Podcast
Questions and Answers
Which drug works by slowing heart rate in a dose-dependent manner?
Which drug works by slowing heart rate in a dose-dependent manner?
Which statement about prazosin and clonidine is correct?
Which statement about prazosin and clonidine is correct?
How do prazosin and atenolol compare in terms of their pharmacological effects?
How do prazosin and atenolol compare in terms of their pharmacological effects?
Which antihypertensive drug is absolutely contraindicated in pregnancy?
Which antihypertensive drug is absolutely contraindicated in pregnancy?
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What is a significant side effect associated with verapamil therapy?
What is a significant side effect associated with verapamil therapy?
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Which characteristic of enalapril treatment is true?
Which characteristic of enalapril treatment is true?
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Which of the following statements is true regarding the management of hypertension in pregnant women?
Which of the following statements is true regarding the management of hypertension in pregnant women?
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What side effect is most commonly associated with atenolol?
What side effect is most commonly associated with atenolol?
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What mechanism of action is primarily associated with Captopril?
What mechanism of action is primarily associated with Captopril?
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Which of the following drugs is least likely to cause a persistent cough as a side effect?
Which of the following drugs is least likely to cause a persistent cough as a side effect?
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Which class of antihypertensives is most likely to cause postural hypotension?
Which class of antihypertensives is most likely to cause postural hypotension?
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For treating a patient with obesity and hypertension, which medication would be most appropriate considering potential metabolic side effects?
For treating a patient with obesity and hypertension, which medication would be most appropriate considering potential metabolic side effects?
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Which antihypertensive medication is known to primarily affect bradykinin levels?
Which antihypertensive medication is known to primarily affect bradykinin levels?
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Which drug is most likely to be selected for a patient with diabetes and hypertension who develops a cough after starting a new medication?
Which drug is most likely to be selected for a patient with diabetes and hypertension who develops a cough after starting a new medication?
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Identifying systolic blood pressure of 150 mm Hg in a healthy 35-year-old patient may typically warrant the initiation of which of the following treatments?
Identifying systolic blood pressure of 150 mm Hg in a healthy 35-year-old patient may typically warrant the initiation of which of the following treatments?
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In managing hypertension in elderly patients, which strategy is most effective in avoiding drug interactions?
In managing hypertension in elderly patients, which strategy is most effective in avoiding drug interactions?
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Which mechanism of action is shared by both Nitroprusside and Diazoxide?
Which mechanism of action is shared by both Nitroprusside and Diazoxide?
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What is a significant risk associated with the use of Nitroprusside in hypertensive emergencies?
What is a significant risk associated with the use of Nitroprusside in hypertensive emergencies?
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Which adverse effect is least associated with Diazoxide when used in hypertensive emergencies?
Which adverse effect is least associated with Diazoxide when used in hypertensive emergencies?
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What is the primary effect of calcium channel blockers like Verapamil and Diltiazem on cardiac function?
What is the primary effect of calcium channel blockers like Verapamil and Diltiazem on cardiac function?
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Which of the following statements about the time to effect of Nitroprusside and Diazoxide is correct?
Which of the following statements about the time to effect of Nitroprusside and Diazoxide is correct?
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Which class of drugs primarily affects smooth muscle and acts as potent arteriolar dilators?
Which class of drugs primarily affects smooth muscle and acts as potent arteriolar dilators?
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What additional medication is often required with Diazoxide to manage its side effects effectively?
What additional medication is often required with Diazoxide to manage its side effects effectively?
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What is the effect of the cyanide produced from Nitroprusside overdose?
What is the effect of the cyanide produced from Nitroprusside overdose?
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Study Notes
Objectives
- List major groups of antihypertensive drugs and provide examples
- Describe compensatory responses to each major type of antihypertensive drug
- Summarize major sites of action of sympatholytic drugs in clinical use and provide examples of drugs acting at each site
- Identify four mechanisms of action of vasodilator drugs
- Outline major antihypertensive vasodilator drugs and describe their effects
- Describe the differences between the two types of angiotensin antagonists
Classification of Hypertension
- Normal blood pressure: Systolic <120 and Diastolic <80 mm Hg
- Prehypertension: Systolic 120-139 or Diastolic 80-89 mm Hg
- Hypertension stage 1: Systolic 140-159 or Diastolic 90-99 mm Hg
- Hypertension stage 2: Systolic ≥160 or Diastolic ≥100 mm Hg
Autonomic and Hormonal Control of CV Function
- Baroreceptors monitor blood pressure and initiate compensatory responses
- Sympathetic nervous system (SNS) increases heart rate and contractility and constricts blood vessels to increase blood pressure
- Parasympathetic nervous system (PNS) decreases heart rate to lower blood pressure
- Renal blood flow and pressure influence renin secretion, leading to angiotensin II production and ultimately impacting blood volume
- Hormones like aldosterone regulate sodium and water balance to influence blood volume and pressure
Antihypertensive Drugs: Mechanisms of Increased BP
- Heart (pump-based) hypertension: increased cardiac output, with normal peripheral resistance
- Vascular (peripheral resistance) hypertension: increased peripheral resistance, with normal cardiac output
- Renal/volume hypertension: retention of sodium, water, increased blood volume, and increased cardiac output and peripheral resistance
Sites Controlling Blood Pressure
- Arterioles: resistance to blood flow
- Venules: capacitance vessels
- Heart: pump action for blood output
- Kidneys: regulate blood volume through sodium balance
Na and Smooth Muscle
- Increased sodium concentration inside smooth muscle cells leads to increased calcium concentration
- Sensitivity to stimulatory neurotransmitters and hormones increases, leading to increased vasoconstriction and peripheral resistance
- Decreasing sodium reduces intracellular calcium, relaxing smooth muscle and decreasing peripheral resistance
Non-Drug Approach
- Sodium restriction and diuretic therapy
- Weight loss
- Regular exercise
- Eliminate factors elevating blood pressure (e.g., smoking, excess caffeine, stress) and implement stress-reduction techniques
Baroreceptor Reflex Arc
- Baroreceptors in the carotid sinus detect changes in blood pressure
- Signals are transmitted via the vagus nerve to the brainstem
- The brainstem adjusts the activity of the sympathetic and parasympathetic nervous systems to maintain blood pressure
Stepped Care (Method of Treatment)
- Combine antihypertensive drugs sequentially to reduce drug toxicity and compensatory mechanisms
- Step One: Diuretic, beta-blocker, ACE inhibitor
- Step Two: Other sympatholytics
- Step Three: Vasodilators
Overview of Diuretic Agents
- Diuretics act on various segments of the nephron to increase urine output and reduce extracellular fluid volume
- Types include: acetazolamide, osmotic, loop, thiazide, aldosterone antagonists, and ADH antagonists
Diuretics: Mechanism of Action and Clinical Indications
- Thiazides are preferred for mild to moderate hypertension
- Loop diuretics are used in patients with renal impairment and severe hypertension
- Diuretics decrease blood volume initially, then stabilize to near pre-drug levels within weeks
- Chronic effect reduces peripheral resistance due to decreased Na and Ca
Excessive Diuresis/Adverse Effects
- Hyponatremia, hypotension, hypokalemia (unless potassium-sparing diuretic), hypocalcemia, hypomagnesemia, hypochloremic alkalosis, hyperuricemia, and hyperglycemia
Loop/K-Sparing Diuretics
- Loops indicated in CHF and decreased renal function (creatinine clearance less than 50 ml/min)
- K-sparers are often combined with thiazides/loops to stabilize potassium levels
- Spironolactone is useful in CHF (aldosterone antagonist diuretic)
Compensatory Responses to Vasodilators
- Vasodilator drugs reduce vascular resistance, leading to decreased blood pressure
- Compensatory mechanisms increase renin/angiotensin II and aldosterone, increasing sodium retention and vasoconstriction to elevate blood pressure
Beta-Blockers
- Mechanism of action: reduces cardiac output and renin release
- Clinical indications: hypertension, angina, supraventricular tachycardias
- Adverse effects: bradycardia, fatigue, cold extremities
Labetalol/Carvedilol
- Mechanism of action: alpha-1 and nonselective beta blocker with balanced SNS inhibition
- Clinical indications: hypertensive emergency, pheochromocytoma, moderate to severe hypertension (2nd line)
- Adverse effects: potential for asthma
Selective Alpha-1 Blockers
- Mechanism of action: competitive alpha-1 receptors, balanced vasodilation, decreases peripheral resistance
- Clinical indications: hypertension, useful in CHF
- Adverse effects: dizziness, headache, postural hypotension (particularly with first dose), nasal congestion, male impotence
Alpha-2 Adrenergic Receptors
- Mechanism of action: presynaptic receptors in the periphery/CNS exert negative feedback, inhibiting further norepinephrine release; postsynaptic receptors in CNS inhibit vasomotor/cardiac centers, reducing vasomotor tone, blood pressure, and heart rate
Mechanism of Action of Alpha-2 Receptors
- Agonists bind, activating adenylate cyclase, and producing cyclic AMP
- Effects vary based on location and type of receptors
Clonidine
- Mechanism of action: central alpha-2 agonist, reducing sympathetic outflow to the peripheral nervous system
- Clinical indications: hypertension, severe hypertension
- Adverse effects: sedation, dry mouth, sodium retention, potential for hypertensive crisis
Metabolism of Methyldopa
- Metabolism of L-Dopa (tyrosine) in the body
- Steps include decarboxylation, hydroxylation, and methylation
Methyldopa
- Mechanism of action: converted to alpha-methyl-NE, a central alpha-2 agonist, reducing sympathetic outflow
- Clinical indications: hypertension; generally safe during pregnancy
- Adverse effects: sedation, GI disturbances, hemolytic anemia, liver dysfunction
Hydralazine
- Mechanism of action: exact MOA unknown; may affect intracellular calcium release
- Clinical indications: severe hypertension (requires combination treatment usually with diuretics and beta blockers)
- Adverse effects: vasodilation, edema, headache, reflex tachycardia
Hydralazine (cont.)
- Adverse effects: excessive vasodilation, edema, headache, reflex tachycardia
Calcium Antagonists
- Mechanism of action: blocking voltage-dependent slow calcium channels
- Clinical indications: hypertension (especially dihydropyridines), angina, supraventricular arrhythmias
- Types: verapamil, diltiazem, nifedipine
Verapamil/Diltiazem
- Mechanism of action: block voltage-dependent slow calcium channels in cardiac and smooth muscle, affecting heart rate and AV conduction
- Clinical indications: hypertension, angina, supraventricular arrhythmias
- Adverse effects: constipation, edema
Dihydropyridines: Nifedipine Class
- Mechanism of action: arteriolar dilators, no direct cardiac effects
- Clinical indications: hypertension
- Adverse effects: excessive vasodilation, reflex tachycardia, myocardial ischemia (especially with high doses/rapid onset)
MOA of ACEIs & ARBs
- ACEIs and ARBs decrease peripheral resistance and blood pressure by different mechanisms: inhibiting ACE (ACEIs) or blocking angiotensin-II receptors (ARBs)
ACE Inhibitors
- Mechanism of action: inhibits angiotensin-converting enzyme (ACE), decreases angiotensin II, and increases bradykinin
- Clinical indications: hypertension, heart failure, diabetic nephropathy
- Adverse effects: cough, angioedema, hyperkalemia, renal dysfunction
ACE Inhibitors (Pharmacokinetics)
- Captopril: rapid onset, short duration (t1/2=3h), usu. BID-TID, food decreases bioavalibility, excreted unchanged in the urine
- Enalapril: once-daily prodrug, with enalaprilat (active metabolite) with a t1/2 = 11h
- Lisinopril: slow onset, once daily (t1/2 = 12h), excreted unchanged
Angiotensin II Inhibitors - Losartan
- Mechanism of action: competitive AT1 blockers, reducing angiotensin II's effect
- Clinical indications: hypertension
- Adverse effects: similar to ACE inhibitors, but lower risk of cough, dizziness, headache, fatigue, elevated liver enzymes
Other Angiotensin Receptor (AT1) Antagonists Blockers
- Valsartan, irbesartan, candesartan, telmisartan, olmesartan, eprosartan
Selecting AHPT Drugs (Patient Population-Based Recommendations)
- Summarizes recommended and not-recommended antihypertensive drugs based on patient populations and comorbidities
Angiotensin-Converting Enzyme Inhibitors
- Mechanism of action: inhibits ACE to prevent angiotensin II formation
- Clinical use: hypertension, heart failure, diabetic nephropathy
- Adverse effects: cough, angioedema, etc.
Clinical Correlated Questions (and Answers)
- A series of patient case studies and questions that assess understanding of antihypertensive drugs
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