Adefovir dipivoxil, previously called bis-POM PMEA, with trade names Preveon and Hepsera, is an orally-administered acyclic nucleotide analog reverse transcriptase inhibitor (ntRTI) used for treatment of hepatitis B. It is ineffective against HIV-1. Adefovir dipivoxil is the diester prodrug of adefovir.
For the treatment of chronic hepatitis B in adults with evidence of active viral replication and either evidence of persistent elevations in serum aminotransferases (ALT or AST) or histologically active disease.
Adefovir dipivoxil a diester prodrug of adefovir. Adefovir is an acyclic nucleotide analog with activity against human hepatitis B virus (HBV). The concentration of adefovir that inhibited 50% of viral DNA synthesis (IC50) in vitro ranged from 0.2 to 2.5 μM in HBV transfected human hepatoma cell lines. The combination of adefovir with lamivudine showed additive anti-HBV activity.
Mechanism of action
Adefovir dipivoxil is a prodrug of adefovir. Adefovir is an acyclic nucleotide analog of adenosine monophosphate which is phosphorylated to the active metabolite adefovir diphosphate by cellular kinases. Adefovir diphosphate inhibits HBV DNA polymerase (reverse transcriptase) by competing with the natural substrate deoxyadenosine triphosphate and by causing DNA chain termination after its incorporation into viral DNA. The inhibition constant (Ki) for adefovir diphosphate for HBV DNA polymerase was 0.1 μM. Adefovir diphosphate is a weak inhibitor of human DNA polymerases α and γ with Ki values of 1.18 μM and 0.97μM, respectively.
The approximate oral bioavailability of adefovir from HEPSERA is 59%. When a single oral 10 mg dose is given to chronic hepatitis B patients, the peak plasma concentration (Cmax) of adefovir was 18.4 ± 6.26 ng/mL. This occurred between 0.58 - 4 hours post dose (Tmax). The adefovir area under the plasma concentration-time curve (AUC0–∞) was 220 ± 70.0 ng∙h/mL. Food does not affect the exposure of adeforvir.
Volume of distribution
392 ± 75 mL/kg [Vd at steady state, intravenous administration of 1.0 mg/kg/day]
352 ± 9 mL/kg [Vd at steady state, intravenous administration of 3.0 mg/kg/day]
≤4% over the adefovir concentration range of 0.1 to 25 μg/mL
Following oral administration, adefovir dipivoxil is rapidly converted to adefovir. 45% of the dose is recovered as adefovir in the urine over 24 hours at steady state following 10 mg oral doses. Adefovir is not a substrate of the cytochrome P450 enzymes.
Adefovir is renally excreted by a combination of glomerular filtration and active tubular secretion.
Plasma adefovir concentrations declined in a biexponential manner with a terminal elimination half-life of 7.48 ± 1.65 hours.
469 ± 99.0 mL/min [Patients with Unimpaired renal Function receiving a 10 mg single dose]
356 ± 85.6 mL/min [Patients with mild renal impairement receiving a 10 mg single dose]
237 ± 118 mL/min [Patients with moderate renal impairement receiving a 10 mg single dose]
91.7 ± 51.3 mL/min [Patients with severe renal impairement receiving a 10 mg single dose]
Renal tubular nephropathy characterized by histological alterations and/or increases in BUN and serum creatinine was the primary dose-limiting toxicity associated with administration of adefovir dipivoxil in animals. Nephrotoxicity was observed in animals at systemic exposures approximately 3–10 times higher than those in humans at the recommended therapeutic dose of 10 mg/day.
This compound belongs to the class of chemical entities known as 6-aminopurines. These are purines that carry an amino group at position 6. Purine is a bicyclic aromatic compound made up of a pyrimidine ring fused to an imidazole ring.
Multifunctional enzyme that converts the viral RNA genome into dsDNA in viral cytoplasmic capsids. This enzyme displays a DNA polymerase activity that can copy either DNA or RNA templates, and a ribonuclease H (RNase H) activity that cleaves the RNA strand of RNA-DNA heteroduplexes in a partially processive 3'- to 5'-endonucleasic mode. Neo-synthesized pregenomic RNA (pgRNA) are encapsidated to...
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Catalyzes the reversible transfer of the terminal phosphate group between ATP and AMP. Plays an important role in cellular energy homeostasis and in adenine nucleotide metabolism. Adenylate kinase activity is critical for regulation of the phosphate utilization and the AMP de novo biosynthesis pathways. Plays a key role in hematopoiesis.
Involved in maintaining the homeostasis of cellular nucleotides by catalyzing the interconversion of nucleoside phosphates. Efficiently phosphorylates AMP and dAMP using ATP as phosphate donor, but phosphorylates only AMP when using GTP as phosphate donor. Also displays broad nucleoside diphosphate kinase activity.
Major role in the synthesis of nucleoside triphosphates other than ATP. The ATP gamma phosphate is transferred to the NDP beta phosphate via a ping-pong mechanism, using a phosphorylated active-site intermediate. Possesses nucleoside-diphosphate kinase, serine/threonine-specific protein kinase, geranyl and farnesyl pyrophosphate kinase, histidine protein kinase and 3'-5' exonuclease activities....
Transcription factor activity, sequence-specific dna binding
Major role in the synthesis of nucleoside triphosphates other than ATP. Negatively regulates Rho activity by interacting with AKAP13/LBC. Acts as a transcriptional activator of the MYC gene; binds DNA non-specifically (PubMed:8392752). Exhibits histidine protein kinase activity.
Involved in the renal elimination of endogenous and exogenous organic anions. Functions as organic anion exchanger when the uptake of one molecule of organic anion is coupled with an efflux of one molecule of endogenous dicarboxylic acid (glutarate, ketoglutarate, etc). Mediates the sodium-independent uptake of 2,3-dimercapto-1-propanesulfonic acid (DMPS) (By similarity). Mediates the sodium-in...
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Ho ES, Lin DC, Mendel DB, Cihlar T: Cytotoxicity of antiviral nucleotides adefovir and cidofovir is induced by the expression of human renal organic anion transporter 1. J Am Soc Nephrol. 2000 Mar;11(3):383-93. [PubMed:10703662 ]
Wijnholds J, Mol CA, van Deemter L, de Haas M, Scheffer GL, Baas F, Beijnen JH, Scheper RJ, Hatse S, De Clercq E, Balzarini J, Borst P: Multidrug-resistance protein 5 is a multispecific organic anion transporter able to transport nucleotide analogs. Proc Natl Acad Sci U S A. 2000 Jun 20;97(13):7476-81. [PubMed:10840050 ]
Plays an important role in the excretion/detoxification of endogenous and exogenous organic anions, especially from the brain and kidney. Involved in the transport basolateral of steviol, fexofenadine. Transports benzylpenicillin (PCG), estrone-3-sulfate (E1S), cimetidine (CMD), 2,4-dichloro-phenoxyacetate (2,4-D), p-amino-hippurate (PAH), acyclovir (ACV) and ochratoxin (OTA).