Lecture Notes: Drugs to Treat Hypertension

Introduction

• Key Elements of Cardiovascular System:
  • Heart rate
  • Stroke volume
  • Peripheral resistance (affected by vasoconstriction and volume)

Factors Affecting Blood Pressure

• Sympathetic Nervous System:
  • Small arterioles are responsive, affecting peripheral resistance
• Baroreceptors:
  • Located in the arch of the aorta and carotid arteries
  • Regulate vasoconstriction/dilation by sending signals to the medulla
• Renin-Angiotensin-Aldosterone System (RAAS):
  • Activated when blood pressure falls
  • Involves conversion to Angiotensin II, causing vasoconstriction and aldosterone release
  • Increases blood volume and peripheral resistance

Risk Factors and Demographics

• Ethnicity:
  • Black non-Latinos at the highest risk
  • Men more likely than women within this group
• Other Risk Factors:
  • Diabetes, family history, age (men in 40s, women in 50s)
  • By age 70, risk levels between genders equalize
• Complications of Hypertension:
  • Heart disease, strokes, kidney damage, retinopathy

Hypertension Medications

• Target Components:
  • Cardiac output and peripheral resistance
• Types of Drugs:
  • Beta Blockers: Decrease heart rate and force of contraction
  • Diuretics: Decrease blood volume
  • ARBs (Angiotensin Receptor Blockers): Block effect of Angiotensin II
  • ACE Inhibitors: Prevent conversion of Angiotensin I to II
  • Calcium Channel Blockers: Inhibit calcium ion movement, relax vasculature
  • Vasodilators: Directly dilate blood vessels

Specific Drug Mechanisms and Considerations

• ARBs:

  • Block vasoconstriction and aldosterone release
  • Contraindicated in pregnancy, hepatic/renal dysfunction
  • Side effects include dizziness, hypotension, and possible cancer risk

• Calcium Channel Blockers:

  • Decrease cardiac contractility and conductivity
  • Used for angina and hypertension
  • Interacts with grapefruit juice
  • Side effects include peripheral edema, dizziness

• Diuretics:

  • Thiazide Diuretics:
    • Work in distal tubule, can increase glucose and lipid levels
  • Loop Diuretics (e.g., Furosemide):
    • Most potent, work in the loop of Henle
    • Risk of ototoxicity if given too quickly IV
  • Potassium-Sparing Diuretics (e.g., Spironolactone):
    • Retain potassium, risk of hyperkalemia

Nursing Interventions

• Lifestyle Changes:
  • Emphasize importance alongside medication
• Patient Education:
  • Monitor blood pressure, weight, and signs of adverse effects
  • Avoid potassium-rich foods if on potassium-sparing diuretics
• Adverse Effects Management
  • Monitor for symptoms like dizziness, headache, GI disturbances
  • Encourage slow position changes to prevent dizziness

Conclusion

• Emphasize continued lifestyle changes for effective hypertension management
• Careful monitoring of drug interactions and contraindications required