Tag: Calcium Channel Blockers

Calcium Channel Blockers

CALCIUM CHANNEL BLOCKERS

Q. 1 A patient is admitted to the emergency department for evaluation  of an abnormal ECG. Overdose  of an antiarrhythmic drug is considered. Which  of  the  following  drugs  is correctly  paired with its ECG effects?
 A Quinidine:  increased  PR  and  decreased  QT intervals
 B Flecainide:   increased   PR,   QRS,   and   QT intervals
 C Verapamil: increased PR interval
 D Lidocaine: decreased QRS and PR interval
Q. 1 A patient is admitted to the emergency department for evaluation  of an abnormal ECG. Overdose  of an antiarrhythmic drug is considered. Which  of  the  following  drugs  is correctly  paired with its ECG effects?
 A Quinidine:  increased  PR  and  decreased  QT intervals
 B Flecainide:   increased   PR,   QRS,   and   QT intervals
 C Verapamil: increased PR interval
 D Lidocaine: decreased QRS and PR interval
Ans. C

Explanation:

All the associations  listed are incorrect except verapamil. This class IV drug increases PR interval.


Q. 2

Which one of the following drugs causes constipation?

 A

Proranolol

 B

Verapamil

 C

Nitroglycerin

 D

Captopril

Q. 2

Which one of the following drugs causes constipation?

 A

Proranolol

 B

Verapamil

 C

Nitroglycerin

 D

Captopril

Ans. B

Explanation:

Verapamil causes more constipation than other calcium channel blockers. Other common side effects include dizziness, and nausea, hypotension and headache.

Ref: Essentials of Pharmacology By K D Tripathi, 5th Edtion, Page 495.


Q. 3

Which of the following drugs cause relaxation of LES?

1. Nitrates
2. Histamine blockers
3. Morphine
4. Atropine
5. Calcium channel blockers

 

 A

1,2 & 3

 B

1,4 & 5

 C

1,2 & 5

 D

All

Q. 3

Which of the following drugs cause relaxation of LES?

1. Nitrates
2. Histamine blockers
3. Morphine
4. Atropine
5. Calcium channel blockers

 

 A

1,2 & 3

 B

1,4 & 5

 C

1,2 & 5

 D

All

Ans. B

Explanation:

Factor causing relaxation of LES Factor increasing LES pressure
  • Pharmacological agents:nitrates, anticholinergics, barbiturates, calcium channel blockers, caffeine, theophylline, diazepam, dopamine, prostaglandin E1 and E2 and meperidine
  • Pepperdine
  • Chocolate
  • Coffee
  • Alcohol
  • Smoking
  • Fat
  • Antacids
  • Cholinergics
  • Domperidone
  • Metoclopramide
  • Prostaglandin F2

Also know: LES pressure is higher in the supine position than in the upright position.

Ref: Schwarz 9/e, Page 812; Harrison 17/e, Page 1741.

Quiz In Between


Q. 4

Drug of choice for Supraventricular tachycardia is:

 A

Verapamil

 B

Diltiazem

 C

Digoxin

 D

Phenytoin

Q. 4

Drug of choice for Supraventricular tachycardia is:

 A

Verapamil

 B

Diltiazem

 C

Digoxin

 D

Phenytoin

Ans. A

Explanation:

Drugs used in the management of SVT (act by slowing or blocking AV nodal conduction):

  • Adenosine (1st choice)
  • Beta blockers (2nd choice)
  • Calcium channel blocker( verapamil)
  • Diltiazem
  • Esmolol
  • Digoxin
  • Amiodarone
Adenosine and betablockers are the first and second choice drugs used for SVT respectively. Though diltiazem and digoxin are used in SVT, verapamil is used more frequently than those drugs. So verapamil is the single best answer of choice by exclusion.
 
Ref: Harrison’s Principles of Internal Medicine, 16th Edition, Pages 1347, 1349; Manual of Practical Medicine By R Alagappan, 3rd Edition, Pages 114, 116

Q. 5

Preferred drugs in clinical situations associated with hypertensive emergencies:

a) Nitroprusside is preferred in aortic dissection
b) Phentolamine is the first choice in adrenergic crisis
c) Hydralazine is preferred in eclampsia
d) Nitroglycerin is best in acute left ventricular failure
e) Nicardipine in case of cerebrovascular accidents
 

 A

All true

 B

c,d,e-True & a,b-false

 C

a,e-True & b,c,d-False

 D

a,b,d, e-True & c-False

Q. 5

Preferred drugs in clinical situations associated with hypertensive emergencies:

a) Nitroprusside is preferred in aortic dissection
b) Phentolamine is the first choice in adrenergic crisis
c) Hydralazine is preferred in eclampsia
d) Nitroglycerin is best in acute left ventricular failure
e) Nicardipine in case of cerebrovascular accidents
 

 A

All true

 B

c,d,e-True & a,b-false

 C

a,e-True & b,c,d-False

 D

a,b,d, e-True & c-False

Ans. A

Explanation:

Nitroprusside is prefered in aortic dissection, Phentolamine in aortic crisis, Hydralazine in eclampsia, nitroglycerine in hypertension associated with LV Failure and nicardipine in CVA

Ref: Harrisons, Edition18 , Page – 2058

 


Q. 6

CYP3A inhibitors is/are –

 A

Ritonavir

 B

Amiodarone

 C

Verapamil

 D

a and c

Q. 6

CYP3A inhibitors is/are –

 A

Ritonavir

 B

Amiodarone

 C

Verapamil

 D

a and c

Ans. D

Explanation:

Ans. is ‘a’ i.e., Ritonavir; ‘c’ i.e., Verapamil

CYP3A4/3A5 inhibitors are

o Ritonavir                   o Erythromycin         o Itraconazole       o Troieandomycin o Verapamil

o Clarithromycin          o Azamulin              o Diltiazem           o Ketoconazole

o Grapefruit juice (Furano coumarins)

Quiz In Between


Q. 7

Which of the following calcium channel blocker would be useful in the treatment of supra-ventricular tachycardia by suppressing AV node conduction ‑

 A

Amlodipine

 B

Nimodipine

 C

Verapamil

 D

Nifedipine

Q. 7

Which of the following calcium channel blocker would be useful in the treatment of supra-ventricular tachycardia by suppressing AV node conduction ‑

 A

Amlodipine

 B

Nimodipine

 C

Verapamil

 D

Nifedipine

Ans. C

Explanation:

Ans. is ‘c’ i.e., Verapamil

o Amongst calcium channel blockers, verapamil has the most prominent cardiac electrophysiological action.
o CCBs primarily act on SA node and AV node (slow channel – Ca+2 channel action potential) →↓ automaticity in SA node and decreased conduction in AV node.


Q. 8

The drug of choice for rapid correction of PSVT in known asthmatic is –

 A

Adenosine

 B

Esmolol

 C

Neostigmine

 D

Verapamil

Q. 8

The drug of choice for rapid correction of PSVT in known asthmatic is –

 A

Adenosine

 B

Esmolol

 C

Neostigmine

 D

Verapamil

Ans. D

Explanation:

Ans. is ‘d’ i.e., Verapamil

o You know that
1st choice drug for PSVT —› Adenosine
2nd choice drugs for PSVT –> CCBs or β-blockers
o However, adenosine may precipitate bronchospasm in asthmatics, so not preferred in asthmatics.
o β-blockers can also cause bronchoconstriction by inhibiting β-receptor mediated bronchodilatation.
o So, we are left only with CCBs (verapamil)


Q. 9

Which is true about calcium channel blockers –

 A

Verapamil causes reflex tachycardia

 B

Diltiazam causes reflex tachycardia

 C

Nifedipine causes reflex tachycardia

 D

Nifedipine has longer t1/2 than felodipine

Q. 9

Which is true about calcium channel blockers –

 A

Verapamil causes reflex tachycardia

 B

Diltiazam causes reflex tachycardia

 C

Nifedipine causes reflex tachycardia

 D

Nifedipine has longer t1/2 than felodipine

Ans. C

Explanation:

Ans. is ‘c’ i.e., Nifedipine causes reflex tachycardia

o DHPs (nifedipine) cause reflex tachycardia.
o Felodipine – it differs from nifedipine in having greater vascular selectivity, large tissue distribution and longer 0/2.

Quiz In Between


Q. 10

Which of the following is a cerebro selective calcium channel blocker?

 A

Nimodipine

 B

Ziconotide

 C

Verapamil

 D

Diltiazem

Q. 10

Which of the following is a cerebro selective calcium channel blocker?

 A

Nimodipine

 B

Ziconotide

 C

Verapamil

 D

Diltiazem

Ans. A

Explanation:

Ans. is ‘a’ i.e., Nimodipine

o Nimodipine is cerebroselective and is used as an anticonvulsant and calcium channel blocker of choice in subarachnoid hemorrhage.


Q. 11

Verapamil acts by –

 A

Blocking membrane depolarisation

 B

Calcium channel blockers

 C

Membrane stabilising

 D

Blocking membrane repolarisation

Q. 11

Verapamil acts by –

 A

Blocking membrane depolarisation

 B

Calcium channel blockers

 C

Membrane stabilising

 D

Blocking membrane repolarisation

Ans. B

Explanation:

Ans. is ‘b’ i.e., Calcium channel blocker

o Calcium channel blockers delay the recovery of `L’ type calcium channel from inactivated state to resting state —> depression of pacemaker activity and conduction – negative ionotropic, chronotropic and dromotropic effect.

o Amongst CCBs, recovery of Ca’ channel is delayed maximally by verapamil and to a lesser extent diltiazem.

o DHPs do not delay the recovery – no negative chronotropic, ionotropic or bathantotropic effect, infact short acting DHPs like nifedipine can cause tachycardia and paradoxically increase the frequency of angina short acting DHPs should not be used in angina.


Q. 12

Calcium Channel blocker with maximum effect on conduction in heart is –

 A

Nifedipine

 B

Diltiazem

 C

Verapamil

 D

Phenylamine

Q. 12

Calcium Channel blocker with maximum effect on conduction in heart is –

 A

Nifedipine

 B

Diltiazem

 C

Verapamil

 D

Phenylamine

Ans. C

Explanation:

Ans. is ‘c’ i.e., Verapamil

Quiz In Between


Q. 13

Which is true about calcium channel blockers –

 A

Verapamil causes reflex tachycardia

 B

Diltiazam causes reflex tachycardia

 C

Nifedipine causes reflex tachycardia

 D

Nifedipine has longer t1/2 than felodipine

Q. 13

Which is true about calcium channel blockers –

 A

Verapamil causes reflex tachycardia

 B

Diltiazam causes reflex tachycardia

 C

Nifedipine causes reflex tachycardia

 D

Nifedipine has longer t1/2 than felodipine

Ans. C

Explanation:

Ans. is ‘c’ i.e., Nifedipine causes reflex tachycardia

DHPs (nifedipine) cause reflex tachycardia.

o Felodipine – it differs from nifedipine in having greater vascular selectivity, large tissue distribution and longer t1/2.


Q. 14

Racemic mixture of two enantiomers with different pharmaeokinetic and pharmacodynamic properties is seen in –

 A

Dilantin

 B

Digoxin

 C

Verapamil

 D

Octreotide

Q. 14

Racemic mixture of two enantiomers with different pharmaeokinetic and pharmacodynamic properties is seen in –

 A

Dilantin

 B

Digoxin

 C

Verapamil

 D

Octreotide

Ans. C

Explanation:

Ans. is ‘c’ i.e., Verapamil

” Verapamil is prescribed as a racemate, L-Verapamil is a more potent calcium channel blocker than is d­verapamil. However with oral therapy, the 1-enantiomer undergoes more extensive first – pass hepatic metabolism. For this reason, a given concentration of verapamil prolongs the PR interval to a greater extent when the drug is administered intravenously (where concentrations of the 1-and d-enantiomers are equivalent) than when it is administered orally.”


Q. 15

Which of the following is a cerebro selective calcium channel blocker?

 A

Nimodipine

 B

Ziconotide

 C

Verapamil

 D

Diltiazem

Q. 15

Which of the following is a cerebro selective calcium channel blocker?

 A

Nimodipine

 B

Ziconotide

 C

Verapamil

 D

Diltiazem

Ans. A

Explanation:

Ans. is ‘a’ i.e., Nimodipine

o Nimodipine is cerebroselective and is used as an anticonvulsant and calcium channel blocker of choice in subarachnoid hemorrhage.

Quiz In Between


Q. 16

Verapamil is used in all, except –

 A

Angina pectoris

 B

Atrial fibrillation

 C

Ventricular tachycardia

 D

None of the above

Q. 16

Verapamil is used in all, except –

 A

Angina pectoris

 B

Atrial fibrillation

 C

Ventricular tachycardia

 D

None of the above

Ans. C

Explanation:

Ans. is ‘c’ i.e., Ventricular tachycardia

Use of Verapamil as an antiarrhythmic

  1. PSVT ‑
  2. To control ventricular rate in Atrial flutter or Atrial fibrillation (May be used as an alternative to or in addition to Digitalis).

Verapamil is contraindicated in following arrhythmias

1.Ventricular arrhythmias — Injection of verapamil has precipitated ventricular fibrillation, therefore contraindicated.

2.Digitalis toxicity – Verapamil is contraindicated in Digitalis toxicity because additive A-V block may occur.

Heart block and sick sinus.


Q. 17

Verapamil is contraindicated in all, except

 A

PSVT with AV Block

 B

Variant angina

 C

Beta adrenergic toxicity

 D

Digitalis toxicity

Q. 17

Verapamil is contraindicated in all, except

 A

PSVT with AV Block

 B

Variant angina

 C

Beta adrenergic toxicity

 D

Digitalis toxicity

Ans. B

Explanation:

Ans. is ‘b’ i.e., Variant angina

“All CCBs are effective in reducing frequency and severity of classical as well as variant angina”.

Due to these cardiodepressant effects, it is C/I in the following conditions.

           Sick sinus syndrome (causes cardiac arrest)

           A- V block (Accentuate conduction defects)

           Congestive heart failure

           Hypotensive states

           Ventricular tachycardias

           AF with accessory pathway or WPW syndrome.

o Other conditions in which Verapamil is C/I.

           Digoxin toxicity —> Increases plasma digoxin level by decreasing its excretion, toxicity can develop.

           Quinidine and disopyramide —> Both these drugs have cardiac depressant action.

Verapamil is not used with β blockers because their depressant effect on SA and AV node may add up.

β


Q. 18

Calcium channel blockers are used in all, except –

 A

Angina

 B

Supraventricular tachycardia

 C

Sick sinus syndrome

 D

Hypertension

Q. 18

Calcium channel blockers are used in all, except –

 A

Angina

 B

Supraventricular tachycardia

 C

Sick sinus syndrome

 D

Hypertension

Ans. C

Explanation:

Ans. is ‘c’ i.e., Sick sinus syndrome

o Calcium channel blockers suppress SA node automaticity —> can cause cardiac arrest in sick sinus syndrome.

Quiz In Between


Q. 19

Treatment of stable angina include –

 A

Nitrates

 B

CCBs

 C

Streptokinase

 D

a and b

Q. 19

Treatment of stable angina include –

 A

Nitrates

 B

CCBs

 C

Streptokinase

 D

a and b

Ans. D

Explanation:

Ans. is ‘a’ i.e., Nitrates & ‘b’ i.e., CCBs


Q. 20

Nifedipine and beta-blocker are given together –

 A

To decrease pedal edema due to nifedipine

 B

To overcome increased sympathetic activity of nifedipine

 C

Anti CHF action of propranolol

 D

Antiarrhythmic effect of nifedipine

Q. 20

Nifedipine and beta-blocker are given together –

 A

To decrease pedal edema due to nifedipine

 B

To overcome increased sympathetic activity of nifedipine

 C

Anti CHF action of propranolol

 D

Antiarrhythmic effect of nifedipine

Ans. B

Explanation:

Ans. is ‘b’ i.e., To overcome increased sympathetic activity of Nifedipine

β-Blocker is given along with Nifedipine because

a)         Reflex tachycardia (Increased sympathetic activity) caused due to Nifedipine, is prevented by β-blocker.

b)         β-blockers cause dilatation of coronary arteries by unopposed a-mediated vasoconstriction. Nifedipine causes coronary vasodilatation and opposes the spasm caused by β-blockers.

The tendency of β-blocker to cause ventricular dilatation is counteracted by Nifedipine.


Q. 21

Combination use of beta blockers and calcium channel blockers cause –

 A

Heart block

 B

Hypertension

 C

Hypotension

 D

All

Q. 21

Combination use of beta blockers and calcium channel blockers cause –

 A

Heart block

 B

Hypertension

 C

Hypotension

 D

All

Ans. A

Explanation:

Ans. is ‘a’ i.e., Heart block

o CCBs (verapamil, diltiazem) have negative chronotropic effect (↓ SA node automaticity →↓ heart rate) and negative dromotropic effect (1AV node conduction).

o β-blockers have similar effect by blocking β1 sympathetic receptors on heart (normally stimulation of β1 receptors increases heart rate and conduction).

o Simultaneous use of these drugs can cause marked bradycardia and AV block.

Amongst CCBs, DHPs (nefidipine) can be used with β-blockers because DHPs have no direct negative chronotropic and dromotropic effect, rather they cause tachycardia by reflex sympathetic stimulation.

Quiz In Between


Q. 22

Rebound hypertension is seen with –

 A

Amlodipine

 B

Methyldopa

 C

Clonidine

 D

b and c

Q. 22

Rebound hypertension is seen with –

 A

Amlodipine

 B

Methyldopa

 C

Clonidine

 D

b and c

Ans. D

Explanation:

Ans. is ‘b’ i.e., Methyldopa; ‘c’ i.e., Clonidine

Rebound hypertension

o High blood pressure that is associated with the sudden withdrawl of various antihypertensive medications is called rebound hypertension.

o The increase in blood pressure may result in BP greater than when the medication was initiated.

o Depending on the severity of the increase in BP, rebound hypertension may result in hypertensive emergency.

o Rebound hypertension is avoided by gradually reducing the dose, i.e. “dose tapering”, thereby giving the body enough time to adjust to reduction in dose.

o Medications commonly associated with rebound hypertension include:

i) Centrally acting antihypertensive agents–clonidine, methyldopa (very less frequent than clonidine), moxonidine

ii) 0-blockers

Clonidine is the most common drug associated with rebound hypertension.


Q. 23

Which one of the following drugs causes constipation?

 A

Propranolol

 B

Verapamil

 C

Nitroglycerin

 D

Captopril

Q. 23

Which one of the following drugs causes constipation?

 A

Propranolol

 B

Verapamil

 C

Nitroglycerin

 D

Captopril

Ans. B

Explanation:

Ans. is ‘b’ i.e., Verapamil

Drugs causing constipation :

  • Aluminium Hydroxide
  • Ion exchange resins                
  • Verapamil             
  • Calcium carbonate
  • Barium sulphate              
  • Opiates                                     
  • Ferrous sulphate
  • Ganglionic blockers
  • Phenothiazines               
  • Tricyclic antidepresants

Q. 24

Which of the following is not used in controlling heart rate intraoperatively.

 A

Propanolol/Metoprolol

 B

Verapamil

 C

Esmolol

 D

Procainamide

Q. 24

Which of the following is not used in controlling heart rate intraoperatively.

 A

Propanolol/Metoprolol

 B

Verapamil

 C

Esmolol

 D

Procainamide

Ans. B

Explanation:

B i.e. Verapamil 

Intraoperative administration of intravenous blockers (atenolol, metoprolol, propranolol or esmolol)Q is done to avoid tachycardia during induction of anesthesia.

The onset of paroxysmal atrial tachycardia or fibrillation in perioperative period can be treated by the iv administration of drug that abruptly prolong the refractory period of AV node (adenosine) or lengthen the refractory period of accessory pathways (procainamide)Q Digitalis and verapamil may decrease refractory period of accessory pathways (in pre-excitation syndromes like Wolff-Parkinson-White syndrome) responsible for atrial fibrillation and thereby result in an increase in ventricular response rate during this dysrhythmia and thus should be avoided.

Ventricular tachycardia not a/ w hypotension is initially treated by iv administration of lidocaine, amiodarone or lidocaine, amiodarone or procainamide. Symptomatic VT is best treated by external electrical cardioversion.

Quiz In Between


Q. 25

Drugs which interfere with anesthesia are :

 A

Calcium channel blocker nifedipine

 B

Beta blockers

 C

Aminoglycosides

 D

All

Q. 25

Drugs which interfere with anesthesia are :

 A

Calcium channel blocker nifedipine

 B

Beta blockers

 C

Aminoglycosides

 D

All

Ans. D

Explanation:

A i.e. Calcium channel blockers; B i.e. Beta Blockers; C i.e. Aminoglycoside

Aminoglycoside, Tetracycline & Polypeptide antibioticsQ (Mnemonic ATP) potentiate neuromuscular block

– B Blockers & Calcium channel blockerQ may cause Bradycardia & AV block with anesthesia


Q. 26

Calcium channel blockers in anesthesia, True is :

 A

Needs to be decreased as they augment hypotension & muscle relaxation

 B

Withheld because they lower LES pressure

 C

Should be given in normal doses as they prevent MI & angina

 D

All of the above

Q. 26

Calcium channel blockers in anesthesia, True is :

 A

Needs to be decreased as they augment hypotension & muscle relaxation

 B

Withheld because they lower LES pressure

 C

Should be given in normal doses as they prevent MI & angina

 D

All of the above

Ans. C

Explanation:

C i.e. Should be given in normal dose as they prevent MI & Angina

Calcium channel blockers potentiate neuromuscular-block, cause lowering of muscle tone of lower esophageal sphincter but there is no such indication of stoppage of this drug during anesthesia. CCB’s prevent MI & angina during anesthesia & should be given in normal doses (preoperatively)Q.


Q. 27

Which drug is used for Achalasia cardia-

 A

Nifedipine

 B

Propranolal

 C

Atenolol

 D

Bethnecol

Q. 27

Which drug is used for Achalasia cardia-

 A

Nifedipine

 B

Propranolal

 C

Atenolol

 D

Bethnecol

Ans. A

Explanation:

Ans. is ‘a’ i.e., Nefedipine 

Quiz In Between


Q. 28

A Patient with short PR interval and Delta waves on ECG presents to the emergency department with Atrial Fibrillation and rapid ventricular rate. He is hemodynamically stable. All of the following agents may be used in the management, except:

 A

Verapamil

 B

Procainamide

 C

Ibutilide

 D

Amiodarone

Q. 28

A Patient with short PR interval and Delta waves on ECG presents to the emergency department with Atrial Fibrillation and rapid ventricular rate. He is hemodynamically stable. All of the following agents may be used in the management, except:

 A

Verapamil

 B

Procainamide

 C

Ibutilide

 D

Amiodarone

Ans. A

Explanation:

Answer is A (Verapamil)

AV nodal blocking agents such as Calcium channel blockers, Beta blockers and Digoxin should not be used to treat Atrial Fibrillation in patients with WPW Syndrome. Use of these drugs may result in an acute increase in rate over the Accessory pathway placing the patient at risk for development of VF. Procainamide is the drug of choice for treatment of Atrial Fibrillation in patients with WPW Syndrome who are hemodynamically stable. Ibutilide and Amiodarone are also effective.

Treatment of Hemodynamically Stable Atrial Fibrillation in Patients with WPW Syndrome

  • Procainamide is the drug of choice for treatment of Atrial Fibrillation in patients with WPW Syndrome who are hemodynamically stable.
  • Ibutilide and Amiodarone are also effective.
  • Avoid AV nodal blocking agents such as Calcium channel blockers, Beta blockers and Digoxin

The standard treatment of atrial fibrillation is to slow the ventricular rate with AV nodal blocking agents such as Calcium channel blockers, Beta blockers and Digoxin. In Patients with Pre-excitation (WPW Syndrome) the use of these agents should be avoided (contraindicated). Atrial Fibrillation in patients with WPW Syndrome is typically associated with rapid conduction over the AV node as well as the Accessory Pathway. AV nodal blockers slow down conduction and decrease the number of impulses entering the ventricles anterogradely through the AV node (but may increase the rate of conduction through the accessory pathway). This will reduce the number of impulses bombarding the ventricular end of the bypass tract or accessory pathway rendering the bypass tract less refractory. This may paradoxically increase the rate of conduction through the accessory pathway placing the patient at risk for development of VF.

‘Digoxin appears to shorten the refractory period of the Accessory pathway directly and thus increases the ventricular rate’ – Harrison

‘Verapamil appears to shorten the refractory period of the accessory pathway indirectly by causing vasodilatation and a reflex increase in sympathetic tone’ – Harrison


Q. 29

A patient with traumatic paraplegia due to injury of the thoracic cord of ‘T3 level’ is observed to have a blood pressure of 210/120. What should be the initial management?

 A

Subcutaneous LMWH

 B

Steroids

 C

Nifedipine

 D

Normal saline/Dextrose

Q. 29

A patient with traumatic paraplegia due to injury of the thoracic cord of ‘T3 level’ is observed to have a blood pressure of 210/120. What should be the initial management?

 A

Subcutaneous LMWH

 B

Steroids

 C

Nifedipine

 D

Normal saline/Dextrose

Ans. C

Explanation:

Answer is C (Nifedipine):

Presence of accelerated hypertension with blood pressures in excess of 200/100 mm Hg in a patient with high thoracic spinal cord injury (above T6) suggests a diagnosis of Autonomic Dysreflexia. Urgent management of the hypertensive crisis is paramount to prevent complications such as retinal haemorrhage, seizures, hypertensive encephalopathy or an intracerebral haemorrhage.

Oral Clonidine and/or Nifedipine are the most commonly used pharmacological agents to control hypertensive crisis in patients with autonomic dysreflexia

Autonomic Dysreflexia (AD) (Hypertensive Crisis following Spinal Cord injury above T6)

 

What is Autonomic Dysreflexia

Autonomic Dysretlexia (AD) is a syndrome of sympathetic overactivity that typically affects patient with spinal cord injury above or proximal to the upper thoracic level (T6 or above) due to unopposed sympathetic nervous system impulses.

This is an acute medical emergency that occurs in patients whose spinal cord injury lies above the greater splanchnic outflow from thoracolumbar preganglionic sympathetic neurons (T6 or above). This results from interruption of normal feedback mechanism in the sympathetic pathway.

Patients with spinal cord injury below T8 are rarely affected by this condition                                                                                                            .

When does Autonomic Dysreflexia occur

Autonomic Dysreflexia is traditionally/historically believed to occur 4-6 months after the spinal cord injury

(After the phase of spinal shock resolves)

However recently AD has also been reported in early phases after SCI

How does Autonomic Dysreflexia Present

The most characteristic presentation of AD is sudden increase in Blood Pressure (Accelerated Hypertension) often in excess 200mm Hg systolic and 100 mm Hg diastolic.

It is important to note that normal resting Blood Pressure in patients with spinal cord injury is often 80 to 90 mmHg, and a systolic blood pressure of 130 mm Kg may he an early sign of autonomic dysreflexia

 

Bradvcardia in association with hypertension is another typical feature of AD and this results primarily from vagal compensation. Bradvcardia is however present in only 50% of the cases.

What are the Triggering factors for AD

Autonomic Dysreflexia can be triggered by any painful/noxious stimulus in the clermatomes (skin), muscles or viscera below the level of cord injury.

Bladder Distension is the single most common inciting stimuli

 

Trigger Stimuli / Inciting stimuli for AD

•  Distension of Bladder (Due to obstructed urine outflow from spasm/kinked Foley’s catheter)

•  Bowel impaction (Constipation)

•   Irritation from skin lesions (Dermatomes)

Insect bites, pressure sores, constrictive clothing, localized wounds or ingrowing toe nails

•  Labour and pregnancy

•   Gynecological instrumentation and/or patients with SCI undergoing surgery


What is the treatment of AD

Treatment of Autonomic Dysreflexia

Prevention of Trigger Factors

  • Prevention of Trigger Factors
  • Avoid Bladder Distension (leading cause) (prompt catheterization)
  • Avoid Fecal Impaction (Second leading cause) (Manual evacuation, anal sphincter block, bowel programs)
  • Anti-cholinergic Medicines are recommended

Management of Hypertensive crisis

Management of Hypertensive crisis

  • Patient should be brought in a sitting position with legs dangling to take advantage of natural orthostosis.
  • Pharmacological management with oral/transdermal medicine should be initiated

–  Transdermal Nitroglycerine

–  Oral Clonidine

–  Oral Nifedipine

–  Oral Phenoxybenzamine

– Oral Prazocin

  • Pharmacological management with intravenous medicines may be considered in cases of hypertensive crises or encephalopathy or intraoperative hypertension

–  Nitroprusside

–  Diazoxide

–  Trimethaphan
–  Fenoldopam



Q. 30

Calcium channel blocker causing cerebral vasodilatation is:       

September 2006

 A

Nimodipine

 B

Felodipine

 C

Amlod ipine

 D

Nitrendi pine

Q. 30

Calcium channel blocker causing cerebral vasodilatation is:       

September 2006

 A

Nimodipine

 B

Felodipine

 C

Amlod ipine

 D

Nitrendi pine

Ans. A

Explanation:

Ans. A: Nimodipine

Nimodipine binds specifically to LAN/1)e voltage-gated calcium channels.

Nimodipine penetrates blood-brain barrier very effectively due to high lipid solubility. It effectively relaxes cerebral vasculature; approved for prevention and treatment of neurological deficit due to cerebral vasospasm following subarchnoid hemorrhage or ruptured congenital intracranial aneurysms.

Adverse effects particularly, in high dosage group (90 mg) includes itching, gastrointestinal hemorrhage, thrombocytopenia, neurological deterioration, vomiting, diaphoresis, congestive heart failure, hyponatremia, decreasing platelet count, disseminated intravascular coagulation and deep vein thrombosis.

Quiz In Between


Q. 31

Which of the following calcium channel blocker has a predominant peripheral action:     

September 2006

 A

Verapamil

 B

Diltiazem

 C

Nifidepine

 D

Depranil

Q. 31

Which of the following calcium channel blocker has a predominant peripheral action:     

September 2006

 A

Verapamil

 B

Diltiazem

 C

Nifidepine

 D

Depranil

Ans. C

Explanation:

Ans. C: Nifidepine

Sublingual nifedipine has previously been used in hypertensive emergencies. This was found to be dangerous, and has been abandoned.

Sublingual nifedipine causes blood-pressure lowering through peripheral vasodilation.

It can cause an uncontrollable decrease in blood pressure, reflex tachycardia, and a steal phenomenon in certain vascular beds


Q. 32

Drug of choice for managing asthmatic patient with hypertension:      

March 2009

 A

Timolol

 B

Propranolol

 C

Metoprolol

 D

Amlodipine

Q. 32

Drug of choice for managing asthmatic patient with hypertension:      

March 2009

 A

Timolol

 B

Propranolol

 C

Metoprolol

 D

Amlodipine

Ans. D

Explanation:

Ans. D: Amlodipine

The management of hypertension in a patient with asthma or chronic obstructive pulmonary disease (COPD) may be made difficult by the asthma-inducing effect of some antihypertensives. As an example, beta blockers should be used with great caution or not at all in patients with chronic asthma (including chronic obstructive pulmonary disease) or acute allergic or exercise-induced bronchospasm.

Calcium channel blockers are suitable as first line antihypertensive agent for:

  • Asthma/ COPD patients.
  • Recurrent stroke prevention
  • Elderly with poor arterial wall compliance
  • Isolated systolic hypertension
  • Raynaud’s/PVD patients
  • Pregnant hypertensives
  • Diabetes

Q. 33

A = ACE inhibitor, B = beta blocker, C = calcium channel blocker, D= diuretics. For elderly with hypertension antihypertensive drug of choice is ‑

 A

A or D

 B

A or B

 C

A or C

 D

C or D

Q. 33

A = ACE inhibitor, B = beta blocker, C = calcium channel blocker, D= diuretics. For elderly with hypertension antihypertensive drug of choice is ‑

 A

A or D

 B

A or B

 C

A or C

 D

C or D

Ans. D

Explanation:

Ans. is ‘d’ i.e., C or D

Pharmacological treatment of hypertension

Indications of drug therapy (the British hypertension society guidelines).

When sustained BP exceeds 160/100 mmHg or.

When BP is in the range of 140-159 / 90-99 mmHg and there is target organ damage or cardiovascular disease.

For diabetics when BP exceeds 140/90 mmHg.

The optimal target is to lower BP to or below 140/85 mmHg in nondiabetics and 140/80 mmHg in diabetics (WHO target is 130/85 mmHg).

Drug therapy

A simple stepped AB/CD regimen is used.

Quiz In Between


Q. 34

Patient on verapamil should not be given beta blocker as ‑

 A

Conduction block

 B

Bronchospasm

 C

Neurogenic shock

 D

Anaphylaxis

Q. 34

Patient on verapamil should not be given beta blocker as ‑

 A

Conduction block

 B

Bronchospasm

 C

Neurogenic shock

 D

Anaphylaxis

Ans. A

Explanation:

Ans. is ‘a’ i.e., Conduction block

Adverse effects of CCBs

  • Nausea, constipation and bradycardia are more common with verapamil.
  • Verapamil can accentuate conduction defect-should be avoided in 2nd & 3rd degree block, in sick sinus syndrome and along with 13-blocker.
  • Most common side effects of DHPs are palpitation, flushing, hypotension, headache, ankle edema, drowsiness and nausea.
  • Nifedipine can paradoxically increase the frequency of angina in some patients.
  • Nifedine can cause voiding difficulty in elderly (relaxant effect on bladder) and glucose intolerance (decreases insulin release).

Q. 35

Drug of choice for maintenance therapy in PSVT is

 A

Amiodarone

 B

Lignocaine

 C

Verapamil

 D

Adenosine

Q. 35

Drug of choice for maintenance therapy in PSVT is

 A

Amiodarone

 B

Lignocaine

 C

Verapamil

 D

Adenosine

Ans. C

Explanation:

Ans. is ‘c’ i.e., Verapamil


Q. 36

Verapamil is used in all, except

 A

Angina pectoris

 B

Atrial fibrillation

 C

Ventricular tachycardia 

 D

None of the above

Q. 36

Verapamil is used in all, except

 A

Angina pectoris

 B

Atrial fibrillation

 C

Ventricular tachycardia 

 D

None of the above

Ans. C

Explanation:

Ans. is ‘c’ i.e., Ventricular tachycardia 

  • The electrophysiological properties of Verapamil enables it be used as an antiarrhythmic.

Electrophvsiological effects of verapamil

  • The basic action of verapamil is to depress Cal` mediated depolarization. This result in following actions —
  • Decrease S.A. node automaticity
  • Decrease ventricular automaticity
  • Increase A. V. nodal ERP (This is the most consistent action of Verapamil and due to this A-V conduction is markedly slowed however intraventricular conduction is not slowed).
  • Use of Verapamil as an antiarrhythmic

I. PSVT ‑

  • It is effective in 80% cases
  • It should not be used if PSVT is accompanied with hypotension or CHF.
  • To control ventricular rate in Atrial flutter or Atrial fibrillation (May be used as an alternative to or in addition to Digitalis).
  • Verapamil is contraindicated in following arrhythmias
  • entricular arrhythmias — Injection of verapamil has precipitated ventricular ,fibrillation, therefore contraindicated.
  • Digitalis toxicity – Verapamil is contraindicated in Digitalis toxicity because additive A-V block may occur.
  • Heart block and sick sinus.

Other uses of verapamil:

  • Angina pectoris —All CCB’s are effective in reducing frequency and severity of classical as well as variant angina. It is beneficial in angina in the following way
  • Classical angina Reduces cardiac work, mainly as a result of reduced afterload.

Variant angina Prevent arterial spasm.

  1. Hypertension
  2. Hypertrophic cardiomyopathy
  3. Suppress nocturnal leg cramps
  4. Migraine

Quiz In Between


Q. 37

All are arteriolar dilators except ‑

 A

Hydralazine

 B

Minoxidil

 C

Nitrates

 D

Nifedipine

Q. 37

All are arteriolar dilators except ‑

 A

Hydralazine

 B

Minoxidil

 C

Nitrates

 D

Nifedipine

Ans. C

Explanation:

Ans. is ‘c’ i.e., Nitrates 


Q. 38

Which one of the following drugs causes constipation?

 A

Propranolol

 B

Verapamil

 C

Nitroglycerin

 D

Captopril

Q. 38

Which one of the following drugs causes constipation?

 A

Propranolol

 B

Verapamil

 C

Nitroglycerin

 D

Captopril

Ans. B

Explanation:

Ans. is `b’ i.e., Verapamil 

Drugs causing constipation :

  • Aluminium Hydroxide
  • Ion exchange resins  
  • Verapamil       
  • Calcium carbonate
  • Barium sulphate       
  • Opiates              
  • Ferrous sulphate
  • Ganglionic blockers
  • Phenothiazines
  • Tricyclic antidepresan 

Q. 39

Maximum tachycardia is seen with

 A

Nifedipine

 B

Verapamil

 C

Propanolol

 D

Amlodipine

Q. 39

Maximum tachycardia is seen with

 A

Nifedipine

 B

Verapamil

 C

Propanolol

 D

Amlodipine

Ans. A

Explanation:

Ans. is ‘a’ i.e., Nifedipine 

 


Q. 40

Which is true about calcium channel blockers ‑

 A

Verapamil causes reflex tachycardia

 B

Diltiazam causes reflex tachycardia

 C

Nifedipine causes reflex tachycardia

 D

Nifedipine has longer t’/2 than felodipine

Q. 40

Which is true about calcium channel blockers ‑

 A

Verapamil causes reflex tachycardia

 B

Diltiazam causes reflex tachycardia

 C

Nifedipine causes reflex tachycardia

 D

Nifedipine has longer t’/2 than felodipine

Ans. C

Explanation:

Ans. is ‘c’ i.e., Nifedipine causes reflex tachycardia 

Quiz In Between


Q. 41

Calcium channel blockers are used in all, except‑

 A

Angina

 B

Supraventricular tachycardia

 C

Sick sinus syndrome

 D

Hypertension

Q. 41

Calcium channel blockers are used in all, except‑

 A

Angina

 B

Supraventricular tachycardia

 C

Sick sinus syndrome

 D

Hypertension

Ans. C

Explanation:

Ans. is ‘c’ i.e., Sick sinus syndrome 


Q. 42

Maximum plasma protein bound drug is ‑

 A

NTG

 B

Verapamil

 C

Aspirin

 D

GTN

Q. 42

Maximum plasma protein bound drug is ‑

 A

NTG

 B

Verapamil

 C

Aspirin

 D

GTN

Ans. B

Explanation:

Ans. is ‘b’ i.e., Verapamil


Q. 43

Shortest acting calcium channel blocker ‑

 A

Verapami I

 B

Amlodipine

 C

Nimodipinc

 D

Diltiazam

Q. 43

Shortest acting calcium channel blocker ‑

 A

Verapami I

 B

Amlodipine

 C

Nimodipinc

 D

Diltiazam

Ans. C

Explanation:

Ans. is ‘c’ i.e., Nimodipine

  • Nimodipine is shortest acting CCB. →Katzung 10/1/2 – 191
  • Nimodipine selectively relaxes cerebral vasculature – can be used in subarachnoid haemmorrhage or ruptured congenital intracranial aneurism.
  • Amlodipine is longest acting CCB.
  • Amlodipine has maximum oral bioavailabilitv.
  • Nisoldipine has minimum oral bioavailability.

Quiz In Between



Calcium Channel Blockers

CALCIUM CHANNEL BLOCKERS


CALCIUM CHANNEL BLOCKERS

  • Drugs blocking L-type of voltage-gated calcium channels, present in blood vessels & heart.

Drug groups:

  • Three groups of drugs:
  • Phenylalkylamines – 
    • Verapamil, nor-verapamil.
  • Benzothiazepines – 
    • Diltiazem.
  • Dihydropyridines – 
    • Nifedipine, nicardipine, nimodipine, nisoldipine, nitrendipine, isradipine, lacidipine, felodipine & amlodipine.

Drug actions of CCB’s:

  • Inhibits calcium channels & reduces frequency of Ca+ channels opening –> Results in vasodilation.
  • Smooth muscle relaxation in blood vessels & extravascular organs (bronchus, GIT, urinary bladder, uterus).

CCB’s & cardiac activity:

  • Decreased cardiac activity – 
    • Decreased heart rate, AV conduction & contractility.
  • Little direct cardiac activity:
    • Dihydropyridine (DHP) group.
    • Acts mainly on blood vessels – Hence, called peripherally acting CCBs.
  • Strong direct cardiac activity:
    • Verapamil & diltiazem (verapamil > diltiazem).
    • Strong cardiodepressant activity.

Effect of different CCBs on HR & BP:

Drugs

Blood vessel

BP

Heart rate

Direct action

Reflex action

Net action

Verapamil Vasodilation Decreases BP Strong reduction Increases HR Mild reduction
Diltiazem Vasodilation Decreases BP Mild reduction Increases HR Little reduction
DHP Vasodilation Decreases BP No effect Increases HR Increases HR

General indications of CCB’s:

  • Used in angina (both classical & variant angina)
    • Mainly Verapamil, diltiazem & long acting DHPs.
  • DOC for hypertensive patients with migraine.
    • Eg: Flunarizine (weak CCB) – For prophylaxis of migraine.
  • In hypertensive patients with PVD (peripheral vascular diseases – Raynaud’s phenomena).

General contraindications of CCB’s:

  • In sick sinus syndrome –
    • Because of CCB’s reflex tachycardia.
  • In angina –
    • Precipitates acute attack of angina
    • Accentuates angina symptoms by causing tachycardia (Except short-acting DHPs like nifedipine).
  • In Hyperglycemia (mainly Nifedipine):
    • By decreasing insulin release.
  • CCB’s along with β-blockers.

General adverse effects of CCB’s:

  • Reflex tachycardia:
    • Caused due to vasodilatory action.
    • Mainly by DHP’s drugs.
    • Nifedipine (short half-life) – More marked tachycardia.
    • Amlodipine – Long-acting drugs (maximum half-life) – Less tachycardia.
    • This effect nullified by direct cardiodepressant action (except DHPs).
  • Voiding difficulty in elderly:
    • Due to urinary bladder relaxation.
  • Constipation & ankle edema (particularly verapamil).
  • Increases plasma digoxin concentration –
    • By decreasing its excretion.

Individual drug description:

1. Verapamil:

  • Actions:
    • Maximum cardio-depressant action.
    • Causes vasodilation – By blocking calcium channel.
    • Maximum effect on cardiac conduction.
    • Increases PR interval.
  • Metabolic properties:
    • Maximum plasma protein-bound drug.
    • CYP3A inhibitor.
    • Has racemic mixture of two enantiomers with different pharmacokinetic & pharmacodynamic properties.
  • Indications:
    • Treatment of angina, PSVT, hypertension & hypertrophic obstructive cardiomyopathy (HOCM).

2. Diltiazem:

  • Lesser effect on heart than verapamil.
  • Uses:
    • Same indication as verapamil.
    • Suitable for elderly patients, low renin hypertension cases, asthma, migraine or peripheral vascular disease & isolated systolic hypertensive cases.

3. Dihydropyridine drug group:

  • Safe in pregnancy.

3a.) Nifedipine:

  • Predominant peripheral action.
  • Increases angina risk.
    • Increases heart rate & thus cardiac work.
    • Prevented by sustained-release preparation of nifedipine & amlodipine.
  • Possesses natriuretic property.
  • Interferes with anesthesia.
  • Nifedipine & beta-blocker given together – To overcome nifedipine’s increased sympathetic activity.
  • History:
    • Previously used sublingually for hypertensive emergencies.
    • Banned due to increased risk of MI & mortality.
  • Uses:
    • For Achalasia cardia.

3b.) Nicardipine:

  • Longest acting parenteral CCB.
  • DOC for hypertensive emergencies.
  • Combined with beta blockers to avoid tachycardia.

3c.) Nimodipine:

  • Shortest acting CCB’s
  • Relatively Cerebro-selective vasodilator.
  • Used for reversal of compensatory vasoconstriction after subarachnoid hemorrhage.

3d.) Clevidipine:

  • Ultrashort-acting DHP.
  • Recently approved for hypertensive emergencies.
3e.) Amlodipine:
  • DOC for managing asthmatic patient with hypertension.
  • Rebound hypertension is seen.

Exam Important

CALCIUM CHANNEL BLOCKERS

  • Calcium channel blockers block L-type of voltage-gated calcium channels present in blood vessels & heart. 
  • CCB’s causes vasodilation by inhibits calcium channels & reduces frequency of Ca+ channels opening.
  • CCB’s reduces cardiac activity including heart rate, AV conduction & contractility.
  • Dihydropyridine (DHP) group of CCB drugs are referred to as peripherally acting CCB’s.
  • Strong cardio-depressant activity is mainly exhibited by verapamil & diltiazem (verapamil > diltiazem).
  • CCB’s are indicated for both classical & variant angina, mainly verapamil, diltiazem & long acting DHPs.
  • DOC for hypertensive patients with migraine is calcium channel blocker.
  • Flunarizine is weak CCB used for prophylaxis of migraine.
  • CCB’s are used in hypertensive patients with PVD (Raynaud’s phenomena).
  • CCB’s are contraindicated in sick sinus syndrome, as it causes reflex tachycardia.
  • Short-acting DHPs like nifedipine accentuates angina symptoms, by causing tachycardia & precipitates acute anginal attack.
  • Nifedipine causes hyperglycemia by decreasing insulin release.
  • CCB’s along with β-blockers are contraindicated.
  • Nifedipine shows marked tachycardia.
  • Long-acting CCB’s like Amlodipine will show less tachycardiac effects.
  • CCB’s causes urinary bladder relaxation, resulting in voiding difficulty in elderly.
  • CCB’s increases plasma digoxin concentration, by decreasing its excretion.
  • Verapamil shows maximum cardio-depressant action.
  • Verapamil exhibits maximum effect on cardiac conduction.
  • Verapamil increases PR interval.
  • CCB with maximum plasma protein-bound nature is verapamil.
  • Verapamil has racemic mixture of two enantiomers with different pharmacokinetic & pharmacodynamic properties.
  • Verapamil is used for treatment of angina, PSVT, hypertension & hypertrophic obstructive cardiomyopathy (HOCM).
  • Among CCB’s, dihydropyridine drugs are safer in pregnancy.
  • Nifedipine has predominant peripheral action.
  • Nifedipine by increases angina risk by increasing heart rate & thus cardiac work.
  • Nifedipine interferes with anesthesia.
  • Mostly Nifedipine & beta-blocker are given together, to overcome nifedipine’s increased sympathetic activity.
  • Nifedipine is banned for sublingual usage for hypertensive emergencies, due to increased risk of MI & mortality.
  • Nifedipine is also used for achalasia cardia.
  • Longest acting parenteral CCB is Nicardipine.
  • DOC for hypertensive emergencies is Nicardipine.
  • Nimodipine is shortest acting CCB’s with relatively cerebro-selective vasodilating nature.
  • Nimodipine is used for reversal of compensatory vasoconstriction after subarachnoid hemorrhage.
  • Clevidipine is an ultrashort-acting DHP.
  • Clevidipine is recently approved for hypertensive emergencies.
  • Amlodipine is DOC for managing asthmatic patient with hypertension.
  • Rebound hypertension is seen with Amlodipine.

 

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