The use of antihistamine drug Hismanal (astemizole)

NEWS 10/28/1992 The use of antihistamine drug Hismanal (astemizole)
P92-30                                          Food and Drug Administration
FOR IMMEDIATE RELEASE                           Monica Revelle (301) 443-3285
Oct. 28, 1992                                   Susan Cruzan (301) 443-3285

    The Food and Drug Administration today warned doctors against the use of  
the prescription antihistamine drug Hismanal (astemizole) in combination      
with the anti-fungal drugs ketoconazole or itraconazole or the antibiotic     
drug erythromycin.
    Janssen Pharmaceutica, manufacturer of Hismanal, has agreed to send a     
"Dear Doctor" letter to physicians and other health professionals cautioning  
them about the risk of serious cardiac arrhythmias -- heart rhythm            
abnormalities -- in patients who used any of these drugs with Hismanal.
    Hismanal is a nonsedating antihistamine prescribed for the treatment of   
seasonal allergies and hives.  FDA in July had issued a warning about         
exceeding Hismanal's recommended dose of 10 mg (1 tablet) per day because of  
the increased risk of cardiac arrhythmias.  Hismanal is known to cause        
cardiac arrhythmias when present at excessive levels in the blood.  
    FDA recently received reports of serious arrhythmias in two patients who  
took Hismanal with erythromycin, or erythromycin plus ketoconazole, alerting  
FDA to a possible interaction between Hismanal and these drugs, as a cause    
of arrhythmias.  Subsequently, Janssen submitted preliminary information      
indicating that blood levels of Hismanal are greatly increased in patients    
taking ketoconazole.  Itraconazole, recently approved by FDA, was included
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                                                    Page 2, P92-30, Hismanal
in the warning primarily because of its chemical and pharmacologic            
similarity to ketoconazole.
    FDA issued a similar warning in July for other nonsedating antihistamine  
drug products, Seldane and Seldane-D.
    "Because of the potentially serious nature of these interactions, we      
must be extremely cautious, and we urge doctors and patients to avoid         
combining these drugs," said FDA Commissioner David A. Kessler, M.D.  
    The new labeling for Hismanal includes the following boxed warning:
    "Concomitant administration of astemizole (Hismanal) with ketoconazole    
tablets, itraconazole or erythromycin is contraindicated."
    FDA is one of the eight Public Health Service agencies within HHS.
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