkalemia risk is highest early in treatment 6, 4
• Elderly patients are particularly susceptible due to age-related decline in renal function and common use of multiple medications 1, 4

Cough

• Dry, persistent cough occurs in a subset of patients and is a class effect of all ACE inhibitors 1
• While not dangerous, it can significantly impact quality of life and may necessitate switching to an angiotensin receptor blocker 1

Angioedema

• This is a rare but potentially life-threatening adverse effect that can occur at any time during treatment 2
• Discontinue ACE inhibitors immediately if angioedema develops 2

Drug Interactions Requiring Special Attention

NSAIDs and COX-2 Inhibitors

• Co-administration with NSAIDs can cause deterioration of renal function, including possible acute renal failure, particularly in elderly, volume-depleted patients 2
• NSAIDs also attenuate the antihypertensive effect of ACE inhibitors 2
• Monitor renal function periodically when these drugs are used together 2

Diuretics

• Thiazide diuretics potentiate ACE inhibitor effects and increase hypotension risk 2
• Potassium-sparing diuretics (spironolactone, amiloride, triamterene) significantly increase hyperkalemia risk 2
• Monitor serum potassium frequently when combining ACE inhibitors with potassium-sparing diuretics 2

Antidiabetic Medications

• ACE inhibitors may cause an increased blood-glucose-lowering effect with risk of hypoglycemia when combined with insulin or oral hypoglycemic agents 2

Lithium

• ACE inhibitors can cause lithium toxicity by reducing sodium elimination 2
• Monitor serum lithium levels during concurrent use 2

Management Strategies to Minimize Adverse Effects

Initiation Protocol

• Start with the lowest effective dose due to altered pharmacokinetics and pharmacodynamics in elderly patients 1, 3, 7
• Measure both supine and standing blood pressure before and after initiation to detect orthostatic changes 1, 5
• Calculate creatinine clearance before starting therapy, as most ACE inhibitors are renally excreted and accumulate in renal impairment 1, 2
• In heart failure patients, introduce ACE inhibitors even more cautiously with lower doses and preferably under supervision 1, 3
• Consider temporarily discontinuing diuretics for a few days before ACE inhibitor initiation to prevent severe hypotension 1, 3

Dose Titration

• Titrate slowly with prolonged periods between dose adjustments, as elderly patients are more susceptible to adverse effects 1, 3, 7
• The maintenance dosage is determined more by the presence of renal disease or heart failure than by age alone 3
• Once tolerated, titrate up to the maximum well-tolerated dose, as this offers the greatest cardiovascular and renal benefit 3, 4

Ongoing Monitoring

• Monitor blood pressure regularly, checking both supine and standing measurements 1, 5
• Assess renal function and serum potassium within 1-2 weeks of initiation and with each dose increase 6, 4
• Continue periodic monitoring of renal function and electrolytes throughout treatment 2, 4

Special Populations and Contraindications

Severe Renal Impairment

• Avoid or use extreme caution in patients with creatinine clearance <30 mL/min; dose reduction is mandatory 6, 2
• Avoid completely if creatinine clearance <10 mL/min 6
• Patients on hemodialysis require dose adjustment 2

Pregnancy

• ACE inhibitors are contraindicated in pregnancy (Category D) due to fetal renal dysfunction, oligohydramnios, and increased fetal/neonatal morbidity and death 2
• Discontinue immediately when pregnancy is detected 2

Volume Depletion

• Patients who are volume-depleted or on aggressive diuretic therapy are at highest risk for hypotensive reactions 2, 3, 4
• Sodium repletion can help restore renal function if ACE inhibitor-induced acute renal failure occurs 4

Common Pitfalls to Avoid

• Do not start at standard adult doses without considering age-related pharmacokinetic changes and increased drug exposure due to decreased renal clearance 1, 3
• Do not ignore orthostatic blood pressure measurements—always check both supine and standing pressures 1, 5
• Do not overlook baseline renal function assessment, as this is critical for safe dosing 1, 2
• Do not combine with other renin-angiotensin system blockers (ARBs, aliskiren), as dual blockade increases risks of hypotension, hyperkalemia, and renal dysfunction without additional benefit 2
• Do not abruptly discontinue in patients who develop mild, reversible renal function decline, as this may represent the trade-off for long-term renal protection 4