2-Phosphonomethylpentanedioic acid (1, 2-PMPA) is a potent inhibitor of glutamate carboxypeptidase II which has demonstrated robust neuroprotective efficacy in many neurological disease models. However, 1 is highly polar containing a phosphonate and two carboxylates, severely limiting its oral bioavailability. We strategized to mask the polar groups via a prodrug approach, increasing the likelihood of passive oral absorption. Our initial strategy was to cover the phosphonate with hydrophobic moieties such as pivaloyloxymethyl (POM) and isopropyloxycarbonyloxymethyl (POC) while keeping the α- and γ-carboxylates unsubstituted. This attempt was unsuccessful due to the chemical instability of the bis-POC/POM derivatives. Addition of α,γ-diesters and α-monoesters enhanced chemical stability and provided excellent oral exposure in mice, but these mixed esters were too stable in vivo, resulting in minimal release of 1. By introducing POC groups on both the phosphonate and α-carboxylate, we synthesized Tris-POC-2-PMPA (21b), which afforded excellent release of 1 following oral administration in both mice and dog.
- MeSH
- Antigens, Surface MeSH
- Administration, Oral MeSH
- Biological Availability MeSH
- Glutamate Carboxypeptidase II antagonists & inhibitors MeSH
- Protease Inhibitors chemistry pharmacology MeSH
- Microsomes, Liver MeSH
- Humans MeSH
- Mice MeSH
- Neuroprotective Agents chemical synthesis pharmacology MeSH
- Drug Discovery MeSH
- Prodrugs chemical synthesis pharmacology MeSH
- Dogs MeSH
- In Vitro Techniques MeSH
- Structure-Activity Relationship MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Mice MeSH
- Dogs MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, N.I.H., Extramural MeSH
2-(Phosphonomethyl)-pentanedioic acid (2-PMPA) is a potent (IC50 = 300 pM) and selective inhibitor of glutamate carboxypeptidase II (GCPII) with efficacy in multiple neurological and psychiatric disease preclinical models and more recently in models of inflammatory bowel disease (IBD) and cancer. 2-PMPA (1), however, has not been clinically developed due to its poor oral bioavailability (<1%) imparted by its four acidic functionalities (c Log P = -1.14). In an attempt to improve the oral bioavailability of 2-PMPA, we explored a prodrug approach using (5-methyl-2-oxo-1,3-dioxol-4-yl)methyl (ODOL), an FDA-approved promoiety, and systematically masked two (2), three (3), or all four (4) of its acidic groups. The prodrugs were evaluated for in vitro stability and in vivo pharmacokinetics in mice and dog. Prodrugs 2, 3, and 4 were found to be moderately stable at pH 7.4 in phosphate-buffered saline (57, 63, and 54% remaining at 1 h, respectively), but rapidly hydrolyzed in plasma and liver microsomes, across species. In vivo, in a single time-point screening study in mice, 10 mg/kg 2-PMPA equivalent doses of 2, 3, and 4 delivered significantly higher 2-PMPA plasma concentrations (3.65 ± 0.37, 3.56 ± 0.46, and 17.3 ± 5.03 nmol/mL, respectively) versus 2-PMPA (0.25 ± 0.02 nmol/mL). Given that prodrug 4 delivered the highest 2-PMPA levels, we next evaluated it in an extended time-course pharmacokinetic study in mice. 4 demonstrated an 80-fold enhancement in exposure versus oral 2-PMPA (AUC0-t: 52.1 ± 5.9 versus 0.65 ± 0.13 h*nmol/mL) with a calculated absolute oral bioavailability of 50%. In mouse brain, 4 showed similar exposures to that achieved with the IV route (1.2 ± 0.2 versus 1.6 ± 0.2 h*nmol/g). Further, in dogs, relative to orally administered 2-PMPA, 4 delivered a 44-fold enhanced 2-PMPA plasma exposure (AUC0-t for 4: 62.6 h*nmol/mL versus AUC0-t for 2-PMPA: 1.44 h*nmol/mL). These results suggest that ODOL promoieties can serve as a promising strategy for enhancing the oral bioavailability of multiply charged compounds, such as 2-PMPA, and enable its clinical translation.
- MeSH
- Administration, Oral MeSH
- Biological Availability MeSH
- Microsomes, Liver metabolism MeSH
- Mice MeSH
- Organophosphorus Compounds administration & dosage chemistry metabolism pharmacokinetics MeSH
- Prodrugs administration & dosage chemistry metabolism pharmacokinetics MeSH
- Dogs MeSH
- Tissue Distribution MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Mice MeSH
- Dogs MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, N.I.H., Extramural MeSH
The total content of rat liver microsomal cytochrome P450 (CYP) significantly decreased after repeated i.p. administration of the antiviral agent tenofovir ((R)-9-[2-(phosphonomethoxy)propyl] adenine) and tenofovir disoproxil at a daily dose 25 mg/kg, although the content of liver microsomal protein did not change. The decrease of the CYP content was accompanied by concomitant increase of the amount of inactive CYP form, cytochrome P420. This effect was confirmed by a parallel study of the activities of selected CYP forms, CYP2E1 (p-nitrophenol hydroxylation) and CYP1A2 (7-ethoxyresorufin deethylation). The activity (expressed relatively to the protein content) of both CYP forms decreased significantly following the decrease of the total CYP. On the other hand, the CYP2E1 activity expressed relatively to the decreasing total CYP content remained unchanged. However, CYP1A2 activity also decreased when calculated relatively to the total native CYP content indicating lower stability of this form. Semiquantitative RT-PCR showed no significant changes in expression of major rat liver microsomal CYP forms after tenofovir treatment. In conclusion, repeated administration of tenofovir in higher doses led to significant decrease of the relative proportion of active liver microsomal CYPs accompanied by a conversion of these enzymes to the inactive form (CYP420) maintaining the sum of CYP proteins unchanged.
- Keywords
- PMPA, Cytochrome P450, CYP2E1, CYP1A2,
- MeSH
- Adenine analogs & derivatives administration & dosage pharmacology MeSH
- Antiviral Agents administration & dosage pharmacology MeSH
- Cytochrome P-450 CYP1A2 genetics metabolism MeSH
- Cytochrome P-450 CYP2E1 genetics metabolism MeSH
- Cytochromes metabolism MeSH
- Protein Denaturation MeSH
- Down-Regulation MeSH
- Financing, Organized MeSH
- Injections, Intraperitoneal MeSH
- Microsomes, Liver MeSH
- Liver enzymology drug effects MeSH
- Rats MeSH
- RNA, Messenger metabolism MeSH
- Organophosphonates administration & dosage pharmacology MeSH
- Rats, Inbred Lew MeSH
- Prodrugs administration & dosage pharmacology MeSH
- Tenofovir MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Female MeSH
- Animals MeSH
The development of new antiviral agents such as nucleoside analogues or acyclic nucleotide analogues (ANPs) and prodrugs thereof is an ongoing task. We report on the synthesis of three types of lipophilic triphosphate analogues of (R)-PMPA and dialkylated diphosphate analogues of (R)-PMPA. A highly selective release of the different nucleotide analogues ((R)-PMPA-DP, (R)-PMPA-MP, and (R)-PMPA) from these compounds was achieved. All dialkylated (R)-PMPA-prodrugs proved to be very stable in PBS as well as in CEM/0 cell extracts and human plasma. In primer extension assays, both the monoalkylated and the dialkylated (R)-PMPA-DP derivatives acted as (R)-PMPA-DP as a substrate for HIV-RT. In contrast, no incorporation events were observed using human polymerase γ. The dialkylated (R)-PMPA-compounds exhibited significant anti-HIV efficacy in HIV-1/2 infected cells (CEM/0 and CEM/TK-). Remarkably, the dialkylated (R)-PMPA-MP derivative 9a showed a 326-fold improved activity as compared to (R)-PMPA in HIV-2 infected CEM/TK- cells as well as a very high SI of 14,000. We are convinced that this study may significantly contribute to advancing antiviral agents developed based on nucleotide analogues in the future.
- MeSH
- Adenine MeSH
- HIV-2 MeSH
- Anti-HIV Agents * chemistry MeSH
- Humans MeSH
- Nucleotides MeSH
- Organophosphonates * chemistry MeSH
- Prodrugs * chemistry MeSH
- Tenofovir pharmacology MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Keywords
- entecavir,
- MeSH
- Hepatitis B, Chronic * diagnosis drug therapy MeSH
- Humans MeSH
- Disease Management MeSH
- Pregnancy * MeSH
- Tenofovir * therapeutic use MeSH
- Hepatitis B virus drug effects MeSH
- Check Tag
- Humans MeSH
- Male MeSH
- Pregnancy * MeSH
- Female MeSH
- Publication type
- Practice Guideline MeSH
Infekce virem hepatitidy B (HBV) je stále celosvětově zdravotním problém s měnící se epidemiologií v závislosti na řadě faktorů, především na vakcinační politice a migraci. Chronická infekce HBV je dynamický proces, který odráží interakce mezi virovou replikací a hostitelskou imunitní odpovědí. Ne všichni pacienti chronicky infikovaní HBV mají chronickou hepatitidu B. Ukončení léčby nukleotidovými nebo nukleosidovými analogy (NA) je závažným rozhodnutím, protože je spojeno s nebezpečím reaktivace množení viru, které se projeví vzestupem hladiny HBV DNA, aktivity ALT a zánětlivé aktivity v jaterní histologii. Nejbezpečnější je ukončit léčbu až po vymizení HBsAg, což je parametr dosažení imunitní kontroly nad infekcí HBV.
Hepatitis B virus (HBV) infection remains a global public health problem with changing epidemiology due to several factors predominantly vaccination policy and migration. Chronic hepatitis B is a dynamic process reflecting the interaction between HBV replication and the host immune response and not all patients with chronic HBV infection have chronic hepatitis B. Stopping of nucleotide or nucleoside analogues (NA) therapy is a serious resolution due the danger of reactivation of viral replication associated with increasing HBV DNA level, ALT activity and inflammatory activity in the liver histology. The safest stopping rule for NA therapy is HBsAg loss what is the sign of immune control of HBV infection.
- Keywords
- entecavir,
- MeSH
- Antiviral Agents therapeutic use MeSH
- Hepatitis B, Chronic * drug therapy MeSH
- Humans MeSH
- Withholding Treatment MeSH
- Tenofovir therapeutic use MeSH
- Check Tag
- Humans MeSH
- Publication type
- Review MeSH
OBJECTIVES: Pre-exposure prophylaxis (PrEP) for HIV infection is an important intervention for control of the HIV epidemic. The incidence of HIV infection is increasing in the countries of Central and Eastern Europe (CEE). Therefore, we investigated the change in PrEP use in CEE over time. METHODS: The Euroguidelines in Central and Eastern Europe (ECEE) Network Group was initiated in February 2016 to compare standards of care for HIV and viral hepatitis infections in CEE. Data on access to PrEP were collected from 23 countries through online surveys in May-June 2017 (76 respondents) and in November 2018-May 2019 (28 respondents). RESULTS: About 34.2% of respondents stated that tenofovir/emtricitabine (TDF/FTC) was licensed for use in their country in 2017, and 66.7% that it was licensed for use in 2018 (P = 0.02). PrEP was recommended in national guidelines in 39.5% of responses in 2017 and 40.7% in 2018 (P = 0.378). About 70.7% of respondents were aware of "informal" PrEP use in 2017, while 66.6% were aware of this in 2018 (P = 0.698). In 2018, there were 53 centres offering PreP (the highest numbers in Poland and Romania), whereas six countries had no centres offering PreP. The estimated number of HIV-negative people on PreP in the region was 4500 in 2018. Generic TDF/FTC costs (in Euros) ranged from €10 (Romania) to €256.92 (Slovakia), while brand TDF/FTC costs ranged from €60 (Albania) to €853 (Finland). CONCLUSIONS: Although the process of licensing TDF/FTC use for PrEP has improved, this is not yet reflected in the guidelines, nor has there been a reduction in the "informal" use of PrEP. PrEP remains a rarely used preventive method in CEE countries.
- MeSH
- Emtricitabine administration & dosage MeSH
- HIV Infections prevention & control MeSH
- Anti-HIV Agents administration & dosage MeSH
- Humans MeSH
- Pre-Exposure Prophylaxis methods statistics & numerical data MeSH
- Tenofovir administration & dosage MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Europe MeSH
Tenofovir disoproxil fumarate (TDF, form I) is an orally delivered pharmaceutical salt used for the treatment of HIV and chronic hepatitis, which acts as an inhibitor of nucleotide reverse transcriptase. There are many solid forms of TDF described in the literature; 2 of them were identified in the drug products: form I and form A. It seems that during formulation, the active pharmaceutical ingredient undergoes partial to total conversion of TDF form I to TDF form A. The goals of this study were to investigate when and why did the conversion occur and whether the conversion could be avoided and how. The influence of pH and possible interaction with excipients were studied. The conditions enabling using wet granulation in technology while preventing the undesired conversion were found. The stabilization was achieved either by replacement of used disintegrants or by acid addition to the current composition of formulation.
- MeSH
- X-Ray Diffraction methods MeSH
- Hydrogen-Ion Concentration MeSH
- Anti-HIV Agents chemistry metabolism MeSH
- Excipients chemistry metabolism MeSH
- Drug Compounding methods MeSH
- Drug Stability MeSH
- Tenofovir chemistry metabolism MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
OBJECTIVES: Tenofovir and emtricitabine are very effective and well-tolerated antiretrovirals representing current backbone of the antiretroviral combination regimens for the prevention of perinatal HIV transmission. The aim of our study was to determine whether tenofovir or emtricitabine administered in long-term fashion affect expression of two widely described pharmacokinetic determinants, P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2), in maternal or fetal biological tissues. METHODS: For this purpose, pregnant Wistar rats were administered tenofovir (2.25 mg/kg/day), emtricitabine (3.5 mg/kg/day) or saline i.m. for 10 days (from the 12th to 21st gestation day). On the 22nd day, the placenta and maternal/fetal intestine, brain, kidneys and liver were sampled and analysed for Abcb1a, Abcb1b and Abcg2 expression; placental and newborns' weights were also monitored. KEY FINDINGS: We found that long-term application of tenofovir or emtricitabine did not significantly affect expression of Abcb1a, Abcb1b and Abcg2 in either maternal or fetal organs. However, tenofovir administration significantly increased placenta-to-birthweight ratio, a strong indicator of various diseases occurring later in life. CONCLUSIONS: Our data broaden current knowledge on safety profile of tenofovir and emtricitabine use in pregnancy. Nevertheless, further research in other mammal species, including humans, is important to fully elucidate this issue.
- MeSH
- ATP-Binding Cassette Transporters metabolism MeSH
- Emtricitabine administration & dosage MeSH
- Rats MeSH
- ATP Binding Cassette Transporter, Subfamily B metabolism MeSH
- Placenta drug effects metabolism MeSH
- Fetus drug effects metabolism MeSH
- Rats, Wistar MeSH
- Pregnancy MeSH
- Tenofovir administration & dosage MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Pregnancy MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
