Atomoxetine Use May Cause Leukopenia

Abstract

Hematologic disabilities following drug use remains a major problem of drug therapy. Drug-induced leukopenia is a potentially life-threatening side effect that may occur secondary to therapy with various agents. Psychotropic agents may also cause leukopenia (1). Atomoxetine is a selective norepinephrine reuptake inhibitor, known as a non-stimulating and safe alternative therapy for the treatment of ADHD (Attention Deficit Hyperactivity Disorder) particularly in cases of anxiety disorder and Tourette disorder as a co-diagnosis. Most commonly known side effects are weight loss, nausea, chest pain, numbness and burning pain. Hematologic side effects associated with the use of atomoxetine are rare (2). Here, we report the case of a patient with leukopenia associated with atomoxetine. Mr. A was a 15-years old adolescent diagnosed with ADHD according to Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) criteria at a child and adolescent psychiatry outpatient clinic (There was no additional psychopathology according to Kiddie Schedule for Affective Disorders and Schizophrenia for School-Age Children—Present and Lifetime Version (K-SADS-PL) and the Wechsler Intelligence Scale for Children-Revised (WISC-R) is considered normal.). Complete blood count (CBC) values were as follows: Thyroid-Stimulating Hormone (TSH), tetraiodothyronine (sT4), liver functions, kidney functions, ferritin, folate, vitamin B12, and vitamin D seen at normal level. White blood cell (WBC) count was 7.2 (103/μL), haemoglobin (Hb) was 15.7 (g/dL), and platelet count was 246 (103/ μL). Body mass index was 22 and body weight was 63 kilograms. Atomoxetine was prescribed and it was planned to gradually titrate to 60 mg/day. Partial remission was seen at 40 mg/day dose. After 10 days of 60 mg/day increased dose, the patient was admitted to the emergency department with abdominal pain. CBC showed WBC count 2.2 (103/μL), Hb 15.5 (g/dL), and platelet count 263 (103/μL). No infection source could be detected (Sedimentation rate and C-reactive protein were at normal levels). There was no history of fever or additional use of drugs. It was thought that leukopenia and abdominal pain may be related to the use of atomoxetine and the drug was discontinued. CBC were applied 5 days after drug discontinuation: WBC 6.6 (103/ μL), Hb 15.5 (g/dL), and platelet count 235 (103/μL). Methylphenidate treatment was recommended but the family did not accept it. A similar complaint and blood dyscrasia were not encountered in the follow-up. Naranjo Adverse Drug Reactions Probability Scale score was 8 (3). Psychotropic medications can influence hematologic parameters. Leukopenia is a rare but important hematologic disorder that may result in hospitalization (1). Possible mechanisms of toxicity include: (I) inhibiting LETTER TO THE EDITOR