Possible Interaction: Theophylline and St John's Wort

“Lastly, multiple herb-drug interactions have been identified with St. John's wort that involve significantly reduced AUC and blood concentrations of warfarin, digoxin, indinavir, theophylline , cyclosporine, tacrolimus, amitriptyline, midazolam, and phenprocoumon.”

“Results from clinical studies and case reports indicate that self-administered SJW reduce steady state plasma concentrations of amitriptyline, cyclosporine, digoxin, fexofenadine, amprenavir, indonavir, lopinavir, ritonavir, saquinavir, benzodiazepines, theophyline , irinotecan, midazolan and warfarin.”

“For example, St John's wort significantly reduced the area under the plasma concentration-time curve (AUC) and blood concentrations of cyclosporine, midazolam, tacrolimus, amitriptyline, digoxin, indinavir, warfarin, phenprocoumon and theophylline.”

“Case reports or case series suggest interactions of St John’s wort with adrenergic vasopressors, anaesthetics, bupropion, buspirone, ciclosporin, eletriptan, loperamide, nefazodone, nevirapine, oral contraceptives, paroxetine, phenprocoumon, prednisone, sertraline, tacrolimus, theophylline , tibolone, tryptophan, venlafaxine and warfarin.”

“Significantly reduced concentrations of various therapeutic drugs such as digoxin, theophylline , cyclosporine, tacrolimus, tricyclic antidepressants, warfarin, and protease inhibitors can be observed due to interaction of these drugs with St. John's wort , causing treatment failure.”

“ St. Johns wort also causes serious pharmacokinetic interactions by activating the cytochrome CYP3A4, dangerously decreasing blood levels of cyclosporin, warfarin, and theophylline , and reducing the efficacy of contraceptive pills and AIDS therapy.”

“St John's wort, a popular herbal antidepressant, increases clearance of many drugs, and abnormally low cyclosporine, digoxin, theophylline , or protease inhibitor concentrations may be observed in a patient taking any of these drugs in combination with St John's wort.”

“For example, low concentrations of several drugs (e.g., cyclosporine, theophylline , digoxin) can be observed in patients who initiated self-medication with St John's wort.”

“This induction may be responsible for reduced plasma theophylline concentrations upon co-administration of SJW , as reported earlier.”

“Recently, a variety of case reports … due to drug combinations with St. John's wort have been published (e.g. cellular rejection of pancreas-, kidney- as well as heart transplants with ciclosporin … with oral anticoagulants, bleeding with oral contraceptives, reduction of plasma concentration of digoxin, indinavir, amitriptyline, and theophylline).”