Antiarrhythmic drugs according to the pathology

2021-01-28 12:00 AM

There are also some anti-arrhythmic drugs that have not yet been officially classified in the Vaughan-Williams group. It's digital and ATP.

Define

Cardiac arrhythmias are disturbances in the bioelectric activity of the heart in three ways:

Pulse formation.

Conduction impulse.

Coordinate both sides.

Classify

Antiarrhythmic drugs are divided into 4 groups according to the classification of Vaughan-William.

Group I: Membrane stabilizing effect means inhibiting the rapid sodium flow across the cell membrane at depolarization. In this group are divided into 3 subgroups:

Group Ia: Leading by quinidine, which has an anaesthetic effect on the membrane, prolongs the period of effective inertness and electrodynamic potential. The drug has an inhibitory effect on heart contractions.

Group Ib: Has a milder membrane anaesthetic effect. On the contrary, it has the effect of shortening the effective inert period and the kinetic potential. Less inhibition of heart contraction. Represented by Xylocaine.

Group Ic: There are 2 effects above but not change in the period of inertness and electrodynamic potential. The representative is flecainide.

Group II: A drug that inhibits the beta sympathetic receptors and reduces the concentration of catecholamine. Has an inhibitory effect on heart contractions. At the top is propranolol. This group has 2 subgroups: the cardiac selective group and the non-selective cardiac group, in which there are drugs with intrinsic sympathomimetic effects and drugs without intrinsic sympathomimetic effects.

Group III: Led by amiodarone. Has the effect of prolonging the period of inertness and the kinetic potential through inhibition of potassium channels out of the cell. Less reduces heart contraction.

Group IV: Group that inhibits calcium channels slowly entering the cell. Inhibits both automatic transmission and transmission. Reduces heart contraction. The team leader is verapamil.

There are also some anti-arrhythmic drugs that have not yet been officially classified in the Vaughan-Williams group. It's digital and ATP.

Major antiarrhythmic drugs

Quinidine:

Vaughan-Williams Ia group, currently rarely used because of many side effects. Dosage: quinidine sulfate for children 30-60mg / kg / day in 4 divided doses; Adults: 300-600mg / day in 4 divided doses. The slow-acting type has a similar total dose.

Excreted: Through the liver.

DRUG INTERACTIONS: Amiodarone, cimetidine, verapamil increase the concentration of quinidine in the blood. Phenytoin, phenobarbital, rifampicin reduce the concentration of quinidine in the blood. Quinidine also increased digital concentrations by about 50%, as well as increased the effects of warfarin.

Toxicity: Anorexia, vomiting, nausea. Arrhythmia about 15% in adults including torsion and syncope.

Disopyramide:

Vaughan-Williams Group Ia Dose: Adults 300-1000mg / kg / day, divided into 4 doses. Excretion: 50% by the kidneys and 50% by the liver.

Drug Interactions: atenolol, erythromycin increase disopyramide concentrations. Increased effects of warfarin and toxicity of lidocaine.

Side effects: dry mouth, urinary retention, blurred vision, constipation, severe heart failure by reducing heart contraction, arrhythmia.

Lidocaine (Xylocaine):

N wit of Vaughan-Williams Ib.

Dose: Attack dose by intravenous route 0.5-1.0 mg / kg / time. Can be repeated after 5-10 minutes when the results are available, the maximum dose is 5 mg/kg. Maintenance dose: 20-50microg / kg/min, reduce dose if using the drug for more than 24 hours.

Excreted: Through the liver.

DRUG INTERACTIONS: Beta inhibitors, cimetidine increase lidocaine concentrations. Phenytoin, phenobarbital, rapamycin and isoproterenol decrease the concentration. Increased toxicity of lidocaine when used in combination disopyramide.

Side effects: Mainly on the nervous systems such as convulsions, paresthesia, loss of sensation and respiratory arrest.

Flecainide:

Belongs to group Ic.

Dosage: Adults take 200-400mg / day. Excretion: 50% in the liver and 50% in the kidney.

DRUG INTERACTIONS: Amiodarone, cimetidine increase drug concentration in blood. Propranolol increases both concentrations in the blood. Increase digital concentration by about 50%.

Side effects: The neurological manifestations such as tremor, headache, paresthesia, decrease with dose reduction. Reduce heart contraction should not be used in case of heart failure. Has an arrhythmic effect if used in patients with damage to the heart muscle?

Propranolol:

N wit of Vaughan-Williams II.

Dosage: U tube 2-5mg / kg / day divided into 4 times. Intravenously 0.1-0.2mg / kg / dose for 5 minutes. Can be repeated every 6 hours.

Excreted: Through the liver.

DRUG INTERACTIONS: Cimetidine, furosemide, quinidine increase drug concentration. Phenytoin, phenobarbital, rifampicin reduces the concentration in the blood.

Side effects Slow the heart rate, increases heart block, increases heart failure, bronchospasm, increases blood sugar, can depression, impotence.

Amiodarone:

N wit of Vaughan-Williams III.

Dose: attack in adults 10 mg/kg 2 times/day for 10 days, then reduce maintenance dose by 5 mg/kg/day for 2 months and then reduce to half the dose.

DRUG INTERACTIONS: Amiodarone increases the effects of warfarin by about 100%, digoxin 70%, quinidine 33% and procainamide 50%. The drug increases the concentration of flecainide, phenytoin. Has a synergistic effect with beta-blockers and calcium blockers, so this combination should not be used in case of heart failure.

Side effects: very few. May cause pneumonia, eye conjunctival deposition, liver, thyroid dysfunction, tanning if long-term treatment.

Adenosine:

The drug is not in the Vaughan-Willams subgroup but has a good anti-arrhythmic effect, so the author recommends it in group VI. (Digital is recommended in group V).

Dosage: rapid intravenous injection dose of 50-250microg / kg. Can be repeated after 5-15 minutes.

Excretion: Extremely short effects, just under 10 seconds.

DRUG INTERACTIONS: Dipyridamole, diazepam increase adenosine concentration. Theophylline and quinidine lower drug concentrations. Adenosine can have a synergistic effect with verapamil.

Side effects: Shortness of breath, chest pain, vomiting, but rapid relief.

Treatment

Antiarrhythmic drugs Ia: Often used to treat supraventricular arrhythmias.

Drug group Ib: Use only for ventricular arrhythmias.

Drugs of group Ic: For the treatment of ventricular arrhythmias only.

Class II drugs: Mainly used for supraventricular arrhythmias in patients with pre-stimulation syndrome and sometimes used in combination with group Ia drugs to treat patients with atrial fibrillation or atrial flutter. Poor use in ventricular arrhythmias.

Class III drugs: Good effects both on failure and failure. Often used when using group, I alone or in combination but fail.

Adenosine: Very good at cutting paroxysmal supraventricular tachycardia.