Fosphenytoin Sodium and Procainamide Hydrochloride

• Generic Name: fosphenytoin
• Dosage Forms: n.a.
• Other Brand Names: Cerebyx

Treatment of generalized tonic-clonic status epilepticus.

Benzodiazepines (e.g., diazepam, lorazepam, midazolam) are considered drugs of choice for initial treatment of status epilepticus; IV fosphenytoin (or phenytoin) may be used as a second-line agent if seizures continue.

IV fosphenytoin appears to be better tolerated than IV phenytoin (e.g., fewer adverse cardiovascular effects), and some experts state that fosphenytoin is preferred when both agents are available.

Compared with IV phenytoin, IV fosphenytoin sodium is associated with fewer infusion site reactions (e.g., erythema, pain, burning, swelling, pruritus, soft tissue damage, phlebitis, necrosis) and less frequent need for infusion rate reduction, infusion interruption, and/or changes of infusion sites, but is associated with a higher incidence of systemic sensory disturbances (e.g., burning, paresthesia, pruritus).

Prevention and treatment of seizures occurring during neurosurgery.

May be used as a short-term parenteral replacement for oral phenytoin; because of risks associated with parenteral administration, manufacturer states fosphenytoin should only be used when oral phenytoin not possible.

• Generic Name: procainamide
• Dosage Forms: n.a.
• Other Brand Names: Pronestyl, Procan SR, Pronestyl-SR, Procanbid

Comparably effective to quinidine for atrial or ventricular arrhythmias; choice based on pharmacokinetics and adverse effect profile.

Treatment of ventricular arrhythmias (e.g., sustained VT) that in the judgment of the clinician are life-threatening, but usually not the antiarrhythmic of first choice.

Not a first-line drug of choice during cardiac arrest, but may be used for treatment of wide-complex tachycardias in the periarrest period; included in current ACLS treatment guidelines for adult and pediatric tachycardia.

May be used in the treatment of sustained, stable monomorphic VT not associated with angina, pulmonary edema, or hypotension (BP <90 mm Hg) in patients with preserved ventricular function.

Some experts recommend revascularization and β-blockade followed by IV antiarrhythmic drugs, such as procainamide or amiodarone, for patients with recurrent or incessant polymorphic VT due to acute myocardial ischemia.

Because of procainamide's arrhythmogenic potential, lack of evidence for improved survival for class I antiarrhythmic agents, and risk of serious, potentially fatal adverse hematologic effects (see Boxed Warning), particularly leukopenia or agranulocytosis, use for less severe arrhythmias not recommended.

Reserve for suppression and prevention of documented life-threatening ventricular arrhythmias in carefully selected patients in whom the benefits of procainamide therapy outweigh the possible risks.

Avoid treatment of asymptomatic VPCs.

Initiate procainamide therapy only in a hospital setting.

Has been used for treatment of various supraventricular tachycardias (SVTs); because of higher risk of toxicity and proarrhythmic effects, antiarrhythmic agents generally reserved for patients who do not respond to or cannot be treated with AV nodal blocking agents (β-adrenergic blocking agents, verapamil, diltiazem).

May be useful in patients with preexcited atrial fibrillation and rapid ventricular response associated with Wolff-Parkinson-White syndrome; however, direct-current cardioversion is treatment of choice when patient is hemodynamically compromised.

Also has been used for treatment of junctional tachycardia; however, more limited role and generally considered only when IV β-adrenergic blocking agents are ineffective.

Used parenterally (preferably IM) in the treatment of arrhythmias that occur during surgery and anesthesia.

IV procainamide has been used effectively in the treatment of malignant hyperthermia.