Calcium channel blockers word file

Calcium channel blockers word file

1. CALCIUM CHANNEL BLOCKERS
INTRODUCTION: Calcium channel blockers (CCBs) also known as calcium antagonists.
These are several medications that disrupt the movement of calcium (Ca
2
+) through calcium
channels. 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. Therefore 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. they are first line antihypertensive drugs. They are also
used to treat angina.
Classification of CCBs:
Calcium channel blockers are mainly classified into 2 types:
1. Dihydropyridine
2. Non- dihydropyridine
1. Dihydropyridine: Dihydropyridine calcium channel blockers are derived from the
molecule dihydropyridine. They are mostly used to reduce systemic vascular resistance
and arterial pressure. Sometimes they are used to treat angina. They are easily identified
by their suffix ―dipine‖. Dihydropyridine mainly affect arterial vascular smooth muscle
and lower blood pressure by causing vasodilation. Examples of dihydropyridine are as
follows:
 Amlodipine (Norvasc)
 Aranidipine (Sapresta)
 Azelnidipine (Calblock)
 Barnidipine (HypoCa)
 Benidipine (Coniel)
 Cilnidipine (Atelec, Cinalong, Siscard) Not available in US
 Clevidipine (Cleviprex)
 Efonidipine (Landel)
 Felodipine (Plendil)
 Isradipine (DynaCirc, Prescal)
 Lacidipine (Motens, Lacipil)
 Lercanidipine (Zanidip)
 Manidipine (Calslot, Madipine)
 Nicardipine (Cardene, Carden SR)
 Nifedipine (Procardia, Adalat)
 Nilvadipine (Nivadil)
 Nimodipine (Nimotop) This substance can pass the blood-brain barrier and is used to
prevent cerebral vasospasm.
 Nisoldipine (Baymycard, Sular, Syscor)
 Nitrendipine (Cardif, Nitrepin, Baylotensin)
 Pranidipine (Acalas)

2. 2. Non- dihydropyridine: These are often divided into 2 categories: Phenylalkylamine and
Benzothiazepine.
 Phenylalkylamine: Phenylalkylamine calcium channel blockers are relatively selective
for myocardium, reduce myocardial oxygen demand and reverse coronary vasospasm,
and are often used to treat angina. The Phenylalkylamine class of CCBs mainly affect the
cells of the heart and have negative inotropic and negative chronotropic effects They
have minimal vasodilatory effects compared with dihydropyridine. Drug under this
category are Verapamil, Gallopamil.
 Benzothiazepine: It belongs to the molecule Benzothiazepine. These drugs are
intermediate class between dihydropyridine and Phenylalkylamine. They have both
cardiac depressor and vasodilator action.
Mechanism of action:
Calcium-channel blockers (CCBs) bind to L-type calcium channels located on the vascular
smooth muscle, cardiac myocytes, and cardiac nodal tissue (Sino atrial and atrioventricular
nodes). These channels are responsible for regulating the influx of calcium into muscle cells,
which in turn stimulates smooth muscle contraction and cardiac myocytes contraction. In
cardiac nodal tissue, L-type calcium channels play an important role in pacemaker currents
and in phase 0 of the action potentials. Therefore, by blocking calcium entry into the cell,
CCBs cause vascular smooth muscle relaxation (vasodilation), decreased myocardial force
generation (negative inotropy), decreased heart rate (negative chronotropy), and decreased
conduction velocity within the heart (negative dromotropy).
CCBs have four effects:
A. By acting on vascular smooth muscle, they reduce contraction of the arteries and cause an
increase in arterial diameter, a phenomenon called vasodilation (CCBs do not work on
venous smooth muscle).
B. By acting on cardiac muscles (myocardium), they reduce the force of contraction of the
heart.
C. By slowing down the conduction of electrical activity within the heart, they slow down
the heartbeat.
D. By blocking the calcium signal on adrenal cortex cells, they directly reduce aldosterone
production, which correlates to lower blood pressure.
Calcium influx into the myocytes initiate a series of events essential for contractility.
Calcium entry into the myocytes first triggers intracellular calcium release. The released
calcium then binds to the protein troponin. It results in calcium- troponin complex in the
heart muscles. It allows actin and myosin to interact and heart contacts. The same
phenomenon takes place in the vascular smooth muscle cells. Here calcium- Calmodulin
complex is formed in place of calcium- troponin. It permits interaction between actin and
myosin. It results in vasodilation and decreasing blood pressure.

3. FEW COMMONLY USED CCBS
AMLODIPINE
It is a medication used for treatment of hypertension and coronary artery disease. It is
also used in Stable angina (where chest pain occurs after physical and emotional
stress).
Trade name: Norvasc
Mechanism of action: Amlodipine relaxes peripheral and coronary vascular smooth
muscles . It produces coronary vasodilation by inhibiting the entry of calcium ions
into the voltage gated channels of the vascular smooth muscle and myocardium
during depolarization. It decreases cardiac work, decrease cardiac oxygen
consumption.
Indications: Hypertension, Stable angina, Prinzmetal’s angina.
Contraindications:
A. Known hypersensitivity to dihydropyridine.
B. Second or third degree heart block
C. Lactation
Availability: It is available in Tablets—2.5, 5, 10 mg.
Dosage:
Adults: Initially, 5 mg PO daily; dosage may be gradually increased over 10–14 days
to a maximum dose of 10 mg PO daily.
Geriatric: Initially, 2.5 mg PO
Side effects: Dizziness, light-headedness, headache, asthenia, fatigue, lethargy,
peripheral edema, somnolence, flushing, nausea, abdominal pian.
Nursing considerations:
1. Monitor patient carefully (BP, cardiac rhythm, and output) while adjusting drug
to therapeutic dose; use special caution if patient has CHF..
2. Monitor BP very carefully if patient is also on nitrates.
3. Monitor cardiac rhythm regularly during stabilization of dosage
4. Use with caution in patients with heart failure. It is contraindicated in patients
with second or third degree heart block.

4. NIFEDIPINE
It is calcium channel blocker used as an antianginal and antihypertensive drug.
Trade name: Adalat, Adalat CC.
Mechanism of action:
Nifedipine blocks the slow calcium channels thus preventing the flow of calcium ions into the
cell. It produces peripheral and coronary vasodilatation, reduces afterload, peripheral
resistance and BP, increases coronary blood flow and causes reflex tachycardia. It has little or
no effect on cardiac conduction and rarely has negative inotropic activity.
Availability:
It is available in ER tablets—30, 60, 90 mg; capsules—10, 20 mg.
Dosage:
In hypertension: 10-40 mg BID, or 20-90 mg once daily.
In angina pectoris: 10-40 mg BID or 30-90 mg once daily.
In Raynaud’s syndrome: Liquid filled capsules: 5-20 mg TID.
Indications: Chronic stable angina, Prinzmetal’s angina, HTN.
Contraindications: Acute MI, cardiogenic shock, acute unstable angina.
Side effects: Peripheral edema, hypotension, palpitations, tachycardia, flushing, dizziness,
headache, nausea, increased micturition frequency, lethargy, eye pain, mental depression,
visual disturbances, gingival hyperplasia, myalgia, tremor, impotence, fever, paradoxical
increase in ischemic chest pain during initiation of treatment, rashes, abnormalities in liver
function (including cholestasis.
Nursing Considerations:
1. Allergy to nifedipine; pregnancy; lactation
2. Ensure that patients do not chew or divide sustained-release tablets.
3. Protect drug from light and moisture.

5. VERAPAMIL
It is a calcium channel blockers that is used to treat hypertension, chest pain from cardiac
ischemia and supraventricular tachycardia.
Trade name: Various names.
Availability:
Mechanism of action: Verapamil inhibits entry of calcium ions into arterial smooth muscle
as well as the myocytes and conducting tissues. These actions lead to reversal and
preventions of coronary artery spasm, reduction in afterload through peripheral vasodilatation
and reduction in ventricular rate in patients with chronic atrial flutter or fibrillation and
reduction in the occurrence of paroxysmal supraventricular tachycardia. Verapamil reduces
BP, relieves angina and slows AV conduction.
Dosage:
Arrhythmias: 240–480 mg/day, Capsules: 120–240 mg/day PO in the morning, IV use only.
Initial dose, 2.5–10 mg over 2 min.
Indications:
 Angina pectoris due to coronary artery spasm (Prinzmetal’s variant angina)
 Effort-associated angina
 Chronic stable angina
 Unstable, crescendo, preinfarction angina
 Essential hypertension
 Parenteral: Treatment of supraventricular tachyarrhythmia.
 Parenteral: Temporary control of rapid ventricular rate in atrial flutter or atrial
fibrillation
Contraindications: Cardiogenic shock, severe bradycardia, severe left ventricular
dysfunction, uncompensated heart failure, hypotension (systolic pressure <90 mm Hg),
porphyria.
Side effects: Bradycardia, CHF, MI, AV block, worsening heart failure, transient asystole,
hypotension, pulmonary and peripheral edema, nausea. Constipation, fatigue, hypotension,
dizziness, headache, palpitation, flushing, nausea, rashes, alopecia, hyperprolactinaemia,
increased LFT and arthralgia.
Nursing considerations:
1. Allergy to verapamil; sick sinus syndrome; heart block; IHSS; cardiogenic shock,
severe CHF; hypotension; impaired hepatic or renal function; pregnancy, lactation.
2. Ensure that patient swallows SR tablets whole; patient should not cut, crush, or chew
them.
3. Protect IV solution from light.

6. DILTIAZEM
Diltiazem, a benzothiazepine calcium-channel blocker, is used alone or with an angiotensin-
converting enzyme inhibitor, to treat hypertension, chronic stable angina pectoris, and
Prinzmetal's variant angina. Diltiazem is a non-dihydropyridine (DHP)member of the calcium
channel blocker class, along with Verapamil.
Trade name: Cardizem, Cardizem CD, Cardizem LA, Cardizem SR.
Availability: 30 mg, 60 mg, 90 mg, 120 mg tablets; 120 mg, 180 mg, 240 mg sustained-
release tablets; 60 mg, 90 mg, 120 mg, 180 mg, 240 mg, 300 mg, 360 mg sustained-release
capsules; 120 mg, 180 mg, 240 mg, 300 mg, 360 mg, 420 mg extended-release tablets; 25
mg, 50 mg vials.
Mechanism of actions: Slow channel blocker with pharmacologic actions similar to those of
verapamil. Inhibits calcium ion influx through slow channels into cell of myocardial and
arterial smooth muscle (both coronary and peripheral blood vessels). As a result, intracellular
calcium remains at subthreshold levels insufficient to stimulate cell excitation and
contraction. Slows SA and AV node conduction (antiarrhythmic effect) without affecting
normal arterial action potential or Interventricular conduction.
Indications:
1. Vasospastic angina (Prinzmetal's variant or at rest angina).
2. chronic stable (classic effort-associated) angina
3. Essential hypertension
4. Atrial fibrillation
5. atrial flutter.
6. supraventricular tachycardia.
Contraindications: Known hypersensitivity to drug; sick sinus syndrome (unless pacemaker
is in place and functioning); second- or third-degree AV block; severe hypotension (systolic
<90 mm Hg or diastolic <60 mm Hg); patients undergoing intracranial surgery; bleeding
aneurysms. Safe use during pregnancy (category C), lactation, or in children is not
established.
Route & Dosage:
1. Angina
Adult: PO 30 mg q.i.d., may increase q1–2d as required (usual range: 180–360 mg/d
in divided doses).
2. Hypertension
Adult: PO 60–120 mg sustained-release b.i.d. (usual range: 240–360 mg/d) or 120–
540 mg of CD or LA once daily.
3. Atrial Fibrillation
Adult: IV 0.25 mg/kg IV bolus over 2 min, if inadequate response, may repeat in 15
min with 0.35 mg/kg, followed by a continuous infusion of 5–10 mg/h (max: 15 mg/h
for 24 h).

7. Side effects:
CNS: Headache, fatigue, dizziness, asthenia, drowsiness, nervousness, insomnia, confusion,
tremor, gait abnormality.
CV: Edema, arrhythmias, angina, second- or third-degree AV block, bradycardia,
CHF: flushing, hypotension, syncope, palpitations.
GI: Nausea, constipation, anorexia, vomiting, diarrhoea, impaired taste, weight increase.
Skin: Rash.
Drug interactions: cimetidine may increase diltiazem levels, thus increasing effects.
Nursing implications:
1. Check BP and ECG before initiation of therapy and monitor particularly during
dosage adjustment period.
2. Lab tests: Do baseline and periodic liver and renal function tests.
3. Monitor for and report S&S of CHF.
4. Monitor for headache. An analgesic may be required.
5. Supervise ambulation as indicated.