In March 2020, the FDA offered the following guidance for the REMS program:
Since there is not specific guidance from REMS or FDA, clinicians prescribing clozapine should weigh the potential risks and benefits of Absolute Neutrophil Count (ANC) in individual patients. These should be discussed with patients, and there should be an informed consent discussion with any changes in testing. There are likely to be patients for whom risks related to contracting COVID while getting blood drawn are higher than the risk of not having an ANC test. In evaluating risks, clinicians can include consideration of the following: About two thirds of cases of severe neutropenia occur during the first three months of exposure to clozapine. About one tenth occur between four and six months. The rest occur at a low rate after that period. While risk factors for serious COVID related complications are not yet fully defined, risk appears increased with older age, concurrent medical problems, immunosuppression, and pulmonary problems. With regard to serious mental illness, note that this population may be at increased risk for chronic obstructive pulmonary disease, asthma, obesity and diabetes; and rates of smoking are very high.