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Fosamprenavir
Clinical data
Trade names	Lexiva, Telzir
Other names	Fosamprenavir calcium (USAN US)
AHFS/Drugs.com	Monograph
MedlinePlus	a604012
License data	EU EMA: by INN;
Pregnancy; category	AU: B3; ;
Routes of; administration	By mouth
ATC code	J05AE07 (WHO) ;
Legal status
Legal status	CA: ℞-only; UK: POM (Prescription only); US: ℞-only; EU: Rx-only;
Pharmacokinetic data
Bioavailability	Unknown
Protein binding	90%
Metabolism	Hydrolysed to amprenavir and phosphate in GI tract epithelium
Elimination half-life	7.7 hours
Excretion	Fecal (as metabolites of amprenavir)
Identifiers
	IUPAC name {[(2R,3S)-1-[N-(2-methylpropyl)(4-aminobenzene)sulfonamido]-3-({[(3S)-oxolan-3-yloxy]carbonyl}amino)-4-phenylbutan-2-yl]oxy}phosphonic acid;
CAS Number	226700-79-4 ; as salt: 226700-81-8 ;
PubChem CID	131536; as salt: 131535;
DrugBank	DB01319 ; as salt: DBSALT001228;
ChemSpider	116245 ; as salt: 116244;
UNII	WOU1621EEG; as salt: ID1GU2627N ;
KEGG	D02497 ; as salt: D03835;
ChEBI	CHEBI:82941;
ChEMBL	ChEMBL1664 ; as salt: ChEMBL1200734;
NIAID ChemDB	082186;
CompTox Dashboard (EPA)	DTXSID2048296 ;
Chemical and physical data
Formula	C25H36N3O9PS
Molar mass	585.61 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES O=C(O[C@H]1CCOC1)N[C@@H](Cc2ccccc2)[C@H](OP(=O)(O)O)CN(CC(C)C)S(=O)(=O)c3ccc(N)cc3;
	InChI InChI=1S/C25H36N3O9PS/c1-18(2)15-28(39(33,34)22-10-8-20(26)9-11-22)16-24(37-38(30,31)32)23(14-19-6-4-3-5-7-19)27-25(29)36-21-12-13-35-17-21/h3-11,18,21,23-24H,12-17,26H2,1-2H3,(H,27,29)(H2,30,31,32)/t21-,23-,24+/m0/s1 ; Key:MLBVMOWEQCZNCC-OEMFJLHTSA-N ; ; as salt: InChI=1S/C25H36N3O9PS.Ca/c1-18(2)15-28(39(33,34)22-10-8-20(26)9-11-22)16-24(37-38(30,31)32)23(14-19-6-4-3-5-7-19)27-25(29)36-21-12-13-35-17-21;/h3-11,18,21,23-24H,12-17,26H2,1-2H3,(H,27,29)(H2,30,31,32);/q;+2/p-2/t21-,23-,24+;/m0./s1; Key:PMDQGYMGQKTCSX-HQROKSDRSA-L;
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Fosamprenavir (FPV), sold under the brand names Lexiva and Telzir, is a medication used to treat HIV/AIDS.^[3]^[4] It is a prodrug of the protease inhibitor and antiretroviral drug amprenavir.^[5] It is marketed by ViiV Healthcare as the calcium salt.^[3]^[4]

Fosamprenavir was approved for medical use in the United States in October 2003,^[6] and in the European Union in July 2004.^[4] The human body metabolizes fosamprenavir in order to form amprenavir, which is the active ingredient.^[3]

A head-to-head study with lopinavir showed the two drugs to have comparable potency, but patients on fosamprenavir tended to have a higher serum cholesterol.^[7]

Medical uses

Fosamprenavir is used for the treatment of HIV-1 infections, typically but not necessarily in combination with low-dose ritonavir or other antiviral drugs.^[8]^[9]

Adverse effects

The most common adverse effect is diarrhea. Other common side effects include headache, dizziness and exanthema, which is usually transient. Severe allergic reactions (Stevens–Johnson syndrome) are rare.^[8]

Interactions

Amprenavir (the active metabolite of fosamrenavir, which is found in blood plasma, liver and other organs) is metabolized via the liver enzyme CYP3A4 and also weakly inhibits this enzyme. This means that combination with drugs that are also metabolized by CYP3A4 can increase their plasma concentrations and thus side effects; and combination with drugs that inhibit CYP3A4 can increase amprenavir concentrations.^[8]

When combining fosamprenavir with low doses of the CYP3A4 inhibitor ritonavir, this interaction is intended as it allows for application of lower fosamprenavir doses.^[8]

Pharmacology

Fosamprenavir is quickly activated to amprenavir, even before it reaches the circulation. Amprenavir is a HIV protease inhibitor.^[8]

References

^ "Telzir Product information". Health Canada. 25 April 2012. Archived from the original on 14 June 2021. Retrieved 2 October 2022.
^ "Telzir 700 mg film-coated tablets - Summary of Product Characteristics (SmPC)". (emc). 22 June 2021. Archived from the original on 6 December 2021. Retrieved 2 October 2022.
^ ^a ^b ^c ^d "Lexiva- fosamprenavir calcium tablet, film coated Lexiva- fosamprenavir calcium suspension". DailyMed. 1 October 2020. Archived from the original on 29 January 2022. Retrieved 2 October 2022.
^ ^a ^b ^c ^d "Telzir EPAR". European Medicines Agency. 17 September 2018. Archived from the original on 15 May 2021. Retrieved 2 October 2022.
^ "Fosamprenavir Monograph for Professionals". Archived from the original on 2021-06-28. Retrieved 2022-10-03.
^ "Drug Approval Package: Lexiva (Fosamprenavir Calcium) NDA #021548". U.S. Food and Drug Administration (FDA). Archived from the original on 15 April 2021. Retrieved 2 October 2022.
^ Eron J, Yeni P, Gathe J, Estrada V, DeJesus E, Staszewski S, et al. (August 2006). "The KLEAN study of fosamprenavir-ritonavir versus lopinavir-ritonavir, each in combination with abacavir-lamivudine, for initial treatment of HIV infection over 48 weeks: a randomised non-inferiority trial". Lancet. 368 (9534): 476–82. doi:10.1016/S0140-6736(06)69155-1. PMID 16890834. S2CID 33612672.
^ ^a ^b ^c ^d ^e Jasek W, ed. (2007). Austria-Codex (in German) (62nd ed.). Vienna: Österreichischer Apothekerverlag. pp. 8009–17. ISBN 978-3-85200-181-4.
^ Lexiva. Drugs.com (Report). Monograph.
^ Shen CH, Wang YF, Kovalevsky AY, Harrison RW, Weber IT (September 2010). "Amprenavir complexes with HIV-1 protease and its drug-resistant mutants altering hydrophobic clusters". The FEBS Journal. 277 (18): 3699–714. doi:10.1111/j.1742-4658.2010.07771.x. PMC 2975871. PMID 20695887.

External links

"Fosamprenavir". Drug Information Portal. U.S. National Library of Medicine.
"Fosamprenavir calcium". Drug Information Portal. U.S. National Library of Medicine.