Feasibility and safety of early initiation of a PCSK9 (proprotein convertase subtilisin/kexin type 9) inhibitor in patients with acute myocardial infarction undergoing primary PCI

Background

Recent ESC/EAS Guidelines for the management of dyslipidemia stated that the treatment goal of LDL cholesterol (LDL-C) in very high-risk patients is less than 55mg/dl. PCSK9 inhibitors in addition to strong statins could be a useful strategy for rapid and aggressive lowering of LDL-C. However, the feasibility and safety of early initiation of a PCSK9 inhibitor for AMI patients undergoing primary PCI remain unclear.

Objectives

We examined the effects of early initiation of a PCSK9 inhibitor, evolocumab, on lipid profile and inflammatory markers and its safety in AMI patients undergoing primary PCI.

Methods

This study is a single center, randomized, controlled trial involving 102 patients hospitalized for AMI. The patients were randomly assigned 1:1 to the evolocumab group and the control group. Evolocumab (140 mg) was subcutaneously injected within 24 hours after PCI and then every two weeks. All patients received pitavastatin (2mg/day) in addition to the allocated treatment. The primary endpoints were changes in lipid profile and inflammatory markers from baseline to 4 weeks.

Results

102 patients were enrolled between October 2017 and December 2019. 89 patients were ST-segment elevation myocardial infarction (STEMI), 13 patients were non-STEMI. Primary PCI was successfully performed in all patients. 76 patients were statin-naïve. 2 patients were excluded from analyses because they died severe heart failure in acute phase. Finally, 100 patients (evolocumab; n=51 and control; n=49) were analyzed. Baseline LDL-C was 121.6±30.3 mg/dl in the evolocumab group and 124.7±33.6 mg in the control group. Change in LDL-C from the baseline to 4 weeks was −92.4±32.4 mg/dl (−75%) in the evolocumab group and −44.8±32.1 mg/dl (−33.1%) in the control group (mean difference; 47.6mg/dl, 95% CI; 34.8 to 60.4 mg/dl, p<0.001). LDL-C <70mg/dl at 4 weeks was achieved in 96.0% of the evolocumab group as compared with 26.5% of the control group. Further, in the evolocumab group. LDL <55mg/dl was achieved in 92.1% at 2 weeks and 92.1% at 4 weeks. Regarding inflammatory markers, there were no significant difference in change in high-sensitivity C-reactive protein (p=0.49) and tumor necrosis factor-alpha (p=0.63) between two groups even after adjustment of baseline value. No adverse event associated with evolocumab was observed during this study.

Conclusion

In patients with AMI undergoing primary PCI, early initiation of evolocumab rapidly reduced LDL-C without no adverse event, and achieved LDL-C<55mg/dl in most patients within 2 weeks. Early administration of a PCSK9 inhibitor combined with a strong statin could be a feasible and safe treatment for AMI patients undergoing PCI.

Funding Acknowledgement

Type of funding source: None

Increased oxygen uptake and utilization in the peripheral muscles, rather than cardiac function reserve, may be determinants of increased peak VO2 by cardiac rehabilitation in heart failure

Background

Peak oxygen consumption (peak VO2) is a major prognostic parameter in heart failure (HF). Previous studies have shown a relationship between peak VO2 and impaired oxygen uptake and utilization in the peripheral muscles. The purpose of this study was to clarify the determinant of increased peak VO2 by cardiac rehabilitation (CR) in patients with HF.

Methods

We performed echocardiography during upright ramp bicycle cardiopulmonary exercise test in 30 HF patients (61±1 years of age, 80% male) before and 6 months after CR. HR reserve was determined as the change in HR from rest to peak exercise, expressed as a percentage of the predicted maximal HR reserve. Elastance index (EAI) and LV end-systolic elastance index (ELVI) were derived as the ratio of end-systolic pressure to stroke volume index and end-systolic volume index, respectively. End-systolic pressure was estimated from the equation 0.9 × brachial systolic blood pressure. Ventriculo-arterial coupling (VAC) was calculated as the quotient of EAI and ELVI. The ratio of LDEDVI to E/e' mean was used to evaluate LV diastolic compliance. Systemic vascular resistance index was calculated as mean arterial pressure divided by echocardiography calculated cardiac index and multiplied by 80. The arterial venous oxygen content difference (C (A-V) O2 gradient) was calculated by using the Fick equation as: VO2/echocardiography calculated cardiac output.

Results

Peak VO2 and C (A-V) O2 gradient were increased by CR. However, heart rate reserve, systolic reserve, VAC, diastolic reserve and vasodilation reserve were unchanged by CR (Table 1).

Conclusions

Increased oxygen uptake and utilization in the peripheral muscles, rather than cardiac function reserve, may be determinants of increased peak VO2 by CR in HF.

Table 1

Funding Acknowledgement

Type of funding source: None

P6257Low systolic blood pressure on admission as a predictor of outcome in octogenarian patients with heart failure and preserved ejection fraction

Background

Heart failure (HF) is an epidemic in healthcare worldwide including Asia. It appears that HF will become more serious with aging of the population. The patients with heart failure and preserved ejection fraction (HFpEF) were older, more often female, and frequently have comorbidities including hypertension. However, lower systolic blood pressure (SBP) on admission is associated with poor outcomes in patients with HF. It remains unclear whether this association is similar in very elderly patients with HFpEF.

Purpose

To investigate clinical features and prognosis in octogenarian HFpEF subjects.

Methods

We analyzed 87 consecutive subjects aged 80 years or older who were hospitalized for acute decompensated HF with left ventricular ejection fraction (LVEF) ≥50% between 2015 and 2017. Clinical characteristics and a composite event of cardiac death and HF hospitalization were compared in two groups according to SBP cut-off of 140 mmHg on admission.

Results

The prevalence of lower SBP subjects (mean BP = 118 mmHg) and higher SBP (mean BP = 166 mmHg) subjects were 41.4% and 58.6%, respectively. Lower SBP subjects were more comorbid with atrial fibrillation (72.2 vs. 45.1%, p=0.01). In the lower SBP group, diuretics, mineralocorticoid receptor antagonists (MRA), beta-blockers and ACE inhibitors/ARBs were more commonly used than higher SBP group (Table). During the observational period (median = 1.0 year), lower SBP on admission was associated with a 2.65-fold [95% confidence interval (CI): 1.29–5.55, p=0.009] greater likelihood of experiencing the composite events of cardiac death and rehospitalization for HF (Figure). This observation was still consistent even after adjusting clinical demographics and comorbidity [hazard ratio = 2.95, 95% CI: 1.30–6.87, p=0.01].

Table 1 Lower SBP group (n=36) Higher SBP group (n=51) P-value Atrial fibrillation (%) 72.2 0.01 0.01 Loop diuretic (%) 97.1 83.7 0.08 MRA (%) 47.1 24.5 0.04 Beta-blocker (%) 52.9 44.9 0.51 ACE inhibitor/ARB (%) 59.2 29.4 0.01

Figure 1

Conclusions

In octogenarian patients with acute decompensated HF and preserved LVEF, SBP on admission less than 140 mmHg is significantly associated with poor outcomes. Future studies need to prospectively evaluate optimal SBP treatment goals in very elderly patients with HFpEF.

Discovery of new diphenyloxazole derivatives containing a pyrrolidine ring: orally active prostacyclin mimetics. Part 2

Synthetic and biological evaluation of novel diphenyloxazole derivatives containing a pyrrolidine ring, as a prostacyclin mimetic without the PG skeleton, are described. Asymmetric reduction of a ketone using a chiral Ru complex and reductive amination by NaBH(4) produces four isomers of the tetrahydronaphthalene ring and the pyrrolidine ring with high stereoselectivity. FR193262 (4), (R,R)-diphenyloxazolyl pyrrolidine derivative, displays high potency and agonist efficacy at the IP receptor and has good bioavailability in rats and dogs.

Metabolism investigation leading to novel drug design: orally active prostacyclin mimetics. Part 4

A metabolism study of FR181157 (1) led to the discovery of new oxazole derivatives as active metabolites. The metabolite 6 with an epoxy ring exhibited high anti-aggregative potency with an IC(50) of 5.8 nM and potent binding affinity for the human recombinant IP receptor with a K(i) value of 6.1 nM and selectivity for human IP receptor over all other members of the human prostanoid receptor family.

Discovery of diphenylcarbamate derivatives as highly potent and selective IP receptor agonists: orally active prostacyclin mimetics. Part 3

The new classes of diphenylcarbamate derivatives with a tetrahydronaphthalene skeleton as highly potent and selective IP agonists have been discovered. The optimized diphenylcarbamate type compound FK-788: (R)-4 exhibited potent antiaggregative potency with an IC50 of 18 nM and high binding affinity for the human recombinant IP receptor with K(i) values of 20 nM and selectivity for human IP over all other members of the human prostanoid receptor family. Compound (R)-4 was shown to exhibit good pharmacokinetic properties in rats and dogs, and also good bioavailability in healthy volunteers.

Discovery of Diphenyloxazole and Nδ-Z-Ornithine Derivatives as Highly Potent and Selective Human Prostaglandin EP4Receptor Antagonists

Two novel classes of diphenyloxazole and Ndelta-Z-ornithine derivatives as highly potent and selective EP(4) antagonists have been discovered. The optimized diphenyloxzole 8 and Ndelta-Z-ornithine 11 effectively competed with [(3)H]PGE(2) binding to human recombinant EP(4), with K(i) values of 0.30 nM and 0.91 nM, respectively, and were selective for all members of the human prostanoid receptor family. 8 was shown to exhibit good pharmacokinetic properties in rats and dogs and potent inhibitory activity toward in vitro PGE(2)-promoted IgE synthesis.

Structure-based de novo design of non-nucleoside adenosine deaminase inhibitors

We searched for non-nucleoside inhibitors of adenosine deaminase by rational structure-based de novo design and succeeded in the discovery of 1-(1-hydroxy-4-phenyl-2-butyl)imidazole-4-carboxamide (FR221647: K(i)=5.9 microM to human ADA) as a novel inhibitor with moderate activity and good pharmacokinetics compared with the known inhibitors pentostatin and EHNA.

Synthesis and antibacterial evaluation of novel 2-[N-Imidoylpyrrolidinyl] carbapenems

The synthesis, antibacterial activity and DHP-susceptibility of a series of novel carbapenems, directly linked with heterocyclic moiety are described. Especially, the compounds linked pyrrolidine-carbapenem exhibited to have a good antibacterial activity against Staphylococcus aureus (MRSA) as well as Pseudomonas aeruginosa to maintain a good stability towards DHP-I.

Anti-Helicobacter pylori agents. 5. 2-(Substituted guanidino)-4-arylthiazoles and aryloxazole analogues

To extend the SAR study of guanidinothiazoles as a structurally novel class of anti-H. pylori agents, a series of 2-(substituted guanidino)-4-arylthiazoles and some 4-aryloxazole analogues were synthesized and evaluated for antimicrobial activity against H. pylori. Some of them were also subjected to H2 antagonist and gastric antisecretory assays. Several arylthiazoles were identified as potent anti-H. pylori agents, and of these, thienylthiazole derivative 44 exhibited the strongest activity (MIC = 0.0065 microg/mL) among the compounds obtained in our guanidinothiazole studies. Although 44 was void of H2 antagonist activity, pyridylthiazole derivative 39 had both potent anti-H. pylori and H2 antagonist activities. Thiazolylthiazole derivative 46 also showed potent anti-H. pylori activity, but the H2 antagonist activity was weak. On the other hand, no attractive activities were found in pyrimidyl, oxazolyl, isoxazolyl, imidazolyl, and oxadiazolylthiazole derivatives. The anti-H. pylori activity of the aryloxazole analogues was weaker than those of the corresponding arylthiazole derivatives, though they had potent H2 antagonist activity.

Design, synthesis and biological evaluation of a novel series of potent, orally active adenosine A1 receptor antagonists with high blood-brain barrier permeability

A novel series of 3-(2-substituted-3-oxo-2,3-dihydropyridazin-6-yl)-2-phenylpyrazolo[1,5-a]pyridines (5-38) were synthesized and evaluated for their in vitro adenosine A1 and A(2A) receptor binding activities, and in vitro metabolism by rat liver in order to search for orally active compounds. Most of the test compounds were potent adenosine A1 receptor antagonists with high A1 selectivity and the A1 affinity and A1 selectivity of carbonyl derivatives (5-11) was particularly high. In particular, compound 7 was an extremely potent and selective adenosine A1 antagonist with high A1 selectivity (Ki=0.026 nM, A(2A)/A1=5400). In terms of metabolic stability, 2-oxopropyl (5), 2-hydroxypropyl (12), N-methylacetamide (16), 2-(piperidin-1-yl)ethyl (28) and 1-methylpiperidin-4-yl (32, FR194921) were the most stable compounds in this series of analogues. Further in vivo evaluation indicated that compounds 5, 13, 17, 28 and 32 were detected in both plasma and brain after oral administration in rats. In particular, 32 displayed good plasma and brain concentrations (dose: 32 mg/kg (n=3); after 30 min, plasma conc.=3390+/-651nM, brain conc.=3670+/-496nM; after 60min, plasma conc.=1580+/-348nM, brain conc.=2143+/-434nM), and a good brain/plasma ratio (1.11+/-0.060 (30min), 1.39+/-0.172 (60min)). As a result, we could show that 32 is a good candidate for an orally active adenosine A1 receptor antagonist with high blood-brain barrier permeability and good bioavailability (Ki=6.6nM, A(2A)/A1=820, BA=60.6+/-4.9% (32 mg/kg)).

The anti-inflammatory effect of FR188582, a highly selective inhibitor of cyclooxygenase-2, with an ulcerogenic sparing effect in rats

The anti-inflammatory and ulcerogenic effects of FR188582, 3-chloro-5-[4-(methylsulfonyl) phenyl]-1-phenyl-1H-pyrazole, were investigated. In a recombinant human cyclooxygenase (COX) enzyme activity, FR188582 inhibited COX-2 with an IC50 value of 0.017 microM, and the inhibition of prostaglandin (PG) E2 formation by FR188582 was over 6000 times more selective for COX-2 than COX-1. Oral administration of FR188582 dose-dependently inhibited adjuvant arthritis. This effect was threefold more potent than that of indomethacin. FR188582 and indomethacin dose-dependently suppressed the formation of immunoreactive PGE2, but not immunoreactive leukotriene (LT) B4, in arthritic paw. Unlike indomethacin, FR188582 did not induce visible gastric lesions in rats at doses up to 32 mg/kg, p.o. Furthermore, FR188582 did not inhibit the level of immunoreactive PGE2 and immunoreactive 6-keto PGF1alpha in rat gastric mucosa. These results suggest that FR188582, a highly selective COX-2 inhibitor, has a potent anti-inflammatory effect mediated by inhibition of PGE2 in inflamed tissues. The safety profile of FR188582 appears to be improved over the safety profile of indomethacin.

A novel pyridazinone derivative as a nonprostanoid PGI2 agonist

A novel optically pure pyridazinone derivative was synthesized and identified as a nonprostanoid PGI2 agonist. It inhibited ADP-induced aggregation of human platelets with an IC50 value of 0.081 microM and has high oral bioavailability (56%) with a long half-life (4.3 h) in rats.

Effects of metal combinations on cytotoxicity evaluation using a dynamic extraction method

The effects of metal combinations on cytotoxicity were examined following dynamic extraction by freely gyrating two spherical metals in a glass vessel. The cell viabilities of an Au alloy, a Ag-Pd-Au alloy and Ti were little affected by combinations among three metals. Cell viability ranged between 60 and 80% when precious alloys were in combination with Co-Cr or Ni-Cr alloys. Ti showed a clear difference in cell viability either in combination with Co-Cr or Ni-Cr alloys. The cell viability of the Ti/Co-Cr alloy combination was the same as that of precious alloys/Co-Cr or Ni-Cr alloy combinations. However, in an analogy with Co-Cr alloy/Ni-Cr alloy combination, the Ti/Ni-Cr alloy combination depressed the cell viability below 20%. This suggested that when new metals are to be used in combination with dissimilar metals, the cytotoxicity of the metals could be evaluated in extraction conditions using the mutual dynamic contact of dissimilar metals.

Anti-Helicobacter pylori agents. 4. 2-(Substituted guanidino)-4-phenylthiazoles and some structurally rigid derivatives

In order to find a new class of anti-Helicobacter pylori (H. pylori) agents, a series of 4-[(3-acetamido)phenyl]-2-(substituted guanidino)thiazoles and some structurally rigid analoges were synthesized and evaluated for antimicrobial activity against H. pylori. Among the compounds obtained, high anti-H. pyrori activities were observed in benzyl derivative 34 (MIC = 0.025 microg/mL) and phenethyl derivatives 35 and 36 (MIC = 0.037 microg/mL and 0.017 microg/mL). Though alkyl derivatives generally showed lower activity, the 2-methoxyethyl derivative 28 preserved significant activity (MIC = 0.32 microg/mL) and also exhibited more potent gastric antisecretory activity than ranitidine. Structural restriction by bridging between the thiazole and the phenyl rings with an alkyl chain did not improve the activity in this series.

Orally active cephalosporins. Part 2: synthesis, structure-activity relationships and oral absorption of cephalosporins having a C-3 pyridyl side chain

A series of 7beta-[(Z)-2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamid o]cephalosporins having a pyridine ring connected through various spacer moieties at the C-3 position was designed and synthesized and evaluated for antibacterial activity and oral absorption in rats. All compounds showed potent antibacterial activity against Staphylococcus aureus, whereas antibacterial activity against gram-negative bacteria was markedly influenced by the spacer moiety between the pyridine and cephem nucleus. Oral absorption was influenced by the position of the pyridine nitrogen as well as by the spacer moiety. Among these compounds, FR86830 (14), having a 4-pyridylmethylthio moiety at the C-3 position, showed the most well balanced activity and moderate oral absorption.

Orally active cephalosporins: synthesis, structure-activity relationships and oral absorption of 3-[(E) and (Z)-2-substituted vinyl]-cephalosporins

A series of 7beta-[(Z)-2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamid o]-3-[(E)- and (Z)-2-substituted vinyl]-3-cephem-4-carboxylic acids was designed and synthesized using palladium-catalyzed coupling reactions of a 3-methanesulfonyloxy-3-cephem and an E substituted vinyl stannane or Wittig reaction of a 3-triphenylphosphoniummethyl cephem and an aldehyde as a key step. These compounds were evaluated for in vitro antibacterial activity and oral absorption in rats. A number of them exhibited excellent antibacterial activity against both gram-positive and gram-negative bacteria including Haemophilus influenzae. Among them, FR86524 (2j). having a (Z)-2-(3-pyridyl)vinyl moiety at the C-3 position, had the most well balanced activity. Although FR86254 exhibited low oral absorption, the pivaloyloxymethyl ester (23) of FR86524 showed improved oral absorption.

Novel adenosine A1 receptor antagonists. Synthesis and structure-activity relationships of a novel series of 3-(2-cyclohexenyl-3-oxo-2,3-dihydropyridazin-6-yl)-2-phenylpyrazolo[1,5 -a]pyridines

A novel series of 3-(2-cyclohexenyl-3-oxo-2,3-dihydropyridazin-6-yl)-2-phenylpyrazol o[1,5-a]pyridines was synthesized and evaluated for in vitro adenosine A1 and A2A receptor binding activities. Most of the cyclohexenyl derivatives (7a-e, 8a-s) were found to be potent adenosine A1 receptor antagonists. In a series of analogues of FR166124 (3a), alcohol 7c, nitrile 7e and amide derivatives (7d, 8c, 8r) were found to be more potent A1 antagonists with higher A2A/A1 selectivity than FR166124. Amongst them, 8r showed considerable water solubility (33.3 mg/mL), but lower than that of the sodium salt of FR166124 (> 200 mg/mL). Additionally, FR166124 had strong diuretic activity by both p.o. and iv administration in rats (minimum effective dose=0.1 and 0.032 mg/kg, respectively).

In vitro activities of a new lipopeptide antifungal agent, FK463, against a variety of clinically important fungi

The in vitro antifungal activity and spectrum of FK463 were compared with those of amphotericin B, fluconazole, and itraconazole by using a broth microdilution method specified by National Committee for Clinical Laboratory Standards document M27-A (National Committee for Clinical Laboratory Standards, Wayne, Pa., 1997). FK463 exhibited broad-spectrum activity against clinically important pathogens including Candida species (MIC range, <==0.0039 to 2 microg/ml) and Aspergillus species (MIC range, <==0.0039 to 0.0313 microg/ml), and its MICs for such fungi were lower than those of the other antifungal agents tested. FK463 was also potently active against azole-resistant Candida albicans as well as azole-susceptible strains, and there was no cross-resistance with azoles. FK463 showed fungicidal activity against C. albicans, i.e., a 99% reduction in viability after a 24-h exposure at concentrations above 0.0156 microg/ml. The minimum fungicidal concentration (MFC) assays indicated that FK463 was fungicidal against most isolates of Candida species. In contrast, the MFCs of FK463 for A. fumigatus isolates were much higher than the MICs, indicating that its action is fungistatic against this species. FK463 had no activity against Cryptococcus neoformans, Trichosporon species, or Fusarium solani. Neither the test medium (kind and pH) nor the inoculum size greatly affected the MICs of FK463, while the addition of 4% human serum albumin increased the MICs for Candida species and A. fumigatus more than 32 times. Results from preclinical in vitro evaluations performed thus far indicate that FK463 should be a potent parenteral antifungal agent.

Anti-Helicobacter pylori agents. 3. 2-[(Arylalkyl)guanidino]-4-furylthiazoles

A series of 2-[(arylalkyl)guanidino]-4-[(5-acetamidomethyl)furan-2-yl]thiazole s and some 4-acetamidomethyl positional isomers were synthesized and evaluated for antimicrobial activity against Helicobacter pylori. Among the compounds that had potent antimicrobial activity (MIC < 0. 1 microgram/mL), compounds 31 and 36 additionally possessed H2 antagonist and gastric antisecretory activities. Though compound 51, an analogue incorporating a methyl group onto the furan nucleus of 36, and compound 54, a positional isomer of 51, also showed potent anti-H. pylori activity, the H2 antagonism profile was eliminated from these compounds. Thus, two types of potent anti-H. pylori agents could be derived from the same scaffold.

Discovery of FR166124, a novel water-soluble pyrazolo-[1,5-a]pyridine adenosine A1 receptor antagonist

Novel 3-(2-cycloalkyl and cycloalkenyl-3-oxo-2,3-dihydropyridazin-6-yl)-2-phenylpyrazo lo [1,5-a]-pyridines were synthesized and evaluated for their adenosine A1 receptor binding activities. In this series, FR166124 (3) was found to be the most potent and selective adenosine A1 receptor antagonist, and the double bond of the cyclohexenyl acetic acid group was essential for selectivity of A1 receptor binding. Furthermore, the solubility in water of the sodium salt of FR 166124 was high.

Anti-Helicobacter pylori agents. 2. Structure activity relationships in a new series of 2-alkylguanidino-4-furylthiazoles

SAR for antimicrobial activity against H. pylori was investigated in a new series of 2-alkylguanidino-4-furylthiazoles. Of the compounds obtained, cyclohexylmethyl and ethoxyethyl derivatives were identified as a novel class of anti-H. pylori agents which possessed potent and selective antimicrobial activity against H. pylori. These compounds also showed gastric antisecretory activity.

Anti-Helicobacter pylori agents. 1. 2-(Alkylguanidino)-4-furylthiazoles and related compounds

A series of 2-(alkylguanidino)-4-[5-(acetamidomethyl)furan-2-yl]thiazoles and related compounds were synthesized and evaluated for antimicrobial activity against Helicobacter pylori, inhibitory effect on gastric acid secretion, and histamine H2-receptor antagonist activity. Introduction of alkyl substituents on the guanidino moiety resulted in a significant increase in antimicrobial activity, which was associated with the alkyl chain length. Of the compounds obtained, the n-hexylguanidino derivative 13 demonstrated a 250-fold improvement in activity (MIC = 0.11 micrograms/mL) over the unsubstituted guanidino derivative 7. Alkyl-substituted guanidino derivatives also displayed gastric antisecretion and H2-antagonist activities. However, a simple correlation between the alkyl chain length and the activities was not found in these assays. Replacement of the guanidine with other bioisosteric groups (thiourea, urea, or (dimethylamino)methyl) resulted in loss of all activities tested. Thus the guanidino moiety was found to be essential for activity in this series of compounds.

Studies on 3'-quaternary ammonium cephalosporins--IV. Synthesis and antibacterial activity of 3'-(2-alkyl-3-aminopyrazolium) cephalosporins related to FK037

The synthesis and in vitro antibacterial activity of 7 beta-[(Z)-2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido] cephalosporins bearing various 2-alkyl-3-aminopyrazolium groups at the 3-position are described. Antibacterial activity against MRSA was affected by the nature of the substituent at the 2-position on the 3'-aminopyrazolium groups. Among the cephalosporins prepared in this study, 7 beta-[(Z)-2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido]-3-[3-am ino-2-(2 -hydroxyethyl)-pyrazolio]methyl-3-cephem-4-carboxylate sulfate (23e, FK037) showed extremely potent broad-spectrum activity against both Gram-positive bacteria including MRSA, and Gram-negative bacteria including Pseudomonas aeruginosa. In particular, the in vivo activity against MRSA of FK037 was the highest of all the beta-lactam antibiotics tested.

Studies on 3'-quaternary ammonium cephalosporins--III. Synthesis and antibacterial activity of 3'-(3-aminopyrazolium) cephalosporins

The synthesis and in vitro antibacterial activity of 7 beta-[(Z)-2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido]cephalos porins bearing N-mono or dialkyl and carbamoyl aminopyrazolium, and five- or six-membered rings fused to the 3-aminopyrazolium methyl groups at the 3-position, are described. Aminopyrazolium methyl cephalosporins (23e, f, i), with fused saturated and unsaturated rings were especially effective against Staphylococcus strains compared to 3-amino-2-methylpyrazolium methyl cephalosporin (1). Among the cephalosporins prepared in this work, 7 beta-[(Z)-2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido]-3-(4,5, 6, 7-tetrahydro-1-pyrazolo[1,5-a]pyrimidinio)methyl-3-cephem-4-carbox ylate (23f) showed a good balance of antibacterial activity against both Gram-positive bacteria including Staphylococcus aureus and Gram-negative bacteria including P. aeruginosa. An imidazopyrazolium group at the 3-position in, for example, cephalosporin (23i) was particularly effective for improving antibacterial activity against MRSA.

[Research and development of new oral cephems, cefixime and cefdinir]

This article reviews the structure-activity relationships, biological properties and synthesis of two new oral cephalosporin antibiotics, cefixime (CFIX) and cefdinir (CFDN). Our research into new oral cephalosporin antibiotics began in the late 1970's. The first goal of our research was to discover a new oral cephem possessing similar antibacterial activity and resistance to beta-lactamase as the 3rd generation injectable cephalosporins. We focused our attention on searching for a non-prodrug type cephem, that is, a new parent structure with high intrinsic absorption. We selected ceftizoxime (CZX) as a seed compound due to its relatively high excretion rate (8.5%) in the urine after oral administration to rats. We concentrated our research on the chemical modification of the oxime moiety in CZX based on our hypothesis for oral absorption, and discovered a lead compound with a carboxymethoxyimino group which displayed better urinary excretion (41.0%). Optimization studies led to a new oral cephem, CFIX. However, CFIX shows only low to moderate antibacterial activity against gram-positive bacteria such as S. aureus. Hence, the second goal of our research was to discover a new oral cephem with enhanced activity against gram-positive bacteria. From a consideration of structure-absorption relationships, we studied the activity and absorbability of cephems bearing other acidic functional groups at the oxime moiety of CFIX. As a result, we found a new oral cephem, CFDN with a hydroxyimino group at the 7-position. CFIX has excellent biological properties, displaying potent antibacterial activity against a wide range of gram-positive bacteria except S. aureus and gram-negative bacteria including opportunistic pathogens, high stability towards beta-lactamases and long acting efficacy. CFDN exhibits excellent and well balanced antibacterial activities against gram-positive and gram-negative bacteria. The pharmacokinetic of CFDN in healthy volunteers showed that serum levels were high enough to make CFDN as an effective antibacterial agent. The proposed mechanisms of intestinal absorption of CFIX and CFDN are briefly described. The efficient synthetic methods to CFIX and CFDN were achieved via a common intermediate, 7-amino-3-vinylcephalosporanic acid diphenylmethyl ester from 7-ACA.

[A new oral cephem, cefdinir: its structure-activity relationships and biological profile]

This article reviews structure-activity relationships and biological properties of a new oral cephem, cefidinir (CFDN). It also describes a hypothesis concerning the absorption mechanism from the intestine. Antibacterial activities and the oral absorption efficiencies were studied with regard to 3-vinyl cephalosporins with various 7-acyl side chains. From the study, 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetyl group was selected and various 3-substituents were screened. As a result, it was found that the vinyl compound, CFDN, showed excellent antibacterial activity and good oral absorption in rats. In vitro and in vivo antibacterial activities, the affinity for PBPs and the stability to beta-lactamases revealed that CFDN had well balanced antimicrobial activities against Gram-positive and Gram-negative bacteria and good biological properties. The pharmacokinetics of CFDN in healthy volunteers showed that serum concentration and half life were good enough to make CFDN an effective therapeutic agent. The mechanism of intestinal absorption of CFDN and related oral cephems are discussed and a hypothesis for molecular recognition by the carrier protein in the intestine is proposed.

Studies on beta-lactam antibiotics. XIX. Structure-activity relationships of cephalosporins having a thiadiazolylthiomethyl group at the C-3 side chain

The synthesis and antibacterial activity of 7 beta-[(Z)-2-(2-amino-4-thiazolyl)-2-(hydroxy or alkoxy)iminoacetamido]cephalosporins with various thiadiazolylthiomethyl moieties at the 3-position are discussed. Of the compounds (1a-1e, 7a-7d), 7 beta-[(Z)-2-(2-amino-4-thiazolyl)-2-hydroxyiminoacetamido]-3-[(1,2 ,4- thiadiazol-5-yl)thiomethyl]cephalosporin (1d: FK312) exhibited the highest activity against Gram-positive and Gram-negative bacteria, especially, against methicillin-resistant Staphylococcus aureus. Furthermore, the pharmacokinetic profiles of the compound 1d showed longer serum levels than that of ceftriaxone in rats.

[Studies on FK482 (Cefdinir). IV. Synthesis and structure-activity relationships of 7 beta-[(Z)-2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido]- 3-substituted cephalosporin derivatives]

The synthesis of 7 beta-[(Z)-2-(aminothiazol-4-yl)-2-hydroxyiminoacetamido] cephalosporins (Ia-i) modified at the C-3 position of a cephem nucleus and the effect of the C-3 substituents on the antibacterial activity and oral absorbability are discussed. The cephems (Ie, h and i) having a C-3 substituent such as 1-propenyl, ethylthio and vinylthio group as well as FK482 (cefdinir) exhibited excellent antibacterial activities against both gram-positive and gram-negative bacteria. However, those compounds showed poor absorption rate after oral administration in rats. It is concluded that the vinyl moiety at the 3-position is necessary to display fairly oral absorptivity in a series of 7 beta-[(Z)-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido]c eph ems.

Synthesis and antibacterial activity of 7 beta-[1-(2-aminothiazol-4-yl)-1-cyclopropanecarboxyamido]cephem derivatives

The synthesis and antibacterial activity of several 7 beta-[1-(2-aminothiazol-4-yl)-1-cyclopropanecarboxyamido]cep hem derivatives (1) are described. The structure-activity relationships of 1 are also presented.

Synthesis and biological activity of 3-vinylthio- and 3-vinylthiomethylcephem derivatives

The synthesis and biological properties of some 3-vinylthio- and 3-vinylthiomethylcephem derivatives are described. Both series possess potent antibacterial activity. Among them, 3-[(Z)-2-cyanovinylthiomethyl]cephem derivative was found to have an expanded antibacterial spectrum.