Antihypertensive medications Flashcards

1
Q

Which physiological functions might be acted on by the drugs acting on the heart?

A

1) Rate & Rhythm

2) Myocardial contraction

3) Metabolism and blood flow

  • While the drugs acting on the blood vessels affect the vessel tone mainly (vasoconstriction/Vasodilation)
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2
Q

What are the two mechanisms by which heart medications control the heart?

A

1) Short-term regulation:
- Via the autonomic control of the heart

2) Long-term regulation
- Via the Renin-angiotensins aldosterone system

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3
Q

What are the main adverse effects of the heart drugs?

A
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4
Q

What are the best antihypertensive medications for specific patients?

A

1) Patients with asthma

  • We give angiotensin-II receptor-blocking (AR-B)

ACE-Inhibitors

2) Patients with kidney failure

  • We give Fosinopril

3) Diabetic patients

  • Isinopril & hydrochlorothiazide

A-Blockers

4) Pregnant patients

  • Labetalol
  • Carvedilol

B-BLOCKERS

5) Patients with glaucoma

  • Timolol (inhibits the b-2 receptors decreasing the production of aqueous humor)

6) Reduced Renal Function patients

  • Nadolol (reduced dose)
  • Carteolol (reduced dose)

7) Pheochromocytoma (Tumor in the adrenal gland)

  • Labetalol (both an a- and b-blocker)
  • Phenobenzamine
  • Phentolamine

A-2agonists

8) Renal patients with hypertension

  • Clonidine, usually with a diuretic as it causes sodium and water retention

9) Sympatholitcs

  • Methyldopa (treats preeclampsia)
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4
Q

How does the CNS control the BP?

A

1) Resistance arterioles (they are the major vessels that controls the velocity of blood flow, they control them by vasodilating, or constricting them)

2) Capacitance venules (they hold the most amount of blood, CNS can also control their diameter)

3) Heart-pumped output (they can stimulate the B-receptor, controlling the SV, contractility, etc)

4) It can also control the amount of renin released into the system via stimulating the kidneys

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4
Q

What is the most important site where the heart medication should work on?

A

Resistance arterioles

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4
Q

What is meant by the postural baroreflex?

A

Drugs acting on the resistance arterioles result in (drop in the BP due to vasodilation “postural baroreflex”) where the reflex vasoconstriction “activating the vasomotor” and the HR will increase in “reflex tachycardia”

  • In low BP the kidney activates the RAA system
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5
Q

What is the mechanism of action of the beta blockers?

A

1) Block the activation of b1 adrenoceptors in the heart decreasing the cardiac output

2) blocking the b2-receptors in the kidney decreasing the release of renin and thus the blood volume

  • This drug is an example of a drug that works on two systems autonomic and the kidney
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6
Q

What are the main classes of antihypertensive drugs?

A

1) Angiotensin-converting enzyme inhibitor (ACEI)

2) Angiotensin-II receptor blocker

3) Antiadrenergics (a-blockers, b-blockers, centrally acting “like clonidine”)

4) Calcium channel blockers

5) Diuretics

6) Direct vasodilators

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7
Q

What are the different drugs acting on the renin-angiotensin-aldosterone system?

A

1) Angiotensinogen (a2-globulin in blood “produced by the liver”), is converted to angiotensin-I “inactive” via the enzyme Renin and it is inhibited by RENIN INHIBITORS

2) Angiotensin-I is converted to angiotensin-II via the enzyme ACE “angiotensin converting enzyme”, and it is inhibited by ACEI

3) Angiotensin-II will increase the sympathetic output, vasoconstrictor the vascular smooth muscles, and stimulate the secretion of aldosterone, which is inhibited by the ARB’s (Angiotensin-II receptor blocker), which will decrease the BP

4) Aldosterone will stimulate the retention of sodium and water increasing the BP blocking it via an aldosterone receptor antagonist will decrease the BP

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8
Q

What happens if you inhibit the formation of angiotensin 2?

A

Accumulation of renin

  • Thus ACEI causes the accumulation of renin
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9
Q

Can we give ACEI to asthma patients?

A
  • The enzyme ACE converts angiotensin 1 to angiotensin 2 (Vasoconstrictor) and at the same time it converts bradykinin into an inactive metabolite
  • If we inhibited the ACE, Bradykinin (vasodilator) will then accumulate which is a good thing but its accumulation will irritate the nerve endings of small nerves, producing an irritant cough (Use Icatibant)
  • Angiotensin receptor blockers (ARBs) are away from bradykinin so they’re good substituents in case of asthma
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10
Q

Describe the pharmacokinetics of ACE-Inhibitors

A

1) Captopril

  • Short-acting

2) Enalapril

  • Prodrug like all of them is converted via hydrolysis to a converting enzyme inhibitor in the liver (used in diabetic patients)

3) Enalaprilat

  • Only IV, for hypertensive emergencies

4) Lysinopril

  • Lysine derivative of enalaprilat, the only one which is not a prodrug

5) Fosinopril

  • Given to patients with renal failure

7) Others, etc

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10
Q

What are some examples of ACE-inhibitor medications?

A

1) Captopril (short-acting medication)

2) Enalapril (can be used once or twice daily with better pharmacokinetics)

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11
Q

Describe the pharmacodynamics of the ACE inhibitors

A

1) Blocks the formation of angiotensin-II: (decreases the peripheral resistance due to the blockage of vasoconstriction)

2) Decreases the release of aldosterone and thus decreases the retention of sodium and water

3) Increases the levels of bradykinin and prostaglandins vasodilating the vessels and thus decreasing the peripheral resistance

  • The final result is the vasodilation of the arterioles and venules
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12
Q

Which drug do we describe to a diabetic patient?

A

Lisinopril & hydrochlrothiazide

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12
Q

What are the side effects of ACE inhibitors?

A

1) Cough (Usually due to bradykinin)

2) Angioedema (emergency must be treated as it can be fatal)

3) Proteinuria (From captopril, as it contains sulfur causing hypersensitivity)

4) Loss of Taste (Metallic taste)

5) Acute Renal failure

6) Increased Potassium (Hyperkalemia)

7) Fetal anomalies

8) Neutropenia (due to bone marrow suppression)

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13
Q

Which ACE inhibitor is used in case of kidney failure?

A

Fosinopril

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14
Q

What are the uses of ACE-Inhibitors?

A

1) Among the first-line treatment of hypertension

2) For chronic congestive heart failure

3) After a myocardial infarction

4) Diabetic nephropathy

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15
Q

Which medication is used to suppress the cough of bradykinin (cyclooxygenase inhibitor)?

A

Icatibant

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16
Q

When are the ACE inhibitors contraindicated?

A

In patients suffering from bilateral renal artery stenosis and pregnant women

17
Q

Are ACE inhibitors safe during pregnancy?

A

No, because it will lead to fetal anomalies in the kidneys and urinary tracts (Renal anagenesis)

17
Q

What is the reason behind angioedema and proteinuria?

A

Due to hypersensitivity reactions, it is an emergency

18
Q

Describe the drug interaction between ACE-Inhibitors and other drugs

A

1) With Potassium supplements, potassium-sparing diuretics

2) Non-steroidal anti-inflammatory drugs attenuate the action of antihypertensive medications, but they also attenuate some of their side effects

19
Q

Are the ACE inhibitors and ARB considered teratogenic?

A

Yes, especially to the kidneys

19
Q

Which ACE inhibitor is not eliminated primarily by the kidneys?

A

Fosinopril

20
Q

What are the adverse effects of Losartan and Valsartan?

A

Their side effects are similar to the ACE-Inhibitors but without the:

1) Cough

2) Angioneurotic edema

21
Q

What are the drugs that are selective antagonists for AT1?

A

1) Losartan

2) Valsartan

22
Q

What is an example of a renin inhibitor drug?

A
  • They inhibit the transformation of angiotensinogen into angiotensin-I

Aliskiren

23
Q

What are the adverse effects of renin inhibitors?

A

1) Diarrhea

2) Cough

3) Angioedema

4) Contraindicated during pregnancy

24
Q

Describe the pharmacodynamics of beta blockers

A

1) Decreases the cardiac output

2) Decreases the sympathetic outflow from the central nervous system

3) Inhibits the release of renin from the kidneys

24
Q

What are the examples of Anti-adrenergic drugs?

A
  • They inhibit the activity of the sympathetic nervous system

1) a-blockers: Relaxes the vascular smooth muscles, decreases the peripheral resistance

2) b-blockers: Decreases the heart, force of myocardial contraction, cardiac output, & blood pressure

24
Q

Which one is used more a- or b-blockers?

A

b-blockers, as the a-blocker causes higher mortality

24
Q

Which enzyme is responsible for the metabolism of aliskiren?

A

CYP34 which is mainly found in the liver

25
Q

Where are the B1 and B2 receptors located?

A

B-1:

1) Heart (AV-Node, SA-Node, Ventricular myocardium)

2) Kidneys (juxtaglomerular apparatus)

3) Adipose tissue

B-2:

1) Lungs

2) Blood vessels

3) Uterus

4) Liver

5) Skeletal muscles

25
Q

What are the functions of B-1 and B-2 receptors?

A

B-1:

1) Increases the heart rate

2) Increases the force of contraction

3) Increases the speed of conduction

  • ALL OF THIS WILL LEAD TO A INCREASED CO

B-2:

1) Bronchodilation

2) Vasodilation

3) Relaxes the uterine muscles

4) Facilitates glycogenolysis

26
Q

What is the mechanism of action of beta blockers?

A
  • It will competitively block adrenergic receptors

1) Deactivates the B-1 adrenoceptors in the heart, decreasing the CO, decreasing the blood pressure (reduces all of the cardiac properties, making it an ideal anti-arrhythmic drug)

2) Decreases the activation of the B-1 adrenergic receptors in the kidneys, decreasing the production of renin, thus angiotensin-II:

2a) Decreasing the TPR, and thus decreasing the blood pressure

2b) Decreasing the aldosterone secretion, decreasing the retention of sodium and water, decreasing the blood volume and thus the cardiac output and thus the blood pressure

27
Q

Describe the different forms available of b-blockers, and their pharmacokinetics

A

1) Oral, IV, Sustained release tablets

1) Propranolol (non-selective) & metoprolol (selective)

  • Highly lipid soluble
  • Metabolized in the liver (first pass)

2) Atenolol & Sotalol (selective)

  • Less lipid soluble
  • Excreted in urine unchanged
27
Q

What was the first b-blocker medication?

A

Propranolol

1) antagonized catecholamine action on both B-1 and B-2 receptors

2) Produces a sustained reduction in the TPR

3) Blocked the b-1 receptors in the heart reducing the heart rate and contractility

4) Blocking the B-2 receptors will increase the airway resistance and decrease the catecholamine-induced glycogenolysis and peripheral vasodilation

5) Blocking the b-adrenoceptors in the CNS decreases the sympathetic activity

6) Blocking b-1 decreases the renin release

28
Q

What are the different b-blocker drugs?

A
  • Non-selective (blocks b-1 and b-2 receptors):

1) Nadolol (Extended duration of action “used in a reduced for renal patients”)

2) Timolol (used in glaucoma patients as it inhibits the b-2 receptors decreasing the production of aqueous humor in the body)

3) Carteolol (used in reduced amounts for renal patients)

4) Pindolol

5) Penbutolol

  • Selective:

1) Metoprolol (cardioselective)

2) Atenolol (Cardio-selective)

3) Acebutalol

4) Bisoprolol

5) Nebivolol (releases nitric oxide which vasodilates the vessels)

28
Q

What are the therapeutic uses of a-blockers?

A

1) Hypotension

  • Prazosin and terazosin can cause sedation in the first dosage, that’s why we should lower the first dose or give it before sleep

2) Pheochromocytoma

  • Patients with this condition must be treated (with for ex, phenoxybenzamine) to pre-treat any hypertensive crisis before the surgery

3) Treating Raynaud’s disease (frostbite due to the constriction of the BV)

28
Q

What is the intrinsic sympathetic activity & the membrane block activity of b-blockers?

A

A mechanism by which b-blockers increases the stimulation of the nerve initially and then blocks it, membrane activity is another way by which the b-blockers increases the polarization of the membrane making it not responsive to AP

29
Q

What are the adverse effects and contraindications of b-blockers?

A

1) Heart failure

2) Bradycardia (which could lead to a heart block)

3) Heart block

4) Hypotension

5) Peripheral vascular disease

6) Angina

7) Bronchial asthma (especially the non-selective ones)

8) Triglycerides & decreases the HDL

9) Sedation (propranolol, as it crosses the BBB due to the fact that it is lipophilic)

10) Withdrawl effects (tachycardia, nervousness, increased intensity of angina, increased BP)

30
Q

Which a-blockers are used during pregnancy?

A

1) Labetalol

2) Carvedilol

30
Q

What are the actions of a-blockers?

A

Reduce the sympathetic tone of the vessels, decreasing the TPR, inducing a reflex tachycardia due to the lowered BP

30
Q

What are the a-blocker drugs?

A
  • Non-selective:

1) Phenoxybenzamine
2) Phentolamine
- Used in pheochromocytoma

  • Selective a-blockers:

1) Doxazosin
2) Prazosin
3) Terazosin
- Used to manage hypertension

30
Q

What are the sympatholytics? What are some examples of sympatholytics?

A
  • They are drugs that stimulate the presynaptic alpha-2, less norepinephrine is released and the sympathetic outflow is reduced, decreasing the cardiac output, heart rate, peripheral vascular resistance, and BP

1) Clonidine (Oral, IV, Patch)

2) Methyldopa (safe in pregnancy, it suppresses the formation of catecholamines in the brain reducing the sympathetic signals, and it can cause hemolytic anemia)

30
Q

What are the drugs that block both a- and b-receptors?

A

1) Labetalol

  • A- & B- Blocker
  • Available both orally and IV
  • Useful in treating hypertensive emergencies and in pheochromocytoma
  • Does not cause reflex tachycardia

2) Carvedilol

  • Blocks b-receptors more than a-
30
Q

What is clonidine?

A
  • a2-agonist that diminishes the central adrenergic outflow, it does not decrease the renal blood flow or the glomerular filtration rate and is thus useful in patients with renal diseases, usually used with diuretics as it can cause sodium and water retention
30
Q

When is clonidine used?

A

Hypertensive patients with renal disease

30
Q

What are the adverse effects of clonidine?

A

1) Sedation

2) Dryness of the mouth and nasal mucosa

3) Rebound hypertension is withdrawn abruptly

30
Q

Why must we use a B-blocker and a diuretic to a vasodilator in the treatment of hypertension?

A

To prevent tachycardia we give B-blockers, and to prevent increase in BV (thus BP) we give diuretics as the vasodilator will stimulate the release of renin from the kidneys