Oral Nirmatrelvir-Ritonavir as Postexposure Prophylaxis for Covid-19.

BACKGROUND: Clinical trials of treatments for coronavirus disease 2019 (Covid-19) have not shown a significant benefit of postexposure prophylaxis. METHODS: We conducted a phase 2-3 double-blind trial to assess the efficacy and safety of nirmatrelvir-ritonavir in asymptomatic, rapid antigen test-negative adults who had been exposed to a household contact with Covid-19 within 96 hours before randomization. The participants were randomly assigned in a 1:1:1 ratio to receive nirmatrelvir-ritonavir (300 mg of nirmatrelvir and 100 mg of ritonavir) every 12 hours for 5 days or for 10 days or matching placebo for 5 or 10 days. The primary end point was the development of symptomatic SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection, confirmed on reverse-transcriptase-polymerase-chain-reaction (RT-PCR) or rapid antigen testing, through 14 days in participants who had a negative RT-PCR test at baseline. RESULTS: A total of 2736 participants were randomly assigned to a trial group - 921 to the 5-day nirmatrelvir-ritonavir group, 917 to the 10-day nirmatrelvir-ritonavir group, and 898 to the placebo group. Symptomatic, confirmed SARS-CoV-2 infection developed by day 14 in 2.6% of the participants in the 5-day nirmatrelvir-ritonavir group, 2.4% of those in the 10-day nirmatrelvir-ritonavir group, and 3.9% of those in the placebo group. In each nirmatrelvir-ritonavir group, the percentage of participants in whom symptomatic, confirmed SARS-CoV-2 infection developed did not differ significantly from that in the placebo group, with risk reductions relative to placebo of 29.8% (95% confidence interval [CI], -16.7 to 57.8; P = 0.17) in the 5-day nirmatrelvir-ritonavir group and 35.5% (95% CI, -11.5 to 62.7; P = 0.12) in the 10-day nirmatrelvir-ritonavir group. The incidence of adverse events was similar across the trial groups, with dysgeusia being the most frequently reported adverse event (in 5.9% and 6.8% of the participants in the 5-day and 10-day nirmatrelvir-ritonavir groups, respectively, and in 0.7% of those in the placebo group). CONCLUSIONS: In this placebo-controlled trial, postexposure prophylaxis with nirmatrelvir-ritonavir for 5 or 10 days did not significantly reduce the risk of symptomatic SARS-CoV-2 infection. (Funded by Pfizer; ClinicalTrials.gov number, NCT05047601.).

Nirmatrelvir for Vaccinated or Unvaccinated Adult Outpatients with Covid-19.

BACKGROUND: Nirmatrelvir in combination with ritonavir is an antiviral treatment for mild-to-moderate coronavirus disease 2019 (Covid-19). The efficacy of this treatment in patients who are at standard risk for severe Covid-19 or who are fully vaccinated and have at least one risk factor for severe Covid-19 has not been established. METHODS: In this phase 2-3 trial, we randomly assigned adults who had confirmed Covid-19 with symptom onset within the past 5 days in a 1:1 ratio to receive nirmatrelvir-ritonavir or placebo every 12 hours for 5 days. Patients who were fully vaccinated against Covid-19 and who had at least one risk factor for severe disease, as well as patients without such risk factors who had never been vaccinated against Covid-19 or had not been vaccinated within the previous year, were eligible for participation. Participants logged the presence and severity of prespecified Covid-19 signs and symptoms daily from day 1 through day 28. The primary end point was the time to sustained alleviation of all targeted Covid-19 signs and symptoms. Covid-19-related hospitalization and death from any cause were also assessed through day 28. RESULTS: Among the 1296 participants who underwent randomization and were included in the full analysis population, 1288 received at least one dose of nirmatrelvir-ritonavir (654 participants) or placebo (634 participants) and had at least one postbaseline visit. The median time to sustained alleviation of all targeted signs and symptoms of Covid-19 was 12 days in the nirmatrelvir-ritonavir group and 13 days in the placebo group (P = 0.60). Five participants (0.8%) in the nirmatrelvir-ritonavir group and 10 (1.6%) in the placebo group were hospitalized for Covid-19 or died from any cause (difference, -0.8 percentage points; 95% confidence interval, -2.0 to 0.4). The percentages of participants with adverse events were similar in the two groups (25.8% with nirmatrelvir-ritonavir and 24.1% with placebo). In the nirmatrelvir-ritonavir group, the most commonly reported treatment-related adverse events were dysgeusia (in 5.8% of the participants) and diarrhea (in 2.1%). CONCLUSIONS: The time to sustained alleviation of all signs and symptoms of Covid-19 did not differ significantly between participants who received nirmatrelvir-ritonavir and those who received placebo. (Supported by Pfizer; EPIC-SR ClinicalTrials.gov number, NCT05011513.).

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.).

Summary of the safety and tolerability of two treatment regimens of ceftaroline fosamil: 600 mg every 8 h versus 600 mg every 12 h.

BACKGROUND: The recommended adult dose of ceftaroline fosamil is 600 mg q12h by 1 h intravenous (iv) infusion for 5-14 days in complicated skin and soft tissue infection (cSSTI) and 5-7 days in community-acquired pneumonia (CAP). A dosage of 600 mg q8h by 2 h iv infusion is approved in some regions for cSSTI patients with Staphylococcus aureus infection where the ceftaroline MIC is 2 or 4 mg/L. This analysis compares the safety profiles of the q8h and q12h regimens. METHODS: Safety data from six Phase III, randomized, double-blind clinical trials were collated into the q8h cSSTI pool (ceftaroline fosamil n = 506; NCT01499277) and the q12h pool {ceftaroline fosamil n = 1686; comprising five studies [two cSSTI (NCT00424190 and NCT00423657) and three CAP (NCT01371838, NCT00621504 and NCT00509106)]}. RESULTS: The pattern and incidence of adverse events were similar between the q8h and q12h ceftaroline fosamil pools. Most were gastrointestinal and of mild or moderate intensity. Overall, rash intensity was similar between the q8h pool and the q12h pool. For the q8h regimen, there was a higher frequency of rash in some Asian study sites, associated with longer duration of therapy (≥7 days); most cases were mild and resolved following treatment discontinuation. No dose-related vital sign or ECG abnormalities were detected with either regimen. CONCLUSIONS: The q8h regimen in cSSTI was generally well tolerated; the observed safety profile was consistent with the known safety profile of ceftaroline fosamil, reflective of the cephalosporin class and qualitatively consistent with the q12h regimen.

Results of a double-blind, randomized trial of ceftobiprole treatment of complicated skin and skin structure infections caused by gram-positive bacteria.

Ceftobiprole is the first broad-spectrum cephalosporin with activity against methicillin-resistant Staphylococcus aureus (MRSA) to be assessed in late-stage clinical trials. As a pivotal step in the clinical development of ceftobiprole, a multicenter, global, randomized, double-blind trial was conducted to compare the efficacy of ceftobiprole to that of vancomycin in patients with complicated skin and skin structure infections (cSSSIs) caused by gram-positive bacteria. The primary objective was to assess noninferiority on the basis of the cure rates 7 to 14 days after the completion of therapy in patients administered ceftobiprole 500 mg every 12 h or vancomycin 1 g every 12 h. Of 784 patients randomized, 282 receiving ceftobiprole and 277 receiving vancomycin were clinically evaluable. Of these patients, 93.3% treated with ceftobiprole and 93.5% treated with vancomycin were cured (95% confidence interval of difference, -4.4%, 3.9%). The cure rates for patients with MRSA infections were 91.8% (56/61) with ceftobiprole treatment and 90.0% (54/60) with vancomycin treatment (95% confidence interval of difference, -8.4%, 12.1%). At least one adverse event (AE) was reported by 52% of the ceftobiprole-treated patients and 51% of the vancomycin-treated patients. The most common AEs reported by the ceftobiprole-treated patients were nausea (14%) and taste disturbance (8%). Discontinuation of the study drug because of treatment-emergent AEs occurred in 4% (n = 17) of the ceftobiprole-treated patients and 6% (n = 22) of the vancomycin-treated patients. The results of this trial support the use of ceftobiprole as an effective and well-tolerated treatment option for patients with cSSSIs caused by a spectrum of gram-positive bacteria.

Probability of target attainment for ceftobiprole as derived from a population pharmacokinetic analysis of 150 subjects.

Ceftobiprole is a broad-spectrum cephalosporin with activity against methicillin-resistant Staphylococcus aureus (MRSA) that is undergoing phase III trials for the treatment of complicated skin and skin structure infections and nosocomial pneumonia. The objectives were to describe the pharmacodynamic profiles of ceftobiprole given at 500 mg intravenously (i.v.) every 8 h (q8h) (2-h infusion) and 500 mg i.v. every 12 h (q12h) (1-h infusion) to determine the overall probability of target attainment (PTA) by weighting for the expected distributions of renal function in the populations of interests, to determine the PTA against representative pathogens encountered in clinical trials, and to determine the optimal renal dose adjustment for ceftobiprole at 500 mg i.v. q8h (2-h infusion). Data for a total of 150 subjects in phase I/II trials were analyzed by using the population pharmacokinetic modeling program BigNPOD (nonparametric optimal design). Monte Carlo simulation was performed with the ADAPT II program to estimate the PTA at which the free drug concentrations exceed the MIC for 30 to 60% of the dosing interval (30 to 60% fT > MIC). For ceftobiprole at 500 mg i.v. q12h, the probabilities of achieving 30% and 50% fT > MIC exceeded 90% for MICs < or =2 mg/liter and < or =1 mg/liter, respectively, For ceftobiprole at 500 mg i.v. q8h, the probabilities of achieving 40 and 60% fT > MIC exceeded 90% for MICs < or =4 mg/liter and < or =2 mg/liter, respectively. For ceftobiprole at both 500 mg i.v. q12h and 500 mg i.v. q8h, the probability of achieving a nearly bactericidal effect (50% fT > MIC) exceeded 90% for methicillin-susceptible S. aureus and MRSA. For gram-negative pathogens, the PTA for achieving a nearly maximal bactericidal effect (60% fT > MIC) for ceftobiprole at 500 mg i.v. q8h exceeded 90% for non-AmpC-producing gram-negative organisms. Ceftobiprole at 500 mg i.v. q12h, for patients who had a creatinine clearance rate of < or =50 ml/min, was identified as the most appropriate treatment regimen for patients who require renal dose adjustment for mild to moderate renal impairment.

Augmentin (amoxicillin/clavulanate) in the treatment of community-acquired respiratory tract infection: a review of the continuing development of an innovative antimicrobial agent.

Amoxicillin/clavulanate (Augmentin) is a broad-spectrum antibacterial that has been available for clinical use in a wide range of indications for over 20 years and is now used primarily in the treatment of community-acquired respiratory tract infections. Amoxicillin/clavulanate was developed to provide a potent broad spectrum of antibacterial activity, coverage of beta-lactamase-producing pathogens and a favourable pharmacokinetic/pharmacodynamic (PK/PD) profile. These factors have contributed to the high bacteriological and clinical efficacy of amoxicillin/clavulanate in respiratory tract infection over more than 20 years. This is against a background of increasing prevalence of antimicrobial resistance, notably the continued spread of beta-lactamase-mediated resistance in Haemophilus influenzae and Moraxella catarrhalis, and penicillin, macrolide and quinolone resistance in Streptococcus pneumoniae. The low propensity of amoxicillin/clavulanate to select resistance mutations as well as a favourable PK/PD profile predictive of high bacteriological efficacy may account for the longevity of this combination in clinical use. However, in certain defined geographical areas, the emergence of S. pneumoniae strains with elevated penicillin MICs has been observed. In order to meet the need to treat drug-resistant S. pneumoniae, two new high-dose amoxicillin/clavulanate formulations have been developed. A pharmacokinetically enhanced tablet dosage form of amoxicillin/clavulanate 2000/125 mg twice daily (available as Augmentin XR in the USA), has been developed for use in adult respiratory tract infection due to drug-resistant pathogens, such as S. pneumoniae with reduced susceptibility to penicillin, as well as beta-lactamase-producing H. influenzae and M. catarrhalis. Amoxicillin/clavulanate 90/6.4 mg/kg/day in two divided doses (Augmentin ES-600) is for paediatric use in persistent or recurrent acute otitis media where there are risk factors for the involvement of beta-lactamase-producing strains or S. pneumoniae with reduced penicillin susceptibility. In addition to high efficacy, amoxicillin/clavulanate has a well known safety and tolerance profile of the two new high-dose formulations are not significantly different from those of conventional formulations. Amoxicillin/clavulanate is included in guidelines and recommendations for the treatment of bacterial sinusitis, acute otitis media, community-acquired pneumonia and acute exacerbations of chronic bronchitis. Amoxicillin/clavulanate continues to be an important agent in the treatment of community-acquired respiratory tract infections, both now and in the future.

Oral gemifloxacin versus sequential therapy with intravenous ceftriaxone/oral cefuroxime with or without a macrolide in the treatment of patients hospitalized with community-acquired pneumonia: a randomized, open-label, multicenter study of clinical efficacy and tolerability.

OBJECTIVE: This study aimed to compare the efficacy and safety of oral gemifloxacin, an enhanced-affinity quinolone, with sequential therapy with IV ceftriaxone followed by oral cefuroxime (with or without a macrolide) in patients hospitalized for community-acquired pneumonia (CAP). METHODS: A randomized, open-label, multicenter study comprised adults hospitalized with a clinical and radiologic diagnosis of CAP. Patients were randomized 1:1 to receive either (1) oral gemifloxacin 320 mg once daily (7-14 days); or (2) IV ceftriaxone 2 g once daily (1-7 days) followed by oral cefuroxime 500 mg twice daily (1-13 days) for a total of < or = 14 days. Patients receiving ceftriaxone/cefuroxime were allowed concomitant macrolide treatment. RESULTS: A total of 345 patients were randomized, of whom 341 received at least 1 dose of study medication (gemifloxacin, 169/172; ceftriaxone/cefuroxime, 172/173). Clinical success rates in the clinically evaluable (CE) population at follow-up (day 21-28 post-therapy), the primary end point, were 92.2% (107/116) for gemifloxacin and 93.4% (113/121) for ceftriaxone/cefuroxime (treatment difference, -1.15; 95% CI, -7.73 to 5.43). In patients in Fine risk classes IV and V, the clinical success rate was 87.0% (20/23) for gemifloxacin versus 83.3% (20/24) for ceftriaxone/cefuroxime. No difference in clinical response at follow-up was noted based on macrolide use. Bacteriologic success rates at follow-up in the bacteriologically evaluable (BE) population were 90.6% (58/64) for gemifloxacin and 87.3% (55/63) for ceftriaxone/cefuroxime (treatment difference 3.32; 95% CI, -7.57 to 14.21). The clinical success rate in bacteremic patients at follow-up (BE population) was 100.0%. Both treatments were generally well tolerated. The frequency and types of adverse events were similar between the 2 groups. The most common treatment-related adverse events with gemifloxacin were diarrhea, liver-function adverse events, and rash; with ceftriaxone/cefuroxime, they were diarrhea, elevated hepatic-enzyme activity, and moniliasis. CONCLUSION: The clinical efficacy and tolerability of oral gemifloxacin 320 mg once daily were similar to those of IV ceftriaxone followed by oral cefuroxime (with or without a macrolide) in the treatment of adult patients hospitalized with moderate to severe CAP. Both treatments were effective in bacteremic patients and those at increased risk of mortality.