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

Effect of betamethasone and diclofenac sodium on serum and tissue concentration of amoxicillin. In vivo study in rats

Objective:

Antimicrobial agents in combination with anti-inflammatory drugs have been usually prescribed in both Medicine and Dentistry. However, few scientific reports support this clinical practice. The aim of this study was to evaluate the effect of betamethasone and diclofenac sodium on serum and tissue concentration of amoxicillin in rats.

Methods:

Four polyurethane sponges were implanted in the back skin of 48 rats. After seven days the animals were divided into 6 groups (n=8). Group 1: amoxicillin (25 mg/kg); G2: diclofenac sodium (2.5 mg/kg); G3: betamethasone (0.1 mg/kg); G4: diclofenac sodium and amoxicillin; G5: betamethasone and amoxicillin; and G6: 0.9% sodium chloride solution (1.0 mL - control group). All drugs were administered in a single dose. After 90 minutes, the granulomatous tissues of each animal were surgically removed and weighed. Blood was collected from cervical plexus, centrifuged and 10μL of serum was placed on paper discs. In order to estimate amoxicillin concentration, serum and granulomatous tissues were separately submitted to microbiological assay, which used 10⁸cfu/mL of Staphylococcus aureus ATCC 25923 (penicillin-susceptible strain). After incubation (18 hours, 37°C) the inhibition zones were measured and compared to a regression curve.

Results:

No inhibition zones were observed for groups 2, 3 and 6. Tissue and serum concentrations of both G1 (4.14μg/g and 2.06μg/mL, respectively) and G5 (3.87μg/g and 1.70μg/mL, respectively) showed statistically significant differences (Kruskal-Wallis, p<0.05) in comparison to G4 (1.45μg/g and 0.41μg/mL, respectively). G1 and G5 did not differ significantly (p>0.05).

Conclusion:

Considering single doses, betamethasone did not interfere with amoxicillin levels but diclofenac sodium reduced both tissue and serum levels of amoxicillin in rats.

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.

Amoxicillin-sulbactam versus amoxicillin-clavulanic acid for the treatment of non-recurrent-acute otitis media in Argentinean children

Streptococcus pneumoniae (Sp) and Haemophilus influenzae (Hi) are the leading bacterial cause of acute otitis media (AOM), having the nasopharynx (NP) as their reservoir. In October 2001 we began a prospective, multicenter, randomized, evaluator blind study, comparing the efficacy of amoxicillin-sulbactam (Ax/S) and amoxicillin-clavulanic acid (Ax/C) for the treatment of non-recurrent AOM (nr-AOM). Both antimicrobial susceptibility (AS) to Ax/S and Ax/C from Sp and Hi carried by study children (aged 6-48 months with nr-AOM) and, clinical outcome after treatment with high dose of either Ax/C (7:1) or Ax/S (4:1) (amoxicillin dose: 80 mg/(kg day), b.i.d. for 10 days) were assessed. Nasal cultures (NCs) were taken at Day 0. Follow-up NCs, were done only for Sp carriers. On final analysis 247/289 pts (85.5%) were fully evaluable (120 Ax/S and 127 Ax/C). NP carriage rate of Hi and Sp at Day 0 was 32.2% (93/289 pts) and 28.7% (83/289 pts), respectively. Persistent Sp carriage was detected only in 2 pts. Hi betalactamase positive rate was 13% (12/93). MICs for Ax/S and Ax/C were identical when tested against Sp and Hi isolates (range < or = 0.016-1.0 and < or = 0.016-0.25 mg/L, respectively). Clinical efficacy at Days 12-14 and 28-42 were 98.3% (115/117) and 94.2% (97/103) for Ax/S; and 98.3% (115/117) and 95.1% (98/103) for Ax/C, respectively (pNS). We conclude, that Sp and Hi isolated from NCs of nr-AOM pts were highly sensitive to both drugs and correlated with high clinical efficacy rate.

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.