Drug General Information (ID: DDI58ZEWT3)
  Drug Name Promazine Drug Info Terbinafine Drug Info
  Drug Type Small molecule Small molecule
  Therapeutic Class Antipsychotic Agents Antifungal Agents
  Structure

 Mechanism of Promazine-Terbinafine Interaction (Severity Level: Moderate)
     CYP450 enzyme inhibition Click to Show/Hide Mechanism Graph
Could Not Find 2D Structure
      Drug Name Promazine Terbinafine
      Mechanism CYP450 2D6 substrate CYP450 2D6 inhibitor
      Key Mechanism Factor 1
Factor Name Cytochrome P450 2D6
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Structure Sequence
MGLEALVPLAVIVAIFLLLVDLMHRRQRWAARYPPGPLPLPGLGNLLHVDFQNTPYCFDQLRRRFGDVFSLQLAWTPVVVLNGLAAVREALVTHGEDTADRPPVPITQILGFGPRSQGVFLARYGPAWREQRRFSVSTLRNLGLGKKSLEQWVTEEAACLCAAFANHSGRPFRPNGLLDKAVSNVIASLTCGRRFEYDDPRFLRLLDLAQEGLKEESGFLREVLNAVPVLLHIPALAGKVLRFQKAFLTQLDELLTEHRMTWDPAQPPRDLTEAFLAEMEKAKGNPESSFNDENLRIVVADLFSAGMVTTSTTLAWGLLLMILHPDVQRRVQQEIDDVIGQVRRPEMGDQAHMPYTTAVIHEVQRFGDIVPLGVTHMTSRDIEVQGFRIPKGTTLITNLSSVLKDEAVWEKPFRFHPEHFLDAQGHFVKPEAFLPFSAGRRACLGEPLARMELFLFFTSLLQHFSFSVPTGQPRPSHHGVFAFLVSPSPYELCAVPR
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
      Mechanism Description
  • Decreased metabolism of Promazine caused by Terbinafine mediated inhibition of CYP450 enzyme

Recommended Action
      Management Caution is advised if terbinafine must be used concurrently with medications that undergo metabolism by CYP450 2D6, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever terbinafine is added to or withdrawn from therapy. Due to the long elimination half-life of terbinafine, especially following prolonged use, such interactions may be observed for several months after discontinuation of terbinafine therapy.

References
1 AbdelRahman SM, Gotschall RR, Kauffman RE, Leeder JS, Kearns GL "Investigation of terbinafine as a CYP2D6 inhibitor in vivo." Clin Pharmacol Ther 65 (1999): 465-72. [PMID: 10340911]
2 Gupta AK, Katz HI, Shear NH "Terbinafine and potential drug interactions - Reply." J Am Acad Dermatol 43 (2000): 883-4. [PMID: 11050604]
3 Product Information. Lamisil (terbinafine). Sandoz Pharmaceuticals Corporation, East Hanover, NJ.
4 Van der Kuy PH, Hooymans PM, Verkaaik AJ "Nortriptyline intoxication induced by terbinafine." BMJ 316 (1998): 441. [PMID: 9492672]