Synthesis and biological activity of a new cephalosporin, BMY-28232 and its prodrug-type esters for oral use

The synthesis and structure-activity relationships of 7-[(Z)-2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido]-3-[( Z)-1- propenyl]-3-cephem-4-carboxylic acid (BMY-28232), its 3-alkenyl analogs (6 and 7) and O-substituted derivatives of the oxyimino moiety (10) are described, as well as the oral pharmacokinetics and in vivo activities of the 1-acetoxyethyl ester of BMY-28232 (BMY-28271) and its analogous esters (11). The 3-alkenyl groups were introduced by the Wittig reaction of the ylide (2) prepared from the 3-chloromethyl cephem (1) to afford the Z (main) and E (minor) isomers regarding the 3-side chain. The O-substituted derivatives (10) were prepared by 7-N-acylation of the 7-amino cephem (4a) with the corresponding O-substituted side chain acids (8). The prodrug esters (11) were prepared by esterification of BMY-28232 with an appropriate halide. BMY-28232 was the most active among the 3-alkenyl analogs tested against Gram-negative organisms and much more active than the O-substituted derivatives against Gram-positive bacteria. BMY-28271 showed good oral bioavailability (66%) and good in vivo efficacy in mice against infections of Staphylococcus aureus Smith (PD50, 0.68 mg/kg) and Escherichia coli Juhl (0.54 mg/kg).     

Synthesis and biological activity of novel 3-(2-propenyl)-cephalosporins. II. Preparation of prodrugs

Three prodrug esters (2a approximately 2c) of 3-(2-propenyl)cephem (1a) have been prepared and their oral absorption was determined in rats and mice. While pivaloyloxymethyl ester (2a) did not improve the oral absorption of the parent cephem 1a, [(1-methyl)ethoxycarbonyloxy]ethyl ester (2b) and (5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl ester (2c) improved oral absorption by a factor of five.     

Orally active 2-(alkyloxycarbonyl)-2-alkylideneethyl esters of cephalosporins.

2-(Alkyloxycarbonyl)-2-alkylideneethyl esters of various aminothiazole-oxyimino cephalosporins have been synthesized and studied. They are useful alternatives to the currently existing orally active esters. Among the new esters synthesized, the 3'-azidomethyl cephem ester Ro 41-3399 (7k) presented an oral bioavailability superior to the corresponding pivaloyloxymethyl ester (9) in a rat model and was selected as a candidate for further evaluation.     

Syntheses and pharmacokinetic studies of prodrug esters for the development of oral carbapenem, L-084

We discovered an orally active carbapenem, L-084, through pharmacokinetic studies on various prodrug esters of (1R,5S,6S)-6-[(R)-1-hydroxyethyl]-l-methyl-2-[1-(1,3-thiazolin-2-yl)azetidin-3-yl]thio-1-carbapen-2-em-3-carboxylic acid (LJC11,036). L-084 showed a strong antimicrobial activity against Gram-positive and Gram-negative bacteria and exhibited the highest intestinal absorption among synthesized prodrugs of LJC11,036.     

Studies on cephalosporin antibiotics. VI. Synthesis, antibacterial activity and oral efficacy in mice of new 7 beta-[(Z)-2-(2-aminothiazol-4-yl)-2-(hydroxyimino)-acetamido]-3- (substituted alkylthio)cephalosporins.

A series of new 7 beta-[(Z)-2-(2-aminothiazol-4-yl)-2-(hydroxyimino)acetamido] cephalosporins (1) having various substituted alkylthio groups at the C-3 position of the cephem nucleus were prepared and evaluated for antibacterial activity and oral absorption in rats. Of these, the cephalosporin with a cyanomethylthio group (1a) showed the greatest activity against Staphylococcus aureus and Gram-negative bacteria. Its pivaloyloxymethyl ester (6a), a representative prodrug, exhibited good in vivo efficacy in mice by oral administration. The structure-activity relationships of 1 are also presented.     

Metabolism, pharmacokinetics, tissue distribution, and stability studies of the prodrug analog of an anti-hepatitis B virus dinucleoside phosphorothioate

The alkoxycarbonyloxy dinucleotide prodrug R(p), S(p)-2 is an orally bioavailable anti-hepatitis B virus agent. The compound is efficiently metabolized to the active dinucleoside phosphorothioate R(p), S(p)-1 by human liver microsomes and S9 fraction without cytochrome P450-mediated oxidation or conjugation. The conversion of R(p), S(p)-2 to R(p), S(p)-1 appears to be mediated by liver esterases, occurs in a stereospecific manner, and is consistent with our earlier reported studies of serum-mediated hydrolytic conversion of R(p), S(p)-2 to R(p), S(p)-1. However, further metabolism of R(p), S(p)-1 does not occur. The presence of a minor metabolite, the desulfurized product 10 was noted. The prodrug R(p), S(p)-2 was quite stable in simulated gastric fluid, whereas the active R(p), S(p)-1 had a half-life of <15 min. In simulated intestinal fluid, the prodrug 2 was fully converted to 1 in approximately 3 h, whereas 1 remained stable. To ascertain the tissue distribution of the prodrug 2 in rats, the synthesis of (35)S-labeled R(p), S(p)-2 was undertaken. Tissue distribution studies of orally and intravenously administered radiolabeled [(35)S]2 demonstrated that the radioactivity concentrates in the liver, with the highest liver/plasma ratio in the intravenous group at 1 h being 3.89 (females) and in the oral group at 1 h being 2.86 (males). The preferential distribution of the dinucleotide 1 and its prodrug 2 into liver may be attributed to the presence of nucleoside phosphorothioate backbone because phosphorothioate oligonucleotides also reveal a similar tissue distribution profile upon intravenous administration.     

Cefpodoxime proxetil, its in vitro antibacterial activity, affinity to bacterial penicillin-binding proteins, and synergy of bactericidal activity with serum complement and mouse-cultured macrophages

Cefpodoxime proxetil (CS-807) is an orally active prodrug of an oxime-type cephem antibiotic. The MIC60 values of cefpodoxime (R-3746) the active form of CS-807, were 3.13, 6.25, 0.05, 0.38, 0.2, 0.1, 3.13, 3.13, 6.25, 6.25, 0.1 and 12.5 micrograms/ml against S. aureus, coagulase-negative staphylococci, S. pneumoniae, E. coli carrying R plasmids, P. vulgaris, P. rettgeri, C. freundii, S. marcescens, A. calcoaceticus, P. cepacia, ampicillin-resistant H. influenzae and B. fragilis, respectively. Its activity was stronger than that of cefaclor and ampicillin. R-3746 manifested little activity against P. aeruginosa, methicillin-resistant S. aureus, and Enterococcus spp. R-3746 showed stronger binding affinity than cefaclor with the PBP2 of S. aureus, PBPs 1a, 1bs, 2 and 3 of E. coli, PBPs 1b, 1c and 3 of P. rettgeri, and the PBP3 of P. aeruginosa than cefaclor. Synergy of the bactericidal effect between R-3746 and serum complement was moderate, although the cells of E. coli NIHJ-JC2 and S. aureus 209P were well engulfed and rapidly digested by mouse-cultured macrophages in the presence of greater than 1/8 MIC of R-3746. Good clinical efficacy can be expected of CS-807 provided its pharmacokinetics prove to be good.     

Synthesis and relationship between physicochemical properties and oral absorption of pivaloyloxymethyl esters of parenteral cephalosporins

To obtain fundamental information for designing orally active prodrugs of parenteral cephalosporins, the pivaloyloxymethyl esters of ten parenteral cephalosporins were prepared and their physicochemical properties and oral bioavailability in mice were measured. By esterification, lipophilicity was improved with a decrease in solubility, but all the esters were hydrolyzed to the parent cephalosporins rapidly in homogenates of mouse small intestine. These esters, except cefamandole, showed improved relative bioavailability (BA) when compared with the parent cephalosporins. Quantitative correlation of the partition coefficient (P), hydrolysis rate ($\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$) to the parent cephalosporin and water solubility (S) to the BA of the esters were attempted. A good linear relation between log S and log BA, but no significant relation between log P and log BA or between log $\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and log BA was observed. Among the prodrugs, the ester of Cefotiam, ‘1’, which has log P 1.57, and the highest water solubility, 2.71 mg/ml, showed the best BA, 41.8%. The results of this study indicate the importance of water solubility in designing an orally active ester prodrug of the parenteral cephalosporin, if the lipophilicity and hydrolysis rate are sufficiently high.     

Studies on cephalosporin antibiotics. III. Synthesis, antibacterial activity and oral absorption of new 3-(substituted-alkylthio)-7 beta-[(Z)-2-(2-aminothiazol-4-yl)-2- (carboxymethoxyimino)acetamido]cephalosporins

The synthesis, antibacterial activity and oral absorption in rats of new 7 beta-[(Z)-2-(2-aminothiazol-4-yl)-2-(carboxymethoxyimino)ace tamido] cephalosporins (1) having various substituted-alkylthio groups at the C-3 position of the cephem nucleus are described. Of these, the cephalosporins with a cyanomethylthio group (1d) and fluoroethylthio group (1p) at the C-3 position showed a potent in vitro antibacterial activity against Gram-positive and Gram-negative bacteria as well as good oral absorption in rats. When administered orally to mice infected with Klebsiella pneumoniae, 1d had stronger protective effect than 1p. The structure-activity relationships of 1 are also presented.     

Orally active oxime derivatives of the dopaminergic prodrug 6-(N,N-di-n-propylamino)-3,4,5,6,7,8-hexahydro-2H-naphthalen-1-one. Synthesis and pharmacological activity

A series of racemic and enantiomerically pure oxime derivatives of the potential anti-Parkinson prodrug 6-(N,N-di-n-propylamino)-3,4,5,6,7,8-hexahydro-2H-naphthalen-1-one (1) were synthesized and pharmacologically evaluated. The oximes induced rotational behavior in the Ungerstedt rat rotation model for Parkinson's disease after oral administration. Especially the unsubstituted oxime ((-)-3) and the acetyl-oxime ((-)-10) induced a pronounced and long lasting effect. In this model, large individual differences were observed in responsiveness to treatment between rats. Though less potent than the parent prodrug, the oxime derivatives of (+/-)-1 and (-)-1 can be orally active, acting as cascade prodrugs.     

Orally active carbapenem antibiotics I. Antibacterial and pharmacokinetic potential of 2-phenyl and 2-thienylcarbapenems

In order to design orally active carbapenem antibiotics effective against beta-lactam-resistant pathogens, such as penicillin-resistant Streptococcus pneumoniae (PRSP) and beta-lactamase non-producing ampicillin-resistant Haemophilus influenzae (BLNAR), a series of novel 2-phenylcarbapenems and some 2-thienyl derivatives were synthesized and tested for antibacterial activities. These compounds were highly active against PRSP, BLNAR, and major Gram-positive and Gram-negative bacteria that cause community-acquired infections. Their pivaloyloxymethylester-type prodrug exhibited good oral absorption in mice, suggesting that this series of carbapenems were promising as a prototype of novel orally active beta-lactams.     

Synthesis and antiviral evaluation of alkoxyalkyl derivatives of 9-(S)-(3-hydroxy-2-phosphonomethoxypropyl)adenine against cytomegalovirus and orthopoxviruses

9-(S)-(3-Hydroxy-2-phosphonomethoxypropyl)adenine [(S)-HPMPA] was one of the first acyclic nucleoside phosphonates described and has been reported to have good antiviral activity against most double-stranded DNA viruses, including the herpes group viruses and the orthopoxviruses. However, (S)-HPMPA is not orally bioavailable and has not been developed for clinical use. We have prepared orally bioavailable lipid esters of (S)-HPMPA and report their synthesis and antiviral evaluation against cytomegalovirus and orthopoxviruses. These esters were evaluated in vitro in cells infected with human cytomegalovirus (HCMV), murine cytomegalovirus (MCMV), vaccinia (VV), and cowpox viruses (CV). The most active compound, oleyloxyethyl-(S)-HPMPA, was found to have EC50 value of 0.003 microM against HCMV vs 1.4 microM for unmodified HPMPA. In cells infected with VV and CV, octadecyloxyethyl-(S)-HPMPA had EC50 values of 0.01-0.02 microM versus 2.7-4.0 microM for unmodified HPMPA. When compared with the alkoxyalkyl esters of cidofovir, the corresponding alkoxyalkyl esters of (S)-HPMPA were equally active against HCMV and MCMV but were 15-20-fold more active against VV and CV in vitro. The alkoxyalkyl esters of (S)-HPMPA are promising new compounds worthy of further investigation for treatment of infections caused by herpes viruses and orthopoxviruses.     

盐酸头孢他美酯的合成

盐酸头孢他美酯是一口服前体药,口服后在体内迅速水解为具有抗菌活性的头孢他美。本文报道了盐酸头孢他美酯的制备方法,其生产工艺简单,成本低廉:以3-去乙酰氧基-7-氨基头孢烷酸(7-ADCA)为起始物与活性酯反应,先制备头孢他美(酸),然后和特戊酸卤甲酯反应生成头孢他美酯,最后头孢他美酯成盐得盐酸头孢他美酯。     

Prodrug for bioreductive activation-independent delivery of menahydroquinone-4: human liver enzymatic activation and its action in warfarin-poisoned human liver

The N,N-dimethylglycine esters of menahydroquinone-4 (1-mono, 1; 4-mono, 2; 1,4-bis, 3) were established in previous reports as prodrugs that could achieve the systemic bioreductive activation-independent delivery of menahydroquinone-4 (MKH), the active form of menaquinone-4 (MK-4), in rat. The present study was undertaken to investigate if the prodrugs could undergo cleavage to parent drug (MKH) by a human tissues enzyme catalyzed hydrolytic pathway, the mechanism of the prodrugs for vitamin K-dependent carboxylation in human liver and their action in the warfarin poisoned human liver. The hydrolysis of the esters was shown to be catalyzed by esterases located in human liver but not in human plasma. The susceptibility of the esters to undergo human liver esterase hydrolysis was affected by the esterified position: 1>2>3. By using a human liver microsomal test system, the stimulation of vitamin K-dependent carboxylation with the prodrugs was determined. The prodrug could stimulate the carboxylation activity in the absence of dithiothreitol, an artificial activator of the reductive activation pathway of MK-4. The carboxylation activity of the prodrug was strongly inhibited in the presence of eserine, an esterase inhibitor. The prodrug could also stimulate the carboxylase under warfarin-poisoned conditions, where the vitamin K cycle was strongly inhibited. The results confirmed that the prodrug could generate MKH in human liver (active site), and that the resultant MKH could act as a cofactor for the carboxylase without reductive activation processes of MK-4 to MKH. Such bioreductive activation-independent vitamin K-dependent carboxylation characteristic of the prodrug leads to enhanced pharmacological efficacy in the treatment of hypoprothrombinaemia induced in patients with coumarin and cephalosporin therapies.     

Synthesis and relation between physicochemical properties and oral absorption of 7-O-acylmandelamido-3-methyl-3-cephem-4-carboxylic acids

O-Acylates (IV) of 7-d-mandelamido-3-methyl-3-cephem-4-carboxylic acid (I) were prepared and their physicochemical properties and oral absorption in mice were measured to search for an orally active cephalosporin having a 7-acyl group other than phenylglycine analogs. The pK_a and log P values of IB were 2.8 and 1.02–3.54, respectively, and IV were hydrolyzed to the parent drug (I) in a homogenate of mouse small intestine. The esters, IVb (propionate), IVc (n-butyrate), IVd (i-butyrate), and IVe (n-valerate) produced higher plasma levels of I and improved relative bioavailability (BA) than those observed after oral dosing with I. Among the esters, IVe showed the highest BA, 40.3%. Good correlations between log P and log BA and between log P and peak plasma level (log C_max) were observed. The esters resulting in good BA have log P values similar to those of orally active penicillins having an acyl group other than phenylglycine analogs, e.g. propicillin (PP-PC) and phenethicillin (PE-PC). The present study indicates that an ester prodrug of the parenteral cephalosporin having a 7-acyl group other than phenylglycine analog can be absorbed effectively through the gastrointestinal tract when log P and the pK_a values are in a selected range.     

Orally active esters of cephalosporin antibiotics. Synthesis and biological properties of acyloxymethyl esters of 7-(D-2-amino-2-phenylacetamido)-3-[5-methyl-(1,3,4-thiadiazol-2-yl)thiomethyl]-3-cephem-4-carboxylic acid.

The synthesis of the acetoxymethyl (AOM), pivaloloxymethyl (POM), and phthalidyl (PHTH) esters of 7-[D-(-)-2-amino-2-phenylacetamido]-3-[5-methyl-(1,3,4-thiadiazol-2-yl)thiomethyl]-3-cephem-4-carboxylic acid (1a), a broad-spectrum semisynthetic cephalosporin antibiotic, is described. These esters were examined as potential orally active antibiotic prodrugs. The superior oral absorption of the three esters relative to the unesterified parent, 1a, is demonstrated by differential blood levels as well as measurement of the rate at which doses of the ester leave the gastrointestinal tract and appear in the urine. A study of the decreased stability of the three esters relative to 1a at pH 4.5, 6.5, and 7.5 is also presented.     

In vitro evaluation of the anti-orf virus activity of alkoxyalkyl esters of CDV, cCDV and (S)-HPMPA

Acyclic nucleoside phosphonates (ANPs) and in particular (S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]cytosine (HPMPC, cidofovir, CDV, Vistide) and its adenine counterpart (S)-9-[3-hydroxy-2-(phosphonomethoxy)propyl]adenine [(S)-HPMPA] are highly active against orf virus infections. This parapoxvirus commonly causes infection in sheep, goats, but also humans. Alkoxyalkyl esters of CDV have an increased oral bioavailability and are more active against orthopoxviruses than the parent compounds. In the present study, the potency of several alkoxyalkyl esters of CDV, cyclic cidofovir (cCDV) and (S)-HPMPA was evaluated against different orf virus isolates in two cell types, human embryonic lung (HEL) fibroblast and primary lamb keratinocytes. Each prodrug was at least 10-fold more active than its parent compound in both cell types. Of all the compounds tested, the (S)-HPMPA alkoxyalkyl esters showed the highest activity and selectivity against orf virus. Our results support the development of alkoxyalkyl esters of ANPs as antivirals not only for the treatment of complicated human orf lesions, but also in the therapy and prophylaxis of contagious ecthyma in sheep and goats.     

Discovery of phosphonic diamide prodrugs and their use for the oral delivery of a series of fructose 1,6-bisphosphatase inhibitors

Like most phosphonic acids, the recently discovered potent and selective thiazole phosphonic acid inhibitors of fructose 1,6-bisphosphatase (FBPase) exhibited low oral bioavailability (OBAV) and therefore required a prodrug to achieve oral efficacy. Syntheses of known phosphonate prodrugs did not afford the desired OBAV; hence, a new class of prodrugs was sought. Phosphonic diamides derived from amino acid esters were discovered as viable prodrugs, which met our preset goals: excellent aqueous stability over a wide pH range, benign byproducts (amino acids and low molecular weight alcohols), and most importantly good OBAV leading to robust oral glucose lowering effects. These desirable properties of phosphonic diamides represent significant improvements over existing prodrug classes. Optimization of the diamide prodrugs of phosphonic acid 2a (MB05032) led to the identification of diamide 8 (MB06322), the first reported orally efficacious FBPase inhibitor.     

In-vivo Activity of Retinoid Esters in Skin is Related to In-vitro Hydrolysis Rate

BMS-181163 (4-acetamidophenyl retinoate, previously reported as BMY-30123), the acetamidophenyl ester of all-trans-retinoic acid (tRA), is topically active in various retinoid-sensitive animal models, but was recently shown to be ineffective for the treatment of acne in patients. To determine whether BMS-181163 functions as a prodrug of tRA in mice but not in man, the relative rates of ester hydrolysis in mouse and human skin homogenates were determined. In-vitro hydrolysis assays showed that BMS-181163 was substantially hydrolysed in mouse skin homogenates and minimally in human skin preparations. In addition, a series of phenyl esters of tRA and several known active synthetic retinoids (Ch-80: (E)-4-[3-oxo-3-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)-1-propenyl] benzoic acid; CD-271: 6-[3-(1-adamantyl)-4-methyoxyphenyl]-2-naphthoic acid; and TTNPB: (E)-4-[2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)-1-propenyl] benzoic acid) was prepared and hydrolysis rates and in-vivo (rhino mouse utriculi reduction) activities were compared. The hydrolysis rates of the six test retinoid phenyl esters, ranging from 0·06 to 2·0 h^?1 were found to correlate with the in-vivo activity. Those esters (BMS-181163 and acetamidophenyl esters of Ch-80 and TTNPB) with a higher hydrolysis rate exhibited in-vivo activity only slightly lower than their parent free acid retinoids. In contrast, the three phenyl esters with a hydrolysis rate less than 0·3 h^?1 were inactive in-vivo. Data from both approaches suggest that the breakdown of the phenyl ester linkage in this series is essential for the respective in-vivo activity and that the active phenyl esters of retinoids function as prodrugs.     

Studies on beta-lactam antibiotics. IX. Synthesis and biological activity of a new orally active cephalosporin, cefixime (FK027)

The synthesis and some biological properties of 7 beta-[(Z)-2-(2-amino-4-thiazolyl)-2-(carboxymethoxyimino) acetamido]-3-vinyl-3-cephem-4-carboxylic acid (3, FK027) are described. Diphenylmethyl 7-amino-3-vinyl-3-cephem-4-carboxylate hydrochloride (8), the cephem precursor to FK027 was prepared from 7-aminocephalosporanic acid (7-ACA) by two parallel routes differing primarily in the protection of the 7-amino group. Compound 8 was alternatively prepared from deacetylcephalosporin C sodium salt (DCCNa) with improved yields. Two pathways for the conversion of 8 to FK027 are provided. The new orally active cephalosporin, FK027, possesses a widely expanded antimicrobial activity and high stability to beta-lactamases.