Propafenone and a syndrome of the lupus erythematosus type

Diagnosis and classification of drug-induced autoimmunity (DIA)

Since sulfadiazine associated lupus-like symptoms were first described in 1945, certain drugs have been reported to interfere with the immune system and induce a series of autoimmune diseases (named drug-induced autoimmunity, DIA), exemplified by systemic lupus erythematosus (SLE). Among the drugs, procainamide and hydralazine are considered to be associated with the highest risk for developing lupus, while quinidine has a moderate risk, and all other drugs have low or very low risk. More recently, drug-induced lupus has been associated with the use of newer biological modulators, such as tumor necrosis factor (TNF)-alpha inhibitors and cytokines. In addition to lupus, other major autoimmune diseases, including vasculitis and arthritis, have also been associated with drugs. Because resolution of symptoms generally occurs after cessation of the offending drugs, early diagnosis is crucial for treatment strategy and improvement of prognosis. Unfortunately, it is difficult to establish standardized criteria for DIA diagnosis. Diagnosis of DIA requires identification of a temporal relationship between drug administration and the onset of symptoms, but the relative risk with respect to dose and duration for each drug has rarely been determined. DIA is affected by multiple genetic and environmental factors, leading to difficulties in establishing a list of global clinical features that are characteristic of most or all DIA patients. Moreover, the distinction between authentic DIA and unmasking of a latent autoimmune disease also poses challenges. In this review, we summarize the highly variable clinical features and laboratory findings of DIA, with an emphasis on the diagnostic criteria.

Adverse dermatologic effects of cardiovascular drug therapy: part I

Cardiovascular disease is common, affecting an increasing number of persons as the population ages. To combat this growing health problem, physicians use a multitude of medications in the treatment of their patients. Although pharmacologic therapy greatly enhances quality of life for a majority of patients, there is always the potential for an unfavorable reaction. For example, cardiovascular drugs can induce a vast array of adverse dermatologic responses. This article reviews the various cutaneous reaction patterns that can occur as a result of treatment with Class I and II antiarrhythmic agents.

Propafenone-induced peripheral neuropathy

Propafenone hydrochloride, a class IC antiarrhythmic drug, is used in the treatment of ventricular and supraventricular arrhythmias. Herein we describe a patient with episodic jabbing and crushing pain in his hands and feet, aching in his forearms, and hyperesthesias of his extremities. He had been taking propafenone for 1 year because of ventricular arrhythmias. Results of a nerve conduction velocity test were abnormal. Electron microscopic findings on a sural nerve biopsy specimen represented distal small fiber neuropathy. Findings on a thermoregulatory sweat test and on autonomic tests were abnormal, compatible with a distal small fiber neuropathy. To our knowledge, peripheral neuropathy has not previously been reported to occur with use of propafenone. In this patient, propafenone seemed to be responsible for the development of peripheral neuropathy, which resolved after use of the drug had been discontinued.

Adverse dermatologic reactions from antiarrhythmic drug therapy

Undesirable cutaneous reactions to drugs may occur early or late in the course of treatment. The ingestion of drugs may also aggravate existing dermatologic conditions. The adverse dermatologic reactions from antiarrhythmic drug therapy are reviewed. The exact incidence of dermatologic side effects from cardiovascular drugs has been difficult to estimate because of sporadic reporting. In this review, the cutaneous side effects are discussed according to drug class and the type of dermatologic reaction.

Propafenone. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in the treatment of arrhythmias

Propafenone is a Class I antiarrhythmic agent with weak beta-adrenoceptor antagonist activity which can be given both intravenously and orally. Dosage must be individualised because of dose-dependent pharmacokinetics, a wide range of clinically effective plasma concentrations (64 to 3271 micrograms/L) after comparable doses, the presence of an active metabolite (5-hydroxy-propafenone) and genetically determined metabolic oxidation. In non-comparative studies propafenone 450 and 900 mg/day orally significantly suppressed premature ventricular complexes and couplets in 96% and 75% of patients, respectively, and abolished ventricular tachycardia in 75% of patients. Efficacy was confirmed in placebo-controlled studies in which propafenone 300 to 900mg daily suppressed premature ventricular complexes (greater than 80%) in 77% of patients; 87% of patients had significant reductions in couplets and abolition of ventricular tachycardia. In patients with ventricular arrhythmias refractory to other antiarrhythmic agents, propafenone 450 to 1200 mg/day suppressed arrhythmias in 63% of patients (in long term therapy 66%). Electrically induced arrhythmias were prevented by intravenously administered propafenone in 12 to 23% of patients. However, long term oral therapy was effective in 77% of patients selected using programmed electrical stimulation. Propafenone was also effective in suppressing atrial and AV nodal/junctional re-entrant tachycardias and Wolff-Parkinson-White tachycardias involving accessory pathways. A limited number of comparisons with other antiarrhythmic drugs indicate that the antiarrhythmic efficacy of propafenone is superior or similar to that of quinidine, disopyramide and tocainide, and comparable to that of lignocaine (lidocaine), flecainide and metoprolol against ventricular arrhythmias and a smaller number of atrial arrhythmias. Cardiovascular side effects indicate a proarrhythmic effect similar to that with other Class I drugs, occasional precipitation of congestive heart failure and conduction abnormalities; the latter two occur more often in patients with underlying ventricular dysfunction. Non-cardiovascular side effects (neurological, gastrointestinal) are well tolerated and generally resolve with continued therapy or dosage reduction. Thus, propafenone is an effective antiarrhythmic agent, and is a useful addition to currently available drugs, although further studies will be required to determine clearly its place in therapy compared with more established antiarrhythmic drugs.