HPE CINV Pocket Guide 2018 | Page 56

the chemotherapy cycle. 27,28 The drug–drug interaction profile of aprepitant is complex. Aprepitant is a substrate and inhibitor of CYP3A4 and an inducer of CYP3A4, CYP2C9 and potentially other isoenzymes. Drug–drug interactions might become relevant when aprepitant is co- administered with corticosteroids, (metabolised through the CYP3A4 pathway) which can lead to an increased exposure to corticosteroids. Therefore, when corticosteroids are administered with aprepitant, doses should be reduced by approximately 50%, except for those cases in which corticosteroids constitute part of the chemotherapeutic regimen. 1,3,27,28 The possibility of increased toxicity should be taken into account when aprepitant is administered with cytotoxics (for example, doxorubicin) that are metabolised by the same pathway. Aprepitant is a weak inducer of CYP2C9, a pathway through which drugs such warfarin and other medications are metabolised (for example, oral contraceptives such as ethinyl estradiol- levonorgestrel). 1,3,27,28 Common adverse reactions reported for aprepitant and fosaprepitant (in part of a combination chemotherapy regimen) include headache, fatigue, anorexia, nausea, constipation, transient mild 56 | 2018 | hospitalpharmacyeurope.com elevation of serum transaminase levels, weakness and hiccups. 1,3,27,28 Aprepitant has been studied extensively in adults and the pharmacokinetic disposition, efficacy, safety and clinical experience in children and adolescents have been investigated. 29–31 A powder for oral suspension has been licensed for prevention of nausea and vomiting associated with MEC and HEC chemotherapy in children, toddlers and infants from the age of six months to 12 years. 30 Clinical trials to study its efficacy in children are ongoing. 32 Netupitant NEPA is an oral fixed dose combination of the highly selective NK1 RA netupitant 300mg and the pharmacologically and clinically distinct 5-HT3 RA, palonosteron 0.5mg. NEPA was approved in the United States (2014) and Europe (2015) for prevention of CINV in patients receiving MEC and HEC (cisplatin HEC + MEC in Europe) and is recommended in international guidelines. 3,33–37 The positive effect in improvement of quality of life of patients has been assessed with NEPA. NEPA plus a single dose of dexamethasone was superior to palonosetron plus dexamethasone in preventing CINV following MEC in acute, delayed and overall