Rifampin Inducer (strong) of hepatic microsomal drug-metabolizing enzymes and P-glycoprotein.
Salicylates Interference with renal excretion of drugs that undergo active tubular secretion. Salicylate renal excretion dependent on urinary pH when large doses of salicylate used. Aspirin (but not other salicylates) interferes with platelet function. Large doses of salicylates have intrinsic hypoglycemic activity.
Corticosteroids: [P] Increased corticosteroid hepatic metabolism; reduced corticosteroid effect.
Mexiletine: [NE] Increased mexiletine metabolism; reduced mexiletine effect.
Sulfonylurea hypoglycemics: [P] Increased hepatic metabolism of tolbutamide and probably other sulfonylureas metabolized by the liver (including chlorpropamide).
Theophylline: [P] Increased theophylline metabolism.
See also Anticoagulants, oral; Antidepressants, tricyclic and heterocyclic; Azole antifungals; Beta-adrenoceptor blockers; Calcium channel blockers; Cyclosporine; Digitalis glycosides; Estrogens; HMG-CoA reductase inhibitors; Opioid analgesics; Phenytoin; Quinidine.
Carbonic anhydrase inhibitors: [NE] Increased acetazolamide serum concentrations; increase salicylate toxicity due to decreased blood pH.
Corticosteroids: [P] Increased salicylate elimination; possible additive toxic effect on gastric mucosa.
Heparin: [NP] Increased bleeding tendency with aspirin, but probably not with other salicylates.
Methotrexate: [P] Decreased renal methotrexate clearance; increases methotrexate toxicity (primarily at anticancer doses).
Selective serotonin reuptake inhibitors (SSRIs): [P] Increased risk of bleeding due to platelet inhibition.
Sulfinpyrazone: [HP] Decreased uricosuric effect of sulfinpyrazone (interaction unlikely with less than 1.5 g of salicylate daily).
See also Acid-reducing agents; Anticoagulants, oral; Probenecid.
Codeine: [HP] Reduced analgesic effect due to inhibition of codeine metabolism to morphine by fluoxetine and paroxetine.
Theophylline: [P] Decreased metabolism of theophylline by fluvoxamine-induced inhibition of CYP1A2.
See also Anticoagulants, oral; Antidepressants, tricyclic and heterocyclic; β-Adrenoceptor blockers; Carbamazepine; Cisapride; Colchicine; Cyclosporine; HMG-CoA reductase inhibitors; Monoamine oxidase inhibitors; Nonsteroidal anti-inflammatory drugs; Phenytoin; Pimozide; Salicylates.
Beta-adrenoceptor blockers: [NP] Decreased theophylline bronchodilation especially with noncardioselective β blockers.
Smoking: [HP] Increased theophylline metabolism.
Tacrine: [NP] Decreased theophylline metabolism.
Ticlopidine: [NP] Decreased theophylline metabolism.
Zileuton: [NP] Decreased theophylline metabolism.
See also Barbiturates; Calcium channel blockers; Carbamazepine; Cimetidine; Lithium; Macrolides; Phenytoin; Quinolones; Rifampin; Selective serotonin reuptake inhibitors.