Drug General Information (ID: DDIDBW9AG4)
  Drug Name Desogestrel Drug Info Tizanidine Drug Info
  Drug Type Small molecule Small molecule
  Therapeutic Class Contraceptive Agents Analgesics
  Structure

 Mechanism of Desogestrel-Tizanidine Interaction (Severity Level: Major)
     CYP450 enzyme inhibition Click to Show/Hide Mechanism Graph
Could Not Find 2D Structure
      Drug Name Desogestrel Tizanidine
      Mechanism CYP450 1A2 inhibitor CYP450 1A2 substrate
      Key Mechanism Factor 1
Factor Name Cytochrome P450 1A2
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Structure Sequence
MALSQSVPFSATELLLASAIFCLVFWVLKGLRPRVPKGLKSPPEPWGWPLLGHVLTLGKNPHLALSRMSQRYGDVLQIRIGSTPVLVLSRLDTIRQALVRQGDDFKGRPDLYTSTLITDGQSLTFSTDSGPVWAARRRLAQNALNTFSIASDPASSSSCYLEEHVSKEAKALISRLQELMAGPGHFDPYNQVVVSVANVIGAMCFGQHFPESSDEMLSLVKNTHEFVETASSGNPLDFFPILRYLPNPALQRFKAFNQRFLWFLQKTVQEHYQDFDKNSVRDITGALFKHSKKGPRASGNLIPQEKIVNLVNDIFGAGFDTVTTAISWSLMYLVTKPEIQRKIQKELDTVIGRERRPRLSDRPQLPYLEAFILETFRHSSFLPFTIPHSTTRDTTLNGFYIPKKCCVFVNQWQVNHDPELWEDPSEFRPERFLTADGTAINKPLSEKMMLFGMGKRRCIGEVLAKWEIFLFLAILLQQLEFSVPPGVKVDLTPIYGLTMKHARCEHVQARLRFSIN
Gene Name CYP1A2
Uniprot ID CP1A2_HUMAN
KEGG Pathway hsa:1544
Protein Family Cytochrome P450 family
Protein Function
A cytochrome P450 monooxygenase involved in the metabolism of various endogenous substrates, including fatty acids, steroid hormones and vitamins (PubMed:9435160, PubMed:10681376, PubMed:11555828, PubMed:12865317, PubMed:19965576). 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:9435160, PubMed:10681376, PubMed:11555828, PubMed:12865317, PubMed:19965576). Catalyzes the hydroxylation of carbon-hydrogen bonds (PubMed:11555828, PubMed:12865317). Exhibits high catalytic activity for the formation of hydroxyestrogens from estrone (E1) and 17beta-estradiol (E2), namely 2-hydroxy E1 and E2 (PubMed:11555828, PubMed:12865317). Metabolizes cholesterol toward 25-hydroxycholesterol, a physiological regulator of cellular cholesterol homeostasis (PubMed:21576599). May act as a major enzyme for all-trans retinoic acid biosynthesis in the liver. Catalyzes two successive oxidative transformation of all-trans retinol to all-trans retinal and then to the active form all-trans retinoic acid (PubMed:10681376). Primarily catalyzes stereoselective epoxidation of the last double bond of polyunsaturated fatty acids (PUFA), displaying a strong preference for the (R,S) stereoisomer (PubMed:19965576). Catalyzes bisallylic hydroxylation and omega-1 hydroxylation of PUFA (PubMed:9435160). May also participate in eicosanoids metabolism by converting hydroperoxide species into oxo metabolites (lipoxygenase-like reaction, NADPH-independent) (PubMed:21068195). Plays a role in the oxidative metabolism of xenobiotics. Catalyzes the N-hydroxylation of heterocyclic amines and the O-deethylation of phenacetin (PubMed:14725854). Metabolizes caffeine via N3-demethylation (Probable).
    Click to Show/Hide
      Mechanism Description
  • Decreased metabolism of Tizanidine caused by Desogestrel mediated inhibition of CYP450 enzyme

Recommended Action
      Management The use of tizanidine in combination with oral contraceptives or other CYP450 1A2 inhibitors should generally be avoided. Caution is advised if concurrent use is clinically necessary. Dosage adjustments may be required in patients who experience excessive adverse effects of tizanidine such as drowsiness, dizziness, lightheadedness, hypotension, bradycardia, or syncope.

References
1 Granfors MT, Backman JT, Laitila J, Neuvonen PJ "Oral contraceptives containing ethinyl estradiol and gestodene markedly increase plasma concentrations and effects of tizanidine by inhibiting cytochrome P450 1A2." Clin Pharmacol Ther 78 (2005): 400-11. [PMID: 16198659]
2 Granfors MT, Backman JT, Neuvonen M, Neuvonen PJ "Ciprofloxacin greatly increases concentrations and hypotensive effect of tizanidine by inhibiting its cytochrome P450 1A2-mediated presystemic metabolism." Clin Pharmacol Ther 76 (2004): 598-606. [PMID: 15592331]
3 Product Information. Vioxx (rofecoxib). Merck &amp Co, Inc, West Point, PA.