Cycloserine (Seromycin), used to treat tuberculosisHydralazine (Apresoline), used to treat high blood pressureIsoniazid, used to treat tuberculosisPenicillamine, used to treat rheumatoid arthritisTheophylline (TheoDur), used to treat asthmaAntibiotics, Tetracycline -- All B complex vitamins, including vitamin B6, interfere with the absorption and effectiveness of antibiotic tetracycline.