Question

Pharmacology

Assignments, Chapter 43, Drugs Affecting Blood Pressure Written Assignments 1. Using a table format, identify the three normal controls of | Learning Objective(s) blood pressure and how angiotensin-converting enzyme | (ACE) inhibitors, angiotensin II receptor blockers (ARBS), calcium channel blockers, and vasodilators affect these controls. 2. There are several classifications of antihypertensive medications used for control of hypertension. Some | classifications are more commonly used in specific populations. What are the common concerns with the use of specific classifications of antihypertensives across the | lifespan? Learning Objective(s) |Group Assignments 1. Each person takes one class of medications to control blood pressure: angiotensin-converting enzyme (ACE) inhibitors, angiotensin II-receptor blockers (ARBS), calcium channel blockers, and vasodilators. The group takes part in a panel discussion describing the therapeutic actions, indications, pharmacokinetics, contraindications, the most common adverse reactions, and the important drug–drug interactions for each medication group.

Answer 1

1. Three normal controls of blood pressure are :-

- cardiac output

- peripheral resistance

- blood volume

#. ACE inhibitors lower your blood pressure by reducing angiotensin II in your body. This allows your blood vessels to relax and widen, making it easier for blood to flow through. It also lowers the amount of water your body retains, which lowers your blood pressure.

#. Calcium channel blockers are drugs used to lower blood pressure. They work by slowing the movement of calcium into the cells of the heart and blood vessel walls, which makes it easier for the heart to pump and widens blood vessels. As a result, the heart doesn't have to work as hard, and blood pressure lowers

#. Vasodilators are medications that open (dilate) blood vessels. They affect the muscles in the walls of your arteries and veins, preventing the muscles from tightening and the walls from narrowing. Heart doesn't have to pump as hard, reducing your blood pressure.

2. Common concerns with the use of specific classification of antihypertensives are :-

- cough

- diarrhoea

- constipation

- dizziness /lightheadedness

3. ACE inhibitors :-

#. MOA

Inhibit the conversion of angiotensin-I to angiotensin-II. Angiotensin-II is a potent vasoconstrictor and promotes the production of aldosterone. Aldosterone promotes sodium and water retention. By inhibiting the production of angiotensin-II, ACE-inhibitors cause vasodilation and indirectly inhibit fluid volume increases that result from the actions of aldosterone.

#. ACE inhibitor uses

ACE inhibitors were initially approved for the treatment of hypertension, and can be used alone or in combination with other antihypertensive medications. Later, they were found useful in other cardiovascular and kidney diseases including:

- Acute myocardial infarction (heart attack) - prevents cardiac remodeling

- Cardiac failure (left ventricular systolic dysfunction)

- Kidney complications of diabetes mellitus (diabetic nephropathy)

In treating heart disease, ACE inhibitors are usually used with other medications. A typical treatment plan often includes an ACE inhibitor, a beta blocker, a long-acting nitrate, and a calcium channel blocker in combinations that are adjusted to the individual patient's needs.

ACE inhibitors have also been used in chronic kidney failure and kidney involvement in systemic sclerosis (hardening of tissues, as scleroderma renal crisis).

#. Interactions

Drug-Drug: Excessive hypotension may occur with concurrent use of diuretics and other antihypertensives. ↑ risk of

hyperkalemia with concurrent use of potassium supplements, potassium-sparing diuretics, potassium-containing

salt substitutes, or angiotensin II receptor antagonists. Antihypertensive response may be ↓ by NSAIDs. Absorption

of fosinopril may be ↓ by antacids (separate administration by 1-2 hr). ↑ levels and may ↑ risk of lithium toxicity.

Quinapril may ↓ absorption of tetracycline, doxycycline, and fluoroquinolones (because of magnesium in tablets).

Telmisartan may ↑ ramipril levels; concurrent use not recommended.

Drug-Food: Food significantly ↓ absorption of captopril and moexipril (administer drugs 1 hr before meals).

#. Contraindications

Contraindicated in: Hypersensitivity; History of angioedema with previous use of ACE inhibitors; OB: Can cause

injury or death of fetus; Lactation: Certain ACE inhibitors appear in breast milk; discontinue drug or use formula.

Use Cautiously in: Renal impairment, hepatic impairment, hypovolemia, hyponatremia, concurrent diuretic therapy;

Black patients with hypertension (monotherapy less effective, may require additional therapy; ↑ risk of angioedema);

Women of childbearing potential; Surgery/anesthesia (hypotension may be exaggerated); Pedi: Safety not established

for most agents; benazepril, fosinopril, and lisinopril may be used in children ≥6 yr (captopril and enalapril may be

used in children of all ages); Geri: Initial dose reduction recommended for most agents due to age-related decline in

renal function.

Exercise Extreme Caution in: Family history of angioedema.

#. Calcium channel blockers :

- MOA :-

preventscalcium ion from being moves into myocardial smooth muscle & vascular smooth muscle, this action decreases the rate ot contractions (HR), and causes vasodilation or peripheral vasculature

- Indications :-

htn

angina

vasospastic angina

superventricular tachydysrhythmias

rapid ventricular rates in a-fib or flutter

- Adverse effects :-

peripheral edema, HF, dysrhythmias, hypotension, dizziness, fainting, drowsiness, HA< confusion, weakness, blurred vision, epistaxis, tinnitus, cough, dyspnea, bradycardia, angina, syncope, palpitations, nasuea, consipation, diarrhea, steven-johnson syndrome, weight gain, muscle cramps, vomiting, dysuria, sexual dysfunction, hyperglycemia, nocturia, polyuria, dry mouth, flushin, sweating, photsensitivity, anorexia, anemia, leukopenia, thrombocytopenia, tremor, paresthesia, joint stiffness, anxiety, confusion, nervousness, abnormal dreams, psychiatric disturbances, gynecomastia, gingival hyperplasia, urinary frequency, dyspepsia, elevated liver enzymes, dysgeusia, tachycardia, quilibrium disturbances, rash, urticara, pruritis, dermatitis, erythema multiforme

#. Interactions :-

- All calcium channel blockers enhance the hypotensive effects of beta blockers

- Grape juice decreases the metabolism of most calcium channel blockers

- Severe hypotension , bradycardia , AV block possible