Nirmatrelvir treatment of SARS-CoV-2-infected mice blunts antiviral adaptive immune responses

Alongside vaccines, antiviral drugs are becoming an integral part of our response to the SARS-CoV-2 pandemic. Nirmatrelvir-an orally available inhibitor of the 3-chymotrypsin-like cysteine protease-has been shown to reduce the risk of progression to severe COVID-19. However, the impact of nirmatrelvir treatment on the development of SARS-CoV-2-specific adaptive immune responses is unknown. Here, by using mouse models of SARS-CoV-2 infection, we show that nirmatrelvir administration blunts the development of SARS-CoV-2-specific antibody and T cell responses. Accordingly, upon secondary challenge, nirmatrelvir-treated mice recruited significantly fewer memory T and B cells to the infected lungs and mediastinal lymph nodes, respectively. Together, the data highlight a potential negative impact of nirmatrelvir treatment with important implications for clinical management and might help explain the virological and/or symptomatic relapse after treatment completion reported in some individuals.

Oral Nirmatrelvir for High-Risk, Nonhospitalized Adults with Covid-19

BACKGROUND

Nirmatrelvir is an orally administered severe acute respiratory syndrome coronavirus 2 main protease (Mpro) inhibitor with potent pan-human-coronavirus activity in vitro.

METHODS

We conducted a phase 2-3 double-blind, randomized, controlled trial in which symptomatic, unvaccinated, nonhospitalized adults at high risk for progression to severe coronavirus disease 2019 (Covid-19) were assigned in a 1:1 ratio to receive either 300 mg of nirmatrelvir plus 100 mg of ritonavir (a pharmacokinetic enhancer) or placebo every 12 hours for 5 days. Covid-19-related hospitalization or death from any cause through day 28, viral load, and safety were evaluated.

RESULTS

A total of 2246 patients underwent randomization; 1120 patients received nirmatrelvir plus ritonavir (nirmatrelvir group) and 1126 received placebo (placebo group). In the planned interim analysis of patients treated within 3 days after symptom onset (modified intention-to treat population, comprising 774 of the 1361 patients in the full analysis population), the incidence of Covid-19-related hospitalization or death by day 28 was lower in the nirmatrelvir group than in the placebo group by 6.32 percentage points (95% confidence interval [CI], -9.04 to -3.59; P<0.001; relative risk reduction, 89.1%); the incidence was 0.77% (3 of 389 patients) in the nirmatrelvir group, with 0 deaths, as compared with 7.01% (27 of 385 patients) in the placebo group, with 7 deaths. Efficacy was maintained in the final analysis involving the 1379 patients in the modified intention-to-treat population, with a difference of -5.81 percentage points (95% CI, -7.78 to -3.84; P<0.001; relative risk reduction, 88.9%). All 13 deaths occurred in the placebo group. The viral load was lower with nirmatrelvir plus ritonavir than with placebo at day 5 of treatment, with an adjusted mean difference of -0.868 log10 copies per milliliter when treatment was initiated within 3 days after the onset of symptoms. The incidence of adverse events that emerged during the treatment period was similar in the two groups (any adverse event, 22.6% with nirmatrelvir plus ritonavir vs. 23.9% with placebo; serious adverse events, 1.6% vs. 6.6%; and adverse events leading to discontinuation of the drugs or placebo, 2.1% vs. 4.2%). Dysgeusia (5.6% vs. 0.3%) and diarrhea (3.1% vs. 1.6%) occurred more frequently with nirmatrelvir plus ritonavir than with placebo.

CONCLUSIONS

Treatment of symptomatic Covid-19 with nirmatrelvir plus ritonavir resulted in a risk of progression to severe Covid-19 that was 89% lower than the risk with placebo, without evident safety concerns. (Supported by Pfizer; ClinicalTrials.gov number, NCT04960202.).

Antiviral pills could change pandemic's course

[Figure: see text].

Twelve-week ravidasvir plus ritonavir-boosted danoprevir and ribavirin for non-cirrhotic HCV genotype 1 patients: A phase 2 study

BACKGROUND AND AIM

The need for all-oral hepatitis C virus (HCV) treatments with higher response rates, improved tolerability, and lower pill burden compared with interferon-inclusive regimen has led to the development of new direct-acting antiviral agents. Ravidasvir (RDV) is a second-generation, pan-genotypic NS5A inhibitor with high barrier to resistance. The aim of this phase 2 study (EVEREST study) was to assess the efficacy and safety of interferon-free, 12-week RDV plus ritonavir-boosted danoprevir (DNVr) and ribavirin (RBV) regimen for treatment-naïve Asian HCV genotype 1 (GT1) patients without cirrhosis.

METHODS

A total of 38 treatment-naïve, non-cirrhotic adult HCV GT1 patients were enrolled in this multicenter, open-label, single-arm phase 2 study (NCT03020095). All patients received a combination of RDV 200 mg once daily (q.d.) plus DNVr 100 mg/100 mg twice daily (b.i.d.) and oral RBV 1000/1200 mg/day (body weight < 75/≥ 75 kg) for 12 weeks. The primary endpoint was the rate of sustained virologic response 12 weeks after the end of treatment (SVR12).

RESULTS

Of 38 patients, all (100%) achieved SVR12. During the study, no treatment-related serious adverse events, no patients discontinued treatment due to adverse events, and no deaths were reported. Six of 37 (16%) patients with available sequences had HCV NS5A resistance-associated variants at baseline. All patients (6/6) with baseline NS5A resistance-associated variants achieved SVR12.

CONCLUSIONS

Twelve-week RDV and DNVr in combination with RBV for 12 weeks achieves the SVR12 rate of 100% in treatment-naïve non-cirrhotic Asian patients with HCV GT1 infection. This interferon-free regimen is also safe and well tolerated.

Hepatic Effects of Pharmacological Doses of Hydroxy-Cobalamin[c-lactam] in Mice

The vitamin B₁₂ analog hydroxy-cobalamin[c-lactam] (HCCL) impairs hepatic mitochondrial protein synthesis and function of the electron transport chain in rats. We aimed to establish an in vivo model for mitochondrial dysfunction in mice, which could be used to investigate hepatotoxicity of mitochondrial toxicants. In a first step, we performed a dose-finding study in mice treated with HCCL 0.4 mg/kg and 4 mg/kg i.p. for two to four weeks. The plasma methylmalonate concentration was strongly increased at 4 mg/kg starting at three weeks of treatment. We subsequently treated mice daily with 4 mg/kg HCCL i.p. for three weeks and characterized liver function and histology as well as liver mitochondrial function. We found an increase in liver weight in HCCL-treated mice, which was paralleled by hepatocellular accumulation of triglycerides. In liver homogenate of HCCL-treated mice, the complex I activity of the electron transport chain was reduced, most likely explaining hepatocellular triglyceride accumulation. The activity of CPT1 was not affected by methylmalonyl-CoA in isolated liver mitochondria. Despite impaired complex I activity, mitochondrial superoxide anion production was not increased and the hepatocellular glutathione (GSH) pool was maintained. Finally, the mitochondrial DNA content was not altered with HCCL treatment. In conclusion, treatment of mice with HCCL is associated with increased liver weight explained by hepatocellular triglyceride accumulation. Hepatocellular fat accumulation is most likely a consequence of impaired activity of the mitochondrial electron transport chain. The impairment of complex I activity is not strong enough to result in ROS accumulation and reduction of the GSH stores.

Modelling the interaction between danoprevir and mericitabine in the treatment of chronic HCV infection

BACKGROUND

Modelling HCV RNA decline kinetics under therapy has proven useful for characterizing treatment effectiveness.

METHODS

Here we model HCV viral kinetics (VK) in 72 patients given a combination of danoprevir, a protease inhibitor, and mericitabine, a nucleoside polymerase inhibitor, for 14 days in the INFORM-1 trial. A biphasic VK model with time-varying danoprevir and mericitabine effectiveness and Bliss independence for characterizing the interaction between both drugs provided the best fit to the VK data.

RESULTS

The average final antiviral effectiveness of the drug combination varied between 0.998 for 100 mg three times daily of danoprevir and 500 mg twice daily of mericitabine and 0.9998 for 600 mg twice daily of danoprevir and 1,000 mg twice daily of mericitabine. Using the individual parameters estimated from the VK data collected over 2 weeks, we were not able to reproduce the low sustained virological response rates obtained in a more recent study where patients were treated with a combination of mericitabine and ritonavir-boosted danoprevir for 24 weeks.

CONCLUSIONS

This suggests that drug-resistant viruses emerge after 2 weeks of treatment and that longer studies are necessary to provide accurate predictions of longer treatment outcomes.

Management of Complicated Appendicitis and Comparison of Outcome with Other Primary Sites of Intra-abdominal Infection: Results of a Trial Comparing Ertapenem and Piperacillin-Tazobactam

A post-hoc analysis of data from a trial of complicated intra-abdominal infection was performed to compare the demographic and disease characteristics of patients with complicated appendicitis to those whose primary infection involved other intra-abdominal sites, assess the impact of site of primary infection on outcome, and compare the efficacy and safety of ertapenem 1 g daily with piperacillin-tazobactam 3.375 g every 6 h for treatment of complicated appendicitis. Compared with patients who had primary infection of the colon or another site in the abdomen, patients with complicated appendicitis were younger, had less severe disease (based on lower APACHE II score and lower proportion with generalized peritonitis), and were less likely to be managed by percutaneous drainage of an abscess or to have a postoperative infection. Patients with complicated appendicitis were more likely to have a favorable outcome than were patients with infection of the colon (OR, 3.02; 95% CI, [1.54-5.901; P = .001). At the test-of-cure assessment, 109/123 (88.6%) microbiologically evaluable patients with complicated appendicitis who received ertapenem and 102/113 (90.3%) who received piperacillin-tazobactam had a favorable combined clinical and microbiologic outcome. The frequency and severity of drug-related adverse events were similar in the two treatment groups.

Synthesis and evaluation of γ-lactam analogs of PGE₂ as EP4 and EP2/EP4 agonists

To identify topically effective EP4 agonists and EP2/EP4 dual agonists with excellent subtype selectivity, further optimization of the 16-phenyl ω-chain moiety of the γ-lactam 5-thia prostaglandin E analog and the 2-mercaptothiazole-4-carboxylic acid analog were undertaken. Rat in vivo evaluation of these newly identified compounds as their poly (lactide-co-glycolide) microsphere formulation, from which sustained release of the test compound is possible, led us to discover compounds that showed efficacy in a rat bone fracture healing model after its topical administration without serious influence on blood pressure and heart rate. A structure-activity relationship study is also presented.

Virologic escape during danoprevir (ITMN-191/RG7227) monotherapy is hepatitis C virus subtype dependent and associated with R155K substitution

Danoprevir is a hepatitis C virus (HCV) NS3/4A protease inhibitor that promotes multi-log(10) reductions in HCV RNA when administered as a 14-day monotherapy to patients with genotype 1 chronic HCV. Of these patients, 14/37 experienced a continuous decline in HCV RNA, 13/37 a plateau, and 10/37 a rebound. The rebound and continuous-decline groups experienced similar median declines in HCV RNA through day 7, but their results diverged notably at day 14. Plateau group patients experienced a lesser, but sustained, median HCV RNA decline. Baseline danoprevir susceptibility was similar across response groups but was reduced significantly at day 14 in the rebound group. Viral rebound in genotype 1b was uncommon (found in 2/23 patients). Population-based sequence analysis of NS3 and NS4A identified treatment-emergent substitutions at four amino acid positions in the protease domain of NS3 (positions 71, 155, 168, and 170), but only two (155 and 168) were in close proximity to the danoprevir binding site and carried substitutions that impacted danoprevir potency. R155K was the predominant route to reduced danoprevir susceptibility and was observed in virus isolated from all 10 rebound, 2/13 plateau, and 1/14 continuous-decline patients. Virus in one rebound patient additionally carried partial R155Q and D168E substitutions. Treatment-emergent substitutions in plateau patients were less frequently observed and more variable. Single-rebound patients carried virus with R155Q, D168V, or D168T. Clonal sequence analysis and drug susceptibility testing indicated that only a single patient displayed multiple resistance pathways. These data indicate the ascendant importance of R155K for viral escape during danoprevir treatment and may have implications for the clinical use of this agent.

Oral combination therapy with a nucleoside polymerase inhibitor (RG7128) and danoprevir for chronic hepatitis C genotype 1 infection (INFORM-1): a randomised, double-blind, placebo-controlled, dose-escalation trial

BACKGROUND

Present interferon-based standard of care treatment for chronic hepatitis C virus (HCV) infection is limited by both efficacy and tolerability. We assessed the safety, tolerability, and antiviral activity of an all-oral combination treatment with two experimental anti-HCV drugs-RG7128, a nucleoside polymerase inhibitor; and danoprevir, an NS3/4A protease inhibitor-in patients with chronic HCV infection.

METHODS

Patients from six centres in New Zealand and Australia who were chronically infected with HCV genotype 1 received up to 13 days oral combination treatment with RG7128 (500 mg or 1000 mg twice daily) and danoprevir (100 mg or 200 mg every 8 h or 600 mg or 900 mg twice daily) or placebo. Eligible patients were sequentially enrolled into one of seven treatment cohorts and were randomly assigned by interactive voice or web response system to either active treatment or placebo. Patients were separately randomly assigned within each cohort with a block size that reflected the number of patients in the cohort and the ratio of treatment to placebo. The random allocation schedule was computer generated. Dose escalation was started in HCV treatment-naive patients; standard of care treatment-experienced patients, including previous null responders, were enrolled in higher-dose danoprevir cohorts. Investigators, personnel at the study centre, and patients were masked to treatment allocation. However, the pharmacist who prepared the doses, personnel involved in pharmacokinetic sample analyses, statisticians who prepared data summaries, and the clinical pharmacologists who reviewed the data before deciding to initiate dosing in the next cohort were not masked to treatment allocation. The primary outcome was change in HCV RNA concentration from baseline to day 14 in patients who received 13 days of combination treatment. All patients who completed treatment with the study drugs were included in the analyses. This study is registered with ClinicalTrials.gov, NCT00801255.

FINDINGS

88 patients were randomly assigned to a study drug treatment regimen (n=74 over seven treatment groups; 73 received at least one dose of study drug) or to placebo (n=14, all of whom received at least one dose). The median change in HCV RNA concentration from baseline to day 14 ranged from -3·7 to -5·2 log(10) IU/mL in the cohorts that received 13 days of combination treatment. At the highest combination doses tested (1000 mg RG7128 and 900 mg danoprevir twice daily), the median change in HCV RNA concentration from baseline to day 14 was -5·1 log(10) IU/mL (IQR -5·6 to -4·7) in treatment-naive patients and -4·9 log(10) IU/mL in previous standard of care null responders (-5·2 to -4·5) compared with an increase of 0·1 log(10) IU/mL in the placebo group. The combination of RG7128 and danoprevir was well tolerated with no treatment-related serious or severe adverse events, no grade 3 or 4 changes in laboratory parameters, and no safety-related treatment discontinuations.

INTERPRETATION

This oral combination of a nucleoside analogue polymerase inhibitor and protease inhibitor holds promise as an interferon-free treatment for chronic HCV.

FUNDING

Roche Palo Alto.

Attenuation of chronic thermotolerance by KNK437, a benzylidene lactam compound, enhances thermal radiosensitization in mild temperature hyperthermia combined with low dose-rate irradiation

PURPOSE

We investigated whether the attenuation of chronic thermotolerance by KNK437, a heat shock protein inhibitor, can modify the effect of thermal radiosensitization in mild temperature hyperthermia (MTH) combined with low dose-rate irradiation (LDRI).

MATERIALS AND METHODS

The human lung adenocarcinoma cell line A549 was simultaneously exposed to LDRI with MTH at 41 degrees C and KNK437 at a dose of 100 microM. Cell survival was estimated by a clonogenic assay. Cell cycle change during treatment was analyzed by flow cytometry. Expression levels of the heat shock proteins hsp72, hsp27 and heat shock factor 1 (HSF-1) were measured by Western blotting.

RESULTS

KNK437 inhibited the expression of inducible hsp72 and hsp27, but produced no change in the mobility shift of HSF-1. The cytotoxicity of LDRI was enhanced by MTH. The survival curve for LDRI + MTH revealed no development of chronic thermotolerance up to 48 h. Simultaneous LDRI and KNK437 treatment also resulted in enhanced cell killing. The radiosensitizing effect of KNK437 was enhanced by simultaneous exposure of the cells to MTH. Flow cytometry analysis of cell cycle progression demonstrated marked G2 arrest and mild G1 arrest with LDRI alone, but mild G1 arrest with MTH alone, and mild G2-M, S-phase accumulation with KNK437 alone. The marked G2 arrest caused by LDRI was partially suppressed by the addition of MTH, and was also suppressed by KNK437 treatment.

CONCLUSIONS

Exposure of A549 cells to KNK437 caused inhibition of hsp72 and hsp27 expression. The addition of KNK437 increased not only thermosensitivity to MTH, but also radiosensitivity to LDRI. KNK437 also enhanced the MTH-induced radiosensitization under these experimental conditions.

Discovery of orally active butyrolactam 11β-HSD1 inhibitors

A series of metabolically stable butyrolactam 11beta-HSD1 inhibitors have been synthesized and biologically evaluated. These compounds exhibit excellent HSD1 potency and HSD2 selectivity, pharmacokinetic, and pharmacodynamic profiles.

Pharmacodynamics of antimicrobials: treatment optimisation

As bacterial resistance continues to increase, optimising the potential for successful clinical outcomes with antimicrobial therapy requires consideration of pharmacodynamic concepts in order to maximise bacterial eradication and minimise the potential for further resistance. Based on the pharmacodynamic characteristics of specific antibiotics, dosage modifications can be implemented to improve the likelihood of bactericidal exposure. Considering their concentration-dependent bactericidal activity, aminoglycosides benefit from increased dosages and infrequent administration, so as to achieve a maximum concentration/minimum inhibitory concentration (MIC) of 10-12. In contrast, beta-lactams are concentration-independent killers and benefit greatest by increasing the time above the MIC (T > MIC). This can be accomplished with the use of prolonged or continuous infusion. By optimising pharmacodynamic parameters with these methodologies, successful treatment of pathogens may be possible in patient populations for whom standard dosing regimens are not effective.

A multicenter phase II study of the cryptophycin analog LY355703 in patients with platinum-resistant ovarian cancer

LY355703 is a synthetic product structurally related to the cryptophycin family isolated from the blue-green algae, which exerts a potent destabilization of microtubules during mitosis. This study was performed to determine the activity of LY355703 in patients with platinum-resistant advanced ovarian cancer and to characterize its toxicity profile. Twenty-six patients were enrolled in this study. Resistant disease was defined as a platinum-free interval of <6 months from primary treatment or rechallenge. LY355703 (1.5 mg/m(2)) was administered intravenously on days 1 and 8, every 3 weeks, infused over 2 h. From 24 patients evaluable for response, three partial responses (12.5%) and seven disease stabilizations were registered (29.2%), for an overall clinical benefit of 41.7%. Fourteen patients (58.3%) experienced a progression of the disease during treatment. Among the 25 patients evaluable for toxicity, two episodes of grade 3 anemia (8%); one, grade 3 thrombocytopenia (4%); one, grade 4 elevation of creatinine (4%); and one, grade 3 hyperbilirubinemia (4%) were reported. LY355703 has a modest activity in patients with platinum-resistant advanced ovarian cancer. Nevertheless, the considerable rate of disease stabilization in the absence of serious adverse events in this poor-prognosis study population suggests that this novel cryptophycin may deserve further investigation in this setting.

Ketene aminal-based lactam derivatives as a novel class of orally active FXa inhibitors

N,N'-Disubstituted ketene aminals are good bioisosteres of thiourea functional groups. We report the design and synthesis of a novel class of ketene aminal-based lactam derivatives as potent and orally active FXa inhibitors.

Efficacy of a triple therapy with rabeprazole, amoxicillin, and faropenem as second-line treatment after failure of initial Helicobacter pylori eradication therapy

BACKGROUND/AIMS

Triple therapy consisting of lansoprazole, amoxicillin, and clarithromycin (LAC regimen) is widely used to eradicate Helicobacter pylori in Japan. However, the need for appropriate treatment after failure of initial therapy to eradicate H. pylori has been increasing. We therefore assessed the efficacy of a combination of rabeprazole, amoxicillin, and faropenem for second-line eradication therapy.

METHODOLOGY

The subjects were 116 patients positive for H. pylori infection. Patients initially received lansoprazole 60 mg/day, amoxicillin 1500 mg/day and clarithromycin 400 mg/day in two divided doses for 7 days. Patients in whom eradication treatment failed were given rabeprazole 20 mg/day and amoxicillin 1500 mg/day in two divided doses, and faropenem 600 mg/day in three divided doses (RAF regimen) for 7 consecutive days. H. pylori status was assessed by the 13C-urea breath test combined with rapid urease test or H. pylori culture method 8 weeks after completion of therapy. Susceptibility to clarithromycin was determined by the agar dilution method, and genetic polymorphism of CYP2C19 was analyzed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

The initial H. pylori eradication rate with the LAC regimen was 76.4% (84/110). Assessment of the CYP2C19 genotypes of the patients in whom eradication therapy failed revealed that homozygous extensive metabolizers accounted for 70.0% (16/23) and heterozygous extensive metabolizers for 30.0% (7/23), with no poor metabolizers. The acquired resistance rate for clarithromycin was 52.0% (12/23). The success rate of re-eradication with the RAF regimen was 91.3% (21/23) with no serious adverse effects.

CONCLUSIONS

Triple therapy comprising rabeprazole, amoxicillin, and faropenem is effective for second-line eradication treatment of H. pylori infection, regardless of the genetic polymorphism of CYP2C19 or the presence of resistance to clarithromycin.

Pharmacodynamics of ceftazidime plus the serine beta-lactamase inhibitor AM-112 against Escherichia coli containing TEM-1 and CTX-M-1 beta-lactamases

A strain of Escherichia coli containing TEM-1 and CTX-M-1 was tested in an in vitro pharmacokinetic model against ceftazidime with and without AM-112, a serine beta-lactamase inhibitor. Ceftazidime alone was less effective than ceftazidime plus AM-112, and a single dose was more effective than three fractionated doses.

Pharmacokinetics and pharmacodynamics of ertapenem: an overview for clinicians

Ertapenem, a Group 1 carbapenem, is a once-a-day parenteral beta-lactam antibiotic recently licensed in the USA and Europe. Monotherapy with ertapenem dosed as 1 g once a day has been shown to be highly effective in clinical trials for the treatment of complicated infections of skin and skin structures, complicated intra-abdominal infections, community-acquired pneumonia, acute pelvic infections and complicated urinary tract infections. Dosing modifications have not been recommended for adults on the basis of gender, age, weight or liver disease. Presently there are no data regarding the use of ertapenem in children. Dose reductions are indicated for patients with advanced renal insufficiency. Ertapenem is neither a substrate nor an inhibitor of P-glycoprotein or cytochrome P450 enzymes; significant drug interactions between ertapenem and drugs handled by these systems are not expected.

Ertapenem: a new opportunity for outpatient parenteral antimicrobial therapy

Ertapenem is a parenteral carbapenem antimicrobial with pharmacological properties that allow it to be given once daily. This makes it a consideration for outpatient parenteral antimicrobial therapy (OPAT). In comparison with information from the OPAT Outcomes Registry, ertapenem seems well suited for the types of infections and bacteria that are commonly treated with OPAT, plus it has additional activity against anaerobic bacteria. This added spectrum makes it possible to treat complicated skin/skin-structure, complicated intra-abdominal and pelvic infections with a single antibiotic instead of the multiple agents that have usually been required. Ertapenem is also comparable to other OPAT antimicrobials in terms of adverse effects and clinical outcomes. This antimicrobial can be given with any delivery model, although its stability when mixed is such that daily preparation or self-mixing systems need to be considered. Ertapenem should be added to the growing list of once-daily parenteral antibiotics that can be given to outpatients.

Ertapenem: a Group 1 carbapenem with distinct antibacterial and pharmacological properties

Ertapenem, a Group 1 carbapenem, is the most recent beta-lactam antibiotic to enter clinical practice in the USA and Europe. While structurally a carbapenem, the overall molecular structure of ertapenem has been modified to focus its antibacterial spectrum on important community-acquired aerobic and anaerobic pathogens, and to increase its plasma half-life, permitting once-a-day dosing for this parenteral antibiotic. A number of chemical features are responsible for the unique properties of ertapenem. The inclusion of a trans-1-hydroxyethyl group in the structure of ertapenem enables the drug to maintain antibacterial efficacy against the vast majority of beta-lactamase-producing organisms. A critical 1beta-methyl substituent shields the beta-lactam carbonyl group and serves to reduce dehydropeptidase (DHP)-1 catalysed hydrolysis of the beta-lactam, enabling ertapenem to be administered without a DHP-1 inhibitor. A meta-substituted benzoic acid substituent increases the molecular weight and lipophilicity of the molecule, and the carboxylic acid moiety, ionized at physiological pH, results in ertapenem having a net negative charge. As a result, ertapenem is highly protein bound and has an extended half-life, permitting a once-a-day treatment regimen.

Safety and tolerability of ertapenem

Ertapenem is a Group 1 carbapenem that was licensed in the USA in November 2001 and in Europe in April 2002. Its safety profile has been assessed in 240 healthy volunteers participating in 12 clinical pharmacology studies and in 2046 patients enrolled in five Phase IIa and eight Phase IIb/III clinical trials. The most common drug-related adverse events (AEs) reported in trials comparing ertapenem and piperacillin-tazobactam and in trials comparing ertapenem and ceftriaxone were: diarrhoea (ertapenem versus piperacillin-tazobactam 5.0% versus 7.0%; ertapenem versus ceftriaxone 5.6% versus 5.9%); infused vein complications (ertapenem versus piperacillin-tazobactam 4.5% versus 7.9%; ertapenem versus ceftriaxone 3.2% versus 4.6%); nausea (ertapenem versus piperacillin-tazobactam 2.5% versus 3.4%; ertapenem versus ceftriaxone 3.4% versus 3.3%); and elevations in alanine aminotransferase levels (ertapenem versus piperacillin-tazobactam 8.8% versus 7.3%; ertapenem versus ceftriaxone 8.3% versus 6.9%). Most ertapenem-related AEs were reported as mild-to-moderate in intensity. Ertapenem was not associated with prolongation of the QTc interval. Local reactions of moderate-to-severe intensity at the infusion site were infrequent and occurred with similar frequency in the ertapenem and comparator treatment groups. No overall differences in safety were observed between elderly (aged > or = 65 years and > or = 75 years) and younger patients. Ertapenem, 1 g once a day given by intravenous infusion or intramuscular injection, was generally well tolerated and had overall safety and tolerability profiles similar to those of piperacillin-tazobactam and ceftriaxone.

Efficacy of amikacin combinations for nocardiosis

We isolated five bacterial strains from patients diagnosed as having nocardiosis. Bacterial species were identified based on the similarities in the nucleotide sequences of 16S ribosomal RNAs. Three of the five strains were identified as Nocardia asteroids, but unexpectedly other two were Streptomyces hygroscopicus and Rothia dentocariosa. The latter two species are not members of the family Nocardiaceae. We investigated the susceptibilities of these five strains to the following nine antimicrobial agents: trimethoprim/sulfamethoxazole (TMP/SMX), minocycline (MINO), erythromycin (EM), amikacin (AMK), cefotaxime (CTX), faropenem (FRPM), imipenem (IPM), ciprofloxacin (CPFX), and sparfloxacin (SPFX). The minimum inhibitory concentration (MIC) ranges (mg/ml) were as follows: TMP-SMX, 4- > 32; MINO, 0.125-8; EM, < or = 0.016- > 32; AMK, 1-2; CTX, 0.063- > 32; FRPM, 0.063-16; IPM, 0.125-2; CPFX, 4-32; and SPFX, 0.5-16. Moreover, the synergistic effects of AMK in combination with each of TMP-SMX, MINO, EM, CTX, IPM, and SPFX were investigated by checkerboard synergy testing. No antagonism was recognized for the three N. asteroides strains. Synergistic and additive effects were observed for the combinations of AMK with CTX, IPM, or SPFX.

Emergence of Enterobacter cloacae as a common pathogen in neonatal units: pulsed-field gel electrophoresis analysis

In the first week of December 2002, three infants hospitalized in the neonatal department of our hospital had blood cultures positive with Enterobacter cloacae. Screening cultures and genotyping showed that 10 of 25 screened patients also carried E. cloacae and that nine isolates belonged to the same clone as that responsible for all three bacteraemias. This epidemic cluster was limited to one of the two units of the department. Surveillance of both units continued until the end of March 2003; 51 of 159 neonates screened were colonized with E. cloacae, 38 out of 80 (47.5%) in the premature unit (PU) and 13 out of 79 (16.4%) in the paediatric intensive care unit (PICU). Pulsed-field gel electrophoresis (PFGE) analysis of 130 available isolates revealed 30 different pulsotypes, including 24 unique pulsotypes from individual patients and six from multiple patients. Antibiotic (particularly beta-lactam) use did not significantly vary from 1999 to 2003. The consumption of alcohol-based hand rub (four-fold higher in the PICU than in the PU) and nurse-to-patient ratio (1:2 in the PICU and 1:4 in the PU) might explain the higher cross-transmission rate in the PU. Finally, despite an epidemiological survey, we failed to identify the causes of the emergence of E. cloacae in our neonatology units. However, improved hygiene practices combined with restriction of admission led to the progressive disappearance of the epidemic strain. The increasing importance of this type of unit and the dramatic consequences of infections emphasize the need for additional research on the constitution of the flora of newborns and the mode of acquisition Gram-negative multi-resistant bacteria.

Treatment of complicated urinary tract infection in adults: combined analysis of two randomized, double-blind, multicentre trials comparing ertapenem and ceftriaxone followed by appropriate oral therapy

The efficacy and safety of parenteral ertapenem, a Group 1 carbapenem, 1 g once a day, for the treatment of complicated urinary tract infections (UTIs; i.e. acute pyelonephritis, UTI in men, or UTI associated with obstruction, foreign body or a urological abnormality interfering with normal voiding) in adults, were compared with those of parenteral ceftriaxone, 1 g once a day, in two similarly designed prospective, double-blind, randomized studies. In both studies, patients could be switched to an oral agent after > or = 3 days of parenteral study therapy. At entry, 850 patients were stratified according to whether they had acute pyelonephritis or other complicated UTI without acute pyelonephritis. Two hundred and fifty-six patients in the ertapenem group and 224 in the ceftriaxone group were microbiologically evaluable. Ninety-six per cent of these patients were switched to oral therapy, usually ciprofloxacin; the median (range) duration of parenteral and total therapy, respectively, was 4 (2-14) days and 13 (14-18) days for ertapenem and 4 (2-14) days and 13 (3-17) days for ceftriaxone. The most common pathogens were Escherichia coli and Klebsiella pneumoniae, which accounted for 64.7% and 9.8% of isolates, respectively. At the primary efficacy endpoint 5-9 days after treatment, 229 (89.5%) patients who received ertapenem and 204 (91.1%) patients who received ceftriaxone had a favourable microbiological response (95% confidence interval, -7.4 to 4.0), indicating that outcomes in the two treatment groups were equivalent. Success rates in both treatment groups were similar when compared by stratum and severity of infection. The frequency and severity of drug-related adverse events were generally similar in both treatment groups. In this combined analysis, ertapenem was highly effective therapy for the treatment of complicated UTIs in adults with moderate-to-severe disease.

Aristolactam BII of Saururus chinensis attenuates glutamate-induced neurotoxicity in rat cortical cultures probably by inhibiting nitric oxide production

Saurolactam and aristolactam BII, aristolactam-type alkaloids isolated from the aerial part of Saururus chinensis (Lour.) Ball (Saururaceae), showed significant neuroprotective activity against glutamate-induced toxicity in primary cultured rat cortical cells. The action mechanism of aristolactam BII, the more potent neuroprotective compound, was investigated using primary cultures of rat cortical cells as an in vitro system. Aristolactam BII attenuated glutamate-induced neurotoxicity significantly when it was added immediately or up to 9 h after the excitotoxic glutamate challenge. The alkaloid could not protect cultured neuronal cells from neurotoxicity induced by kainic acid or N-methyl- D-aspartate in a pre-treatment paradigm. However, aristolactam BII successfully reduced the overproduction of nitric oxide and the level of cellular peroxide in cultured neurons when it was treated as a post-treatment paradigm. These results may suggest that aristolactam BII exerts its significant neuroprotective effects on glutamate-injured primary cultures of rat cortical cells by directly inhibiting the production of nitric oxide.

Stability and compatibility of reconstituted ertapenem with commonly used i.v. infusion and coinfusion solutions

PURPOSE

The stability of ertapenem sodium in various commonly used i.v. infusion solutions and its compatibility with coinfusion solutions was studied.

METHODS

Ertapenem was reconstituted with sterile water for injection and then diluted with various commercial i.v. infusion solutions to concentrations of 10 and 20 mg/mL. The solutions were stored in flexible polyvinyl chloride containers at 4 and 25 degrees C and in sterile glass vials at -20 degrees C. The drug's stability at 4 degrees C was monitored daily for up to 10 days, at 25 degrees C at appropriate hourly intervals for up to 30 hours, and at -20 degrees C. The daily for up to 14 days. Compatibility with the coinfusion solutions was monitored for up to eight hours at room temperature. Stability assays were conducted until the ertapenem concentration decreased by 10% or the corresponding degradation products exceeded the approved specifications. Ertapenem concentrations were determined by a stability-indicating high-performance liquid chromatography assay.

RESULTS

Ertapenem was more stable in solutions stored at 4 degrees C versus 25 degrees C. Samples frozen at -20 degrees C showed extreme variability. Ertapenem 10 mg/mL was stable for a longer time than at the 20-mg/mL concentration. Ertapenem demonstrated the greatest stability in 0.9% and 0.225% sodium chloride solutions.

CONCLUSION

Ertapenem sodium injection 10 and 20 mg/mL are relatively stable in sodium chloride injections and Ringer's solution when stored at 25 and 4 degrees C, but are unstable in mannitol and dextrose solutions. The drug can be coinfused with hetastarch, heparin sodium, and potassium chloride over several hours.

Pharmacokinetic interactions of ceftazidime, imipenem and aztreonam with amikacin in healthy volunteers

The common usage of extended spectrum beta-lactams co-administered with amikacin in everyday clinical practice for infections by multidrug-resistant isolates has created the need to search for pharmacokinetic interaction. Eighteen healthy volunteers were enrolled in the study; six were administered 1g of ceftazidime singly intravenously or combined with 0.5 g of amikacin; six received 0.5 g of imipenem singly or combined with 0.5 g of amikacin and six 1g of aztreonam singly or combined with 0.5 g of amikacin. Blood and urine samples were collected at regular time intervals and apparent serum levels were determined by a microbiological assay. Co-administration of ceftazidime and amikacin resulted in higher C(max) and AUC for amikacin than when administered alone. Co-administration of imipenem and amikacin resulted in higher C(max) for imipenem than when administered alone. The tested interactions did not affect plasma half-life (t(1/2)) and clearance rate of any antimicrobial compared with its single administration. All tested drugs were mainly eliminated by glomerular filtration. It is concluded that co-administration of ceftazidime, imipenem or aztreonam with amikacin in healthy volunteers might affect C(max) and AUC without influencing any other pharmacokinetic parameter. The probable clinical endpoint is that giving ceftazidime, imipenem or aztreonam with amikacin might result in a transient elevation of beta-lactam serum levels without further affecting the complete pharmacokinetic profile of each drug as obtained after administration of the drug alone.

[Application of the MIC breakpoints based on pharmacokinetics and pharmacodynamics parameter in the clinical laboratory]

The effectiveness of time-dependent antibiotics such as beta-lactams is related to the time above the MIC (TAM, %). We constructed a program to calculate the TAMs of beta-lactams using the pharmacokinetic parameters of the Japanese dosing regimen of a phase I study of the Japanese Society for Antimicrobial Chemotherapy (JSAC), and compared them with the MIC breakpoints published by the National Committee for Clinical Laboratory Standards (NCCLS) and JSAC. If the effective TAM was assumed to be more than 40% of the dosing interval, the pharmacokinetic/pharmacodynamic (PK/PD) breakpoints calculated by our program were in agreement with the JSAC breakpoints for pneumonia within 1 dilution MIC. When comparing with the NCCLS breakpoints for Enterobacteriaceae or Staphylococcus, the PK/PD breakpoints dosing three times per day of ampicillin (1 g, intravenous dose; i.v.), piperacillin (2 g, i.v.), cefotaxime (1 g, i.v.) and cefmetazole (1 g, i.v.) were calculated to be less than 2-fold dilution MIC, and those of amoxicillin (0.25 g, oral dose; p.o.) and cefaclor (0.5 g, p.o.) were calculated to be less than 3- to 4-fold dilution of MIC. Our program could calculate TAMs and PK/PD breakpoints by inputting the two factors of MIC and dosing interval. If this information is routinely reported to physicians from clinical laboratories, an appropriate dosing schedule could be proposed for various infectious cases.

Stereoselective pharmacokinetics of clausenamide enantiomers and their major metabolites after single intravenous and oral administration to rats

The pharmacokinetics of clausenamide (CLA) enantiomers and their metabolites were investigated in Wistar rat. After intravenous and oral administration at a dose of 80 and 160 mg/kg each enantiomer, plasma concentrations of (-)- or (+)-CLA and its major metabolites were simultaneously determined by reverse-phase HPLC with UV detection. Notably, stereoselective differences in pharmacokinetics were found. The mean plasma levels of (+)-CLA were higher at almost all time points than those of (-)-CLA. (+)-CLA also exhibited greater t(max), C(max), t(1/2beta), AUC(0-12h), and AUC(0--> infinity) and smaller CL (or CL/F) and V(d) (or V(d)/F), than its antipode. The (+)/(-) isomer ratios for t(1/2beta), t(max), AUC(0-12 h), and AUC(0--> infinity), which ranged from 1.26 to 2.08. The ratio for CL (or CL/F) was about 0.5, and there were significant differences in these values between CLA enantiomers (P < 0.05), implying that the absorption, distribution, and elimination of (-)-CLA were more rapid than those of (+)-CLA. Similar findings for (-)-7-OH-CLA, the major metabolite of (-)-CLA, and (+)-4-OH-CLA, the major metabolite of (+)-CLA, can be also seen in rat plasma. The contributing factors for the differences in stereoselective pharmacokinetics of CLA enantiomers appeared to be involved in their different plasma protein binding, first-pass metabolism and interaction with CYP enzymes, especially with their metabolizing enzyme CYP 3A isoforms.

Phase I and pharmacological studies of the cryptophycin analogue LY355703 administered on a single intermittent or weekly schedule

LY355703 is a synthetic derivative of the marine cryptophycins, cytotoxic agents which induce mitotic arrest by binding at the microtubule vinca binding domain. Promising preclinical features of LY355703 were the 40-400 greater potency than paclitaxel or vinca alkaloids, the broad spectrum of antitumor activity in xenografts and the antitumour activity in multidrug resistant (MDR)-expressing murine tumours. Aims of this study were to define the maximum tolerated dose (MTD) and the dose recommended for Phase II, the pattern of toxicity, the pharmacokinetic profile and to document hints of antitumour activity of LY355703 given as 2-h infusion on day 1 every 3 weeks (Study 1) or, later on, on days 1, 8 and 15 every 4 weeks (Study 2). The latter weekly regimen was selected because of the acute dose-related toxicity reported in Study 1. The dose was escalated using a modified Continual Reassessment Method. Pharmacokinetic studies were performed on day 1 of cycle 1 in both studies; LY355703 plasma concentrations were assessed by liquid chromatography with tandem mass spectrometry. A total of 35 adult patients with solid tumours entered Study 1; the dose was escalated from 0.1 to 1.92 mg/m(2); at this dose 2 of 5 patients presented grade 3 neuropathy and myalgias; 1.48 mg/m(2) was then recommended for Phase II study. A total of 8 patients were treated in Study 2 at 1 mg/m(2); cumulative long-lasting neuroconstipation and neurosensory toxicity precluded the completion of the cycle in 9 out of 15 cycles; the clinical development of the weekly regimen was then discontinued. Other toxicities included cardiac dysrhythmia and mild alopecia. Pharmacokinetics of LY355703 appeared to be linear over the dose range studied. The administration of LY355703 on a 3-week schedule is associated with an acute dose-dependent peripheral neuropathy and myalgia of high interpatient variability for which possible risk factors and pharmacokinetic correlates could not be identified.

Successful treatment of neuroborreliosis with ten day regimens

BACKGROUND

There have been few large reports of the treatment and outcome of neuroborreliosis in children.

METHODS

All 203 children with symptoms, cerebrospinal fluid and serologic findings compatible with neuroborreliosis and treated at one of the four pediatric hospitals in Stockholm from 1994 through 1996 were included. Children were treated with intravenous beta-lactam antibiotics or oral doxycycline for 10 days and followed until the resolution of symptoms.

RESULTS

At the end of treatment 58% and after 2 months 92% of the children had no symptoms. Cerebrospinal fluid findings had no statistically significant influence on the outcome. Facial paralysis persisted longer than other symptoms.

CONCLUSIONS

The prognosis of neuroborreliosis in children 2 months after treatment seems to be excellent with 10-day treatment regimens.

Update on Listeria monocytogenes infection

Listeria monocytogenes is a gram-positive bacillus that causes meningitis, encephalitis, bacteremia, and febrile gastroenteritis. Most disease occurs in immunosuppressed individuals. Recent seroepidemiologic studies show that the infection is foodborne. Due to the increasing number of immunosuppressed individuals at risk for listeriosis, as well as the persistence of substantial foodborne outbreaks, L. monocytogenes has gained worldwide attention as an important pathogen. Heightened surveillance and quality control by the food industry have been instituted, leading to a reduction in the number of cases and deaths from this infection in the past decade. However, due to the ubiquity of the organism in the environment, outbreaks and sporadic disease continue to occur. The standard therapy for listeriosis is a combination of ampicillin and gentamicin or, for patients who are intolerant of b-lactam agents, trimethoprim-sulfamethazole. Despite the availability of therapy, the mortality rate remains high in those with T-cell immunodeficiencies.

Phase I trial of the cryptophycin analogue LY355703 administered as an intravenous infusion on a day 1 and 8 schedule every 21 days

The cryptophycin analogue LY355703 is a potent inhibitor of microtubule polymerization that displays in vitro and in vivo activity in cell lines and tumor xenografts displaying the multidrug-resistant phenotype. In a Phase I trial, 25 patients received LY355703 as a 2-h i.v. infusion on day 1 and day 8 repeated every 3 weeks. Doses were escalated from 0.1 to 2.22 mg/m2 using a modified continual reassessment method. Neurological toxicity was found to be dose-limiting at 1.84 and 2.22 mg/m2. Among four patients treated at these doses, two had grade 4 constipation/ileus, one with severe myalgias, and one had grade 3 motor neuropathy. These findings were reversible. The 1.5 mg/m2 dose level was well tolerated. An amended twice-weekly schedule was pursued in 11 patients in an attempt to improve dose intensity and avoid dose-limiting neurotoxicity. Doses of >0.75 mg/m2 on a day 1, 4, 8, and 11 schedule every 21 days were not tolerated as a result of nausea/constipation, suggesting that LY335703 toxicity is not schedule dependent and is related to cumulative dose. LY355703 plasma concentrations measured by liquid chromatography with tandem mass spectrometry were evaluated using a population pharmacokinetic model. LY355703 was eliminated rapidly with a short terminal half-life that ranged from 0.8 to 3.9 h. Interpatient variability with respect to plasma clearance and volume of distribution, including covariates, was moderate at 32% and 39%, respectively. Maximum plasma concentration and area under the plasma concentration-time curve were linear over the dose range studied. A patient with non-small cell lung cancer previously treated with taxanes experienced a partial response lasting 4 months, and five patients had stable disease lasting > or =3 months. LY355703 at a dose of 1.5 mg/m2 is recommended for Phase II evaluation on a days 1 and 8 schedule. Twice-weekly dosing did not allow improvement in dose intensity or tolerability.

An assessment of antimicrobial consumption in food producing animals in Kenya

Antimicrobial agents are useful for control of bacterial infections in food animals and man. Their prudent use in these animals is important to control any possible development and transfer of resistance between animals and man. The objective of this study was to generate quantitative information to evaluate antimicrobial usage patterns by animal species, route of administration, antimicrobial class and type of use from 1995 to 1999 in Kenya. Theses data are essential for risk analysis and planning and can be helpful in interpreting resistance surveillance data, and evaluating the effectiveness of prudent use efforts and antimicrobial resistance mitigation strategies. Data on quantities of active substance classes were collected from the official records of the Pharmacy and Poisons Board of the Ministry of Health and analysed in MS Excel 2000 program. The mean antimicrobial consumption for the 5-year period was 14 594 +/- 1457 kg per year. This was distributed in the various antimicrobial classes as follows: 7975 kg (54.65%) of tetracyclines, 3103.96 kg (21.27%) of sulfonamides and 954.5 kg (6.56%) of aminoglycosides, 905 kg (6.20%) of beta-lactams, 94 kg (0.64%) of quinolones, 35 kg (0.24%) of macrolides and 24 kg (0.16%) of others (tiamulin). Mean consumption per year among the various food animals was: 10 989 +/- 357 kg in large animals (cattle, sheep, pigs and goats), 2906 +/- 127 kg in poultry alone and 699 +/- 427 kg in both large animals and poultry. These quantities represented 56.56% (8255 kg) consumption per year for parenteral use, 41.79% (6098 kg) for oral use and 1.65% (241 kg) for topical use (intramammary and eye ointments) in cattle. With respect to intended use in food producing animals, the mean consumption per year was: 13 178 kg (90.30%) for therapeutic use (ST), 4 kg (0.03%) for prophylactic treatment (PT) and 1411 +/- 246 kg (9.67%) was used both for therapeutic and prophylactic purposes (GPT). The study confirmed that antimicrobials are not used for growth promotion in Kenya. There was no specific trend in the quantities of active antimicrobial classes. This study has revealed that the tetracyclines, sulfonamides and trimethoprim, nitrofurans aminoglycosides, beta-lactams and the quinolones are the most commonly used drugs in food-producing animals in Kenya. Tetracyclines contributed approximately 55% of the total consumption, and there was an increasing trend in the consumption of quinolones from 1998.

Antitumor activity of cryptophycins: effect of infusion time and combination studies

INTRODUCTION/PURPOSE

Cryptophycins are a family of antitubulin antitumor agents. A synthetic cryptophycin derivative (LY355703, CRYPTO 52) is in early clinical evaluation. The effect of infusion time on the antitumor activity of four cryptophycins was assessed in rats bearing the 13762 mammary carcinoma and combination treatment regimens were assessed in nude mice bearing human tumor xenografts.

METHODS

The cryptophycins were prepared in 2% PEG300/8% cremophor/90% normal saline and delivered by jugular vein catheter on days 7, 9 and 11 post tumor implant to 13762 tumor-bearing rats. The cryptophycins prepared in the same formulation were administered by intravenous bolus injection on an alternate day schedule for five doses to human tumor xenograft bearing nude mice.

RESULTS

An infusion time of 2 h in the rats increased the tumor growth delay produced by CRYPTO 52 and CRYPTO 55, while increasing the infusion time to 6 h continued to increase the tumor growth delay for CRYPTO 292 and CRYPTO 296. Administering CRYPTO 292 at a higher dose two times was more effective than administering it at a lower dose three times. The tumor growth delays produced by the cryptophycins in the rat 13762 mammary carcinoma were greater than those with cisplatin, doxorubicin, 5-fluorouracil and 5 x 3 Gray and comparable with cyclophosphamide and gemcitabine. Combination studies were carried out in human tumor xenografts including the MX-1 breast carcinoma, the Calu-6 non-small cell lung carcinoma, the H82 small cell lung carcinoma and the SW-2 small cell lung carcinoma. CRYPTO 52 and CRYPTO 55 combined with doxorubicin, paclitaxel and 5-fluorouracil to form highly effective regimens against the human MX-1 breast carcinoma. CRYPTO 52 and CRYPTO 55 were also highly effective against the three lung carcinoma xenografts when combined with the antitumor platinum complexes, cisplatin, carboplatin or oxaliplatin.

CONCLUSIONS

Cryptophycins represent a promising new class of antitumor agents that may be optimally administered by intravenous infusion and in combination with doxorubicin, paclitaxel and 5-fluorouracil.

Cryptophycin 52 and cryptophycin 55 in sequential and simultaneous combination treatment regimens in human tumor xenografts

The antitumor activity of cryptophycin 52 (C52) and cryptophycin 55 (C55) in sequential and simultaneous combination treatment regimens in human tumor xenografts models was explored. The antitumor activity of C52 and C55 was compared alone and in sequential combination with gemcitabine or paclitaxel in four lung cancer models, H460 and Calu-6 NSCLC and SW2 and H82 small cell lung carcinoma. The combination of C52 followed by gemcitabine was additive in three tumors and greater-than-additive in the fourth. The combination of C55 followed by gemcitabine was additive in three tumors and less-than-additive in the fourth. The combination of C52 followed by paclitaxel was greater-than-additive in one tumor, additive in one tumor and less-than-additive in two tumors. The combination of C55 followed by paclitaxel was greater-than-additive in two tumors and less-than-additive in two tumors. The simultaneous combination of C52 or C55 with fractionated radiation therapy was assessed in the H460 NSCLC tumor. Both cryptophycins produced a tumor response that was additive along with radiation therapy. The HCT116 colon carcinoma was used to compare the antitumor activity of simultaneous or sequential combination of 5-fluorouracil or irinotecan with C52. C52 produced greater-than-additive tumor response when administered either simultaneously with or sequentially with 5-fluorouracil or iriniotecan. Finally, when administered to animals bearing intraperitoneal OVCAR-3 ovarian carcinoma, C52, docetaxel and paclitaxel resulted in mean survival times of 123, 80 and 85 days compared with 72 days in the untreated controls. In combination with carboplatin, C52, docetaxel and paclitaxel resulted in mean survival times of 140, 105 and 135 days. Cryptophycins have the potential to be useful chemotherapeutic agents in a wide variety of clinical combinations regimens.

The suppository form of antibiotic administration: pharmacokinetics and clinical application

The rectal route of antibiotic administration might be used effectively when other routes of administration are inadequate or unsuitable. With the use of various adjuvants, the rectal route can provide satisfactory pharmacokinetics and acceptable local tolerance. Experiments in animals have demonstrated the influence of the pharmaceutical formulation of suppositories on the rectal absorption and systemic distribution of beta-lactams and aminoglycosides. In healthy volunteers and in children under treatment, similar adjuvants--mainly glyceride mixtures or non-ionic surface agents--have increased the rectal absorption of aminopenicillins, cephalosporins and macrolides. Other antibiotics, including metronidazole and cotrimoxazole, have been investigated in respect of their potential rectal administration.

Activity of a novel nonpeptidyl growth hormone secretagogue, L-700,653, in swine

L-700,653 is a potent nonpeptidyl GH secretagogue consisting of a benzolactam structure: (4'-[[3(R)-[[3-[(2(S),3-dihydroxypropyl) amino]3-methyl-1-oxobutyl]amino]2,3,4,5-tetrahydro-2-oxo-1H-1-benzaze pin- 1-yl]methyl][1,1'-biphenyl]2-carboxamide hydrochloride). When administered sc by a Medi-Jector device at 0, 0.003, 0.01, 0.03, and 0.1 mg/kg BW to male castrated swine (approximately 50 kg BW), L-700,653 stimulated dose-related increases in peak plasma GH concentrations by 20% (P = NS), 150% (P = NS), 250% (P < 0.05), and 340% (P < 0.05), respectively, over the saline vehicle control value (11.3 +/- 6.5 ng/ml) and stimulated increases in GH areas under the curve (AUCs) by 10% (P = NS), 30% (P = NS), 90% (P < 0.05), and 100% (P < 0.01), respectively, over the saline vehicle control value (799 +/- 145 ng/min.ml). After sc administration of L-700, 653, there were no significant changes in plasma LH levels. Subcutaneous dose of 0.03 or 0.1 mg/kg increased plasma cortisol AUCs by 60% (P = NS) and 150% (P < 0.03) over the control value (2461 +/- 935 ng/min.ml) and increased cortisol peaks by 80% (P = NS) and 200% (P < 0.01), respectively, over the control value (38.3 +/- 12.3 ng/ml). Repeated sc administration of L-700,653 (0.03 or 0.1 mg/kg) at 0800, 1400, and 2000 h daily over 3 days consistently increased mean GH peak and GH AUC at each treatment period, with minimal and maximal increases of 40% and 190% in GH peak level at the 0.03 mg/kg dose and 100% and 400% increases in GH peak level at the 0.01 mg/kg dose, respectively. Continuous i.v. infusion of L-700,653, at either 0.01 or 0.1 mg/kg BW.h over a 180-min period, increased GH AUCs by 60% (P = NS) or 470% (P < 0.01) and GH peaks by 190% (P = NS) or 1520% (P < 0.01), respectively, over the control value (589 +/- 313 ng/min.ml; 7.0 +/- 11.1 ng/ml). After a 180- to 300-min saline infusion, an iv bolus dose of 0.1 mg/kg L-700,653 resulted in GH responses inversely proportional to the previous infusion dose, i.e. 0, 0.01, or 0.1 mg/kg.(ABSTRACT TRUNCATED AT 400 WORDS)

Efficacy and tolerability of an amoxycillin/clavulanic acid combination in the treatment of common bacterial infections. A general practitioner trial

The efficacy and tolerability of a combination of amoxycillin 250 mg and clavulanic acid 125 mg (A-CA) (Augmentin; Beecham) was evaluated under general practice conditions. One hundred and sixty-four patients were treated with either A-CA tablets or amoxycillin 250 mg capsules, taken 3 times daily for 7 days at the start of a meal. Ten patients with treatment failure on amoxycillin were re-treated with A-CA. In the initial stage of the trial 102 patients were randomly allocated to either amoxycillin or A-CA treatment; of these 89 could be assessed clinically and 63 could be assessed bacteriologically, of whom 32 had received amoxycillin and 31 A-CA treatment. Subsequently a further 62 patients were treated with A-CA; 50 were assessed clinically and 40 bacteriologically. Bacteriological assessment was possible in 109 patients, 71 on A-CA, 32 on amoxycillin, and 6 who received A-CA after having failed on amoxycillin treatment. In this study A-CA was bacteriologically significantly superior to amoxycillin in treating urinary tract infections (P less than 0,024), skin and soft tissue infections (P less than 0.05) and all infections caused by amoxycillin-resistant organisms (P less than 0.013). No difference was shown in infections caused by amoxycillin-sensitive organisms. Side-effects most commonly associated with A-CA treatment were gastro-intestinal (6,7%) and consisted of nausea and diarrhoea. This trial has a special significance for general practitioners in that it shows a high incidence of penicillin-resistant organisms (51%). This observation, as yet limited to one area in South Africa, has wide implications for general practice management of infections.