title: Letter: Elimination of interference by phenazopyridine hydrochloride ("Pyridium") in determining ethchlorvynol ("Placidyl").
mesh_terms: D000779:Anesthetics, Local / Q000097:blood*; D002725:Chloroform; D003124:Colorimetry; D004984:Ethchlorvynol / Q000097:blood* / Q000652:urine; D005069:Evaluation Studies as Topic; D005189:False Positive Reactions; D006801:Humans; D008722:Methods; D010621:Phenazopyridine / Q000097:blood / Q000652:urine; D011725:Pyridines / Q000097:blood*
chemical_list: D000779:Anesthetics, Local; D011725:Pyridines; D004984:Ethchlorvynol; D002725:Chloroform; D010621:Phenazopyridine