จาก CBC จะพบว่าผู้ป่วยมีปริมาณเม็ดเลือดขาวต่ำ และเป็นลักษณะของ agranulocytosis คือการที่มีนิวโทรฟิลน้อยกว่า 100 /μL (ซึ่งในผู้ป่วยพบว่ามีเพียง 15 /μL)
Phenytoin-Induced Agranulocytosis เป็นผลข้างเคียงที่พบได้แต่น้อยมาก
ใน Agranulocytosis ถ้าอาการต่อเนื่องยาวนานมากกว่า 3-4 สัปดาห์ อัตราการติดเชื้อจะเป็น100%.ผู้ป่วยที่มี agranulocytosis มักจะมีลักษณะดังต่อไปนี้:
-Sudden onset of malaise
-Sudden onset of fever, possibly with chills and prostration
-Stomatitis and periodontitis accompanied by pain
-Pharyngitis, with difficulty in swallowing
การดูแลรักษาคือรีบให้ยาปฎิชีวนะคล้ายกับใน febrile neutropenia หยุดยาที่สงสัยหรือแก้สาเหตุ ถ้าอาการรุนแรงอาจต้องให้ G-CSF หรือ Granulocyte transfusions
Phenytoin adverse drug reaction(hematologic effect)ตอบลบ
Aplastic anemia has occurred secondary to phenytoin administration, with the usual onset being 4 to 13 months after initiation of therapy (average, 9 months) (Robins, 1962; Tomita et al, 1985).
Blood coagulation disorder
Two infants born to mothers treated with 300 to 500 milligrams/day of phenytoin for several years were noted to have partial thromboplastin time and prothrombin time prolongation, with marked reduction in factor 7 and factor 2. The infants were subsequently treated with intramuscular (IM) vitamin K (Solomon et al, 1972b).
a) Eosinophilia was present in 3 patients with phenytoin- induced reversible pseudolymphoma syndrome (Rosenthal et al, 1982). Eosinophilia was also reported in a 10-year-old black female with phenytoin-induced interstitial nephritis (Matson et al, 1985). Three cases of phenytoin-induced necrotizing vasculitis with eosinophilia have been reported, 2 of which resulted in patient fatalities (Gaffey et al, 1986; Yermakov et al, 1983).
a) A cohort study investigating frequency of serious BLOOD DYSCRASIAS in patients taking anticonvulsants has reported the total overall rate for all patients was 3 to 4 per 100,000 prescriptions. Rates did not differ between phenytoin, phenobarbital, carbamazepine, or valproate throughout all age groups (Blackburn et al, 1998). MACROCYTOSIS and MEGALOBLASTIC ANEMIA that respond to folic acid therapy have also occurred (Prod Info Kapseals(R) Dilantin(R), 98).
2) Hematologic complications associated with phenytoin have included thrombocytopenia, reversible bone marrow granulomata, leukopenia, granulocytopenia, agranulocytosis, and pancytopenia with or without bone marrow suppression. Aplastic anemia, hemolytic anemia, macrocytosis, and megaloblastic anemia that respond to folic acid therapy have also occurred.
a) A hemolytic anemia rate of 1.1 per 100,000 phenytoin prescriptions has been reported by the United Kingdom Department of Health's General Practice Research Database with 5-year records of 8068 phenytoin recipients (Blackburn et al, 1998).
a) Rare cases of leukopenia have been reported with phenytoin therapy; however, the majority of cases have occurred with concomitant antiepileptic therapy (Prod Info Kapseals(R) Dilantin(R), 98; O'Connor et al, 1994; Reynolds, 1972; Best, 1968). Leukopenia appears to occur only occasionally, is mild and transient, and usually occurs during the early months of therapy (Reynolds, 1972).
a) Hematologic complications associated with phenytoin have included PANCYTOPENIA with or without bone marrow suppression (Prod Info Kapseals(R) Dilantin(R), 98). Pancytopenia has also been observed following intravenous administration of phenytoin in combination with lidocaine (Tomita et al, 1985). Phenytoin has been associated with AGRANULOCYTOSIS when given in combination with procainamide (Prod Info Kapseals(R) Dilantin(R), 98; Fleet, 1984).
a) A neutropenia rate of 0.5 per 100,000 phenytoin prescriptions has been reported by the United Kingdom Department of Health's General Practice Research Database with 5-year records of 8068 phenytoin recipients (Blackburn et al, 1998).
2) LITERATURE REPORTS
a) A 15-year-old female receiving 300 milligrams/day of phenytoin for 11 days developed neutropenia with symptoms of drowsiness, chills, fever and an unsteady gait (Tsan et al, 1976). Hospitalization of the patient revealed a platelet count of 70,000/cubic millimeter (mm(3)), a white blood cell count of 1200/mm(3) with 78% lymphocytes, and a bone marrow aspiration that demonstrated marked phagocytosis of myeloid precursors by marrow histiocytes. Discontinuation of the phenytoin resulted in defervescence of the patient's fever and the appearance of neutrophils in the peripheral blood within a week.
a) Thrombocytopenia associated with phenytoin is rare. A thrombocytopenia rate of 1.1 per 100,000 phenytoin prescriptions has been reported by the United Kingdom Department of Health's General Practice Research Database with 5-year records of 8068 phenytoin recipients (Blackburn et al, 1998). It usually occurs within 2 to 4 weeks of the beginning of therapy. Phenytoin-induced thrombocytopenia is thought to be the result of an immune-mediated process caused by antiplatelet antibodies induced by phenytoin acting as a hapten. It usually resolves within 5 days of drug discontinuation (Prod Info Kapseals(R) Dilantin(R), 98; Alehan et al, 1999).
ขอบคุณครับคุณ nestaky ข้อมูลเยอะดีครับตอบลบ