The FDA has required the manufacturer of the secondgeneration antipsychotic quetiapine (Seroquel) to add a warning to the labeling saying that use of the drug should be avoided in combination with other drugs that prolong the electrocardiographic QTc interval (Table 1). The warning is based only on postmarketing reports of QT-interval prolongation in patients who overdosed on the drug, had concomitant illness, or were taking other drugs known to cause electrolyte imbalances or increase the QT interval. QT prolongation can lead to torsades de pointes, a potentially fatal cardiac...

Propafenone (Rythmol - Knoll), a class IC antiarrhythmic drug used in Europe for treatment of various arrhythmias for more than 10 years, was recently marketed in the USA for oral treatment of life-threatening ventricular arrhythmias such as sustained ventricular tachycardia. This restrictive labeling reflects concerns arising from the interim report of the Cardiac Arrhythmia Suppression Trial, in which post-myocardial infarction patients with asymptomatic or mildly symptomatic ventricular arrhythmias treated with the class IC antiarrhythmic drugs encainide (Enkaid) or flecainide...

Flecainide (Tambocor -3M Pharmaceuticals), first introduced in 1985 for treatment of ventricular arrhythmias, was recently approved by the US Food and Drug Administration for oral use to prevent supraventricular arrhythmias. The indications for using flecainide to treat ventricular arrhythmias were limited after a controlled trial found that post-myocardial infarction patients with asymptomatic ventricular arrhythmias who took the drug had twice as high a mortality rate as patients who took placebo (DS Echt et al, N Engl Med, 324:781, 1991).

Moricizine (mor i'; siz een) hydrochloride (Ethmozine - Du Pont), a class I antiarrhythmic drug developed in the USSR, was recently approved by the US Food and Drug Administration (FDA) for oral treatment of life-threatening ventricular arrhythmias.

Sotalol (hydrochloride (Betapace -Berlex; Sotacor -Bristol Laboratories of Canada), an antiarrhythmic drug that prolongs repolarization (Class III) and also has beta-adrenergic-blocking activity (Class II), was recently approved by the US Food and Drug Administration (FDA) for oral treatment of life-threatening ventricular arrhythmias.

Recently pharmaceutical manufacturers have marketed a stereoisomer of a successful drug nearing patent expiration as a new drug. Examples, such as esomeprazole (Nexium) , levalbuterol (Xopenex), escitalopram (Lexapro) and dexmethylphenidate

Older patients are especially susceptible to drug-induced cognitive impairment. They are more likely to be taking multiple drugs, to have higher blood levels of those drugs because of renal or hepatic dysfunction, and to have pre-existing cognitive problems that make it difficult to detect the role of drugs causing new symptoms or making old ones worse.

Dronedarone (Multaq - Sanofi-Aventis) has been approved by the FDA for oral treatment of atrial fibrillation and flutter. Amiodarone (Cordarone, and others) is the most effective drug for this indication, but has considerable toxicity.

As the weather becomes warmer, physicians may see more photosensitivity reactions due to systemic or topical drugs, perfumes, cosmetics or sunscreens. Even brief exposure to sunlight in warm or cold weather can cause intense cutaneous reactions in patients with drug-induced photosensitivity, and some patients may continue to be sensitive to sunlight long after stopping use of the offending agent.

The drugs of choice for treatment of common cardiac arrhythmias are listed in Tables 1 and 2. Some drugs are recommended for indications that have not been approved by the FDA.