Details of Drug-Drug Interaction
| Drug General Information (ID: DDIRU0H589) | |||||||||
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| Drug Name | Quinidine | Drug Info | Tetrabenazine | Drug Info | |||||
| Drug Type | Small molecule | Small molecule | |||||||
| Therapeutic Class | Group I Antiarrhythmics | Nephropathic Cystinosis Therapy | |||||||
| Structure | |||||||||
| Mechanism of Quinidine-Tetrabenazine Interaction (Severity Level: Major) | |||||||||
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| CYP450 enzyme inhibition Click to Show/Hide Mechanism Graph | |||||||||
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| Drug Name | Quinidine | Tetrabenazine | |||||||
| Mechanism 1 | 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.
Click to Show/Hide
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| Mechanism Description |
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| Increased risk of prolong QT interval Click to Show/Hide Mechanism Graph | |||||||||
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| Drug Name | Quinidine | Tetrabenazine | |||||||
| Mechanism 2 | Prolong QT interval | Prolong QT interval | |||||||
| Key Mechanism Factor 2 | |||||||||
| Factor Name | QT interval | ||||||||
| Factor Description | Long QT syndrome is a heart signaling disorder that can cause a fast, chaotic heartbeat (arrhythmia). Many people may not exhibit symptoms, and usually the condition is detected during routine medical tests. In others, the most common symptoms include: sudden fainting, palpitations, dizziness, seizures, sudden death. | ||||||||
| Mechanism Description |
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| Recommended Action | |||||||||
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| Management | Due to increased risk of QT prolongation and torsade de pointes arrhythmia, concomitant use of tetrabenazine with quinidine should generally be avoided. If coadministration is required, the dosage of tetrabenazine should be reduced. In patients already stabilized on tetrabenazine, the daily dosage of tetrabenazine should be halved. The maximum dosage recommended is 25 mg per dose and 50 mg per day during coadministration with a potent CYP450 2D6 inhibitor. Patients and their caregivers should be advised to notify their physician if they experience new or worsening depression, suicidal thoughts, parkinsonism, restlessness, agitation, dysphagia, and/or excessive sedation while taking tetrabenazine. Patients should also be advised 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. Ambulatory patients should avoid hazardous activities requiring mental alertness and motor coordination until they know how these agents affect them, and to notify their doctor if they experience excessive or prolonged CNS effects that interfere with their normal activities. | ||||||||
| References | |||||||||||||||||||
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| 1 | Cerner Multum, Inc. "Australian Product Information.". | ||||||||||||||||||
| 2 | Product Information. Xenazine (tetrabenazine). Prestwick Pharmaceuticals Inc, Washington DC, VA. | ||||||||||||||||||