Medications with narrow therapeutic windows include theophylline, digoxin, lithium, and warfarin. Both theophylline and isoniazid levels should be monitored. Examples include caffeine, theophylline, and theobromine. Disulfiram disrupts metabolism of several other compounds, including paracetamol (acetaminophen), theophylline and caffeine. Tea contains small amounts of theobromine and slightly higher levels of theophylline than coffee. When theophylline is administered intravenously, bioavailability is 100%. Yerba mate contains three xanthines&colon; caffeine, theobromine and theophylline, the main one being caffeine. Tea also contains small amounts of theobromine and theophylline. It is classified as a xanthine alkaloid, others of which include theophylline and caffeine. There are some cases of theophylline slowing down isoniazid elimination. Paraxanthine is believed to exhibit a lower toxicity than caffeine and the caffeine metabolite, theophylline. Aminophylline is a compound of the bronchodilator theophylline with ethylenediamine in 2&colon;1 ratio. Flumequine was found to have no effect on theophylline pharmacokinetics. Theophylline toxicity can be treated with beta blockers. Lower concentrations of theophylline, theobromine, paraxanthine, liberine, and methylliberine can be found.