Loratadine drug interactions

Besides, the eompetitive substrates for CYP3A4 do not signifieantly give rise to drug-drug interaction, as could be seen with astemizole and terfenadine, by virtue of the fact that the parent molecule (loratadine) overwhelmingly lacks effect on rectifying channels located in the cardiac tissue. 

Drug/Food interactions Food increased the AUC of loratadine by approximately 40% and the metabolite by approximately 15% absorption was delayed by 1 hour. Although not expected to be clinically important, take on an empty stomach. 

Drugs that inhibit CYP3A4 inhibit the clearance of terfenadine, an antihistamine that can prolong the QTC interval. This can cause potentially dangerous interactions. In a double-blind, placebo-controlled study of the effect of nefazodone (600 mg/day for 1 week) on the pharmacokinetics of terfenadine (120 mg/day for 14 days) and another antihistamine, loratadine (20 mg/day for 14 days), in 67 healthy volunteers, nefazodone significantly reduced the clearance of terfenadine and prolonged the mean QTC interval (27). In addition, nefazodone produced a similar but smaller decrease in the clearance of loratadine and combined treatment also significantly increased the QTC interval. This effect of nefazodone on... 

Healthy subjects were given terfenadine 60 mg every 12 hours for 14 days, with montelukast 10 mg daily from day 8 to day 14. It was found that the terfenadine pharmacokinetics and the QTc interval were unaltered by concurrent use. No adverse interactions were seen in large numbers of patients given montelukast 10 or 20 mg and loratadine 10 mg, and the combination was found to be beneficial in the treatment of allergic rhinitis and conjunctivitis. No special precautions are therefore needed if these drugs are given concurrentiy. 

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