Details of Drug-Drug Interaction
| Drug General Information (ID: DDI2PELUZ1) | |||||||||
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| Drug Name | Terbinafine | Drug Info | Pitolisant | Drug Info | |||||
| Drug Type | Small molecule | Small molecule | |||||||
| Therapeutic Class | Antifungal Agents | Cns Stimulants | |||||||
| Structure | |||||||||
| Mechanism of Terbinafine-Pitolisant Interaction (Severity Level: Major) | |||||||||
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| CYP450 enzyme inhibition Click to Show/Hide Mechanism Graph | |||||||||
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| Drug Name | Terbinafine | Pitolisant | |||||||
| Mechanism | CYP450 2D6 inhibitor | CYP450 2D6 substrate | |||||||
| Key Mechanism Factor 1 | |||||||||
| Factor Name | Cytochrome P450 2D6 |
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Structure
Sequence
MGLEALVPLAVIVAIFLLLVDLMHRRQRWAARYPPGPLPLPGLGNLLHVDFQNTPYCFDQLRRRFGDVFSLQLAWTPVVVLNGLAAVREALVTHGEDTADRPPVPITQILGFGPRSQGVFLARYGPAWREQRRFSVSTLRNLGLGKKSLEQWVTEEAACLCAAFANHSGRPFRPNGLLDKAVSNVIASLTCGRRFEYDDPRFLRLLDLAQEGLKEESGFLREVLNAVPVLLHIPALAGKVLRFQKAFLTQLDELLTEHRMTWDPAQPPRDLTEAFLAEMEKAKGNPESSFNDENLRIVVADLFSAGMVTTSTTLAWGLLLMILHPDVQRRVQQEIDDVIGQVRRPEMGDQAHMPYTTAVIHEVQRFGDIVPLGVTHMTSRDIEVQGFRIPKGTTLITNLSSVLKDEAVWEKPFRFHPEHFLDAQGHFVKPEAFLPFSAGRRACLGEPLARMELFLFFTSLLQHFSFSVPTGQPRPSHHGVFAFLVSPSPYELCAVPR
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| Gene Name | CYP2D6 | ||||||||
| Uniprot ID | CP2D6_HUMAN | ||||||||
| KEGG Pathway | hsa:1565 | ||||||||
| Protein Family | Cytochrome P450 family | ||||||||
| Protein Function |
A cytochrome P450 monooxygenase involved in the metabolism of fatty acids, steroids and retinoids (PubMed:18698000, PubMed:19965576, PubMed:20972997, PubMed:21289075, PubMed:21576599). Mechanistically, uses molecular oxygen inserting one oxygen atom into a substrate, and reducing the second into a water molecule, with two electrons provided by NADPH via cytochrome P450 reductase (NADPH--hemoprotein reductase) (PubMed:18698000, PubMed:19965576, PubMed:20972997, PubMed:21289075, PubMed:21576599). Catalyzes the epoxidation of double bonds of polyunsaturated fatty acids (PUFA) (PubMed:19965576, PubMed:20972997). Metabolizes endocannabinoid arachidonoylethanolamide (anandamide) to 20-hydroxyeicosatetraenoic acid ethanolamide (20-HETE-EA) and 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acid ethanolamides (EpETrE-EAs), potentially modulating endocannabinoid system signaling (PubMed:18698000, PubMed:21289075). Catalyzes the hydroxylation of carbon-hydrogen bonds. Metabolizes cholesterol toward 25-hydroxycholesterol, a physiological regulator of cellular cholesterol homeostasis (PubMed:21576599). Catalyzes the oxidative transformations of all-trans retinol to all-trans retinal, a precursor for the active form all-trans-retinoic acid (PubMed:10681376). Also involved in the oxidative metabolism of drugs such as antiarrhythmics, adrenoceptor antagonists, and tricyclic antidepressants.
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| Mechanism Description |
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| Recommended Action | |||||||||
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| Management | A dosage reduction is recommended for pitolisant during coadministration with strong inhibitors of CYP450 2D6. For patients receiving a strong CYP450 2D6 inhibitor, the dose of pitolisant should be initiated at 8.9 mg once daily and increased after 7 days to a maximum dosage of 17.8 mg once daily. For patients already receiving a stable dose of pitolisant, the dose of pitolisant should be reduced by half when initiating treatment with a strong CYP450 2D6 inhibitor. Patients should be monitored for clinical response and increased adverse effects such as headache, insomnia, nausea, anxiety, increased heart rate, QT prolongation, hallucinations, abdominal pain, upper respiratory tract infections, and musculoskeletal pain. | ||||||||
| References | |||||||||||||||||||
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| 1 | Cerner Multum, Inc. "UK Summary of Product Characteristics.". | ||||||||||||||||||
| 2 | Product Information. Wakix (pitolisant). Harmony Biosciences, LLC, Plymouth Meeting, PA. | ||||||||||||||||||