Biochemistry - University of Arizona



Pharmacology

Lecture 8 Antihypertensive Drugs

1) List the rationale for the drug treatment of hypertension. 10-15% of the population is affected by hypertension and the lifetime probability of developing HTN is 90%. HTN, particularly systolic blood pressure, is strongly related to coronary heart disease, heart failure, stroke and peripheral arterial disease. Effective drug treatment lowers blood pressure and reduces the risk for these diseases.

2) List the classes of antihypertensive drugs available in the U.S.

Diuretics – Osmotic Diuretics, Carbonic Anhydrase Inhibitors, Loop Diuretics, and Thiazide Diuretics.

Adrenergic Inhibitors – Central Adrenergic Agonists, Alpha Adrenergic Antagonists, Beta Adrenergic Antagonists, and Dopamine Agonist.

Vasodilators – Angiotensin Converting Enzyme (ACE) Inhibitors, Angiotensin II Receptor Antagonists, and Calcium Channel Antagonists.

3) For the prototype drugs of each class of antihypertensive drugs; describe the following: Mechanism of action, Hemodynamic effects, Adverse drug effects, Drug-drug interactions, Drug-disease interactions.

|Drug Class |Prototype Drug |Mechanism of Action |Hemodynamic Effects |Adverse Drug Effects |Drug-Drug |Drug-Disease |

| | | | | |Interactions |Interactions |

|Diuretics (See |Thiozides, |Negative salt and water |Early drop in CO due to |Fluid and electrolyte imbalance, | | |

|Diuretic section) |Furosemide, |balance, ↑PGI2 synthesis &|↓volume Peripheral |particularly hypokalemia with | | |

| |Spronol-acetone, |action, vasodilaton |resistance decreased |thiazides and loop diuretics | | |

| |Triamterene | | | | | |

|Central Agonists |Clonidine |Central α2a recptor |↓ CO, ↓ systemic vascular|Short ½life. Missed dose = | | |

| | |stimulation |resistance |rebound HTN | | |

|Alpha Antagonists |Prazosin |Block peripheral α1 |↓ systemic vascular |Orthostatic HTN w/1st dose. Give | | |

| | |adrenoreceptors |resistance |1st HS. | | |

|Beta Antagonists |Propranolol |Non-selective β receptor |↓ Heart rate and |Bad dreams, depression |May interact |Asthma, COPD, severe |

| | |blockade |contractility, ↑ systemic|Cardio – worsen CHF and occlusive|w/CCBs or digoxin |heart failure, OPVD, |

| | | |vascular resistance |peripheral vascular disease |causing A-V block |high° A-V block |

| | | | |(OPVD) | | |

| | | | |Lungs – bronchospasm | | |

| |Metoprolol |Cardioselective β1 | | | | |

| | |receptor blockade | | | | |

|Vasodilators |Hydralazine |Relax vascular smooth |↓ systemic vascular |Immuno – lupus like Sx | | |

| | |muscle ? |resistance |Cardio - ↑ HR use β block | | |

| |Minoxidil |Vasodilation - ↑ K+ |↓ systemic vascular |Cardio - ↑ HR use β block Fluid | | |

| | |channel hyperpolarize SM |resistance |retention, Hypertrichosis | | |

| |Na+ |Causes NO release, relaxes|↓ cardiac preload and |Hypotension, cyanide and | |Kidney or liver disease|

| |nitro-prusside |SM |afterload |thiocyanate poisoning | | |

|ACE Inhibitors |Captopril |Inhibits ACE - ↓ |↓ systemic vascular |HTN w/1st dose, Cough & | |Pregnancy |

| | |angiotensin II, ↑ |resistance and preload |angioedema w/↑ kinin, renal | | |

| | |bradykinin | |insufficiency, hyperkalemia, | | |

| | | | |proteinurea | | |

|Angiotensin II |Losartan |Blocks angiotensin II |Vasodilation w/↓ preload |Unkown (no cough) | |Pregnancy |

|receptor | |receptor binding |↓afterload | | | |

|Antagonists | | | | | | |

|Calcium Channel |Verapamil, |Bind Ca2+ channels ↓ Ca2+ |Vasodilation |Constipation, peripheral edema, |Digoxin, β |Unstable angina, MI, |

|Antagonists |diltiazem, |for muscle contraction | |worsen CHF, headache |blockers = A-V |HTN? |

| |nifedipine | | | |block | |

|Dopamine Agonist |Fenoldopam |Dopamine (DA) 1 agonist |↑ renal blood flow ↑Na+ | | | |

| | | |excretion | | | |

4) Describe the use of drugs in the management of hypertension as recommended in JNC VII report. The following tables describe the recommended drugs for the management of hypertension. The first table gives BP values and their corresponding treatments while the second table gives conditions with compelling indications and the recommended drugs for each condition.

|BP classification |Systolic BP, mmHg|Diastolic BP, mmHg|Lifestyle |Without Compelling Indication |With Compelling Indications |

| | | |Modification | | |

|Normal | ................
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