Drug General Information (ID: DDI9PUF86E)
  Drug Name Fexofenadine Drug Info Letermovir Drug Info
  Drug Type Small molecule Small molecule
  Therapeutic Class Antiallergic Agents Antiviral Agents
  Structure

 Mechanism of Fexofenadine-Letermovir Interaction (Severity Level: Moderate)
     Transporter inhibition Click to Show/Hide Mechanism Graph
Could Not Find 2D Structure
      Drug Name Fexofenadine Letermovir
      Mechanism 1 OATP1B1 substrate OATP1B1 inhibitor
      Key Mechanism Factor 1
Factor Name Liver organic anion transporter 1
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Structure Sequence
MDQNQHLNKTAEAQPSENKKTRYCNGLKMFLAALSLSFIAKTLGAIIMKSSIIHIERRFEISSSLVGFIDGSFEIGNLLVIVFVSYFGSKLHRPKLIGIGCFIMGIGGVLTALPHFFMGYYRYSKETNINSSENSTSTLSTCLINQILSLNRASPEIVGKGCLKESGSYMWIYVFMGNMLRGIGETPIVPLGLSYIDDFAKEGHSSLYLGILNAIAMIGPIIGFTLGSLFSKMYVDIGYVDLSTIRITPTDSRWVGAWWLNFLVSGLFSIISSIPFFFLPQTPNKPQKERKASLSLHVLETNDEKDQTANLTNQGKNITKNVTGFFQSFKSILTNPLYVMFVLLTLLQVSSYIGAFTYVFKYVEQQYGQPSSKANILLGVITIPIFASGMFLGGYIIKKFKLNTVGIAKFSCFTAVMSLSFYLLYFFILCENKSVAGLTMTYDGNNPVTSHRDVPLSYCNSDCNCDESQWEPVCGNNGITYISPCLAGCKSSSGNKKPIVFYNCSCLEVTGLQNRNYSAHLGECPRDDACTRKFYFFVAIQVLNLFFSALGGTSHVMLIVKIVQPELKSLALGFHSMVIRALGGILAPIYFGALIDTTCIKWSTNNCGTRGSCRTYNSTSFSRVYLGLSSMLRVSSLVLYIILIYAMKKKYQEKDINASENGSVMDEANLESLNKNKHFVPSAGADSETHC
Gene Name OATP1B1
Uniprot ID SO1B1_HUMAN
KEGG Pathway hsa:10599
Protein Family Organo anion transporter (TC 2.A.60) family
Protein Function
Mediates the Na(+)-independent uptake of organic anions such as pravastatin, taurocholate, methotrexate, dehydroepiandrosterone sulfate, 17-beta-glucuronosyl estradiol, estrone sulfate, prostaglandin E2, thromboxane B2, leukotriene C3, leukotriene E4, thyroxine and triiodothyronine. Involved in the clearance of bile acids and organic anions from the liver.
    Click to Show/Hide
      Mechanism Description
  • Decreased clearance of Fexofenadine due to the transporter inhibition by Letermovir 
      Mechanism 2 OATP1B3 substrate OATP1B3 inhibitor
      Key Mechanism Factor 2
Factor Name Liver organic anion transporter 2
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Structure Sequence
MDQHQHLNKTAESASSEKKKTRRCNGFKMFLAALSFSYIAKALGGIIMKISITQIERRFDISSSLAGLIDGSFEIGNLLVIVFVSYFGSKLHRPKLIGIGCLLMGTGSILTSLPHFFMGYYRYSKETHINPSENSTSSLSTCLINQTLSFNGTSPEIVEKDCVKESGSHMWIYVFMGNMLRGIGETPIVPLGISYIDDFAKEGHSSLYLGSLNAIGMIGPVIGFALGSLFAKMYVDIGYVDLSTIRITPKDSRWVGAWWLGFLVSGLFSIISSIPFFFLPKNPNKPQKERKISLSLHVLKTNDDRNQTANLTNQGKNVTKNVTGFFQSLKSILTNPLYVIFLLLTLLQVSSFIGSFTYVFKYMEQQYGQSASHANFLLGIITIPTVATGMFLGGFIIKKFKLSLVGIAKFSFLTSMISFLFQLLYFPLICESKSVAGLTLTYDGNNSVASHVDVPLSYCNSECNCDESQWEPVCGNNGITYLSPCLAGCKSSSGIKKHTVFYNCSCVEVTGLQNRNYSAHLGECPRDNTCTRKFFIYVAIQVINSLFSATGGTTFILLTVKIVQPELKALAMGFQSMVIRTLGGILAPIYFGALIDKTCMKWSTNSCGAQGACRIYNSVFFGRVYLGLSIALRFPALVLYIVFIFAMKKKFQGKDTKASDNERKVMDEANLEFLNNGEHFVPSAGTDSKTCNLDMQDNAAAN
Gene Name OATP1B3
Uniprot ID SO1B3_HUMAN
KEGG Pathway hsa:28234
Protein Family Organo anion transporter (TC 2.A.60) family
Protein Function
Mediates the Na(+)-independent uptake of organic anions such as 17-beta-glucuronosyl estradiol, taurocholate, triiodothyronine (T3), leukotriene C4, dehydroepiandrosterone sulfate (DHEAS), methotrexate and sulfobromophthalein (BSP). Involved in the clearance of bile acids and organic anions from the liver.
    Click to Show/Hide
      Mechanism Description
  • Decreased clearance of Fexofenadine due to the transporter inhibition by Letermovir 

Recommended Action
      Management Caution is advised when letermovir is used concurrently with drugs that are substrates of CYP450 2C8, CYP450 3A4, and/or OATP 1B1 and 1B3, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever letermovir is added to or withdrawn from therapy. Moreover, clinicians should be aware that the magnitude of CYP450 3A- and OATP1B1/3-mediated drug interactions with coadministered drugs may be different when letermovir is used with cyclosporine. The combined effect of the two drugs on CYP450 3A4 may be similar to that of a strong CYP450 3A4 inhibitor, hence clinicians should refer to the prescribing information for dosing recommendations of the CYP450 3A4 substrate with a strong CYP450 3A4 inhibitor. Similarly, letermovir and cyclosporine may demonstrate some additive effects on OATP1B1 inhibition, although cyclosporine by itself is already a strong OATP1B1/3 inhibitor.

References
1 Product Information. Prevymis (letermovir). Merck & Company Inc, Whitehouse Station, NJ.