Tedizolid Phosphate | Anti-Bacterial | Ribosomal Protein Inhibitors | Treatment of Acute Bacterial Skin and Skin Structure (ABSSS) Infections

Tedizolid phosphate is a novel, second-generation oxazolidinone prodrug which is rapidly converted in vivo by plasma phosphatases to Tedizolid [(5R)-3-{3-fluoro-4-[6-(2-methyl-2H-tetrazol-5-yl)pyridin-3-yl]phenyl}-5-(hydroxymethyl)-1,3-oxazolidin-2-one], a synthetic second-generation oxazolidinone antibiotic.

Tedizolid Phosphate

Like Linezolid (first generation oxazolidinone antibiotic) Tedizolid inhibits the synthesis of bacterial proteins by interacting with the 50S subunit of bacterial ribosome, resulting in inhibition of protein synthesis [1].

Tedizolid has been shown to have activity against clinically relevant gram-positive aerobic and anaerobic bacteria, such as Staphylococcus species, Streptococcus species, Enterococcus species, and Haemophilus influenzae.  It has also shown activity against isolates resistant to Vancomycin, Daptomycin, and Linezolid. Tedizolid has nearly equivalent oral and intravenous (IV) bioavailability; therefore, it is developed for oral and IV administration.

Tedizolid: 2D and 3D Structure

Cross-resistance is unlikely, because like a typical oxazolidinone Tedizolid inhibits bacterial protein synthesis by a different mechanism of action from other non-oxazolidinone antibacterial drugs.

Just like Linezolid, Tedizolid behave as Monoamine oxidase inhibitor (MAOI) inhibiting the activity of the monoamine oxidase enzyme family (MAO-A and MAO-B). MAOIs have a long history of use as medications prescribed for the treatment of depression [2].

In early 2013, U.S Food and Drug Administration (US-FDA) designated Tedizolid as a “qualified infectious disease product,” a designation that was created by the Generating Antibiotic Incentives Now (GAIN) Act to provide pharmaceutical companies with incentives to promote the development of antibacterial and antifungal drugs to combat drug-resistant pathogens.

Tedizolid phosphate is an inactive prodrug has few important functions of its own. It enables significantly improved solubility in water and excellent oral bioavailability while also masking the C-5 hydroxymethyl from interactions with monoamine oxidase (MAO). The phosphate group is readily cleaved in blood by serum phosphatase and does not impair antimicrobial potency [2].

Linezolid has also been reported to be associated with peripheral and optic neuropathies, but in a murine model that predicts serotonergic activity, serotonergic effects at doses of Tedizolid up to 30-fold above the human equivalent did not differ from the control group.

On June 20 2014, Tedizolid was approved by the US-FDA as once-day dosage therapy for the treatment of Acute Bacterial Skin and Skin Structure Infections (ABSSSI) [3] caused by certain susceptible bacteria, including Staphylococcus aureus (including methicillin-resistant strains, MRSA, and methicillin-susceptible strains), various Streptococcus species (S. pyogenes, S. agalactiae, and S. anginosus group including S. anginosus, S. intermedius, and S. constellatus), and Enterococcus faecalis.

Multidrug-resistant Gram-positive organisms: Concern and Treatment

Multidrug-resistant Gram-positive organisms are commonly causative of nosocomial infections and are associated with significant morbidity and mortality. Some of the most concerning of these pathogens include methicillin-resistant Staphylococcus aureus (MRSA) and Vancomycin resistant enterococci (VRE).

Since MRSA was first described in the 1960s, it has become more widespread-first in hospitals and later in the community setting. It still is a major concern as an infection from hospital affecting a large number of patients/people communities. For decades, Vancomycin has been the cornerstone of therapy for invasive MRSA infections. However, recent studies have demonstrated increases in Vancomycin minimum inhibitory concentrations (MICs) for some MRSA strains, including Vancomycin-intermediate and hetero-resistant strains, and reports of clinical failures with Vancomycin have increased [4].

Enterococci are common pathogens in urinary tract infections and endocarditis. Enterococci treatment is a permanent riddle as these pathogens are inherently resistant to most classes of antibiotics, including all commercially available cephalosporins. In addition, enterococci have the ability to develop resistance through mutations and through the transfer of plasmids and transposons from other bacteria. Enterococci remain a common cause of nosocomial infections despite the use of rigorous infection control measures and with Vancomycin no longer a viable therapy in these patients, the search for new and better options in the antimicrobial/antibiotic space is very important.

In April 2000, Linezolid, the first of a new class of antibiotics called oxazolidinones, was approved by the (FDA) for the treatment of serious gram-positive infections, including MRSA, VRE, and Streptococcus pneumoniae. Though Linezolid is blessed with features such unique mechanism of action, the availability of i.v. and oral formulations, and its potent in vitro activity but the problems soon arised. The limitations of Linezolid include the need for twice-daily dosing, drug interaction potential (with serotonergic agents), and concern for bone marrow suppression with prolonged therapy. In addition, reports of Linezolid-resistant strains of S. aureus and enterococci were reported shortly after it became available on the market.

Tedizolid is the developed to overcome the failures of Linezolid. It is once-a-day pill and is also effective against Linezolid-resistant strains. Tedizolid is designed on Linezolid template using a rational drug design algorithm where new functional groups are added in manner that side-effects from Linezolid are minimized.

Tedizolid: Spectrum of Bactericidal Activity and Mechanism of Action

Tedizolid is active against gram positive organisms, including staphylococci, streptococci, enterococci, and certain anaerobes. In comparison with Linezolid, Tedizolid has been shown to have 4- to 16-fold greater in vitro activity against methicillin-sensitive S. aureus, MRSA, streptococci, and enterococci. Tedizolid also has activity against some gram-negative pathogens [4, 5].

Several in vitro studies also demonstrated the activity of Tedizolid against Linezolid resistant bacteria especially S. aureus with the chloramphenicol-florfenicol resistance (cfr) gene. Organisms resistant to oxazolidinones via mutations in genes encoding 23S ribosomal RNA or ribosomal proteins (L3 and L4) are generally cross-resistant to Tedizolid.

Mechanism: The mechanism of action of Tedizolid just like its predecessor Linezolid is through inhibition of protein synthesis. Tedizolid inhibits the translation process of bacterial protein synthesis by binding to the peptidyl transferase center of the 50S ribosomal subunit and preventing the formation of the 70S initiation complex.

Tedizolid also has additional interactions with the peptidyl transferase binding site region of 23S rRNA, which is believed to contribute to its lower minimum inhibitory concentration (MIC) values compared with Linezolid [1,2].

Dosages and Approvals:

Tedizolid phosphate (Tradename: Sivextro) is developed and launched by Cubist Pharmaceuticals (a subsidiary of Merck) following acquisition of Trius Therapeutics. The originator of Tedizolid is Dong-A Pharmaceuticals. In 2007, Trius Therapeutics announced that they have entered into a license agreement with Dong-A pharma on a novel series of oxazolidinone-class antibacterial compounds. Under the agreement, Trius has acquired exclusive worldwide rights, outside of Korea, to develop, manufacture and market these agents. Trius initiated Phase I trials with the lead compound, Tedizolid (also known as TR-701, DA-7218).

Tedizolid is available as a 200 mg tablet and as a vial containing 200 mg lyophilized powder for injection. The recommended dose is one 200 mg tablet orally taken with or without food or one 200 mg IV infusion daily for six days for the treatment of SSTIs in patients 18 years of age and older. The 200 mg vial must be reconstituted with Sterile Water for Injection and subsequently diluted in 250 ml of normal saline. After reconstitution and dilution, Tedizolid should be infused over one hour. Tedizolid is incompatible with solutions containing divalent cations, including Lactated Ringer’s and Hartmann’s Solution. Advanced age, hepatic impairment, and/or renal impairment do not necessitate a dosage adjustment [3].

Reported Activities for Tedizolid:

A summary of various activities reported for Tedizolid in scientific literature. The important bactericidal activities are [6]:

Gram-positive bacteria      

          MIC₉₀(Inhibition of Corynebacterium jeikeium Activity) = 0.5 ug/ml

          MIC₉₀(Inhibition of Listeria monocytogenes Activity) = 0.25 ug/ml

Staphylococcus species  

          MIC₉₀(Inhibition of S. aureus  (MS) Activity) = 0.25-0.50 ug/ml

          MIC₉₀(Inhibition of S. aureus  (MR) Activity) = 0.25-1.0 ug/ml

          MIC₉₀(Inhibition of Coagulase-negative staphylococci  (MS) Activity) = 0.5 ug/ml

          MIC₉₀(Inhibition of Coagulase-negative staphylococci  (MR) Activity) = 0.5 ug/ml

Streptococcus species     

          MIC₉₀(Inhibition of S. pneumoniae Activity) = 0.25 ug/ml

          MIC₉₀(Inhibition of S. pneumoniae  (PI and PR) Activity) = 0.25-0.50 ug/ml

          MIC₉₀(Inhibition of S. agalactiae Activity) = 0.25-0.50 ug/ml

          MIC₉₀(Inhibition of S. pyogenes Activity) = 0.25-0.50 ug/ml

          MIC₉₀(Inhibition of Viridans group Activity) = 0.25 ug/ml

Enterococcus species      

          MIC₉₀(Inhibition of E. faecalis  (VS and VR) Activity) = 0.50-1.0 ug/ml

          MIC₉₀(Inhibition of E. faecium  (VS) Activity) = 0.50-1.0 ug/ml

          MIC₉₀(Inhibition of E. faecium  (VR) Activity) = 0.5 ug/ml

Gram-negative bacteria    

          MIC₉₀(Inhibition of Haemophilus influenzae Activity) = 16 ug/ml

          MIC₉₀(Inhibition of Moraxella catarrhalis Activity) = 4 ug/ml

Anaerobes        

          MIC₉₀(Inhibition of Bacteroides fragilis group Activity) = 4 ug/ml

          MIC₉₀(Inhibition of Clostridium perfringes Activity) = 2 ug/ml

          MIC₉₀(Inhibition of Peptostreptococcus species Activity) = 0.5 ug/ml

          MIC₉₀(Inhibition of Prevotella species Activity) = 4 ug/ml

Other Activities for Tedizolid

IC₅₀ (Inhibition of MAO-A Activity) = 8.7 uM

IC₅₀ (Inhibition of MAO-B Activity) = 5.7 uM

IC₅₀ (Inhibition of Mitochondrial Protein Synthesis (MPS) Activity) = 0.3 uM

Summary

Common name: DA-70157; DA-70218; DA-7157; DA-7218; TR-700; TR-701; TR-701 FA; TR-701 free acid; Tedizolid phosphate; Torezolid; Torezolid phosphate; BAY 1192631; Tedizolid

Trademarks: Sivextro

Molecular Formula: C17H15FN6O3 {C17H16FN6O6P}

CAS Registry Number: 856866-72-3 {856867-55-5}

CAS Name: (R)-3-(3-fluoro-4-(6-(2-methyl-2H-tetrazol-5-yl)pyridin-3-yl)phenyl)-5-(hydroxymethyl)oxazolidin-2-one {(R)-(3-(3-fluoro-4-(6-(2-methyl-2H-tetrazol-5-yl)pyridin-3-yl)phenyl)-2-oxooxazolidin-5-yl)methyl dihydrogen phosphate}

Molecular Weight: 396.38 {450.32}

SMILES:OC[C@H](OC1=O)CN1C(C=C2)=CC(F)=C2C3=CN=C(C4=NN(C)N=N4)C=C3 { O=P(O)(O)OC[C@H](OC1=O)CN1C(C=C2)=CC(F)=C2C3=CN=C(C4=NN(C)N=N4)C=C3}

InChI Key: XFALPSLJIHVRKE-GFCCVEGCSA-N {QCGUSIANLFXSGE-GFCCVEGCSA-N}

InChI: InChI=1S/C17H15FN6O3/c1-23-21-16(20-22-23)15-5-2-10(7-19-15)13-4-3-11(6-14(13)18)24-8-12(9-25)27-17(24)26/h2-7,12,25H,8-9H2,1H3/t12-/m1/s1 { InChI=1S/C17H16FN6O6P/c1-23-21-16(20-22-23)15-5-2-10(7-19-15)13-4-3-11(6-14(13)18)24-8-12(30-17(24)25)9-29-31(26,27)28/h2-7,12H,8-9H2,1H3,(H2,26,27,28)/t12-/m1/s1}

Mechanism of Action: Ribosomal Protein Inhibitors; Monoamine Oxidase Inhibitors; Serotonin Modulators

Activity: Treatment of Acute Bacterial Skin and Skin Structure (ABSSSI) Infections; Anti-Bacterial Agents; Anti-Infective Agents; Antibiotics

Status: Launched 2016 (US)

Chemical Class: Small molecules; Oxazolidinones; Flourine containing; Tetrazoles; Organic phosphoric acids

Originator: Dong-A Pharmaceuticals/ Cubist Pharmaceuticals

*Data in { } bracket is for Tedizolid phosphate.

Tedizolid Phosphate Synthesis

WO2010042887A2: The patent reports the procedure that can easily be performed at an industrial level. 5-bromo-2-cyanopyridine was treated with sodium azide and ammonium chloride in DMF to produce tetrazole, which was isolated by precipitation of the tetrazole ammonium salt. Subsequent methylation with methyl iodide in THF/DMF (3:1) afforded a 3.85:1 mixture of desired methylated tetrazole and the corresponding N1-regioisomer. Acidification with 6 M HCl followed by treatment with 50% aqueous NaOH (to pH = 10.6) enabled isolation of desired methylated tetrazole in 96% isomeric purity; crude product was further purified by recrystallization from isopropyl acetate. A Suzuki reaction of methyl tetrazole with boronic acid intermediate followed by recrystallization from ethyl acetate produced N-protected triaryl system. Subsequent, deprotonation of the amine using lithium hexamethyldisilazide (LiHMDS) followed by reaction with R-(-)-glycidyl butyrate in the presence of 1,3-dimethyl tetrahydropyrimidin-2(1H)-one (DMPU) generated Tedizolide in 85% yield. Reaction with POCl₃ in THF at 1-2 ºC followed by subjection to sodium hydroxide and subsequent acidification furnished Tedizolid phosphate in 76% yield across the three steps.

Intermediate:

Final Synthesis:

For more details please visit Ref 8,9.

Eur J Med Chem 2011, 46(4), 1027-1039: The article reports the discovery of Tedizolid phosphate and structure-activity relationship for various analogues.

Intermediate 1: To a solution of 2,5-dibromopyridine in DMF was added copper cyanide and sodium cyanide. The reaction mixture was stirred for 7 h at 150 ⁰C. After being cooled to room temperature, the reaction mixture was poured into water and extracted with EtOAc. The organic layer was washed with brine, dried over anhydrous MgSO₄, filtered and concentrated in vacuo to obtain the 2-cyano-5-bromopyridine. To a solution of 2-cyano-5-bromopyridine in DMF (100 mL) was added sodium azide and ammonium chloride. The reaction mixture was stirred for 3 h at 110 ⁰C. After being cooled to room temperature, the reaction mixture was poured into water and extracted with EtOAc. The organic layer was washed with brine, dried over anhydrous MgSO₄, filtered and concentrated in vacuo to obtain 2-(tetrazol-5-yl)-5-bromopyridine.

To a solution of 2-(tetrazol-5-yl)-5-bromopyridine in DMF at 0 ⁰C was slowly added NaOH and iodomethane. After being stirred at room temperature for 6 h, the reaction mixture was poured into water and extracted with EtOAc. The organic layer was washed with brine, dried over anhydrous MgSO₄, filtered and concentrated in vacuo. The crude product was purified by column chromatography to obtain 2-(2-Methyltetrazol-5-yl)-5-bromo pyridine (overall yield 45%).

Intermediate 2: To a solution of 3-fluoroaniline and NaHCO₃ in THF was slowly added N-carbobenzyloxy chloride. After being stirred for 2 h at 0 ⁰C, the reaction mixture was poured into water and extracted with EtOAc. The organic layer was washed with brine, dried over anhydrous MgSO₄, filtered and concentrated in vacuo. The residue was washed with n-hexane to obtain N-Carbobenzyloxy-3-fluoroaniline. To the product in THF at -78 ⁰C was added n-butyllithium in n-hexane under nitrogen condition. After the solution was stirred at -78 ⁰C for 10 min, (R)-(-)-glycidyl butylate was slowly added. The mixture was stirred at -78 ⁰C for 2 h and stirred at room temperature for 24 h. After completion of the reaction, an aqueous saturated ammonium chloride (NH₄Cl) solution was added and the mixturewas extracted with EtOAc. The organic layer was washed with brine, dried over anhydrous MgSO₄ and concentrated in vacuo, to give (R)-3-(3-Fluorophenyl)-2-oxo-5-oxazolidinylmethanol.

To a solution of above in acetonitrile was added trifluoroacetic acid silver salt (CF₃COOAg) and iodine. After being stirred for 24 h at room temperature, the reaction mixture was poured into water and extracted with EtOAc. The organic layer was washed with brine, dried over anhydrous MgSO₄, filtered and concentrated in vacuo to obtain (R)-3-(4-Iodo-3-fluorophenyl)-2-oxo-5-oxazolidinylmethanol. To a 1,4-dioxane solution of the previous product was added hexabutylditin and Pd(PPh₃)₂Cl₂. The reaction mixture was stirred for 2 h at 100 ⁰C. The solution was filtered through celite and the filtrate was concentrated on a rotary evaporator. The residue was purified by column chromatography to obtain (R)-3-(4-Tributylstannyl-3-fluorophenyl)-2-oxo-5-oxazolidinyl methanol (61%).

Final synthesis: To a solution of intermediate 2 in NMP was added intermediate 1, LiCl and Pd(PPh₃)₂Cl₂. The reaction mixture was stirred for 4 h at 120 ⁰C. After being cooled to room temperature, the reaction mixture was poured into water and extracted with EtOAc. The organic layer was washed with brine, dried over anhydrous MgSO₄, filtered and concentrated in vacuo. The residue was further purified by column chromatography to obtain Tedizolid (yield 26%). In the next step, to Tedizolid in triethyl phosphate was added phosphorous oxychloride. The solution was stirred for 2 h at room temperature. The reaction mixture was extracted with ethyl acetate and stirred for 30 min. And the solution was then poured into water and stirred for 2 h at 0 ⁰C. The product is isolated by filtration and washed with acetone to obtain Tedizolid phosphate (yield 67%).

Identifications:

1H NMR (Estimated) for Tedizolid

Experimental: ¹H NMR (DMSO-d₆) δ 8.90 (s, 1H), 8.18 (m, 2H), 7.70 (m, 2H), 7.49 (dd, J = 8.8 Hz, 2.4 Hz,1H), 5.25 (t, J = 5.6 Hz, 1H), 4.74 (m, 1H), 4.46 (s, 3H), 4.14 (t, J = 8.8 Hz, 1H), 3.88 (m, 1H), 3.68 (m, 1H), 3.58 (m, 1H).

13 CNMR (Estimated) for Tedizolid

Experimental: ¹³C NMR (DMSO-d₆) δ 163.56, 159.03, 154.06, 149.18, 144.78, 140.30, 136.96, 131.42, 130.73, 121.89, 118.36, 113.81, 105.18, 73.39, 61.52, 45.96, 39.63.

Sideeeffects: The most common treatment-emergent adverse reactions (TEAEs, greater than 2% cases) in patients with acute bacterial SSSI who were treated with Tedizolid were nausea (8%), headache (6%), diarrhea (4%), vomiting (3%), and dizziness (2%).

Additional adverse reactions reported in patients with acute bacterial SSSI treated with Tedizolid at a rate of less than 2% include anemia, palpitations, tachycardia, asthenopia, vision blurred, visual impairment, vitreous fl oaters, infusion-related reactions, drug hypersensitivity, C. difficile-associated colitis, oral candidiasis, vulvovaginal mycotic infection, increased hepatic transaminases, decreased white blood cell count, hypesthesia, paresthesia, seventh nerve paralysis, insomnia, pruritus, urticaria, dermatitis, flushing, and hypertension.

Serious adverse reactions occurred in 1.8% of patients treated with Tedizolid, and Tedizolid was discontinued as the result of an adverse reaction in 0.5% of patients.

Tedizolid is Pregnancy Category C. There are no adequate and well-controlled studies of Tedizolid in pregnant women. Tedizolid should only be used during pregnancy if the benefit justifies the potential risk to the fetus. Tedizolid is known to produce fetal developmental toxicities in animal models.

Others: While clinical breakpoints have not been established for Tedizolid, one study suggested breakpoints as well as interpretive criteria for diskdiffusion methods of susceptibility testing. For all staphylococci, the recommended breakpoints were less than or equal to 2, 4, and greater than or equal to 8 ug/ml for susceptible, intermediate, and resistant bacterial strains, respectively. The suggested susceptible breakpoint for enterococci, streptococci, Corynebacterium jeikeium, and Listeria monocytogenes was less than or equal to 2 ug/mL, with no intermediate and resistant categories. No recommended MIC range was given for Moraxella catarrhalis or Haemophilus influenzae [7].

Tedizolid differs in structure from the first-generation oxazolidinone Linezolid in that it contains a D ring and a hydroxymethyl group on C-5 of ring A. It is believed the D-ring structure adds additional sites for hydrogen bonding and further stabilizes interactions with the target site. The utilization of the phosphorylated prodrug, Tedizolid phosphate, enables significantly improved solubility in water and excellent oral bioavailability while also masking the C-5 hydroxymethyl from interactions with monoamine oxidase (MAO). The phosphate group is readily cleaved in blood by serum phosphatase and does not impair antimicrobial potency.

It is believed that the structural difference at the C-5 position of ring A of Tedizolid (specifically its smaller hydroxymethyl group as compared with Linezolid’s acetamide group) result in its retained activity against bacterial strains that possess multiresistant cfr (chloramphenicol-florfenicol resistance) gene.

SAR for Zolid-Family

Tedizolid was found to be a weak, reversible inhibitor of MAO-A and MAO-B activity with only minimal effects observed with the prodrug, Tedizolid phosphate. In vitro, Tedizolid just like Linezolid inhibits 50% of MAO-A and MAO-B activity, on average, at 8.7 and 5.7 uM, respectively, whereas Linezolid has a higher 50% inhibitory concentration (IC₅₀) for MAO-A (46.0 uM) but a lower IC₅₀ for MAO-B (2.1 uM). Overall, both agents are two to three orders of magnitude less potent MAO inhibitors.

Linezolid has also been reported to be associated with peripheral and optic neuropathies. This effect, typically reported following longer courses of therapy, is hypothesized to be associated with inhibition of mitochondrial protein synthesis (MPS). In a murine model that predicts serotonergic activity, serotonergic effects at doses of Tedizolid up to 30-fold above the human equivalent did not differ from the control group.

References:

1. Chahine, E. B.; et. al. Tedizolid: A New Oxazolidinone Antibiotic for Skin and Soft Tissue Infections. Consult Pharm 2015, 30(7), 386-394. (FMO only)

2. Rybak, J. M.; et. al. Tedizolid Phosphate: a Next-Generation Oxazolidinone. Infect Dis Ther 2015, 4(1), 1-14. (free article)

3. Tedizolid Phosphate (Approval)

4. Kisgen, J. J.; et. al. Tedizolid: a new oxazolidinone antimicrobial. Am J Health Syst Pharm 2014, 71(8), 621-633. (FMO only)

5. Kanafani, Z. A.; et. al. Tedizolid (TR-701): a new oxazolidinone with enhanced potency. Expert Opin Investig Drugs 2012, 21(4), 515-522. (FMO only)

6. Shaw, K. J.; et. al. In Vitro Activity of TR-700, the Antibacterial Moiety of the Prodrug TR-701, against Linezolid-Resistant Strains. Antimicrob Agents Chemother 2008, 52(12), 4442-4447. (free article)

7. Lepak, A. J.; et. al. Comparative pharmacodynamics of the new oxazolidinone tedizolid phosphate and linezolid in a neutropenic murine Staphylococcus aureus pneumonia model. Antimicrob Agents Chemother 2012, 56(11), 5916-5922. (free article)

8. Philipson, D. Crystalline form of r)-3-(4-(2-(2-methyltetrazol-5-yl)pyridin-5-yl)-3-fluorophenyl)-5-hydroxymethyl oxazolidin-2-one dihydrogen phosphate. WO2010091131A1

9. Philipson, D.; et. al. Methods for preparing oxazolidinones and compositions containing them. WO2010042887A2

10. Im, W. B.; et. al. Discovery of torezolid as a novel 5-hydroxymethyl-oxazolidinone antibacterial agent. Eur J Med Chem 2011, 46(4), 1027-1039. (FMO only)

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