Enalapril

Mechanism

The combination raises risk of hypersensitivity reactions and severe skin reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis, angioedema). Risk is higher in chronic kidney disease. Mechanism: presumed immune reaction to metabolites of both drugs.

Symptoms

Rash, fever, eosinophilia, lymphadenopathy (DRESS syndrome). Severe cases: bullous rash with skin sloughing, angioedema of face and tongue. Symptoms appear 1–8 weeks into the combination.

Management

Avoid the combination, especially in chronic kidney disease. Alternative to ACE-I: an ARB (losartan, valsartan). If rash or fever emerges, stop both drugs immediately.

Mechanism

NSAIDs reduce renal blood flow via prostaglandin blockade. The ACE-I (enalapril) dilates glomerular efferent arterioles. The combination causes acute kidney injury, especially in older patients, chronic kidney disease, and dehydration.

Symptoms

Reduced urine output, rising creatinine and potassium, oedema. Symptoms appear earlier in older patients and in chronic kidney disease.

Management

For prolonged celecoxib therapy, check creatinine 2–4 weeks after start, then every 3 months. In older patients and chronic kidney disease, paracetamol is preferable.

Mechanism

Trimethoprim blocks collecting duct sodium channels (amiloride-like mechanism) and reduces potassium secretion. Enalapril (ACE-I) additionally retains potassium through aldosterone suppression.

Symptoms

Muscle weakness, paraesthesia in the limbs, slowed pulse, arrhythmias. ECG shows peaked T waves and widened QRS. Severe cases progress to cardiac arrest. Symptoms typically appear within 1–2 weeks of starting the combination.

Management

During co-trimoxazole therapy, check potassium 3–5 days after start. In older patients and chronic kidney disease, prefer alternative antibiotics: nitrofurantoin or fosfomycin.

Mechanism

Ibuprofen (NSAID) suppresses prostaglandin synthesis maintaining glomerular perfusion at lower blood pressure. On enalapril, which dilates efferent arterioles, the combination raises acute kidney injury risk (the 'triple whammy' with a diuretic is more dangerous still).

Symptoms

Reduced urine output, rising creatinine and potassium. Blood pressure rise and oedema. Symptoms appear earlier in older patients and chronic kidney disease.

Management

Avoid chronic ibuprofen on enalapril. If a short course is needed, use the minimum effective dose for 5–7 days with pantoprazole cover. For chronic analgesia: paracetamol, celecoxib, or topical NSAIDs.

Mechanism

Enalapril and other ACE inhibitors reduce renal blood flow and glomerular filtration, decreasing lithium excretion. Lithium plasma concentration rises 25–40% with risk of neurotoxicity and renal injury. Effect is greatest in the elderly and with dehydration.

Symptoms

Tremor, confusion, nausea, diarrhea within 2–4 weeks of enalapril start. Lab: lithium above 1.2 mmol/L.

Management

Check lithium before enalapril, then on days 7 and 14 and at 4 weeks. Reduce lithium by 25–50% if level rises above target. Warn the patient about toxicity signs and the need for adequate water intake.

Mechanism

Dual RAAS blockade: ACE-I blocks angiotensin II formation, ARB blocks its receptors. Additive risk of hyperkalaemia, hypotension, and acute kidney injury without additional clinical benefit.

Symptoms

Weakness, dizziness on standing, syncope. Reduced urine output, rising serum creatinine. Weakness and paraesthesia from hyperkalaemia. Symptoms typically appear in the first 1–4 weeks.

Management

The combination is not prescribed. Large trials (ONTARGET, ALTITUDE) showed no benefit and more adverse effects. Choose one agent: ACE-I if tolerated, ARB if there is a dry cough or intolerance.

Mechanism

Enalapril (an angiotensin-converting enzyme inhibitor, ACE-I) reduces aldosterone synthesis, while spironolactone directly blocks aldosterone receptors. Both retain potassium; hyperkalaemia develops in renal impairment or diabetes.

Symptoms

Muscle weakness, paraesthesia in the limbs, slowed pulse, arrhythmias. The electrocardiogram shows peaked T waves and a widened QRS complex. Severe cases progress to cardiac arrest. The risk is higher with renal impairment, diabetes mellitus, dehydration and age over 70.

Management

The combination is used deliberately and with potassium monitoring. The enalapril SmPC does not recommend combining enalapril with spironolactone because of the risk of hyperkalaemia; if the combination is indicated, use it with caution and frequent potassium checks (enalapril SmPC). Such an indication exists: the European Society of Cardiology (ESC) recommends a mineralocorticoid receptor antagonist such as spironolactone, together with an angiotensin-converting enzyme (ACE) inhibitor and a beta-blocker, for all patients with heart failure with reduced ejection fraction (ESC 2021). In heart failure, start spironolactone at 25 mg once daily if potassium is no higher than 5.0 mmol/L and creatinine no higher than 2.5 mg/dL, and do not exceed 50 mg a day (spironolactone SmPC). Check potassium and creatinine within a week of starting or increasing the dose, then monthly for the first 3 months, every 3 months until the end of the first year and every 6 months after that; stop spironolactone temporarily or permanently if potassium is above 5 mmol/L or creatinine above 4 mg/dL (spironolactone SmPC). Take particular care in impaired renal function and when potassium is 5.0 mmol/L or higher (ESC 2021). Potassium supplements are usually stopped when heart failure patients start spironolactone (US spironolactone label, FDA). Do not add an angiotensin II receptor blocker to an ACE inhibitor plus spironolactone because of the risk of renal dysfunction and hyperkalaemia (ESC 2021).

Mechanism

Dual RAAS blockade – increased hyperkalaemia, hypotension, and acute kidney injury without outcome improvement (ONTARGET).

Symptoms

Muscle weakness, paraesthesia, slowed pulse, arrhythmias. ECG: peaked T waves, widened QRS. Severe cases progress to cardiac arrest.

Management

The combination is not prescribed. Choose one: ACE-I (enalapril) if tolerated, ARB (telmisartan) if there is a dry cough.

Mechanism

Enalapril suppresses aldosterone – less potassium excreted. With triamterene additive hyperkalaemia, especially in CKD.

Symptoms

Hyperkalaemia within 2 weeks.

Management

Check potassium and creatinine at 1 and 4 weeks. Reduce triamterene if K+ above 5.0.

Mechanism

Dual K+-sparing effect: enalapril suppresses aldosterone, trimethoprim blocks ENaC. Hyperkalaemia.

Symptoms

Hyperkalaemia within 5 days.

Management

Check K+ and creatinine on day 5. Alternative – fosfomycin or nitrofurantoin for UTI.

Mechanism

Dual RAAS blockade (ACE-I + ARB). Proven in ONTARGET and VA NEPHRON-D trials: increased hyperkalaemia, hypotension, and acute kidney injury without cardioprotection.

Symptoms

Muscle weakness, paraesthesia, slowed pulse, arrhythmias. ECG: peaked T waves, widened QRS. Severe cases progress to cardiac arrest.

Management

The combination is not prescribed. Choose one: ACE-I (enalapril) if tolerated, ARB (valsartan) if there is a dry cough or intolerance.

Mechanism

High aspirin doses (above 1 g/day) weaken the hypotensive and cardioprotective effects of the ACE-I via vasodilator prostaglandin suppression. At cardioprotective doses (75–100 mg/day), the clinical effect is minimal.

Symptoms

Gradual blood pressure rise at high aspirin doses. At cardioprotective doses, no significant changes.

Management

Cardioprotective aspirin doses (75–100 mg) are acceptable without adjustment. At high aspirin doses, monitor blood pressure and increase enalapril if needed. Alternative analgesic: paracetamol.

Mechanism

Additive hypotension. Alprazolam sedation may mask orthostatic symptoms.

Symptoms

Lower blood pressure, postural dizziness, fatigue. Older patients: fall risk.

Management

In older patients, check standing and sitting blood pressure 1–2 weeks after start. Alternative anxiolytic: hydroxyzine or a short lorazepam course.

Mechanism

Additive orthostatic hypotension. Enalapril (ACE-I) dilates vessels; amitriptyline blocks α1-adrenoceptors and reduces compensatory response. Older patients: fall and delirium risk.

Symptoms

Postural dizziness, syncope, fatigue. Older patients: fall and fracture risk.

Management

In older patients, check standing and sitting blood pressure 1–2 weeks after starting amitriptyline. For neuropathic pain, alternative: gabapentin or pregabalin (no α1-blockade).

Mechanism

Dexamethasone has minimal mineralocorticoid activity but, at high doses and prolonged use, blunts the ACE inhibitor's antihypertensive effect. The effect is weaker than with prednisolone.

Symptoms

Possible rise in blood pressure with long-term therapy. Weakness, fatigue, paraesthesias, arrhythmia. Symptoms develop at potassium above 5.5 mmol/L; life-threatening above 6.5 mmol/L.

Management

For short dexamethasone courses, no specific adjustment needed. For long-term therapy, check BP every 1–2 weeks. If BP rises, intensify antihypertensive therapy (increase enalapril or add a thiazide). Potassium and creatinine monthly.

Mechanism

Additive antihypertensive effect; in hypovolaemic patients it can trigger acute kidney injury. The triad of ACE inhibitor + diuretic + NSAID is especially dangerous (the "triple whammy").

Symptoms

Decreased urine output, rising creatinine, oedema, nausea, fatigue. Higher risk in older patients and in dehydration.

Management

On starting the combination, begin enalapril at the lowest dose (2.5 mg). Check creatinine and potassium at 1–2 weeks, then every 3 months. In older patients with acute illness and dehydration, both drugs are temporarily stopped until volume is restored.

Mechanism

Additive antihypertensive effect. In the first weeks hydrochlorothiazide increases renin-angiotensin system activity, raising sensitivity to the ACE inhibitor. A standard fixed combination for arterial hypertension.

Symptoms

Symptomatic hypotension on starting: dizziness, weakness, especially on standing. In older patients: fall risk. Potassium monitoring matters — thiazide depletes, ACE inhibitor retains.

Management

On starting the combination, begin enalapril at the lowest dose (2.5 mg) at bedtime. Check creatinine and potassium at 1–2 weeks, then every 6 months. In older patients, take the first dose seated.

Mechanism

ACE inhibitors improve tissue insulin sensitivity and potentiate metformin's glucose-lowering effect. They do not cause hypoglycaemia alone but lower the threshold on insulin or sulfonylureas.

Symptoms

Signs of hypoglycaemia: sweating, tremor, hunger, tachycardia, confusion. Symptoms appear at glucose below 3.9 mmol/L.

Management

On metformin alone, no dose adjustment needed. In patients on insulin or sulfonylureas, intensify glucose self-monitoring for the first 2 weeks after starting enalapril. The effect is helpful in type 2 diabetes with arterial hypertension.

Mechanism

Target combination in heart failure with reduced ejection fraction and in arterial hypertension. Synergistic reduction of blood pressure, preload, and afterload.

Symptoms

On starting, in older or hypovolaemic patients: symptomatic hypotension, dizziness, fatigue. Metoprolol bradycardia is amplified as sympathetic activation drops.

Management

Start both drugs at minimal doses with up-titration every 2 weeks to target. Check standing/sitting BP, heart rate, creatinine and potassium at 2 weeks. In heart failure, the goal is maximum tolerated dose; the RCT evidence base is extensive.

Mechanism

Glucocorticoids retain sodium and water via mineralocorticoid effect, blunting the ACE inhibitor's antihypertensive effect. Both can also cause hyperkalaemia (prednisolone via muscle catabolism, ACE inhibitor via aldosterone suppression).

Symptoms

Return or rise of blood pressure, leg oedema. Hyperkalaemia symptoms in CKD: Weakness, fatigue, paraesthesias, arrhythmia. Symptoms develop at potassium above 5.5 mmol/L; life-threatening above 6.5 mmol/L.

Management

For short prednisolone pulses (3–7 days), no specific adjustment needed. For long-term therapy, check BP weekly in the first month; if it rises, increase enalapril or add a diuretic. Potassium and creatinine every 2 weeks in the first month.

Mechanism

Target combination in hypertension: synergistic BP lowering via different mechanisms (calcium channel blockade plus RAAS suppression). Amlodipine partly offsets peripheral oedema via arteriolar vasodilation; enalapril balances it through venular action.

Symptoms

Possible mild leg oedema (mainly from amlodipine) and a rare dry cough (from enalapril). On starting in older patients: dizziness.

Management

Standard fixed combination in hypertension. Start with minimal doses (5 mg + 5 mg) with up-titration every 2–4 weeks. Check creatinine and potassium 1–2 weeks after enalapril start, then every 6 months.