Details of Drug Interaction | MecDDI

Drug General Information (ID: DDILUJWZ64)
Drug Name			Loperamide		Drug Info		Tacrolimus		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Antidiarrheals				Immunosuppressive Agents
Structure

Mechanism of Loperamide-Tacrolimus Interaction (Severity Level: Major)
Transporter inhibition Click to Show/Hide Mechanism Graph

Drug Name		Loperamide				Tacrolimus
Mechanism		P-gp substrate				P-gp inhibitor
Key Mechanism Factor 1
		Factor Name		P-glycoprotein 1				× Structure Sequence MDLEGDRNGGAKKKNFFKLNNKSEKDKKEKKPTVSVFSMFRYSNWLDKLYMVVGTLAAIIHGAGLPLMMLVFGEMTDIFANAGNLEDLMSNITNRSDINDTGFFMNLEEDMTRYAYYYSGIGAGVLVAAYIQVSFWCLAAGRQIHKIRKQFFHAIMRQEIGWFDVHDVGELNTRLTDDVSKINEGIGDKIGMFFQSMATFFTGFIVGFTRGWKLTLVILAISPVLGLSAAVWAKILSSFTDKELLAYAKAGAVAEEVLAAIRTVIAFGGQKKELERYNKNLEEAKRIGIKKAITANISIGAAFLLIYASYALAFWYGTTLVLSGEYSIGQVLTVFFSVLIGAFSVGQASPSIEAFANARGAAYEIFKIIDNKPSIDSYSKSGHKPDNIKGNLEFRNVHFSYPSRKEVKILKGLNLKVQSGQTVALVGNSGCGKSTTVQLMQRLYDPTEGMVSVDGQDIRTINVRFLREIIGVVSQEPVLFATTIAENIRYGRENVTMDEIEKAVKEANAYDFIMKLPHKFDTLVGERGAQLSGGQKQRIAIARALVRNPKILLLDEATSALDTESEAVVQVALDKARKGRTTIVIAHRLSTVRNADVIAGFDDGVIVEKGNHDELMKEKGIYFKLVTMQTAGNEVELENAADESKSEIDALEMSSNDSRSSLIRKRSTRRSVRGSQAQDRKLSTKEALDESIPPVSFWRIMKLNLTEWPYFVVGVFCAIINGGLQPAFAIIFSKIIGVFTRIDDPETKRQNSNLFSLLFLALGIISFITFFLQGFTFGKAGEILTKRLRYMVFRSMLRQDVSWFDDPKNTTGALTTRLANDAAQVKGAIGSRLAVITQNIANLGTGIIISFIYGWQLTLLLLAIVPIIAIAGVVEMKMLSGQALKDKKELEGSGKIATEAIENFRTVVSLTQEQKFEHMYAQSLQVPYRNSLRKAHIFGITFSFTQAMMYFSYAGCFRFGAYLVAHKLMSFEDVLLVFSAVVFGAMAVGQVSSFAPDYAKAKISAAHIIMIIEKTPLIDSYSTEGLMPNTLEGNVTFGEVVFNYPTRPDIPVLQGLSLEVKKGQTLALVGSSGCGKSTVVQLLERFYDPLAGKVLLDGKEIKRLNVQWLRAHLGIVSQEPILFDCSIAENIAYGDNSRVVSQEEIVRAAKEANIHAFIESLPNKYSTKVGDKGTQLSGGQKQRIAIARALVRQPHILLLDEATSALDTESEKVVQEALDKAREGRTCIVIAHRLSTIQNADLIVVFQNGRVKEHGTHQQLLAQKGIYFSMVSVQAGTKRQ
		Gene Name		ABCB1
		Uniprot ID		MDR1_HUMAN
		KEGG Pathway		hsa:5243
		Protein Family		ABC transporter superfamily
		Protein Function		Translocates drugs and phospholipids across the membrane (PubMed:8898203, PubMed:2897240, PubMed:9038218). Catalyzes the flop of phospholipids from the cytoplasmic to the exoplasmic leaflet of the apical membrane. Participates mainly to the flop of phosphatidylcholine, phosphatidylethanolamine, beta-D-glucosylceramides and sphingomyelins (PubMed:8898203). Energy-dependent efflux pump responsible for decreased drug accumulation in multidrug-resistant cells (PubMed:2897240, PubMed:9038218). Click to Show/Hide
Mechanism Description		Decreased clearance of Loperamide due to the transporter inhibition by Tacrolimus

Recommended Action
Management		Caution is recommended if loperamide is used with potent P-gp inhibitors. Particular caution is advised when drugs that inhibit other pathways of loperamide elimination (CYP450 2C8 CYP450 3A4) are also used, since they may act synergistically with P-gp inhibitors to increase loperamide concentrations. Patients should be counseled to not exceed the recommended dosage and frequency or duration of use of loperamide, and to seek prompt medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes such as dizziness, lightheadedness, fainting, palpitation, irregular heart rhythm, shortness of breath, or syncope. If loperamide-induced cardiotoxicity is suspected, promptly discontinue loperamide and initiate therapy to manage and prevent cardiac arrhythmias and adverse outcomes. Electrical pacing or cardioversion may be necessary if torsade de pointes persists despite pharmacotherapy. "

References
1	Adachi Y, Suzuki H, Sugiyama Y "Quantitative evaluation of the function of small intestinal P-glycoprotein: comparative studies between in Situ and in Vivo." Pharm Res 20 (2003): 1163-9. [PMID: 12948013]
2	Crowe A, Wong P "Potential roles of P-gp and calcium channels in loperamide and diphenoxylate transport." Toxicol Appl Pharmacol 193 (2003): 127-37. [PMID: 14613723]
3	Eggleston W, Clark KH, Marraffa JM "Loperamide abuse associated with cardiac dysrhythmia and death." Ann Emerg Med 69 (2017): 83-6. [PMID: 27140747]
4	Sadeque AJ, Wandel C, He H, Shah S, Wood AJ "Increased drug delivery to the brain by P-glycoprotein inhibition." Clin Pharmacol Ther 68 (2000): 231-7. [PMID: 11014404]
5	US Food and Drug Administration "FDA warns about serious heart problems with high doses of the antidiarrheal medicine loperamide (Imodium), including from abuse and misuse.".