MEDizzy - A 41-year-old man was admitted to a psychiatric hospital

Feed Library Learning Discuss Leaderboard Journal

NEUROLEPTIC DRUGS

A 41-year-old man was admitted to a psychiatric hospital because of worsening of his psychosis. The man was recently diagnosed with paranoid schizophrenia and had been treated with risperidone and aripiprazole without success. A new treatment was started. One week later, a blood test gave the following results: • White blood cell count: 1200/mm3 (normal 4500−11,000/mm3) • Neutrophils 12% (normal 54−62%) • Red blood cell count: 4.3 million/mm3 (normal 4.0−5.5 million/mm3) • Platelet count: 145,000/mm3 (normal 150,000−400,000/mm3) • Hemoglobin (Hb): 15 g/dL (normal >12 g/dL) Which of the following drugs did the patient most likely receive as the new treatment?

ExplanationThe correct answer is A. The low white blood cell count and the low neutrophil percentage indicate that the man was most likely suffering from drug-induced agranulocytosis. Agranulocytosis is the most fatal adverse drug reaction, accounting for 26% of all drug-related deaths. Clozapine can cause agranulocytosis in about 0.8% of patients (a rate lower than the original estimate of 1 to 2%). The onset of the disorder is variable, as it can occur a few days after starting the treatment or even several years after a daily chronic treatment. However, the first 6 months of clozapine therapy is the period of greatest risk. Discontinuation of the drug usually results in correction of neutrophil count within 30 days. B, D Phenothiazines can cause agranulocytosis, but the risk is only 1/10 that of clozapine. C Agranulocytosis due to these drugs can occur, but it is exceptionally rare.