Brand Name
Procan SR, Promine, Pronestyl, Pronestyl-SR
Class and Category
Chemical class: Ethyl benzamide monohydrochloride
Therapeutic class: Antiarrhythmic
Pregnancy category: C
Indications and Dosages
To treat life-threatening ventricular arrhythmias
CAPSULES, TABLETS
Adults. 50 mg/kg daily in 8 divided doses (every 3 hr), adjusted as needed
and tolerated. Maximum: 6 g daily (maintenance).
Children. 12.5 mg/kg q.i.d.
E.R. TABLETS
Adults. Maintenance: 50 mg/kg
daily in divided doses q.i.d. (every 6 hr), adjusted as needed and tolerated. Maximum:
6 g daily (maintenance).
I.V. INFUSION OR INJECTION
Adults. Initial: 100 mg diluted in D5W and given
at no more than 50 mg/min. Repeated every 5 min until arrhythmia is controlled
or maximum total dose of 1 g is reached. Or, 10 to 15 mg/kg I.V. bolus given at
25 to 50 mg/min. Maintenance: 1 to 4 mg/min by continuous infusion.
I.M. INJECTION
Adults. 50 mg/kg daily in divided doses every 3 to 6 hr.
To treat ventricular extrasystoles and arrhythmias
associated with anesthesia and surgery
I.V. INFUSION OR INJECTION
Adults. Initial: 100 mg diluted in D5W and given
at no more than 50 mg/min. Dosage repeated every 5 min until arrhythmia is
controlled or maximum total dose of 1 g is reached. Or, 10 to 15 mg/kg I.V.
bolus given at 25 to 50 mg/min. Maintenance: 1 to 4 mg/min by continuous
infusion.
I.M. INJECTION
Adults. 100 to 500 mg every 3 to 6 hr.
DOSAGE ADJUSTMENT
For elderly patients or those with cardiac or hepatic
insufficiency, dosage possibly reduced or dosing intervals increased. For
patients with creatinine clearance less than 50 ml/min/1.73 m2, initial dosage
reduced to 1 to 2 mg/min.
Route Onset
Peak Duration
P.O. Unknown
Unknown 60– 90 min
P.O. Unknown
60–90 Unknown
I.V. Unknown
Immediate Unknown
I.M. 10–30
min 15–60 min Unknown
Mechanism of Action
Prolongs recovery period after myocardial repolarization by
inhibiting sodium influx through myocardial cell membranes. This action
prolongs refractory period, causing myocardial automaticity, excitability, and conduction
velocity to decline.
Contraindications
Complete heart block, hypersensitivity to procainamide or its
components, systemic lupus erythematosus, torsades de pointes
Interactions
DRUGS
antiarrhythmics: Additive cardiac effects
anticholinergics, antidyskinetics, antihistamines: Possibly
intensified atropine-like adverse effects, increased risk of ileus
antihypertensives: Additive hypotensive effects
antimyasthenics: Possibly antagonized effect of
antimyasthenic on skeletal muscle
bethanechol: Possibly antagonized cholinergic effect of
bethanechol
bone marrow depressants: Possibly increased leukopenic or
thrombocytopenic effects
bretylium: Possibly decreased inotropic effect of
bretylium and enhanced hypotension
neuromuscular blockers: Possibly increased or prolonged
neuromuscular blockade
pimozide: Possibly prolonged QT interval, leading to
life-threatening arrhythmias
Adverse Reactions
CNS: Chills, disorientation, dizziness, lightheadedness
CV: Heart block (second-degree), hypotension, pericarditis, prolonged
QT interval, tachycardia
EENT: Bitter taste
GI: Abdominal distress, anorexia, diarrhea, nausea, vomiting
HEME: Agranulocytosis, neutropenia, thrombocytopenia
MS: Arthralgia, myalgia
RESP: Pleural effusion
SKIN: Pruritus, rash
Other: Drug-induced fever
Nursing Considerations
• Place patient in a supine position before giving procainamide
I.M. or I.V. to minimize hypotensive effects.Monitor blood pressure often and
ECG tracings continuously during administration and for 30 minutes afterward.
• Inspect parenteral solution for particles and discoloration
before giving drug; discard if particles are present or solution is darker than
light amber.
•When possible, give drug by I.V. infusion or injection, as
prescribed, rather than by I.M. injection.
• If drug is to be given I.M. and patient’s platelet count is
below 50,000/mm3, notify prescriber at once because patient may develop
bleeding, bruising, or hematomas from procainamide-induced bone marrow suppression
and thrombocytopenia. Expect to give procainamide I.V.
• For I.V. injection, dilute procainamide with D5W according to
manufacturer’s instructions before administration.
• For I.V. infusion, dilute 200 to 1,000 mg of procainamide to a
concentration of 2 or 4 mg/ml using 50 to 500 ml of D5W.
• Administer I.V. infusion with an infusion pump or other
controlled-delivery device.
• Don’t exceed 500 mg in 30 minutes by I.V. infusion or 50 mg/min
by I.V. injection because heart block or cardiac arrest may occur.
• Anticipate that patient has reached maximum clinical response
when ventricular tachycardia resolves, hypotension develops, or QRS complex is
50% wider than original width.
• Expect to give first oral dose 3 to 4 hours after last I.V. dose.
PATIENT
TEACHING
•
Instruct patient to swallow E.R. procainamide tablets whole, without breaking, crushing,
or chewing them.
•
If patient has trouble swallowing, tell her to crush regular-release tablets or
open capsules and mix contents with food or fluid.
•
Instruct patient to take drug 1 hour before or 2 hours after meals with a full
glass of water. Inform her that she may take drug with food if GI irritation
develops.
•
Urge patient to obtain needed dental work before therapy starts or after blood
count returns to normal because drug can cause myelosuppression and increased
risk of bleeding and infection. Encourage good oral hygiene during therapy, and
urge patient to consult prescriber before having dental procedures.
•
Advise patient to notify prescriber immediately about bruising, chills,
diarrhea, fever, or rash.
