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Pharmacology (Topics A) > A23. Drugs used for the treatment of hypertension II: Ca++-channel blockers and other vasodilators > Flashcards

A23. Drugs used for the treatment of hypertension II: Ca++-channel blockers and other vasodilators Flashcards

1
Q

What is the MOA of Calcium Channel Blockers (CCB)?

A
  1. They slow down the pacemaker.
  2. In working cells they may shorten action potential.
  3. They can be negative inotropic, if they bind to the cardiac L type channels.
  4. They are weaker vasodilators, but action is measurable and effective.
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2
Q

What is the physiological function of calcium channels in the body?

A
  1. L-type in heart and smooth muscle.
  2. In heart they finish depolarization.
  3. In muscles they are responsible for plateau phase.
  4. In smooth muscle, calcium influx results in smooth muscle constriction.
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3
Q

List the non-selective calcium channel blockers.

A
  1. Verapamil: strongest cardiac depressor of the group.
  2. Diltiazem
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4
Q

What is the MOA of Verapamil (CALAN, ISOPTIN)?

A

Verapamil is the strongest cardiac depressor of the Nondihydropyridine group in the Ca2+ channel blockers. Blocks Ca2+ channel in cardiac tissue and vascular smooth muscle. It produce vasodilation, slow heart rate and conduction. It also decreases cardiac contractility.

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5
Q

What is the MOA of Diltiazem?

A

Diltiazem is similar to verapamil. It is a vasodilator and a antiarrhythmic agent (Class IV). It is part of the Nondihydropyridine Ca2+ channel blockers. It blocks Ca2+ Channels in cardiac tissue and vascular smooth muscle. It produces vasodilation, slowes heart rate and conduction and decreases cardiac contractility.

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6
Q

What is the MOA of vessel selective calcium channel blockers (aka Dihydropyridines)?

A

They block L-type CC in vasculature and thereby reduce the afterload.

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7
Q

What are the side effects of Calcium Channel Blockers (CCB)?

A

For the most part relatively few SE. They are well tolerated. The side effects include:

  1. Hypotension: especially Nifedipine
  2. Coronary steal phenomenon: rarely can occur and causes angina. Especially in Nifedipine.
  3. Ankle Edema: (maybe because arteries are dilated more than veins, and if you stand then venous removal is not efficient. Can worsen this aspect of heart failure.)
  4. Gingival Hyperplasia: more so verapamil
  5. Constipation: relaxing intestinal muscles (also more so verapamil, but not exclusively)
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8
Q

List the Vasodilators.

A

Act “behind the receptor”, not really receptor blockers.

  1. Nitrates
  2. Hydralazine
  3. Openers of ATP dependent potassium channels.
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9
Q

What is the MOA of Hydralazine?

A
  1. Also known as Dihydralazine.
  2. Its MOA is not understood, but maybe similar to nitrates.
  3. Known to be very potent arteriole vasodilator by decreasing the resistance.
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10
Q

What is the MOA of openers of ATP dependent potassium channels?

A
  1. They act by opening K channel causing hyperpolarization of the membrane.
  2. Arterioles contain this channel, and these drugs make them relax.
  3. Same thing happens in pancreatic β cells, preventing insulin release.
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11
Q

What is the MOA of Nitrates?

A

Nitrates cause nitric oxide release. NO activates guanylyl cyclase → cGMP in smooth muscle → activity of myosin light chain ↓ → smooth muscle relaxes. Some nitrates are more efficient in veins, others show no preference.

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12
Q

What is the MOA of Nitroglycerine?

A

Proper name is Glyceryl trinitrate. It is potent venodilator that decreases preload.

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13
Q

What are the adverse effects of using Verapamil?

A
  1. Hypotension
  2. Peripheral edema
  3. Heart failure (HF)
  4. Constipation
  5. Gingival hyperplasia
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14
Q

What are the clinical indications to start Verapamil?

A
  1. Treatment of Hypertension (Antihypertensive)
  2. Angina Pectoris (Antianginal)
  3. Supraventricular tachycardia (Antiarrhythmic agent - Class IV)
  4. Prevention/Prophylaxis of Migraine Headache.
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15
Q

What are the indications of Nimodipine?

A

Nimodipine is not really an anti-hypertensive drug. It is used for subarachnoid hemorrhage. It eliminates reactive vasoconstriction that develops due to bleeding.

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16
Q

What is the MOA of Isosorbide mononitrate?

A

It is similar to nitroglycerine. Isosorbide mononitrate is a drug used principally in the treatment of angina pectoris (prophylacti treatment?) and acts by dilating the blood vessels so as to reduce the blood pressure. Isosorbide mononitrate reduces the workload of the heart by producing venous and arterial dilation. By reducing the end diastolic pressure and volume, isosorbide mononitrate lowers intramural pressure, hence leading to an improvement in the subendocardial blood flow. The net effect when administering isosorbide mononitrate is therefore a reduced workload for the heart and an improvement in the oxygen supply/demand balance of the myocardium.

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17
Q

List the Nitrates.

A
  1. Nitroglycerine.
  2. Isosorbide mononitrate.
  3. Molsidomin.
  4. Sodium-nitroprusside.
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18
Q

What are the indications for openers of the ATP dependent potassium channels?

A
  1. Hypertension: causes relaxation of arterioles.
  2. Treats Androgenic hair loss, used locally (Minoxidil)
  3. It prevents insulin release so it can be used in insulinoma.
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19
Q

What are the interactions of Verapamil?

A

Interactions include:

  1. Digoxin: increase level of digoxin
  2. Cyclosporine
  3. Quinidine
  4. Carbamazepine
  5. Grapefruit juice: increases serum levels.
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20
Q

What are the contraindications of taking Nitrates?

A

It is contraindicated in hypertrophic cardiomyopathy.

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21
Q

What are the SE of Diltiazem?

A

Usually well tolerated

  1. Dizziness
  2. Hypotension
  3. Peripheral edema
  4. Constipation
  5. Gingival hyperplasia
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22
Q

What are the side effects of Nitroglycerin?

A
  1. Hypotension: orthostatic hypotension which can cause reflex tachycardia. Prevent reflex tachycardia with β blocker; angina pts often have β blocker + nitrate. Strong risk if combined with an erectile dysfunction medication.
  2. Between 30 and 70% of pts feel strong throbbing headache, migraine-like. Not as strong as migraine though. Nitrate headache starts w/in 1 hour of administration. Nitrates can provoke a migraine in people prone to migraines, but that starts about 4-6 hours after administration. Migraines may be a CI.
23
Q

What are the clinical indications of Diltiazem?

A
  1. Hypertension
  2. Angina pectoris
  3. Supraventricular tachycardia
24
Q

Which drug interactions can Diltiazem encounter?

A
  1. Digoxin: increases level of digoxin
  2. Cyclosporine
  3. Quinidine
  4. Carbamazepine
  5. Grapefruit: increases serum levels.
25
Q

What are the indications for giving sodium-nitroprusside?

A

Only hypertensive crisis.

26
Q

What is the MOA of non selective calcium channel blockers (aka cardiac type)?

A

It blocks L-type CC in heart and vasculature.

27
Q

What are the SE of sodium-nitroprusside?

A
  1. Light sensitivity: very light sensitive, otherwise no action.
  2. Lactic acidosis
  3. Cyanide poisoning: In structure, contains cyanide that can be released from molecule. unlikely though. treatment is sodium-thiosulfate so that cyanide changes to a less toxic ion.
28
Q

What are the indications for starting non-selective calcium channel blockers?

A
  1. Antiarrhythmic indications (type IV): used for SVTs, especially if they involve AV node. Don’t use if they have ventricular arrhythmia! dangerous.
  2. Can be given in Angina
  3. Special cardiac indications: Hypertrophic cardiomyopathy.
  4. Antihypertension can be an indication
  5. Cluster headaches: get extremely high dose of verapamil (800mg).
29
Q

List the vessel selective calcium channel blockers (dihydropyridines).

A
  1. Nifedipine: prototype but short-acting, only used in time-release form.
  2. Amlodipine: most popular
  3. Felodipine
  4. Others: Lacidipine, Isradipine, Nicardipine, Nisodipine and Lercanidipine
30
Q

What are the indications for dihydropyridines?

A
  1. Good antihypertensive drugs: Nimodipine is not really an anti-hypertensive drug, used for subarachnoid hemorrhage. Eliminates reactive vasoconstriction that develops due to bleeding.
  2. Heart: only negative inotropic effect, not strong. can cause reflex tachycardia, which makes them able to be combined with β blockers well (remember! Use β blockers for dihydropyridines, NOT for verapamil/diltiazem)
  3. Raynaud
  4. Angina: Amlodipine and slow-release. Nifedipine are indicated for chronic stable angina. Also indicated for Prinzmetal angina.
31
Q

List the drugs in openers of the ATP dependent potassium channels.

A
  1. Minoxidil
  2. Diazoxide
32
Q

What are the side effects of using openers of the ATP dependent potassium channels?

A
  1. Minoxidil: similar SE to hydralazine with coronary steal.
  2. These drugs can cause hyperglycemia by inhibiting insulin release.
33
Q

What is the MOA of Sodium Nitroprusside?

A

Dilates both veins and arteries, very strong.

34
Q

What are the side effects of taking Hydralyzine?

A
  1. Strongly provokes reflex tachycardia. Combine with β blocker to prevent this from happening.
  2. Slows kidney perfusion → hyperaldosteronism → water retention (in long run). Prevent via diuretic.
  3. Subendocardial arteries seem to be affected differently, has coronary steal syndrome that can cause angina or even MI.
  4. Similar problem in brain (stroke) or mesentery infarction.
  5. Can cause drug-induced lupus.
35
Q

Is Hydralyzine safe to take during pregnancy?

A

Supposedly safe in pregnancy.

36
Q

What are some speical considerations you need to take into acount with Verapamil?

A

It supresses cardiac contractility more than other Ca2+ channel blockers.

37
Q

What are the contraindications of Nitroglycerin?

A

Migraines maybe due to the side effects of Nitroglycerin.

38
Q

What is the MOA of Felodipine?

A

Felodipine is a long-acting 1,4-dihydropyridine calcium channel blocker (CCB). It acts primarily on vascular smooth muscle cells by stabilizing voltage-gated L-type calcium channels in their inactive conformation. By inhibiting the influx of calcium in smooth muscle cells, felodipine prevents calcium-dependent myocyte contraction and vasoconstriction. In addition to binding to L-type calcium channels, felodipine binds to a number of calcium-binding proteins, exhibits competitive antagonism of the mineralcorticoid receptor, inhibits the activity of calmodulin-dependent cyclic nucleotide phosphodiesterase, and blocks calcium influx through voltage-gated T-type calcium channels.

39
Q

Where is Hydralysine used?

A

Rarely used in most countries, maybe more in US.

40
Q

What are the indiactions of Nitroglycerin?

A
  1. Most essential in treatment of chronic stable angina pectoris. Preload leads to wall stress on the heart, more oxygen is needed, hypoxia → angina. So this drug acts almost immediately to reduce the wall stress, takes 5-10 minutes.
  2. Can also be used for Hypertensive Crisis.
41
Q

Pharmacokinetics of Nitroglycerin?

A

Administration: 1. Usually sublingual nitroglycerine (to absorb faster, avoid first pass metabolism) 2. Pill: can also use NTG as prophylaxis, usually orally-given pills. first pass metabolism destroys a lot of it, so the dose is much higher! 3. Sprays. 4. Transdermal patch: can also be used. very lipid soluble drug. Tolerance/Resistance: rapid tolerance develops, so need to take a break by taking it in the morning only, not at night (when effort angina is less). Tolerance can be lost in 1 day too.

42
Q

What is the MOA of Nifidipine?

A

Nifedipine has been formulated as both a long- and short-acting 1,4-dihydropyridine calcium channel blocker. It acts primarily on vascular smooth muscle cells by stabilizing voltage-gated L-type calcium channels in their inactive conformation. By inhibiting the influx of calcium in smooth muscle cells, nifedipine prevents calcium-dependent myocyte contraction and vasoconstriction. A second proposed mechanism for the drug’s vasodilatory effects involves pH-dependent inhibition of calcium influx via inhibition of smooth muscle carbonic anhydrase.

prototype but short-acting, only used in time-release form

43
Q

What are the indications of Felodipine?

A

Felodipine is used to treat mild to moderate essential hypertension.

44
Q

What are the indications for Nifedipine?

A

Nifedipine is used to treat hypertension and chronic stable angina.

45
Q

How is Sodium-Nitroprusside administered?

A

Sodium-Nitroprusside is administered via parenteral infusion. It however not available in hungary, but in other countries it is.

46
Q

How is the pharmacokinetics like for the non-selective calcium channel blockers?

A
  1. It has to be taken 3 x day → low patient compliance.
  2. Strong first-pass metabolism of verapamil do not combine verapamil with other negative dromotropic agents!!
  3. Do not combine with β blocker, very risky because it may cause a grade III AV block.
47
Q

What is the MOA of Amlodipine?

A

Amlodipine is a popular antihypertensive drug belonging to the group of drugs called dihydropyridine calcium channel blockers. Amlodipine is commonly used in the treatment of high blood pressure and angina. Amlodipine has antioxidant properties and an ability to enhance the production of nitric oxide (NO), an important vasodilator that decreases blood pressure.

48
Q

What are the SE of Minoxidil?

A

Similar SE to hydralazine with coronary steal.

49
Q

What is the MOA of Diazoxide?

A

Diazoxide is a benzothiadiazine derivative that is a peripheral vasodilator used for hypertensive emergencies. It lacks diuretic effect, apparently because it lacks a sulfonamide group.

50
Q

What is the MOA of Molsidomin?

A

Molsidomine is an orally active, long-acting vasodilator, which belongs to the class of medications known as syndnones. Molsidomine, a cardiovascular drug, acts in a similar fashion to organic nitrates,but tolerance doesn’t develop. The SIN-1A metabolite of molsidomine has a pharmacologically active group of nitric oxide, which increases levels of cyclic GMP, and decreases intracellular calcium ions in smooth muscle cells. This leads to relaxation of smooth muscle in the blood vessels, and inhibits platelet aggregation. It can be given 3x/day.

51
Q

What are the indications of Amlodipine?

A

Amlodipine may be used alone or in combination with other antihypertensive and antianginal agents for the treatment of the following conditions

  1. Hypertension
  2. Coronary artery disease: Angiographically documented coronary artery disease in patients without heart failure or an ejection fraction < 40%
  3. Angina: Chronic stable angina, Vasospastic angina (Prinzmetal’s or Variant angina).
52
Q

Why is amlodipine a popular hypertensive drug?

A

The option for single daily dosing of amlodipine is an attractive feature of this drug.

53
Q

What are the inidcations of Minoxidil?

A

Also treats androgenic hair loss, used locally (baldness, hair growth promoter)

54
Q

What are the indications of Molsidomin?

A
  1. Ischemic heart disease
  2. Angina
  3. Chronic heart failure
  4. Pulmonary hypertension

Pharmacology (Topics A) (39 decks)

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