Thyroid and renal tumors in patients treated with long-term lithium: case series from a lithium clinic, review of the literature and international pharmacovigilance reports.

BACKGROUND: Cancer had never been considered as a relevant problem in patients treated with lithium until 2015, when a document published by the European Medicine Agency concluded that long-term use of lithium might induce renal tumors. A few months later, we observed the case of a woman treated with lithium for 18 years who was diagnosed with both thyroid and renal tumors. METHODS: This study aimed to investigate the correlation between lithium treatment and thyroid or renal tumors. We analyzed clinical records in our lithium clinic database, causes of death of patients who had been visited at least once at the lithium clinic, reports of lithium adverse reactions in the European and WHO pharmacovigilance databases, and published cases of thyroid and renal tumors in long-term lithium-treated patients. RESULTS: Of the 1871 lithium patients who had been visited at least once between 1980 and 2013, eight had been diagnosed with thyroid papillary carcinoma and two with clear-cell renal-cell carcinoma. No cases of thyroid cancer and only one case of renal tumor were the cause of death according to the 375 available death certificates. VigiAccess database contained a total of 29 and 14 cases of renal and thyroid tumors, respectively. EudraVigilance database contained 21 cases of renal and 8 of thyroid neoplasms. Literature search yielded 6 published cases of thyroid papillary carcinoma and 25 cases of various renal tumors. However, two population-based studies did not find any increased risks of cancer in patients exposed to lithium, whereas two nationwide studies did not find any excess of renal tumors. CONCLUSION: So far it has not been possible epidemiologically to confirm an increased risk of thyroid or renal cancers associated with lithium. Such a conclusion is supported by the findings of low rates and mortalities of thyroid or renal cancers from the present lithium clinic data.

Clozapine toxicity due to a multiple drug interaction: a case report.

INTRODUCTION: We report the case of a multiple drug interaction involving clozapine, antifungals and oral contraceptives, which resulted in an increased clozapine plasma level, pericarditis with pericardial effusion and eosinophilia in a young Caucasian woman. These symptoms and signs disappeared a few days after discontinuation of clozapine. At present, we are not aware of reports of clozapine-antifungals interaction, whereas there is only one other case report on the interaction between oral contraceptives and clozapine. The purpose of this case report is to show the risk of potentially serious adverse effects stemming from drug interactions involving medications routinely used in clinical practice. CASE PRESENTATION: A 29-year-old Caucasian woman diagnosed with a schizoaffective disorder was admitted to a psychiatric unit for acute psychosis (hallucinations, delusions and catatonic behavior). She denied smoking tobacco products and was on long-term oral contraceptives. During the first month of hospitalization she was treated with antipsychotics and for 1 week she took simultaneously fluconazole and miconazole gel, after being diagnosed with oral candidiasis. On the last day of antifungals treatment, 29 days after admission, clozapine was started with resolution of psychotic symptoms. After 3 weeks, her clozapine plasma level had increased to 542 ng/mL and eosinophilia was observed. She complained of nausea, vomiting and palpitations; echocardiography showed echocardiographic abnormalities and pericardial effusion. Oral contraceptives were discontinued and after 1 week clozapine was interrupted, with a complete resolution of side effects and pericardial effusion within 4 days. CONCLUSIONS: Clozapine is metabolized by cytochrome P450. The use of inhibitors or other substrates of cytochrome P450, such as antifungals and oral contraceptives, can cause long-lasting interactions and clozapine toxicity. The Naranjo algorithm shows clozapine is a definite cause of pericarditis (score 9) and both clozapine-antifungals and clozapine-contraceptives interactions resulted probable (score 5) in Drug Interaction Probability Scale. A good knowledge on drugs that act as substrates, inhibitors or inducers of cytochrome P450 is mandatory. When those drugs are used in patients taking clozapine, blood level monitoring of clozapine should be recommended, since a lower dose of clozapine might be required to prevent clozapine toxicity.

Squamous-cell carcinoma of the tongue following therapy of rheumatoid arthritis with abatacept.

KEY CLINICAL MESSAGE: A patient affected by rheumatoid arthritis developed a squamous-cell carcinoma probably due to abatacept, according to Naranjo algorithm. The case describes this adverse reaction for the first time and highlights the need for additional studies to establish the long-term risk profile of abatacept.