Miracid Drug Interactions

Gastric acid secretion decreased by PPIs can influence the absorption of other drugs (e.g., resulting in increased digoxin and decreased ketoconazole and itraconazole absorption). Drug solubility may be reduced at neutral pH compared with acidic conditions. PPIs have been demonstrated to reduce the bioavailability of many clinically relevant drugs by 50% or more compared with the control values. Other important drug interactions are connected to hepatic CYP-mediated oxidative metabolism. PPIs may alter drug metabolism by induction or inhibition of the cytochrome P450 enzymes. This is an important consideration in patients taking medication with a narrow therapeutic window (diazepam, phenytoin and warfarin).
Omeprazole inhibits its own CYP2C19-mediated metabolism, but it is also able to affect the degradation of other drugs metabolized through the CYP2C19 isoenzyme.
Other CYP isoenzymes besides CYP2C19 are also involved in the interactions related to the metabolism of omeprazole. Coadministration of ketoconazole inhibits the omeprazole-omeprazole sulfone transformation. This interaction is exerted through the inhibition of the CYP3A4 isoenzyme, involved in the metabolism of both ketoconazole and omeprazole. If the activity of CYP2C19 is decreased or inhibited (in poor metabolizers or owing to environmental factors), the CYP3A4-mediated pathway becomes the main, alternative pathway of the elimination of PPIs.
Metabolism/Transport Effects: Substrate of CYP2A6 (minor), CYP2C19 (major), CYP2C9 (minor), CYP2D6 (minor), CYP3A4 (minor);
Note: Assignment of major/minor substrate status based on clinically relevant drug interaction potential;
Inhibits CYP1A2 (weak), CYP2C19 (moderate), CYP2C9 (moderate), CYP2D6 (weak), CYP3A4 (weak);
Induces CYP1A2 (weak/moderate).
Avoid Concomitant Use: Avoid concomitant use of omeprazole with any of the following: Clopidogrel; Dasatinib; Delavirdine; Erlotinib; Nelfinavir; Pimozide; Ponatinib; Posaconazole; Rifampin; Rilpivirine; Risedronate; St John's Wort.
Increased Effect/Toxicity: Omeprazole may increase the levels/effects of: amphetamines; aripiprazole; benzodiazepines (metabolized by oxidation); carvedilol; cilostazol; citalopram; clozapine; cyclosporine (systemic); CYP2C19 substrates; CYP2C9 substrates; dexmethylphenidate; escitalopram; fosphenytoin; lomitapide; methotrexate; methylphenidate; phenytoin; pimozine; raltegravir; risedronate; saquinavir; tacrolimus (systemic); vitamin K antagonists; voriconazole; alprazolam; carbamazepine; clobazam; clorazepate; diazepam; digoxin; disulfiram; fluvastatin; midazolam; triazolam; armodafinil.
The levels/effects of omeprazole may be increased by: fluconazole; ketoconazole (systemic); voriconazole.
Decreased Effect: Omeprazole may decrease the levels/effects of: atazanavir; ampicillin; bisphosphonate derivatives; bosutinib; cefditoren; clopidogrel; clozapine; dabigatran etexilate; dasatinib; delavirdine; erlotinib; gefitinib; indinavir; iron salts; itraconazole; ketoconazole (systemic); mesalamine; multivitamins/minerals (with A,D,E,K, folate, iron); mycophenolate; nelfinavir; nilotinib; ponatinib; posaconazole; rilpivirine; risedronate; vismodegib; bendamustine.
The level/effects of omeprazole may be decreased by: CYP2C19 inducers (strong); peginterferon alfa-2b; rifampin; St John's Wort; tipranavir.
Ethanol/Nutrition/Herb Interactions: Ethanol: Avoid ethanol (may cause gastric mucosal irritation).
Food: Food delays absorption.
Herb/Nutraceutical: Avoid use of St John's Wort; ginkgo biloba; cranberry (may decrease efficacy of omeprazole).