Ch 26 Antidysrhythmic Drugs.pdf

Ch 26: An)dysrhythmic drugs • Classes: indica,on, contraindica,ons, adverse effects, drug interac,ons, nursing implica,ons, pa,ent teaching Class 1a Drugs: Mechanism of Ac.on: Membrane-stabilizing drugs as they possess local anaesthe,c proper,es. They work by stabilizing the membrane and have depre...

Ch 26: An)dysrhythmic drugs • Classes: indica,on, contraindica,ons, adverse effects, drug interac,ons, nursing implica,ons, pa,ent teaching Class 1a Drugs: Mechanism of Ac.on: Membrane-stabilizing drugs as they possess local anaesthe,c proper,es. They work by stabilizing the membrane and have depressant effects on phase 0 of the ac,on poten,al. Drugs in 1a include procainamide, quinidine, and disopyramide. Indica.on for use of Class 1a Drugs: Atrial fibrilla,on, premature atrial contrac,ons, premature ventricular contrac,ons, ventricular tachycardia, Wolff-Parkinson-White syndrome. Adverse Effects: Procainamide: Hypotension, rash, diarrhea, nausea, vomi,ng, agranulocytosis, SLE-like syndrome Quinidine: Hypotension, QT prolonga,on, light-headedness, diarrhea, biOer taste, anorexia, blurred vision, ,nnitus, angina Drug Interac.ons: Class 1b Drugs: Mechanism of Ac.on: Share similar characteris,cs to class 1a drugs but act preferen,ally on ischemic myocardial ,ssue and liOle effects on conduc,on velocity in normal ,ssue. These drugs have weak depressive effect in phase 0 depolariza,on, the APD, and the ERP. Drugs in 1b include lidocaine hydrochloride and phenytoin. Indica.on for use of Class 1b Drugs: Ventricular dysrhythmias only (premature ventricular contrac,ons, ventricular tachycardia, ventricular fibrilla,on) Adverse Effects: Lidocaine Hydrochloride: Bradycardia, dysrhythmia, hypotension, anxiety, metallic taste Drug Interac.ons: Nursing Implica.ons: With lidocaine, vials of clear solu,on are labelled as either for cardiac use or not for cardiac use. This is important to remember when reading the vial’s label so that the wrong drug is not given. It is also important to remember that lidocaine solu,ons need to be used with extreme cau,on and that it is the plain solu,on that is used to treat various cardiac condi,ons. Parenteral solu,ons of these drugs are usually stable for only 24 hours. Lidocaine is also used as an anaesthe,c, so the different concentra,ons of the drug need to be double-checked, if not triplechecked. In addi,on, lidocaine comes in a solu,on with epinephrine, a potent vasoconstrictor. This combined solu,on is indicated when the surgeon or physician is suturing or repairing wounds, with the lidocaine ac,ng as an anaesthe,c and the epinephrine causing vasoconstric,on of the local blood vessels and helping to control bleeding of the area, or in dental or oral situa,ons. The solu,on with epinephrine must never be used intravenously, but only as a topical anaesthe,c. With lidocaine, document vital signs prior to ini,a,on of and during therapy, and closely monitor the ECG. O\en, when pa,ents are receiving this drug, they are in a cardiac step-down unit, telemetry unit, or intensive care se]ng. Class 1c Drugs: Mechanism of Ac.on: They produce a more pronounced blockage of the sodium channel than class 1a and 1b but have liOle effects on repolariza,on or the APD. Drugs in this class significantly slow conduc,on in the atria, AV node and ventricles. Because of their marked effects on conduc,on, they strongly suppress PVCs, reducing or elimina,ng them. Drugs in this class include flecainide acetate and propafenone hydrochloride. Indica.on for use of Class 1c Drugs: Ventricular tachycardia and supraventricular tachycardia dysrhythmias, atrial fibrilla,on, and fluOer; Wolff-Parkinson-White syndrome. Adverse Effects: Flecainide Acetate: Dizziness, visual disturbances, dyspnea, palpita,ons, nausea, vomi,ng, diarrhea, weakness Propafenone Hydrochloride: Prodysrhythmic effect, angina, tachycardia, syncope, AV block, dizziness, fa,gue, dyspnea Drug Interac.ons: Class 2 Drugs: Mechanism of Ac.on: These are beta blockers; they work by blocking the sympathe,c nervous system s,mula,on to the heart and the hearts conduc,on system. This prevents catecholaminemediated ac,ons on the heart. The results of class 2 drugs include decreased heart rate, delayed AV node conduc,ons, reduced myocardial contrac,lity and decreased myocardial automa,city. Drugs in this class specifically for an,dysrhythmic include acebutolol hydrochloride, esmolol, metoprolol, propranolol hydrochloride and sotalol Sotalol has class 3 proper,es along with class 2. *Saved by the suffix: -olol Indica.on for use of Class 2 Drugs: Both supraventricular and ventricular dysrhythmias (act as a general myocardial depressants). Adverse Effects: β-blockers: Bradycardia, hypotension, dizziness, fa,gue, AV block, heart failure, hyperglycemia, mask the symptoms of hypoglycemia, bronchospasm, wheezing, dry mouth, erec,le dysfunc,on. Class 3 Drugs: Mechanism of Ac.on: These increase the APD by prolonging repolariza,on in phase 3. The primary role of potassium channels in cardiac ac,on poten,als is cell repolariza,on; these drugs are also referred to as calcium channel blockers. They affect fast ,ssue and are most used to manage dysrhythmias that are difficult to treat and use for those where other therapies have failed Drugs In this class include amiodarone, dronedarone hydrochloride and sotalol. Indica.on for use of Class 3 Drugs: Life-threatening ventricular tachycardia or fibrilla,on. Atrial fibrilla,on or fluOer resistant to other drugs. Adverse Effects: Amiodarone Hydrochloride: Pulmonary toxicity, thyroid disorders, bradycardia, hypotension, SA node dysfunc,on, AV block, ataxia, QT prolonga,on, torsades de pointes, vomi,ng, cons,pa,on, photosensi,vity, abnormal liver func,on test results, jaundice, visual disturbances, hyperglycemia or hypoglycemia, and dermatologic reac,ons including rash, toxic epidermal necrolysis, vasculi,s, blue–grey colouring of the skin (face, arms, neck) Ibu,lide Fumarate: Nonsustained ventricular tachycardia, ventricular extrasystoles, tachycardia, hypotension, AV block, headache, nausea Sotalol Hydrochloride: Bradycardia, chest pain, palpita,ons, fa,gue, dizziness, lightheadedness, weakness, dyspnea Drug Interac.ons: Class 4 Drugs Mechanism of Ac.on: They are calcium channel blockers; these drugs are also useful for those with hypertension and angina. The drugs in this class work on preven,ng the ventricles from bea,ng as fast as the atria. They do this by blocking and slowing the inward flow of calcium ions into the slow calcium channels in cardiac conduc,on ,ssues. Drugs in this class 4 include dil,azem hydrochloride and verapamil hydrochloride. Indica.on for use of Class 4 Drugs: Paroxysmal supraventricular tachycardia; rate control for atrial fibrilla,on and fluOer. Adverse Effects: Calcium channel blockers: Cons,pa,on, bradycardia, heart block, hypotension, dizziness, dyspnea Drug Interac.ons: Nursing Implica.ons: Beta blockers, dil,azem, and verapamil may all be used to manage abnormal rhythms and are to be given only a\er checking and documen,ng pulse rates and blood pressures. Contact the health care provider and withhold the drug—if supported by facility policy and the health care provider’s guidelines—if the pulse rate is 60 beats per minute or lower or 100 beats per minute or higher or if the systolic blood pressure is 90 mm Hg or lower. Unclassified An)dysrhythmic Mechanism of Ac.on: It works by slowing the electrical conduc,on ,me through the AV node and is indicated for the conversion of paroxysmal supraventricular tachycardia to sinus rhythm, especially when it has failed to respond to the medica,on verapamil. Other uses include coexis,ng condi,ons such as heart failure, hypotension, or le\ ventricular dysfunc,on which limits the use of verapamil. Because of its short life of 10 seconds, it is only be administered IV rapidly, as it can commonly cause asystole. If given in the parenteral form, the pa,ent must have heart monitoring. Drugs in this class include adenosine. Nursing Implica.ons: Amiodarone may lead to GI upset, which may be pre- vented or decreased by taking the drug with a meal or a snack. Photosensi,vity (sunburn and other exaggerated skin reac,ons to the sunlight) and photophobia (light sensi,vity) are other concerns with this drug. With photosensi,vity, protec,ve clothing, a hat, and sunscreen are needed. Emphasize the importance of eye protec,on, such as with sunglasses or ,nted contact lenses, to pa,ents taking this medica,on. Encourage consump,on of fluids and a high-fibre diet to minimize the cons,pa,on that is a common adverse effect of an,dysrhythmic drugs. When beta blockers are used with an an,dysrhythmic, any shortness of breath, weight gain, changes in baseline blood glucose levels, or excessive fa,gue must be reported to the health care provider immediately. General General An.dysrhythmic Contraindica.on: Drug allergy to a specific product. Other contraindica,ons may include second- or third-degree AV block, bundle branch block, cardiogenic shock, sick sinus syndrome, or any other major ECG changes General An.dysrhythmic Nursing Implica.ons: When antidysrhythmics are administered, monitor vital signs, especially pulse rate and blood pressure, before administering the drug; if pulse rate is lower than 60 beats per minute, notify the health care provider. During the initiation of therapy, closely monitor the ECG and vital signs because of possible prolongation of the QT interval by more than 50%. The result may be the occurrence of a variety of conduction disturbances. Advise patients that oral dosage forms are better tolerated if taken with food and fluids to help minimize GI upset, unless otherwise ordered. During treatment with quinidine (or with any of the antidysrhythmics), immediately report to the health care provider any patient report of angina, hypotension, lightheaded- ness, loss of appetite, tinnitus, or diarrhea. An infusion pump is recommended for intravenous dosing of any of the classes of antidysrhythmics, with proper solution and dilution. Pa.ent Teaching: