Drug General Information (ID: DDIS6K0RJO)
  Drug Name Pentobarbital Drug Info Oxycodone Drug Info
  Drug Type Small molecule Small molecule
  Therapeutic Class Anxiolytics/Sedatives/Hypnotics Analgesics
  Structure

 Mechanism of Pentobarbital-Oxycodone Interaction (Severity Level: Major)
     CYP450 enzyme induction Click to Show/Hide Mechanism Graph
Could Not Find 2D Structure
      Drug Name Pentobarbital Oxycodone
      Mechanism 1 CYP450 3A4 inducer CYP450 3A4 substrate
      Key Mechanism Factor 1
Factor Name Cytochrome P450 3A4
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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 Oxycodone caused by Pentobarbital mediated induction of CYP450 enzyme
     Additive CNS depression effects Click to Show/Hide Mechanism Graph
Could Not Find 2D Structure
      Drug Name Pentobarbital Oxycodone
      Mechanism 2 CNS depression effects CNS depression effects
      Key Mechanism Factor 2
Factor Name CNS depression effects
Factor Description CNS depressants are drugs that inhibit or suppress brain activity and can reduce mental and physical processes. Excessive CNS depression can lead to decreased heart rate, slow breathing (less than 10 breaths per minute), extreme confusion or loss of memory, nausea and vomiting, poor judgment, blue lips or fingertips, irritability and aggression, and clammy or cold skin.
      Mechanism Description
  • Additive CNS depression effects by the combination of Pentobarbital and Oxycodone 

Recommended Action
      Management The use of opioids in conjunction with other CNS depressants such as barbiturates should generally be avoided unless alternative treatment options are inadequate. Particular caution is advisable when a barbiturate is added to or withdrawn from therapy in patients receiving opioids that are CYP450 3A4 substrates, as there may be an increased risk of withdrawal symptoms (e.g., restlessness, insomnia, sweating, lacrimation, or rhinorrhea) following initiation of the barbiturate and overdose following discontinuation. A dosage adjustment for one or both drugs may be required.

References
1 Product Information. Apadaz (acetaminophen-benzhydrocodone). KemPharm, Inc, Coralville, IA.
2 Bell J, Seres V, Bowron P, Lewis J, Batey R "The use of serum methadone levels in patients receiving methadone maintenance." Clin Pharmacol Ther 43 (1988): 623-9. [PMID: 3378383]
3 Liu S-J, Wang RI "Case report of barbiturate-induced enhancement of methadone metabolism and withdrawal syndrome." Am J Psychiatry 141 (1984): 1287-8. [PMID: 6486271]
4 Product Information. Duragesic Transdermal System (fentanyl). Janssen Pharmaceutica, Titusville, NJ.
5 Cerner Multum, Inc. "Australian Product Information.".
6 Product Information. Ionsys (fentanyl). Ortho McNeil Pharmaceutical, Raritan, NJ.
7 Product Information. Zohydro ER (HYDROcodone). Zogenix, Inc, San Diego, CA.
8 Product Information. OxyContin (oxycodone). Purdue Frederick Company, Norwalk, CT.
9 Cerner Multum, Inc. "UK Summary of Product Characteristics.".
10 Product Information. Butorphanol Tartrate (butorphanol). Apotex Corporation, Weston, FL.