If combined with adrenergic stimulating drugs used for treating asthma, for example, albuterol (Proventil, Ventolin) or pirbuterol (Maxair), the adrenergic blocking effects of labetalol may counteract the effects of the stimulating drugs and reduce their effectiveness for treating asthmatic attacks. More of the adrenergic drug may be needed.
Glutethimide (Doriden) may decrease the effectiveness of labetalol by increasing its elimination. When both drugs are used together, more labetalol or less glutethimide may be needed.
Cimetidine (Tagamet) may increase the effectiveness of labetalol by blocking its elimination and increasing its levels in the blood. Therefore, less labetalol may be needed when cimetidine and labetalol are used together.
Halothane anesthesia may contribute to the blood pressure lowering effects of labetalol.
PREGNANCY: There are no adequate studies of labetalol during pregnancy.
NURSING MOTHERS: Labetalol is excreted in human breast milk. Therefore, it should be used cautiously in nursing mothers because of the risk that the infant may develop a slow heart rate.
Medically reviewed by Eni Williams, PharmD
Reference: FDA Prescribing Information
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