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Indications and Dosage
Intravenous
Prophylaxis of chemotherapy-induced nausea and vomiting Adult: In combination therapy w/ a corticosteroid (e.g. dexamethasone) and 5-HT3 antagonist: 150 mg given via IV infusion over 20-30 min approx 30 min prior to chemotherapy on day 1 of cycle only.
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Reconstitution
IV infusion: Add 5 mL of NaCl 0.9% soln to a vial labelled as containing 150 mg. Swirl gently to avoid foaming. Dilute further w/ 145 mL of NaCl 0.9% to a total volume of 150 mL, w/ a final concentration of 1 mg/mL.
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Incompatibility
Incompatible w/ soln containing divalent cations (e.g. Ca, Mg, Hartmann’s soln, lactated Ringer’s inj).
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Contraindications
Hypersensitivity. Concomitant use w/ pimozide, cisapride, terfenadine.
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Special Precautions
Moderate to severe hepatic impairment. Pregnancy and lactation.
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Adverse Reactions
Nervous: Asthenia, fatigue, malaise, dizziness, somnolence, peripheral neuropathy, headache, weakness, anxiety.
CV: Palpitations, hot flush. GI: Nausea, anorexia, constipation, diarrhoea, abdominal pain, GERD, dry mouth, flatulence, eructation, dyspepsia. Resp: Hiccups. Hepatic: Increased ALT/AST, alkaline phosphatase. Genitourinary: UTI, dysuria. Haematologic: Neutropenia, anaemia, leucopenia. Musculoskeletal: Limb pain. Dermatologic: Pruritus, acne, urticaria. Others: Infusion site reactions (e.g. pain, induration). Potentially Fatal: Hypersensitivity reactions (e.g. Steven-Johnson syndrome/toxic epidermal necrolysis, anaphylaxis and anaphylactic shock). |
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IV/Parenteral: B
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Patient Counseling Information
This drug may cause dizziness and fatigue, if affected, do not drive or operate machinery.
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Monitoring Parameters
Monitor INR (in patients taking warfarin) for 2 wk (particularly at 7-10 days) following admin; signs or symptoms of hypersensitivity reaction.
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Drug Interactions
Decreased INR of prothrombin time w/ warfarin. Increased plasma concentration of midazolam or other benzodiazepines (e.g. alprazolam, triazolam). May decrease efficacy of OC. May decrease plasma concentration of CYP2C9 substrates (e.g. tolbutamide). Increased exposure w/ CYP3A4 inhibitors (e.g. clarithromycin, ketoconazole, protease inhibitors, nefazodone). Decreased serum concentration w/ phenytoin. Decreased exposure w/ CYP3A4 inducers (e.g. rifampicin, carbamazepine). May increase serum concentration of corticosteroids.
Potentially Fatal: Increased serum concentration and risk of QT interval prolongation w/ pimozide, cisapride, terfenadine. |
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Food Interaction
Increased serum concentration w/ grapefruit and grapefruit juice. Decreased serum concentration w/ St John’s wort.
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Action
Description:
Mechanism of Action: Fosaprepitant is a prodrug of aprepitant. It prevents acute and delayed emesis by inhibiting a substance P/neurokin-1 (NK1) receptor. It also augments antiemetic effect of 5HT3 receptor antagonist and corticosteroids. Pharmacokinetics: Absorption: Time to peak plasma concentration: W/in 30 min. Distribution: Aprepitant: Crosses blood brain barrier. Volume of distribution: Approx 70 L. Plasma protein binding: >95%. Metabolism: Rapidly converted in hepatic and extrahepatic tissues into aprepitant which undergoes extensive metabolism via oxidation primarily by CYP3A4 enzyme and some by CYP1A2 and CYP2C19 enzymes into 7 weakly-active metabolites. Excretion: Mainly via urine (57% as metabolites); faeces (45% as metabolites). Elimination half-life: Approx 9-13 hr. |
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Chemical Structure
 Source: National Center for Biotechnology Information. PubChem Database. Fosaprepitant, CID=135413538, https://pubchem.ncbi.nlm.nih.gov/compound/Fosaprepitant (accessed on Jan. 21, 2020) |
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Storage
Store between 2-8°C.
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MIMS Class
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References
Anon. Fosaprepitant. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 08/09/2017. Buckingham R (ed). Fosaprepitant. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 08/09/2017. Emend Injection Powder, Lyophilized for Solution (Merck Sharp and Dohme Corp.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 08/09/2017. Joint Formulary Committee. Fosaprepitant. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 08/09/2017. McEvoy GK, Snow EK, Miller J et al (eds). Aprepitant/Fosaprepitant Dimeglumine. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 08/09/2017. Preston CL (ed). Interactions Search Results for Fosaprepitant Pimozide. Stockley’s Drug Interactions [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 11/09/2017.
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