Limitations and obstacles of the spontaneous adverse drugs reactions reporting: Two “challenging” case reports
A 58-year-old female was admitted to the emergency room for hematuria. A complete blood count was performed, which showed hemoglobin of 15.3 g/dl and a white blood cells count (WBCs) of 4700/mm3. Furthermore, hemogenic tests and urine test revealed a red blood cell carpet on urine sediment analysis. Afterwards, the patient was subjected to urological visit and ultrasonography of the urinary tract that did not evidence any current disease. The woman presented a history of gastric carcinoma with negative follow up, and was currently diagnosed with osteoporosis in advanced stage, with vertebral collapse, which was treated with risedronate 35 mg tablets (one tablet once a week). Two days before admission, the patient had undergone treatment with tizanidine (Navizan®-Athena Pharma Italia S.r.l.) 4 mg tablets (one tablet twice daily) for lower back pain. Her medical history did not reveal either recurrent cystitis or cystitis refractory to therapy or previous urinary tract infections such as to account for the current clinical presentation. There were also no predisposing conditions that could be responsible for the onset of this adverse event. Previous history of drug or alcohol abuse and allergies were not reported.\nSubsequently, tizanidine treatment was discontinued and the patient was treated with ciprofloxacin 500 mg twice a day, which resulted in improvement of the above mentioned renal adverse reaction and related symptoms. To assess the possible causal relationship between the drug and the observed adverse event (causality assessment) the Naranjo probability scale was used.\nThe value obtained by this algorithm was 4 indicative of a possible causal association between the suspected drug and the renal adverse reaction.