Comparative pharmacokinetics of cyclacillin and amoxicillin in infants and children

Abstract

Concentrations of cyclacillin in serum over a 6-h period were similar in fasted and milk-fed infants who received 25-mg/kg doses of cyclacillin suspension. Measured by the concentration in serum after oral adnministration of 15-mg/kg doses, cyclacillin was absorbed more rapidly, reached larger concentrations, and -was cleared more promptly than was amoxicillin.Cyclacillin is an aminoalicyclic semisynthetic penicillin that has been approved by the Food Each child received either cyclacillin or amoxicillin trihydrate oral suspension (125 or 250 mg/ 5 ml) administered four or three times daily, respectively, for 10 days. Most children were studied on two separate occasions; once while fasting and once when the antibiotic was administered with 4 oz. (ca. 118 ml) of milk or milk formula (Similac or Enfamil). Fifteen children received cyclacillin only, and 12 received both drugs in crossover fashion. There was a 4-to 5-day interval between studies in most children. None of the children was receiving any other medication before or at the time of the studies. A research nurse administered the drugs to all children. Blood samples were obtained immediately before and at 15, 30, 45, 60, 180, and 360 min after the dose.Concentrations of cyclacillin and amoxicilhin in body fluids were assayed by the agar disk diffusion micromethod, using Sarcina lutea (ATCC 9341) as the test organism (6). Body fluid specimens and reference samples were diluted identically in pooled serum for measurement of serum concentrations. The day-to-day variation in the assay was ±10%.The equation for the regression line of the log serum concentrations of antibiotic against time was calculated by the method of least mean squares (5). The serum half-life was determined by dividing log1o2 by the slope of the line (5). The curve of the area under the serum concentration time, expressed as micrograms per hour per milliliter, was formulated by successive trapezoidal approximation (5).In vitro susceptibilities of 11 strains of H.

Comparing Pharmacokinetics of Amoxicillin Given Twice or Three Times per Day to Children Older than 3 Months with Pneumonia

“…The pharmacokinetics of amoxicillin in this study was comparable to the results of a previously published study of 24 infants and children of similar ages (4 to 45 months; 40% higher than the concentration at 2 h) (8).…”

The Impact of Dosing Frequency on the Efficacy of 10-Day Penicillin or Amoxicillin Therapy for Streptococcal Tonsillopharyngitis: A Meta-analysis

“…Although amoxicillin is considered to be pharmacologically equivalent to penicillin, there is evidence that amoxicillin is better absorbed and produces higher and longer serum and tissue concentrations. 15,16,18,19 In additional support of this finding, recent studies published in this journal and in Pediatric Infectious Diseases Journal found that amoxicillin given TID for 6 days or QD for 10 days was as efficacious as standard 10-day penicillin. 34,35 Therefore, it seemed reasonable to repeat the analysis excluding the study that used amoxicillin.…”

“…Studies of amoxicillin have been included in this meta-analysis because amoxicillin is often used both in clinical trials as well as in clinical practice as an alternative to penicillin, because it compares favorably with respect to gastrointestinal tolerability, serum and tonsillar half-life, cost, absorption that is less affected by food ingestion, and spectrum of bacterial coverage that is only slightly wider than that of penicillin. [15][16][17][18][19] This meta-analysis also includes 2 subanalyses to determine whether the results are robust for specific groups. Because streptococcal tonsillopharyngitis leading to rheumatic fever is of particular significance in children, 20 sensitivity analysis of the studies that enrolled predominantly children was performed.…”

Characterization of the Population Pharmacokinetics of Ampicillin in Neonates Using an Opportunistic Study Design

“…The PK of ampicillin have been studied in children and adults (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14), but data on dosing in the neonatal population are sparse. Current dosing regimens take into account the gestational age (GA)-and postmenstrual age (PMA)-related variation in renal drug clearance and recommend lower doses and less frequent dosing in the most premature neonates (1).…”