en داروسازی بالینی Clinical Pharmacy گزارش مورد case report <span style="font-size:11pt"><span style="line-height:200%"><span style="font-family:Calibri,sans-serif"><span style="font-size:12.0pt"><span style="line-height:200%"><span new="" roman="" style="font-family:" times="">Methotrexate (MTX), a folate antagonist, is widely used for the medical management of ectopic pregnancy (EP) and is generally considered safe when administered as a single low-dose regimen (50 mg/m&sup2;). Severe toxicity is rare and typically associated with high-dose or prolonged therapy. We report a case of life-threatening pancytopenia and multisystem toxicity following a single intramuscular 90 mg dose of MTX in a 32-year-old woman with no prior medical history treated for left tubal EP.</span></span></span></span></span></span><br> <span style="font-size:11pt"><span style="line-height:200%"><span style="font-family:Calibri,sans-serif"><span style="font-size:12.0pt"><span style="line-height:200%"><span style="font-family:"Times New Roman",serif"></span></span></span></span></span></span><br> <span style="font-size:11pt"><span style="line-height:200%"><span style="font-family:Calibri,sans-serif"><span style="font-size:12.0pt"><span style="line-height:200%"><span new="" roman="" style="font-family:" times="">Four days after MTX administration, the patient developed gastrointestinal symptoms. By Day 11, she presented with severe pancytopenia, mucositis, petechiae, purpura, hepatic dysfunction, and pleural effusion. She required intensive care unit admission and comprehensive management, including intravenous leucovorin rescue, granulocyte colony-stimulating factor (filgrastim), broad-spectrum antibiotics, antifungal therapy, platelet and packed red blood cell transfusions, urinary alkalinization, and supportive care. Hematologic parameters gradually recovered, with white blood cell count rising from a nadir of 900/&micro;L to 68,300/&micro;L by Day 19, and liver function improved progressively. She was discharged in stable condition.</span></span></span></span></span></span><br> <span style="font-size:11pt"><span style="line-height:200%"><span style="font-family:Calibri,sans-serif"><span style="font-size:12.0pt"><span style="line-height:200%"><span style="font-family:"Times New Roman",serif"></span></span></span></span></span></span><br> <span style="font-size:11pt"><span style="line-height:200%"><span style="font-family:Calibri,sans-serif"><span style="font-size:12.0pt"><span style="line-height:200%"><span new="" roman="" style="font-family:" times="">This case underscores that severe MTX toxicity may occur even after a standard single low dose in patients without recognized risk factors. Pharmacogenetic variability&mdash;particularly polymorphisms in genes involved in folate metabolism and drug transport&mdash;may contribute to heightened susceptibility. Careful clinical and laboratory monitoring, early recognition of atypical symptoms, and prompt initiation of rescue therapy are essential to prevent fatal outcomes.</span></span></span></span></span></span><br> &nbsp; Methotrexate, Ectopic Pregnancy, Pancytopenia, Multisystem toxicity, Genetic susceptibility, Pharmacogenetic 0 0 http://pbr.mazums.ac.ir/browse.php?a_code=A-10-1466-2&slc_lang=en&sid=1 Faezeh Shadfar f94cliniclap@gmail.com 100319475328460012384 100319475328460012384 Yes Assistant Professor of Clinical Pharmacy, Faculty of Pharmacy, Urmia University of Medical Science, Iran. Leila Shadfar fsh971@gmail.com 100319475328460012385 100319475328460012385 No Imam Khomeini Hospital, Urmia University of Medical Sciences, Urmia, Iran.