Drug Interactions of OTC Antihistamines (Part 2):

Drug Interactions of Second Generation Antihistamines:

More presentations from Naina Mohamed Pakkir Maideen

·      Second generation OTC Antihistamines include Loratadine, Cetirizine and Fexofenadine.

·      Amiodarone may elevate the risk of “Torsades de pointes” by blocking CYP3A4 induced metabolism of Loratadine.

·      P-glycoprotein (P-gp) inhibitors such as Tocofersolan, Nilotinib, Lomitapide and Simeprevir block the P-glycoprotein-mediated efflux transport of Fexofenadine and increase the plasma levels of Fexofenadine.

·      Amiodarone also increase the plasma levels of Fexofenadine by blocking CYP enzymes induced metabolism and P-glycoprotein efflux transport of Fexofenadine.

·      Fruit Juices like Grapefruit juice, Orange juice and Apple juice decrease the effectiveness of fexofenadine by inhibiting organic anion transporting polypeptide (OATP).

·       Patients should thoroughly read the labels of all over-the-counter and prescription medicines.

·      Patients should talk to their doctor or pharmacist before taking any new prescription or over the counter medication.

·      Physicians should be aware of potential drug interactions with OTC medicines when prescribing new medications.

·      Pharmacists can be instrumental in assisting patients with using OTC medications safely and effectively.

·      Pharmacists should warn consumers of the risks of misusing OTC pain relievers.