Recurrence of eosinophilic pneumonia after clozapine treatment

Exploratory disproportionality analysis of potentially drug-induced eosinophilic pneumonia using United States Food and Drug Administration adverse event reporting system

Drug-induced eosinophilic pneumonia (EP) is an uncommon adverse drug reaction. Many drugs have been reported to cause EP, the evidence mainly being in the form of case reports/case series. This study aims to conduct an exploratory analysis of the United States Food and Drug Administration adverse event reporting system (FAERS) database to identify previously unknown drugs that can cause EP and supplement the available evidence for known culprit drugs. A retrospective case-noncase study was conducted using individual case safety reports (ICSRs) reported to the US FAERS from the first quarter of 2004 to the second quarter of 2024. Cases of potentially drug-induced EP were identified using OpenVigil application by conducting a narrow and broad scope search using the Medical Dictionary of Regulatory Activities preferred terms. A base list of drugs described in select literature to have caused EP was used to categorize known and unknown drugs. A disproportionality analysis was performed, with a reporting odds ratio > 2, lower end of the 95% confidence interval > 1, and a minimum of 3 reported cases considered a signal of disproportionate reporting (SDR). During the study period, 8,702,548 individual case safety reports (ICSRs) were submitted to the FAERS. Of these, 855 ICSRs using the narrow scope search and 1411 ICSRs using the broad scope search reported EP. The three most commonly reported drugs with an SDR for EP using the narrow scope search were daptomycin, naltrexone, and prednisone. The most common indications for the use of the drugs were infections, immunological conditions, asthma, and central nervous system disorders. In total, there were 45 drugs with an SDR but no supporting literature evidence available. The number of drugs implicated in causing EP has increased over the years. Several antimicrobial agents, followed by drugs affecting the central nervous system and anticancer drugs, including monoclonal antibodies, can produce EP. The list of suspected drugs identified in this study, especially those with SDR and literature evidence, should be strongly considered as a possible cause in patients presenting with pneumonia not explained otherwise.

Successful rechallenge with clozapine after discontinuation due to drug-induced pneumonia: A case report

Background

There have been a limited number of case reports of clozapine-induced pneumonia. Few have reported rechallenging of clozapine after discontinuation due to the side-effect.

Case Presentation

A 43-year-old man was diagnosed with schizophrenia after developing auditory hallucinations and delusions of persecution and reference. After diagnosing him with treatment-resistant schizophrenia, clozapine was started. From a starting dose of 12.5 mg/day, we increased it by 25 mg every 2-3 days to reach 150 mg/day by Day 15. On Day 17, his body temperature suddenly rose to 39.6°C (103.3°F) without any other apparent physical symptoms. Blood biochemistry testing showed elevated C-reactive protein (CRP) and high counts of leukocytes and neutrophils, but not eosinophils. Chest computed tomography revealed ground-glass opacities in the lower lobes of both lungs. Suspecting bacterial pneumonia, we started him on levofloxacin 500 mg/day. However, pneumonia exacerbated, and eosinophilia became apparent 5 days after the onset of fever. We suspected acute eosinophilic pneumonia induced by clozapine and discontinued its administration the same day. The patient clinically recovered the next day after stopping clozapine. After stopping clozapine, his psychiatric symptoms, such as persecutory/referential delusions, irritability, and polydipsia, became worse. We decided to rechallenge with clozapine in incremental doses slower than the standard protocol, along with careful monitoring of CRP and eosinophil counts. Pneumonia has not recurred, and his psychiatric symptoms have been well managed.

Conclusion

Our experience suggests that some patients with inflammatory reactions to clozapine can still take the drug if it is reintroduced with caution.

Eosinophilic pneumonia during treatment with clozapine: reports from a retrospective case series

Clozapine is an atypical antipsychotic known to cause multiple hematologic abnormalities, most seriously agranulocytosis, but also notably eosinophilia. It is considered as an allergic reaction with a spontaneous remission, however, sometimes, it may predict subsequent major inflammatory complications. The aim of this study was to investigate the relationship between clozapine usage and drug-induced pneumonia based on characteristic respiratory symptoms and radiological findings, retrospectively in 69 Japanese treatment-resistant schizophrenia patients. Comparisons of the 26 weeks consecutive levels: white blood cell count with neutrophil and eosinophil, relative to their baseline levels were performed within total subjects and two groups divided by the findings of pneumonia. The crude odds ratios with 95% confidence intervals for developing pneumonia and potential confounders were calculated. The levels of eosinophils significantly increased at 1 month in each group. The introduction season between October and January and higher eosinophil level at first month were correlated with the risk of pneumonia, which occurred independent of clozapine dosage and term and relapsed in subjects when developed within initial 1 month. Clozapine-induced eosinophilic pneumonia was considered transient and reversible, however, the risks and benefits must be considered and close monitoring should be done to avoid life-threatening conditions during clozapine treatment.

Haematological side effects associated with clozapine: A retrospective study from India

OBJECTIVE

To evaluate the incidence of clozapine induced haematological side effects among patients receiving clozapine.

METHODS

Data of 333 patients who were on clozapine for a mean duration of 52.96 (45.18) months were reviewed for haematological abnormalities.

RESULTS

Most of the patients (n = 320; 96.1 %) were diagnosed with psychotic disorders, mainly schizophrenia. These patients were receiving clozapine in the dose range of 12.5 mg-600 mg/day, with a mean dose of 212.08 (102.43) mg/day at the time of review of their records. About one-tenth (N = 33; 9.9 %) of patients developed eosinophilia (absolute eosinophil count >600), and 8.2 % (N = 27) experienced thrombocytopenia (platelet count <100,000 cmm³) and 7 patients developed anaemia (haemoglobin level <10 gm%). Only 2 (0.6%) patients developed neutropenia. Mean dose (mg/day) at which haematological side-effects occurred were as follows: 159.85 (87.65) mg/day for eosinophilia; 193.98 (148.93) mg/day for thrombocytopenia; 78.57 (22.49) mg/day for anaemia. In a small proportion of patients, clozapine was discontinued due to the haematological abnormalities and in other patients these abnormalities normalized on its own in subsequent follow-up.

CONCLUSION

Clozapine is associated eosinophilia and thrombocytopenia, which are often benign and in majority of the patients these normalize with time.