Antipsychotic drugs elevate prolactin levels; the elevation persists during chronic administration. Tissue culture experiments indicate that approximately one-third of human breast cancers are prolactin dependent in vitro , a factor of potential importance if the prescription of these drugs is contemplated in a patient with a previously detected breast cancer. Although disturbances such as galactorrhea , amenorrhea , gynecomastia , and impotence have been reported, the clinical significance of elevated serum prolactin levels is unknown for most patients. An increase in mammary neoplasms has been found in rodents after chronic administration of antipsychotic drugs. Neither clinical studies nor epidemiologic studies conducted to date, however, have shown an association between chronic administration of these drugs and mammary tumorigenesis; the available evidence is considered too limited to be conclusive at this time.
Ms. S frequently requires administration of oral and IM haloperidol, as needed, when she becomes aggressive with the staff. She has poor insight into her mental illness and does not believe that she needs medication. Ms. S has a long history of stopping her oral antipsychotic after a few days, reporting that it is “harming her baby.” Monotherapy has been tried with various long-acting injectable antipsychotics (LAIAs), but she still exhibits persistent delusions. The treatment team decides to add a second LAIA, haloperidol decanoate, 200 mg every 4 weeks, to her regimen.