Drug General Information (ID: DDIBR9E6WZ)
  Drug Name Phenobarbital Drug Info Drospirenone Drug Info
  Drug Type Small molecule Small molecule
  Therapeutic Class Anticonvulsants Contraceptive Agents
  Structure

 Mechanism of Phenobarbital-Drospirenone Interaction (Severity Level: Major)
     CYP450 enzyme induction Click to Show/Hide Mechanism Graph
Could Not Find 2D Structure
      Drug Name Phenobarbital Drospirenone
      Mechanism CYP450 3A4 inducer CYP450 3A4 substrate
      Key Mechanism Factor 1
Factor Name Cytochrome P450 3A4
×
Structure Sequence
MALIPDLAMETWLLLAVSLVLLYLYGTHSHGLFKKLGIPGPTPLPFLGNILSYHKGFCMFDMECHKKYGKVWGFYDGQQPVLAITDPDMIKTVLVKECYSVFTNRRPFGPVGFMKSAISIAEDEEWKRLRSLLSPTFTSGKLKEMVPIIAQYGDVLVRNLRREAETGKPVTLKDVFGAYSMDVITSTSFGVNIDSLNNPQDPFVENTKKLLRFDFLDPFFLSITVFPFLIPILEVLNICVFPREVTNFLRKSVKRMKESRLEDTQKHRVDFLQLMIDSQNSKETESHKALSDLELVAQSIIFIFAGYETTSSVLSFIMYELATHPDVQQKLQEEIDAVLPNKAPPTYDTVLQMEYLDMVVNETLRLFPIAMRLERVCKKDVEINGMFIPKGVVVMIPSYALHRDPKYWTEPEKFLPERFSKKNKDNIDPYIYTPFGSGPRNCIGMRFALMNMKLALIRVLQNFSFKPCKETQIPLKLSLGGLLQPEKPVVLKVESRDGTVSGA
Gene Name CYP3A4
Uniprot ID CP3A4_HUMAN
KEGG Pathway hsa:1576
Protein Family Cytochrome P450 family
Protein Function
A cytochrome P450 monooxygenase involved in the metabolism of sterols, steroid hormones, retinoids and fatty acids (PubMed:10681376, PubMed:11093772, PubMed:11555828, PubMed:14559847, PubMed:12865317, PubMed:15373842, PubMed:15764715, PubMed:20702771, PubMed:19965576, PubMed:21490593, 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). Catalyzes the hydroxylation of carbon-hydrogen bonds (PubMed:2732228, PubMed:14559847, PubMed:12865317, PubMed:15373842, PubMed:15764715, PubMed:21576599, PubMed:21490593). Exhibits high catalytic activity for the formation of hydroxyestrogens from estrone (E1) and 17beta-estradiol (E2), namely 2-hydroxy E1 and E2, as well as D-ring hydroxylated E1 and E2 at the C-16 position (PubMed:11555828, PubMed:14559847, PubMed:12865317). Plays a role in the metabolism of androgens, particularly in oxidative deactivation of testosterone (PubMed:2732228, PubMed:15373842, PubMed:15764715, PubMed:22773874). Metabolizes testosterone to less biologically active 2beta- and 6beta-hydroxytestosterones (PubMed:2732228, PubMed:15373842, PubMed:15764715). Contributes to the formation of hydroxycholesterols (oxysterols), particularly A-ring hydroxylated cholesterol at the C-4beta position, and side chain hydroxylated cholesterol at the C-25 position, likely contributing to cholesterol degradation and bile acid biosynthesis (PubMed:21576599). Catalyzes bisallylic hydroxylation of polyunsaturated fatty acids (PUFA) (PubMed:9435160). Catalyzes the epoxidation of double bonds of PUFA with a preference for the last double bond (PubMed:19965576). Metabolizes endocannabinoid arachidonoylethanolamide (anandamide) to 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acid ethanolamides (EpETrE-EAs), potentially modulating endocannabinoid system signaling (PubMed:20702771). Plays a role in the metabolism of retinoids. Displays high catalytic activity for oxidation of all-trans-retinol to all-trans-retinal, a rate-limiting step for the biosynthesis of all-trans-retinoic acid (atRA) (PubMed:10681376). Further metabolizes atRA toward 4-hydroxyretinoate and may play a role in hepatic atRA clearance (PubMed:11093772). Responsible for oxidative metabolism of xenobiotics. Acts as a 2-exo-monooxygenase for plant lipid 1,8-cineole (eucalyptol) (PubMed:11159812). Metabolizes the majority of the administered drugs. Catalyzes sulfoxidation of the anthelmintics albendazole and fenbendazole (PubMed:10759686). Hydroxylates antimalarial drug quinine (PubMed:8968357). Acts as a 1,4-cineole 2-exo-monooxygenase (PubMed:11695850). Also involved in vitamin D catabolism and calcium homeostasis. Catalyzes the inactivation of the active hormone calcitriol (1-alpha,25-dihydroxyvitamin D(3)) (PubMed:29461981).
    Click to Show/Hide
      Mechanism Description
  • Increased metabolism of Drospirenone caused by Phenobarbital mediated induction of CYP450 enzyme

Recommended Action
      Management Women using hormonal contraceptives should be advised of the risk of breakthrough bleeding and unintended pregnancy during concomitant therapy with enzyme-inducing anticonvulsants.

References
1 Baciewicz AM "Oral contraceptive drug interactions." Ther Drug Monit 7 (1985): 26-35. [PMID: 2859674]
2 Back DJ, Bates M, Bowden A, et al "The interaction of phenobarbital and other anticonvulsants with oral contraceptive steroid therapy." Contraception 22 (1980): 495-503. [PMID: 7471739]
3 Back DJ, Breckenridge AM, Crawford FE, MacIver M, Orne ML, Rowe PH "Interindividual variation and drug interactions with hormonal steroid contraceptives." Drugs 21 (1981): 46-61. [PMID: 7009137]
4 Back DJ, Grimmer SF, Orme ML, Proudlove D, Mann RD, Breckenridge AM "Evaluation of Committee on Safety of Medicines yellow card reports on oral contraceptive-drug interactions with anticonvulsants and antibiotics." Br J Clin Pharmacol 25 (1988): 527-32. [PMID: 3408633]
5 Back DJ, Orme ML "Pharmacokinetic drug interactions with oral contraceptives." Clin Pharmacokinet 18 (1990): 472-84. [PMID: 2191822]
6 Coulam CB, Annegers JF "Do anticonvulsants reduce the efficacy of oral contraceptives?" Epilepsia 20 (1979): 519-26. [PMID: 477641]
7 Crawford P, Chadwick DJ, Martin C, et al "The interaction of phenytoin and carbamazepine with combined oral contraceptive steroids." Br J Clin Pharmacol 30 (1990): 892-6. [PMID: 2126946]
8 D'Arcy PF "Drug interactions with oral contraceptives." Drug Intell Clin Pharm 20 (1986): 353-62. [PMID: 3519141]
9 Diamond MP, Greene JW, Thompson JM, VanHooydonk JE, Wentz AC "Interaction of anticonvulsants and oral contraceptives in epileptic adolescents." Contraception 31 (1985): 623-32. [PMID: 4042660]
10 D'Arcy PF. Drug interactions with oral contraceptives. Drug Intell Clin Pharm. 1986;20(5):353-362. [PMID: 3519141]
11 Faculty of Sexual & Reproductive Healthcare "FSRH Clinical Guidance: Drug Interactions with Hormonal Contraception.".
12 Fattore C, Cipolla G, Gatti G, Limido GL, Sturm Y, Bernasconi C, Perucca E "Induction of ethinylestradiol and levonorgestrel metabolism by oxcarbazepine in healthy women." Epilepsia 40 (1999): 783-7. [PMID: 10368079]
13 FFPRHC Guidance (April 2005). Drug interactions with hormonal contraception. J Fam Plann Reprod Health Care 31 (2005): 139-51. [PMID: 15921558]
14 Furlan AJ, Rothner AD "Anti-epileptic drugs and failure of oral contraceptives." Lancet 1 (1974): 1113. [PMID: 4135275]
15 Haukkamaa M "Contraception by Norplant subdermal capsules is not reliable in epileptic patients on anticonvulsant treatment." Contraception 33 (1986): 559-65. [PMID: 3095023]
16 Janz D, Schmidt D "Letter: Anti-epileptic drugs and failure of oral contraceptives." Lancet 1 (1974): 1113. [PMID: 4135275]
17 Kenyon IE "Unplanned pregnancy in an epileptic. (Letter to the editor)." Br Med J 1 (1972): 686. [PMID: 5015305]
18 Klosterskov Jensen P, Saano V, Haring P, Svenstrup B, Menge GP "Possible interaction between oxcarbazepine and an oral contraceptive." Epilepsia 33 (1992): 1149-52. [PMID: 1464278]
19 Laengner H, Detering K "Letter: Anti-epileptic drugs and failure of oral contraceptives." Lancet 2 (1974): 600. [PMID: 4140317]
20 Mattson RH, Cramer JA, Darney PD, Naftolin F "Use of oral contraceptives by women with epilepsy." JAMA 256 (1986): 238-40. [PMID: 3723710]
21 Notelovitz M, Tjapkes J, Ware M "Interaction between estrogen and dilantin in a menopausal woman." N Engl J Med 304 (1981): 788-9. [PMID: 6258075]
22 O'Brien MD, Guillebaud J "Contraception for women with epilepsy." Epilepsia 47 (2006): 1419-22. [PMID: 16981856]
23 Odlind V, Olsson SE "Enhanced metabolism of levonorgestrel during phenytoin treatment in a woman with norplant implants." Contraception 33 (1986): 257-61. [PMID: 3087695]
24 Product Information. Aptiom (eslicarbazepine). Sunovion Pharmaceuticals Inc, Marlborough, MA.
25 Product Information. Fycompa (perampanel). Eisai Inc, Teaneck, NJ.
26 Product Information. Norplant System (levonorgestrel) Wyeth-Ayerst Laboratories, Philadelphia, PA.
27 Product Information. Trileptal (oxcarbazepine) Novartis Pharmaceuticals, East Hanover, NJ.
28 Rapport DJ, Calabrese JR "Interactions between carbamazepine and birth control pills." Psychosomatics 30 (1989): 462-4. [PMID: 2798744]
29 Saano V, Glue P, Banfield CR "Effects of felbamate on the pharmacokinetics of a low-dose combination oral contraceptive." Clin Pharmacol Ther 58 (1995): 523-31. [PMID: 7586946]
30 Schindlbeck C, Janni W, Friese K "Failure of Implanon contraception in a patient taking carbamazepin for epilepsia." Arch Gynecol Obstet 273 (2006): 255-6. [PMID: 16208481]
31 Shane-McWorter L, Cerveny JD, MacFarlane LL, Osborn C "Enhanced metabolism of levonorgestrel during phenobarbital treatment and resultant pregnancy." Pharmacotherapy 18 (1998): 1360-4. [PMID: 9855340]
32 Szoka PR, Edgren RA "Drug interactions with oral contraceptives: compilation and analysis of an adverse experience report database." Fertil Steril 49 (1988): s31-8. [PMID: 3282933]
33 Wilbur K, Ensom MHH "Pharmacokinetic drug interactions between oral contraceptives and second-generation anticonvulsants." Clin Pharmacokinet 38 (2000): 355-65. [PMID: 10803456]