Al- or Mg-containing antacids; Ca, Fe & Zn salts; sucralfate, dairy products, enteral feeds, didanosine w/ Al & Mg ion buffering agents; fenbufen, opioid analgesics, papaveretum; azlocillin; zolmitriptan; antineoplastic & immunosuppressants; foscarnet; cimetidine & ranitidine; probenecid; xanthines eg, theophylline & caffeine.