Intravenous amoxicillin-sulbactam against Escherichia coli: optimizing the dose, component ratio and infusion time using a human pharmacodynamic model.

Amoxicillin-sulbactam (AMX-SUL) is an aminopenicillin/beta-lactamase inhibitor combination currently available in 29 countries which may be a suitable option for treating intra-abdominal infections. the aim of this study was to identify the optimal dose and ratio between components of this formulation through an ex-vivo human pharmacodynamic model against Escherichia coli. Four volunteers were randomized to receive alternatively a single dose of AMX-SUL infused either over 30 min or 3h in the following ratios (g/g): 1/0.5; 1/1, 2/0.5 and 0/2. time-kill studies were performed with the 0-, 0.5-, 2-, 4-, 6- and 8-h post-dosing sera against E. coli ATCC 25922 (AMX MIC, 2 microg/ml; AMX-SUL MIC, 2 microg/ml) and E. coli ATCC 35218 (AMX MIC, 1024 microg/ml; AMX-SUL MIC, 4-8 microg/ml). AMX-SUL 1g/0.5 g infused over 30 min was only active at 0.5 h after dose, being inferior to both AMX-SUL 1g/1g and AMX-SUL 2g/0.5 g against E. coli ATCC 25922, for which the 2h post-dose serum proved active. When tested against E. coli ATCC 35218, AMX-SUL 1g/0.5 g and AMX-SUL 2g/0.5 g were active only at 0.5 h post-dose, whereas AMX-SUL 1g/1g showed bactericidal activity 0.5h post-dose and was able to inhibit bacterial growth 2 h post-dose. When infused over 3h, the antimicrobial activity of AMX-SUL was better than the 30-min infusion. Moreover, AMX-SUL 1g/1g was able to inhibit, and kill to some extent, the E. coli ATCC 25922 strain at 4h post-dose (i.e. 67% and 50% of a 6- and 8-h dosing interval, respectively). The present study suggests that 1g/1g is the best formulation for AMX-SUL against E. coli. The infusion over 3h optimizes its pharmacodynamic profile, as well as that of the 1g/0.5g combination. These findings encourage the performance of clinical trials to assess the efficacy of this combination, given as an extended infusion, in the treatment of community-acquired intra-abdominal infections.

Review of pharmacokinetic, pharmacodynamic and clinical studies with a modern combination of amoxicillin/sulbactam.

Amoxicillin/sulbactam is a modern antimicrobial combination. This combination proved to be useful for the treatment of several infections caused by different microorganisms, mainly with the beta-lactamase-producing species. In this review we present the most relevant pharmacokinetic, pharmacodynamic and clinical information associated with its use.

An ex-vivo pharmacodynamic study comparing bactericidal activity of amoxicillin/sulbactam, azithromycin, doxycycline and levofloxacin against Streptococcus pneumoniae.

We designed a 4-way crossover, ex-vivo pharmacodynamic study to compare the bactericidal rate of amoxicillin/sulbactam (AMX-SUL), azithromycin (AZM), doxycycline (DOX) and levofloxacin (LVX) against Streptococcus pneumoniae ATCC 49619. Six volunteers were randomized to receive alternatively a single tablet of the above drugs. Venous blood samples were obtained immediately before and at 2, 4 and 6 h after dose to perform time-kill studies and to determine antibiotic levels in serum. AMX-SUL was the only drug showing bactericidal activity with the sera obtained at every time after dose, as defined by a > or = 3-log10 cfu/ml decrease in the viable cell counts compared to the original inoculum after a 24-h incubation. AZM was only inhibitory at 2h after dose (i.e. a 1.3-log10 cfu/ml decrease in the viable cell counts) and proved bactericidal at 4 and 6 h post-dose. LVX proved bactericidal with the 2-h serum, was only inhibitory with the 4-h serum (e.g. a 1.5-log10 cfu/ml decrease) and was unable to avoid bacterial growth at 6 h post-dose. Bacterial growth was observed with DOX at every time after dose. This study may shed light on the understanding of breakthrough pneumococcal bacteremia during the course of oral therapy with AZM in patients with community-acquired nia (CAP), as well as the increasing treatment failures observed with LVX, and the selection of bacterial resistance during therapy reported with both drugs. It also provides the basis for a "warning signal" on the use of oral DOX and confirms the efficacy of AMX-SUL.

[Acid-supressing capacity of omeprazole 20 mg tablets vs pantoprazole 20 and 40 mg tablets. A pilot study in volunteers]. / Capacidad ácidosupresora del omeprazol 20 mg comprimidos versus pantoprazol 20 y 40 mg comprimidos. Estudio piloto en voluntarios.

OBJECTIVE: To compare the acid-supressing capacity of omeprazole (OZ) 20 mg tablets vs pantoprazole (PZ) 20 and 40 mg tablets, in healthy volunteers, with 24-h intragastric pH-metry. MATERIAL AND METHODS: Open, randomized, cross-over trial in 10 healthy volunteers; on days 0.8 and 22, 24-h intragastric pH-metry. Day 0, basal, thereafter 7 days with OZ or PZ 20 mg/day; day 8, pH-metry, then "wash out" for 7 days and thereafter 7 more days' therapy with PZ or OZ. On day 22 a 24-h intragastric pH control was performed again. In the last treatment stage, all of them were administered pantoprazole 40 mg/day for 8 days again with a 24-h pH recording at the end. RESULTS: 24-h pH-metry expressed as the time (hours) in which the pH was < or = 4 and the values as mean +/- standard deviation. BASAL 22.12 +/- 1.54, POST-OZ 9.78 +/- 6.72, POST-PZ 20 15.65 +/- 5.65, POST-PZ 40 8.57 +/- 5.93. Statistical evaluation with two way repeated measures ANOVA p < 0.0001. Newman Keuls post-hoc test: (1) vs (2) p < 0.003; (1) vs (3) p < 0.03; (2) vs (4) 0.65. CONCLUSIONS: According to the results it might be stated that both proton pump inhibitors have acid-supressing capacity and omeprazole in equal dosis is more effective than pantoprazole as acid-supressor, with statistically significative differences. There was no difference between 20 mg omeprazole and 40 mg pantoprazole.

Capacidad ácidosupresora del omeprazol 20 mg comprimidos versus pantoprazol 20 y 40 mg comprimidos en voluntarios / Acid-supressing capacity of omeprazole 20 mg tablets vs pantoprazole 20 and 40 mg tablets. A pilot study in volunteers

OBJECTIVE: To compare the acid-supressing capacity of omeprazole (OZ) 20 mg tablets vs pantoprazole (PZ) 20 and 40 mg tablets, in healthy volunteers, with 24-h intragastric pH-metry. MATERIAL AND METHODS: Open, randomized, cross-over trial in 10 healthy volunteers; on days 0.8 and 22, 24-h intragastric pH-metry. Day 0, basal, thereafter 7 days with OZ or PZ 20 mg/day; day 8, pH-metry, then "wash out" for 7 days and thereafter 7 more days' therapy with PZ or OZ. On day 22 a 24-h intragastric pH control was performed again. In the last treatment stage, all of them were administered pantoprazole 40 mg/day for 8 days again with a 24-h pH recording at the end. RESULTS: 24-h pH-metry expressed as the time (hours) in which the pH was < or = 4 and the values as mean +/- standard deviation. BASAL 22.12 +/- 1.54, POST-OZ 9.78 +/- 6.72, POST-PZ 20 15.65 +/- 5.65, POST-PZ 40 8.57 +/- 5.93. Statistical evaluation with two way repeated measures ANOVA p < 0.0001. Newman Keuls post-hoc test: (1) vs (2) p < 0.003; (1) vs (3) p < 0.03; (2) vs (4) 0.65. CONCLUSIONS: According to the results it might be stated that both proton pump inhibitors have acid-supressing capacity and omeprazole in equal dosis is more effective than pantoprazole as acid-supressor, with statistically significative differences. There was no difference between 20 mg omeprazole and 40 mg pantoprazole.

Capacidad ácidosupresora del omeprazol 20 mg comprimidos versus pantoprazol 20 y 40 mg comprimidos en voluntarios / Acid-supressing capacity of omeprazole 20 mg tablets vs pantoprazole 20 and 40 mg tablets. A pilot study in volunteers

OBJECTIVE: To compare the acid-supressing capacity of omeprazole (OZ) 20 mg tablets vs pantoprazole (PZ) 20 and 40 mg tablets, in healthy volunteers, with 24-h intragastric pH-metry. MATERIAL AND METHODS: Open, randomized, cross-over trial in 10 healthy volunteers; on days 0.8 and 22, 24-h intragastric pH-metry. Day 0, basal, thereafter 7 days with OZ or PZ 20 mg/day; day 8, pH-metry, then "wash out" for 7 days and thereafter 7 more days therapy with PZ or OZ. On day 22 a 24-h intragastric pH control was performed again. In the last treatment stage, all of them were administered pantoprazole 40 mg/day for 8 days again with a 24-h pH recording at the end. RESULTS: 24-h pH-metry expressed as the time (hours) in which the pH was < or = 4 and the values as mean +/- standard deviation. BASAL 22.12 +/- 1.54, POST-OZ 9.78 +/- 6.72, POST-PZ 20 15.65 +/- 5.65, POST-PZ 40 8.57 +/- 5.93. Statistical evaluation with two way repeated measures ANOVA p < 0.0001. Newman Keuls post-hoc test: (1) vs (2) p < 0.003; (1) vs (3) p < 0.03; (2) vs (4) 0.65. CONCLUSIONS: According to the results it might be stated that both proton pump inhibitors have acid-supressing capacity and omeprazole in equal dosis is more effective than pantoprazole as acid-supressor, with statistically significative differences. There was no difference between 20 mg omeprazole and 40 mg pantoprazole.(AU)

Capacidad ácidosupresora del omeprazol 20 mg comprimidos versus pantoprazol 20 y 40 mg comprimidos. Estudio piloto en voluntarios. / [Acid-supressing capacity of omeprazole 20 mg tablets vs pantoprazole 20 and 40 mg tablets. A pilot study in volunteers]

OBJECTIVE: To compare the acid-supressing capacity of omeprazole (OZ) 20 mg tablets vs pantoprazole (PZ) 20 and 40 mg tablets, in healthy volunteers, with 24-h intragastric pH-metry. MATERIAL AND METHODS: Open, randomized, cross-over trial in 10 healthy volunteers; on days 0.8 and 22, 24-h intragastric pH-metry. Day 0, basal, thereafter 7 days with OZ or PZ 20 mg/day; day 8, pH-metry, then [quot ]wash out[quot ] for 7 days and thereafter 7 more days therapy with PZ or OZ. On day 22 a 24-h intragastric pH control was performed again. In the last treatment stage, all of them were administered pantoprazole 40 mg/day for 8 days again with a 24-h pH recording at the end. RESULTS: 24-h pH-metry expressed as the time (hours) in which the pH was < or = 4 and the values as mean +/- standard deviation. BASAL 22.12 +/- 1.54, POST-OZ 9.78 +/- 6.72, POST-PZ 20 15.65 +/- 5.65, POST-PZ 40 8.57 +/- 5.93. Statistical evaluation with two way repeated measures ANOVA p < 0.0001. Newman Keuls post-hoc test: (1) vs (2) p < 0.003; (1) vs (3) p < 0.03; (2) vs (4) 0.65. CONCLUSIONS: According to the results it might be stated that both proton pump inhibitors have acid-supressing capacity and omeprazole in equal dosis is more effective than pantoprazole as acid-supressor, with statistically significative differences. There was no difference between 20 mg omeprazole and 40 mg pantoprazole.

Efficacy of amoxicillin-sulbactam, given twice-a-day, for the treatment of community-acquired pneumonia: a clinical trial based on a pharmacodynamic model.

The present multicenter study reports the results of a clinical trial, designed on the basis of a pharmacodynamic study published previously (Bantar et al., J. Chemother 2000; 12: 223-227) to assess the efficacy of amoxicillin/sulbactam (875 mg/125 mg), given orally twice-a-day for 7 days in the treatment of patients with community-acquired pneumonia (CAP). Eighty-four evaluable subjects older than 19 years with clinical symptoms and features suggestive of CAP, consulting from June 2000 to March 2002 and meeting the PORT risk class I through III, were enrolled in the study. Mean age (y +/- standard deviation) was 46.7 +/- 16.3 and 62% of the patients had some co-morbidity predisposing for CAP. Several individuals (77.4%) fell into a low-risk class (i.e. PORT I or II) and 22.6% of patients belonged to a moderate-risk class at the start of treatment. Six patients (6.45%) had pneumococcal bacteremia. Streptococcus pneumoniae was the organism most frequently isolated (61.9% of all the patients in whom an etiologic diagnosis was made), followed by Haemophilus influenzae. Clinical success was observed in 97.6% of the patients (confidence interval 95%, 94.3%-100%). Almost all the individuals with clinical success became afebrile within the first 3 days of therapy. Ten patients (11.8%) reported mild or moderate adverse events (especially diarrhea) possibly related to the antimicrobial therapy, but this did not lead to withdrawal from the trial. The results of this study suggest that amoxicillin/sulbactam (875 mg/125 mg) is an efficacious and well tolerated option for treating patients with CAP belonging to a low-moderate risk class and support the use of a short, oral (7-day) b.i.d. regimen.

Rationale for treating community-acquired lower respiratory tract infections with amoxicillin/sulbactam combination through pharmacodynamic analysis in the setting of aminopenicillin-resistant organisms.

In order to establish a rationale for treating community-acquired lower respiratory tract infections, we assess here the pharmacodynamics of amoxicillin/sulbactam, 500mg/500mg, a formulation marketed in Argentina since 1988 and currently available in 17 countries, against the major pathogens, in comparison with that of a novel formulation (875mg/125mg, see J Chemother 2000; 12: 223-227). In time-kill studies, both bactericidal and inhibitory activity were seen in the 1.5- and 6-h sera, obtained from 12 volunteers after a single oral dose, against both a penicillin-susceptible and an -intermediate Streptococcus pneumoniae strain, as well as against Moraxella catarrhalis and a beta-lactamase-negative Haemophilus influenzae strain. Only the 1.5-h sera proved bactericidal against a penicillin-resistant S. pneumoniae strain (MIC, 2 microg/ml) and a beta-lactamse-positive H. influenzae isolate. This study suggests that amoxicillin/sulbactam (500mg/500mg) is still a suitable option for treating community-acquired lower respiratory tract infections, allowing a b.i.d. dosing schedule. Caution should be taken with pneumonia caused by beta-lactamase-positive H. influenzae or penicillin-resistant (MIC > or =2 microg/ml) S. pneumoniae isolates. Either shorter dosing intervals (t.i.d.) or a higher amoxicillin content in the formulation (i.e. 875 mg) may be required in these situations.

[Escherichia coli eradication from the blader urine by amoxicillin-sulbactam. Intrinsic activity of the inhibitor]. / Erradicación de Escherichia coli de la orina vesical por amoxicilina-sulbactam. Actividad intrínseca del inhibidor.

RATIONALE: At urine concentrations obtained after the oral administration of amoxicillin-sulbactam (500/500 mg) this combination inhibits roughly 90% of Escherichia coli and Proteus mirabilis strains. AIMS: To administer amoxicilin-sulbactam 875/125 mg and to determine: a) minimum inhibitory concentration (MIC) of sulbactam for E. coli and P. mirabilis; b) urine inhibitory titres power (UIT) against amoxicillin-resistant E. coli or P. mirabilis; c) urine concentrations of sulbactam; and to verify whether sulbactam 125 mg as single drug, attains a high enough UIT to support the intrinsic action of the inhibitor; and to compare the activity of amoxicillin-sulbactam and amoxicillin-clavulanate and that of sulbactam and clavulanate. METHODS: Twelve healthy volunteers received a single oral dose of amoxicillin-sulbactam 875/125 mg or amoxicillin-clavulanate 875/125 mg, according to a randomized cross-over design. Urine samples were drawn at: 0 (basal), 2, 4, and 6 hours after dosing. Urine pH, specific gravidity and UIP were assessed. Thirty nine strains isolated from urine samples were used: 30 TEM-1 producing E. coli strains and 3 extended spectrum CTX-M-2 betalactamase-producing E. coli; and 6 P. mirabilis resistant to both combinations. In 6 healthy volunteers, sulbactam 125 mg was administered orally and UIT against E. coli (MIC amoxicillin > 2048 mg/l) was assessed. RESULTS AND DISCUSSION: MIC-90 for amoxicillin plus sulbactam or clavulanate were similar to those for sulbactam or clavulanate alone, without any difference attributable to the chemical composition of the urine. The activity of amoxicillin plus the inhibitors could be due, not only to the inhibition of betalactamase but also to the intrinsic effect of the inhibitor. Both combinations showed an equivalent inhibitory activity. Two-hour UIT remained high for the entire 6-h evaluation period. Sulbactam concentration far exceed sulbactam MIC for the 6h-period, inhibiting urine E. coli. We disagree with the cut-off limit proposed for intermediate values of NCCLS, which, for these antimicrobial are 16/8, a value lower than those obtained in urine samples after the administration of betalactamase inhibitors. This may be an explanation for the beneficial effect of amoxicillin-sulbactam in the recovery of uncomplicated lower urinary tract infections in women when the involved strains were considered resistant by diffusional methods.

A pharmacodynamic model to support a 12-hour dosing interval for amoxicillin/sulbactam, a novel oral combination, in the treatment of community-acquired lower respiratory tract infections.

We evaluated, by time-kill studies, the pharmacodynamics of amoxicillin/sulbactam (AMX/SUL, 875 mg/125 mg), a novel oral combination, against the major respiratory pathogens in 12 volunteers receiving a single dose. The sera corresponding to 50% of a 12-h dosing interval displayed either bactericidal or inhibitory activity against both a penicillin-susceptible and a penicillin-intermediate Streptococcus pneumoniae strain (penicillin MIC of 0.03 and 0.25 microg/ml, respectively), as well as against a beta-lactamase-positive Moraxella catarrhalis and a beta-lactamase-negative Haemophilus influenzae strain. Both the peak samples and those corresponding to 4 h after dose (i.e. 33% of a 12-h dosing interval) proved active against both a penicillin-resistant S. pneumoniae (MIC, 2 microg/ml) and a beta-lactamase-positive H. influenzae strain. The AMX-SUL formulation evaluated in this study showed pharmacodynamic features that support clinical trials to assess its efficacy in the treatment of lower respiratory tract infections with a 12-h dosing interval regimen.

[The pharmacokinetic study of a daily dose of theophylline]. / Estudio farmacocinético de una dosis diaria de teofilina.

Theophylline pharmacokinetics, administered in tablets containing 600 mg in a sustained-release hydrophilic matrix for a once daily intake, was evaluated after being administered to 6 healthy volunteers during 7 days at 8 pm. Plasmatic levels at -2, 0, 2, 3, 4, 6, 8, 10, 12, 14, 18 and 24 hours in relation with 8 pm intake, were obtained at the 7th day of administration. A plasmatic curve was obtained with a maximum concentration at 12 hours of 10.18 mcg/ml, a minimum concentration of 3.27 mcg/ml and an area under the concentration/time curve of 198.4 mcg.h/ml. These data make it evident that the tablet studied shows a release profile without excessive peaks and an average concentration at steady state within therapeutical range, and suggests its use in asthma.