Pharmacokinetic study of a paediatric formulation of amoxycillin and clavulanic acid in children

Amoxicillin and penicillin G dosing in pediatric community-acquired pneumococcal pneumonia in the era of conjugate pneumococcal vaccines

BACKGROUND

Parenteral penicillin G (PENG) and oral amoxicillin (AMOX) are recommended as treatment for pediatric community-acquired pneumonia (CAP). With recent epidemiologic penicillin susceptibility data for Streptococcus pneumoniae, the most common etiology of CAP, the objective of this study was to evaluate optimal dosing regimens of PENG and AMOX based on population pharmacokinetics linked to current susceptibility data.

METHODS

Using NONMEM v7.3, Monte Carlo simulations (N = 10,000) were conducted for AMOX 15 mg/kg/dose PO every 8 h (standard-dose), AMOX 45 mg/kg/dose PO every 12 h (high-dose), and PENG 62,500 units/kg/day IV every 6 h using six virtual subjects with ages spanning 3 months to 15 years old. The probability of target attainment (PTA) was determined for both serum and epithelial lining fluid (ELF) to achieve free drug concentrations above the minimum inhibitory concentration (%fT>MIC) across the population of pneumococci for 30%-50% of the dosing interval.

RESULTS

In 2018, all 21 (100%) pneumococcal isolates were susceptible to both PENG and AMOX based on Clinical and Laboratory Standards Institute (CLSI; MIC at 2 mg/L) breakpoints, and 15 of 21 (71%) were susceptible based on EUCAST (MIC at 0.5 mg/L) breakpoints. As compared to CLSI, EUCAST breakpoints consistently achieved higher PTA for all antibiotic regimens. At 50% fT>MIC in the serum at the susceptible MICs, standard-dose AMOX achieved >4% PTA (CLSI) and >86% PTA (EUCAST); high-dose AMOX achieved >73% PTA (CLSI) and >99% PTA (EUCAST); and PENG achieved 0% PTA (using CLSI) and 100% PTA (using EUCAST). Standard-dose AMOX, high-dose AMOX, and PENG achieved >71%, >93%, and 100% PTA, respectively, in the serum at 30%-50% fT>MIC when each patient was stochastically linked to an MIC based on the frequency distribution of national susceptibility data. The PTA was consistently lower in ELF as compared with serum for all regimens.

CONCLUSION

Based on the recent rates of resistance, antibiotic doses evaluated provide appropriate exposure for pediatric CAP based on the serum and ELF data associated with predicted clinical and microbiologic success for pneumococcus. High-dose AMOX may still be required to treat pediatric CAP, especially if using CLSI breakpoints. Ongoing surveillance for resistance is essential.

Pharmacokinetics of Clavulanic Acid in the Pediatric Population: A Systematic Literature Review

Background and Objective

Clavulanic acid is a commonly used β-lactam inhibitor in pediatrics for a variety of infections. Clear insight into its mode of action is lacking, however, and a target has not been identified. The dosing of clavulanic acid is currently based on that of the partner drug (amoxicillin or ticarcillin). Still, proper dosing of the compound is needed because clavulanic acid has been associated with adverse effects. In this systematic review, we aim to describe the current literature on the pharmacokinetics of clavulanic acid in the pediatric population

Methods

We performed a systematic search in MEDLINE, Embase.com, Cochrane Central, Google Scholar, and Web of Science. We included all published studies reporting pharmacokinetic data on clavulanic acid in neonates and children 0–18 years of age.

Results

The search resulted in 18 original studies that met the inclusion criteria. In general, the variation in drug exposure was large, which can be partly explained by differences in disease state, route of administration, or age. Unfortunately, the studies’ limited background information hampered in-depth assessment of the observed variability.

Conclusion

The pharmacokinetics of clavulanic acid in pediatric patients is highly variable, similar to reports in adults, but more pronounced. Significant knowledge gaps remain with regard to the population-specific explanation for this variability. Model-based pharmacokinetic studies that address both maturational and disease-specific changes in the pediatric population are therefore needed. Furthermore, additional pharmacodynamic studies are needed to define a clear target. The combined outcomes will eventually lead to pharmacokinetic-pharmacodynamic modeling of clavulanic acid and targeted exposure.

Clinical Trial Registration

PROSPERO CRD42020137253.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40262-022-01116-3.

In vitro activity and pharmacodynamics of oral beta-lactam antibiotics against Streptococcus pneumoniae from southeast Missouri

STUDY OBJECTIVES

To determine the frequency of reduced susceptibility to penicillin, and to compare the in vitro activity and pharmacodynamics of oral beta-lactam antibiotics against clinical isolates of Streptococcus pneumoniae from southeast Missouri.

SETTING

Cape Girardeau, Missouri (population 35,500). Interventions. Minimum inhibitory concentrations (MICs) were determined for penicillin, amoxicillin, amoxicillin-clavulanic acid, cefprozil, cefuroxime, cefpodoxime, cefaclor, and loracarbef by E test for 108 isolates of S. pneumoniae. The MIC50, MIC90, and percentage susceptibility were calculated for each agent. Pharmacokinetic variables were obtained from the literature, and serum concentration-time profiles were simulated for a 25-kg child taking pediatric dosages commonly administered to treat otitis media. The average time above MIC (T > MIC) was calculated as percentage of the dosing interval using free concentrations and the MIC for each individual isolate. Analysis of variance (Scheffe post hoc test) was used to determine differences among agents for in vitro activity and T > MIC (level of significance, p<0.05).

MEASUREMENTS AND MAIN RESULTS

The frequency of penicillin-nonsusceptible S. pneumoniae was 28.7% (31/108). For 25 penicillin-intermediate isolates, amoxicillin and amoxicillin-clavulanic acid were significantly more active than cefprozil, cefaclor, and loracarbef. The T > MIC for amoxicillin and amoxicillin-clavulanic acid, simulated at 13.3 mg/kg every 8 hours, was significantly longer than that for all other beta-lactams.

CONCLUSION

Amoxicillin and amoxicillin-clavulanic acid have superior in vitro activity and longer T > MIC for penicillin-intermediate isolates than the other oral beta-lactams.