4CPS-014 Comparison of two protocols for the administration of leucovorin rescues after high dose methotrexate infusion of 24 hours

• Published in: European journal of hospital pharmacy. Science and practice 2023-03, Vol.30 (Suppl 1), p.A28-A28
• Main Authors: Escolà Rodríguez, A, Arranz Pasqual, N, Bastida, C, Albanell, M, Monge Escartín, I, Maté Arbaiza, P, Ruiz Boy, S, Carcelero San Martín, E, Soy Muner, D
• Format: Article
• Language: English
• Subjects: Conflicts of interest; Creatinine; Drug dosages; Lymphoma; Section 4: Clinical pharmacy services
• ISSN: 2047-9956; 2047-9964
• DOI: 10.1136/ejhpharm-2023-eahp.61

Background and ImportanceTherapeutic drug monitoring (TDM) of methotrexate (MTX) in plasma is a standard procedure to early identify patients with delayed drug elimination and adjust leucovorin dose. Adequate leucovorin rescues (LR) should start within 42-48h of the beginning of high dose (HD)-24h-MTX infusion to avoid MTX toxicity but extending LR more than needed can reduce MTX antitumour effect. Before implementation of new PETHEMA-2019 protocol at our hospital, standard LR were prescribed and MTX plasma concentration was determined 48h after infusion completion. Following new protocol recommendations, pharmacists started TDM.Aim and ObjectivesTo assess whether the implementation of the new protocol allowed reducing the total leucovorin dose administered after HD-24h-MTX infusion. Secondary outcomes: compare the incidence of toxicity and the level of compliance of appropriate MTX sampling times and LR between both protocolsMaterial and MethodsRetrospective observational study conducted at a university tertiary hospital. Adults treated with a HD-24h-MTX infusion as treatment for acute lymphoblastic leukaemia (ALL) and Burkitt lymphoma from May 2019 to June 2022 were included. Patients were stratified (1:1) according to the protocol followed. Data collected were: age, sex, haematology malignancy, MTX dose, LR and serum creatinine.ResultsFifty-eight HD-24h-MTX infusions were analysed corresponding to 20 patients for the new protocol (75% males; mean ± SD age 49 ± 15 years; 7 with lymphoma, 11 ALL-B, 2 ALL-T) and to 20 for the original (65% male; mean ± SD age 49 ± 16 years; 10 lymphoma; 7 ALL-B, 3 ALL-T). The median [interquartile range] leucovorin dose administered per cycle following the original protocol was an 87% higher than the dose administered with the new protocol (597 mg/m2 [475,700] vs 75 mg/m2 [45,180], p