PROCAINAMIDE HYDROCHLORIDE

(proe-kane-a'mide)

Procanbid, Pronestyl, Pronestyl SR
Classifications: antiarrhythmic, class ia;
Therapeutic: antiarrhythmic, class ia
Pregnancy Category: C

Availability

250 mg, 375 mg, 500 mg tablets, capsules; 250 mg, 500 mg, 750 mg, 1000 mg sustained release tablets; 100 mg/mL, 500 mg/mL injection

Action

Class IA antiarrhythmic agent. Depresses excitability of myocardium to electrical stimulation, reduces conduction velocity in atria, ventricles, and His-Purkinje system. Increases duration of refractory period, especially in the atria.

Therapeutic Effect

Effectively used for atrial arrhythmias; produces slight change in contractility of cardiac muscle and cardiac output; suppresses automaticity of His-Purkinje ventricular muscle. Produces peripheral vasodilation and hypotension, especially with IV use.

Uses

Prophylactically to maintain normal sinus rhythm following conversion of atrial flutter or fibrillation by other methods; to prevent recurrence of paroxysmal atrial fibrillation and tachycardia, paroxysmal AV junctional rhythm, ventricular tachycardia, ventricular and atrial premature contractions. Also cardiac arrhythmias associated with surgery and anesthesia.

Unlabeled Uses

Malignant hyperthermia.

Contraindications

Myasthenia gravis; hypersensitivity to procainamide or procaine; blood dyscrasias; bundle branch block; complete AV block, second and third degree AV block unassisted by pacemaker; QT prolongation; pregnancy (category C).

Cautious Use

Patient who has undergone electrical conversion to sinus rhythm; bone marrow suppression; hypotension, cardiac enlargement, CHF, MI, coronary occlusion, ventricular dysrhythmia from digitalis intoxication; hepatic or renal insufficiency; electrolyte imbalance; bronchial asthma; history of SLE.

Route & Dosage

Arrhythmias
Adult: PO 50 mg/kg/d in divided doses (b.i.d. for Procanbid); max: 5 g/d IM 0.5–1 g q4–8h until able to take PO IV 100 mg q5min at a rate of 25–50 mg/min until arrhythmia is controlled or 1 g given, then 2–6 mg/min
Child: PO 15–50 mg/kg/d divided q3–6h IM 50 mg/kg/d divided q3–6 until PO tolerated IV 3–6 mg/kg q 10–30 min (max: 100 mg/dose), then 20–80 mcg/kg/min

Renal Impairment
Oral doses Cl_cr 10–50 mL/min: give q6–12h; <10 mL/min: give q8–24h. IV doses Reduce loading dose to 12 mg/kg, then maintenance by 1/3 to 2/3.
Hemodialysis: Give 200 mg supplemental dose post dialysis

Administration

Oral

Give first PO dose at least 4 h after last IV dose
Give oral preparation on empty stomach, 1 h before or 2 h after meals, with a full glass of water to enhance absorption. If drug causes gastric distress, give with food.
Crush immediate release (but NOT sustained release) tablet if patient is unable to swallow it whole.
Swallow sustained release tablet whole. It has a wax matrix that is not absorbed but appears in the stool.

Intramuscular

Assess procainamide blood levels if more than three IM injections are required.

Intravenous

Use IV route for emergency situations.

PREPARE: Direct: When given direct IV, dilute each 100 mg with 5–10 mL of D5W or sterile water for injection. IV Infusion: When given by IV infusion, add 1 g of procainamide to 250–500 mL of D5W solution to yield 4 mg/mL in 250 mL or 2 mg/mL in 500 mL.

ADMINISTER: Direct: Usual rate 20 mg/min. Faster rates (up to 50 mg/min) should be used with caution. IV Infusion for Adult: 2–6 mg/min. IV Infusion for Child: 20–80 mcg/kg/min.

INCOMPATIBILITIES Solution/additive: Bretylium, esmolol, ethacrynate, milrinone, phenytoin. Y-site: Inamrinone (amrinone), milrinone.

Control IV administration over several hours by assessment of procainamide plasma levels.
Use an infusion pump with constant monitoring. Keep patient in supine position. Be alert to signs of too rapid administration of drug (speed shock: irregular pulse, tight feeling in chest, flushed face, headache, loss of consciousness, shock, cardiac arrest).

Store solution for up to 24 h at room temperature and for 7 d under refrigeration at 2°–8° C (36°–46° F). Slight yellowing does not alter drug potency, but discard solution if it is markedly discolored or precipitated.

Adverse Effects (≥1%)

CNS: Dizziness, psychosis. CV: Severe hypotension, pericarditis, ventricular fibrillation, AV block, tachycardia, flushing. GI: Bitter taste, nausea, vomiting, diarrhea, anorexia, (all mostly PO). Hematologic: Agranulocytosis with repeated use; thrombocytopenia. Body as a Whole: Fever, muscle and joint pain, angioneurotic edema, myalgia, SLE-like syndrome (50% of patients on large doses for 1 y): Polyarthralgias, pleuritic pain, pleural effusion. Skin: Maculopapular rash, pruritus. erythema, skin rash.

Diagnostic Test Interference

Procainamide increases the plasma levels of alkaline phosphatase, bilirubin, lactic dehydrogenase and AST. It may also alter results of the edrophonium test.

Interactions

Drug: Other antiarrhythmics add to therapeutic and toxic effects; anticholinergic agents compound anticholinergic effects; antihypertensives add to hypotensive effects; cimetidine may increase levels with increase in toxicity.

Pharmacokinetics

Absorption: 75–95% from GI tract. Peak: 15–60 min IM; 30–60 min PO. Duration: 3 h; 8 h with sustained release. Distribution: Distributed to CSF, liver, spleen, kidney, brain, and heart; crosses placenta; distributed into breast milk. Metabolism: In liver to N-acetylprocainamide (NAPA), an active metabolite (30–60% metabolized to NAPA). Elimination: In urine. Half-Life: 3 h procainamide, 6 h NAPA.

Nursing Implications

Assessment & Drug Effects

Check apical radial pulses before each dose during period of adjustment to the oral route.
Patients with severe heart, liver, or kidney disease and hypotension are at particular risk for adverse effects.
Monitor the patient's ECG and BP continuously during IV drug administration.
Discontinue IV drug temporarily when (1) arrhythmia is interrupted, (2) severe toxic effects are present, (3) QRS complex is excessively widened (greater than 50%), (4) PR interval is prolonged, or (5) BP drops 15 mm Hg or more. Obtain rhythm strip and notify physician.
Ventricular dysrhythmias are usually abolished within a few minutes after IV dose and within an hour after PO or IM administration.
Report promptly complaints of chest pain, dyspnea, and anxiety. Digitalization may have preceded procainamide in patients with atrial arrhythmias. Cardiotonic glycosides may induce sufficient increase in atrial contraction to dislodge atrial mural emboli, with subsequent pulmonary embolism.
Therapeutic procainamide blood levels are reached in approximately 24 h if kidney function is normal but are delayed in presence of renal impairment.

Patient & Family Education

Keep a record of weekly weight. Notify physician if weight gain of 1 kg (2 lb) or more is accompanied by local edema.
Record and report date, time, and duration of fibrillation episodes when taking maintenance doses: Light-headedness, giddiness, weakness, or faintness.
Keep a record of pulse rates. Report to physician changes in rate or quality.
Report to physician signs of reduced procainamide control: Weakness, irregular pulse, unexplained fatigability, anxiety.
Do not double dose or change an interval because a previous dose was missed. Take procainamide at evenly spaced intervals around the clock unless otherwise prescribed.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

(217)