Phosphorylated Morpholine Acetal Human Neurokinin-1 Receptor Antagonists as Water-Soluble Prodrugs
Merck Research Laboratories, P.O. Box 2000, Rahway, New Jersey 07065, and Merck, Sharp & Dohme, Neuroscience Research Centre, Terlings Park, Eastwick Road, Harlow, Essex CM20 2QR, U.K. Journal of Medicinal Chemistry
(Impact Factor: 5.45).
04/2000; 43(6):1234-41. DOI: 10.1021/jm990617v
The regioselective dibenzylphosphorylation of 2 followed by catalytic reduction in the presence of N-methyl-D-glucamine afforded 2-(S)-(1-(R)-(3, 5-bis(trifluoromethyl)phenyl)ethoxy)-3-(S)-(4-fluoro)phenyl-4-(5-(2- phosphoryl-3-oxo-4H,-1,2,4-triazolo)methylmorpholine, bis(N-methyl-D-glucamine) salt, 11. Incubation of 11 in rat, dog, and human plasma and in human hepatic subcellular fractions in vitro indicated that conversion to 2 would be expected to occur in vivo most readily in humans during hepatic circulation. Conversion of 11 to 2 occurred rapidly in vivo in the rat and dog with the levels of 11 being undetectable within 5 min after 1 and 8 mg/kg doses iv in the rat and within 15 min after 0.5, 2, and 32 mg/kg doses iv in the dog. Compound 11 has a 10-fold lower affinity for the human NK-1 receptor as compared to 2, but it is functionally equivalent to 2 in preclinical models of NK-1-mediated inflammation in the guinea pig and cisplatin-induced emesis in the ferret, indicating that 11 acts as a prodrug of 2. Based in part on these data, 11 was identified as a novel, water-soluble prodrug of the clinical candidate 2 suitable for intravenous administration in humans.
Available from: Mithun Raje
- "One drawback of aprepitant was its low water solubility that required a special formulation. Phosphorylation of the oxotriazolyl ring produced a water soluble pro-drug L-758,298 (Fig. 6) later renamed fosaprepitant (Hale et al., 2000). This compound metabolically converted to aprepitant, both in vitro and in vivo, displayed high efficacy in the treatment of CINV (Navari, 2008). "
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ABSTRACT: Nausea and vomiting are major side effects of chemotherapy and one key reason for non-compliance with cancer treatment. The introduction of 5-HT3 receptor antagonists in the 1990s was a major advance in the prevention of acute emesis, and highlighted the critical role of serotonin in the emetic response. The next major advance in the treatment of chemotherapy induced nausea and vomiting (CINV) occurred in 2003 with the introduction of aprepitant, a tachykinin 1 (NK1) receptor antagonist. Aprepitant not only reduced acute emesis but also helped in the reduction of delayed emesis. Also in 2003, palonosetron, a second generation 5-HT3 receptor antagonist became available. Unlike the first generation 5-HT3 receptor antagonists, palonosetron demonstrated efficacy in preventing both acute and delayed emesis. This review focuses on the mechanism of action of 5-HT3 and NK1 receptor antagonists in acute and delayed CINV prevention. We discuss first, the medicinal chemistry that led to the discovery of these antagonists to underline their common structural features. Second, we discuss their performance in the clinic and what it tells us about the emetic response. Finally, we present recent mechanistic studies that help provide a rationale for efficacy differences between palonosetron and other 5-HT3 receptor antagonists in the clinic. In vitro and in vivo experiments have shown that palonosetron can inhibit substance P-mediated responses, presumably through its unique interactions with the 5-HT3 receptor. The crossroads of acute and delayed emesis seem to include interactions among the 5-HT3 and NK1 receptor signaling pathways and inhibitions of these interactions could lead to improved treatment of CINV.
Available from: Hirohisa Yoshizawa
- "Fosaprepitant is a water-soluble phosphoryl prodrug for aprepitant. When administered intravenously, fosaprepitant is rapidly converted to aprepitant . Treatment with fosaprepitant (115 mg) has been initially approved in Western countries as an alternative to oral aprepitant (125 mg) on day 1 of a 3-day antiemetic regimen. "
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We evaluated the efficacy and safety of single-dose fosaprepitant in combination with intravenous granisetron and dexamethasone.Patients and methodsPatients receiving chemotherapy including cisplatin (≥70 mg/m(2)) were eligible. A total of 347 patients (21% had received cisplatin with vomiting) were enrolled in this trial to receive the fosaprepitant regimen (fosaprepitant 150 mg, intravenous, on day 1 in combination with granisetron, 40 μg/kg, intravenous, on day 1 and dexamethasone, intravenous, on days 1-3) or the control regimen (placebo plus intravenous granisetron and dexamethasone). The primary end point was the percentage of patients who had a complete response (no emesis and no rescue therapy) over the entire treatment course (0-120 h).ResultsThe percentage of patients with a complete response was significantly higher in the fosaprepitant group than in the control group (64% versus 47%, P = 0.0015). The fosaprepitant regimen was more effective than the control regimen in both the acute (0-24 h postchemotherapy) phase (94% versus 81%, P = 0.0006) and the delayed (24-120 h postchemotherapy) phase (65% versus 49%, P = 0.0025).Conclusions
Single-dose fosaprepitant used in combination with granisetron and dexamethasone was well-tolerated and effective in preventing chemotherapy-induced nausea and vomiting in patients receiving highly emetogenic cancer chemotherapy, including high-dose cisplatin.
Available from: Ian Olver
- "Fosaprepitant dimeglumine is a white powder which is freely water soluble and is a phosphoryl prodrug of aprepitant (Hale et al 2000). Its antiemetic properties are attributable to aprepitant, which is a selective neurokinin 1 (NK1) receptor antagonist with low affi nity for NK2 and NK3 receptors (Watson et al 1998). "
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ABSTRACT: Fosaprepitant is a prodrug of aprepitant, a neurokinin(1) (NK(1)) receptor antagonist used in prophylactic antiemetic regimens used prior to cytotoxic chemotherapy. Fosaprepitant is being developed to provide a parenterally administered alternative to the orally administered aprepitant. Fosaprepitant is rapidly converted to aprepitant and an intravenous dose of 115 mg is bioequivalent to 125 mg orally, with similar plasma concentrations at 24 hours. In phase I and II trials fosaprepitant shows efficacy, but the large randomized efficacy studies have utilized aprepitant. When it is added to dexamethasone and a 5HT(3) receptor antagonist on day 1 prior to chemotherapy aprepitant improves the control of acute post chemotherapy emesis and when continued on days 2 and 3 with dexamethasone it demonstrated even greater improvement in the control of delayed emesis. This has been shown with both cisplatin-containing regimens and those based upon cyclophosphamide and an anthracycline. Fosaprepitant is well tolerated with mild to moderate venous irritation being the only additional toxicity to those seen with oral aprepitant, and that is a function of dose, concentration, and infusion rate. Headaches are the other toxicity most commonly reported. Fosaprepitant can be used as a parenteral alternative to aprepitant in regimens to control chemotherapy-induced emesis.
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