Clozapine and patient safety

Characteristics and causes of reported clozapine-related medication errors: analysis of the Ministry of Health database in Saudi Arabia

BACKGROUND

Clozapine has shown great efficacy in treating treatment-resistant schizophrenia, but it is associated with a variety of medication- related safety problems. Despite this, there remains a lack of research on medication errors (MEs) associated with its use.

AIM

To characterize the nature and contributory factors of clozapine-related MEs reported from government hospitals and primary care centres in Saudi Arabia (SA).

METHOD

A cross-sectional analysis was carried out on MEs related to clozapine use reported to the General Administration of Pharmaceutical Care at the Ministry of Health (MOH) in Saudi Arabia between 2018 and 2022. The data were analysed descriptively to examine the nature and contributory factors of MEs.

RESULTS

A total of 1,165 MEs were reported. The majority of reported errors involved patients aged > 18 years old, with 72.2% (n = 841) being male. The central region was found to report errors more frequently (32.3%, n = 376). Pharmacists were reported to detect errors most frequently (59.6%, n = 695). MEs most often occurred in the prescribing stage (77.8%, n = 906), with "missing prescription information" (30.1%, n = 351) being the most frequent finding. The most frequent contributing factor was the lack of policy (33.1%, n = 351). The majority of errors did not reach the patients (92.3%, n = 1,075), and those that did reach patients rarely resulted in harm (0.3%, n = 2).

CONCLUSION

This study identified areas for improvement which could expedite the development of remedial interventions to reduce the risk of errors.

Cost-effectiveness of HLA-DQB1/HLA-B pharmacogenetic-guided treatment and blood monitoring in US patients taking clozapine

Less than 1% of adult patients with schizophrenia taking clozapine develop agranulocytosis, and most of these cases occur within the first weeks of treatment. The human leukocyte antigen (HLA) region has been associated with genetic susceptibility to clozapine-induced agranulocytosis (single amino acid changes in HLA-DQB1 (126Q) and HLA-B (158T)). The current study aimed to evaluate the cost-effectiveness, from a healthcare provider’s perspective, of an HLA genotype-guided approach in patients with treatment-resistant schizophrenia who were taking clozapine and to compare the results with the current absolute neutrophil count monitoring (ANCM) schemes used in the USA. A semi-Markovian model was developed to simulate the progress of a cohort of adult men and women who received clozapine as a third-line antipsychotic medication. We compared current practices using two genotype-guided strategies: (1) HLA genotyping followed by clozapine, with ANCM only for patients who tested positive for one or both alleles (genotype-guided blood sampling); (2) HLA genotyping followed by clozapine for low-risk patients and alternative antipsychotics for patients who tested positive (clozapine substitution scheme). Up to a decision threshold of $3.9 million per quality-adjusted life-year (90-fold the US gross domestic product per capita), the base-case results indicate that compared with current ANCM, genotype-guided blood sampling prior to clozapine initiation appeared cost-effective for targeted blood monitoring only in patients with HLA susceptibility alleles. Sensitivity analysis demonstrated that at a cost of genotype testing of up to USD700, HLA genotype-guided blood monitoring remained a cost-effective strategy compared with either current ANCM or clozapine substitution.