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13.01.24 Pharmacology lecture - HTN

Unusual causes of HTN
  • Acromegaly
    • Also raises glucose
  • NSAIDs
  • Pheochromocytoma (cf MEN IIa)
    • => HTN, flushing, sweating
    • May cause hypercalcaemia (but may be due to concurrent hyperparathyroidism in MEN IIa)
    • Risk of death! Must exclude

Liddle's syndrome
  • Autosomal dominant disorder characterized by early, and frequently severe, hypertension
  • Looks like hyperadosteronism
    • Low plasma renin activity
    • Metabolic alkalosis due to hypokalemia
    • But normal to low levels of aldosterone
  • Involves abnormal kidney function
    • Caused by dysregulation of an epithelial sodium channel (ENaC)
  • Treatment
    • Low sodium diet
    • Potassium-sparing diuretic that directly blocks the sodium channel
      • Amiloride or triamterene
    • Spironolactone is not effective because it acts by regulating aldosterone and Liddle syndrome does not respond to this regulation

CCB cardiac selectivity order
  • Varapamil
  • Diltiazem
  • Amlodipine
  • Nifedipine
  • Felodipine
  • Nicardipine
  • Lercanidipine


Side effects

  • CCBs
    • Ankle swelling
    • Gingival hyperplasia
  • Diuretics
    • Gout
    • Impotence
  • ACEi
    • Impotence
    • Cough
    • Renal impairment if renal artery stenosis


Contraindications

  • CCBs
    • Heart failure
  • ACEi
    • Pregnancy
    • Renal artery stenosis
  • Diuretics
    • CKD
  • Beta blockers
    • Asthma
  • Alpha blockers
    • Almost none - Very safe!

Notes

  • Carcinoid
    • => Tachycardia but NOT HTN
    • Test 5-HIAA
  • Bilateral adrenal hyperplasia is more common than adrenal adenoma as a cause of hyperaldosteronism
  • Beading of renal arteries
    • Sign of fibromuscular dysplasia
    • Can cause HTN
  • Lifestyle measures are at least as good as one drug
  • Aged, black => CCB
    • Then A+C
    • Then A+C+D
  • Aliskiren = Direct renin inhibitor
  • Losartan is now off-patant
    • => First choice, as there's no cough
    • However half-life is only 2 hours (but can still take OD)
  • ACEi/ARB help protect kidneys in HTN if there's concurrent diabetes or nephropathy
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