Dicloxacillin and flucloxacillin twice daily with probenecid in staphylococcal infections. A clinical and pharmakokinetic evaluation

Addition of probenecid to oral β-lactam antibiotics: a systematic review and meta-analysis

OBJECTIVES

To explore the literature comparing the pharmacokinetic and clinical outcomes from adding probenecid to oral β-lactams.

METHODS

Medline and EMBASE were searched from inception to December 2021 for all English language studies comparing the addition of probenecid (intervention) with an oral β-lactam [flucloxacillin, penicillin V, amoxicillin (± clavulanate), cefalexin, cefuroxime axetil] alone (comparator). ROBINS-I and ROB-2 tools were used. Data on antibiotic therapy, infection diagnosis, primary and secondary outcomes relating to pharmacokinetics and clinical outcomes, plus adverse events were extracted and reported descriptively. For a subset of studies comparing treatment failure between probenecid and control groups, meta-analysis was performed.

RESULTS

Overall, 18/295 (6%) screened abstracts were included. Populations, methodology and outcome data were heterogeneous. Common populations included healthy volunteers (9/18; 50%) and those with gonococcal infection (6/18; 33%). Most studies were crossover trials (11/18; 61%) or parallel-arm randomized trials (4/18; 22%). Where pharmacokinetic analyses were performed, addition of probenecid to oral β-lactams increased total AUC (7/7; 100%), Cmax (5/8; 63%) and serum t½ (6/8; 75%). Probenecid improved PTA (2/2; 100%). Meta-analysis of 3105 (2258 intervention, 847 control) patients treated for gonococcal disease demonstrated a relative risk of treatment failure in the random-effects model of 0.33 (95% CI 0.20-0.55; I2 = 7%), favouring probenecid.

CONCLUSIONS

Probenecid-boosted β-lactam therapy is associated with improved outcomes in gonococcal disease. Pharmacokinetic data suggest that probenecid-boosted oral β-lactam therapy may have a broader application, but appropriately powered mechanistic and efficacy studies are required.

Population pharmacokinetics of free flucloxacillin in patients treated with oral flucloxacillin plus probenecid

Oral flucloxacillin may be coadministered with probenecid to reduce flucloxacillin clearance and increase attainment of pharmacokinetic-pharmacodynamic (PK/PD) targets. The aims of this study were to develop a population PK model of free flucloxacillin when administered orally with probenecid, and to identify optimal dosing regimens for this combination.

METHODS

We performed a prospective observational study of adults (45 participants) treated with oral flucloxacillin 1000 mg and probenecid 500 mg 8-hourly for proven or probable staphylococcal infections. Steady-state mid-dose-interval flucloxacillin measurements (45 concentrations) were combined with existing data from a crossover study of healthy participants receiving flucloxacillin with and without probenecid (11 participants, 363 concentrations). We developed a population pharmacokinetic model of free flucloxacillin concentrations within Monolix, and used Monte Carlo simulation to explore optimal dosing regimens to attain PK/PD targets proposed in the literature (free drug time above minimum inhibitory concentration).

RESULTS

Flucloxacillin disposition was best described by a 1-compartment model with a lag time and first-order absorption. Free flucloxacillin clearance depended on probenecid, allometrically-scaled fat free mass (FFM) and estimated glomerular filtration rate (eGFR). Predicted PK/PD target attainment was suboptimal with standard dosing regimens with flucloxacillin alone, but substantially improved in the presence of probenecid.

CONCLUSION

The simulation results reported can be used to identify dose regimens that optimise flucloxacillin exposure according to eGFR and FFM. Patients with higher FFM and eGFR may require the addition of probenecid and 6-hourly dosing to achieve PK/PD targets. The regimen was well-tolerated, suggesting a potential for further evaluation in controlled clinical trials to establish efficacy.

Pharmacokinetic Drug-drug Interaction of Antibiotics Used in Sepsis Care in China

BACKGROUND

Many antibiotics have a high potential for interactions with drugs, as a perpetrator and/or victim, in critically ill patients, and particularly in sepsis patients.

METHODS

The aim of this review is to summarize the pharmacokinetic drug-drug interaction (DDI) of 45 antibiotics commonly used in sepsis care in China. Literature search was conducted to obtain human pharmacokinetics/ dispositions of the antibiotics, their interactions with drug-metabolizing enzymes or transporters, and their associated clinical drug interactions. Potential DDI is indicated by a DDI index ≥ 0.1 for inhibition or a treatedcell/ untreated-cell ratio of enzyme activity being ≥ 2 for induction.

RESULTS

The literature-mined information on human pharmacokinetics of the identified antibiotics and their potential drug interactions is summarized.

CONCLUSION

Antibiotic-perpetrated drug interactions, involving P450 enzyme inhibition, have been reported for four lipophilic antibacterials (ciprofloxacin, erythromycin, trimethoprim, and trimethoprim-sulfamethoxazole) and three antifungals (fluconazole, itraconazole, and voriconazole). In addition, seven hydrophilic antibacterials (ceftriaxone, cefamandole, piperacillin, penicillin G, amikacin, metronidazole, and linezolid) inhibit drug transporters in vitro. Despite no clinical PK drug interactions with the transporters, caution is advised in the use of these antibacterials. Eight hydrophilic antibiotics (all β-lactams; meropenem, cefotaxime, cefazolin, piperacillin, ticarcillin, penicillin G, ampicillin, and flucloxacillin), are potential victims of drug interactions due to transporter inhibition. Rifampin is reported to perpetrate drug interactions by inducing CYP3A or inhibiting OATP1B; it is also reported to be a victim of drug interactions, due to the dual inhibition of CYP3A4 and OATP1B by indinavir. In addition, three antifungals (caspofungin, itraconazole, and voriconazole) are reported to be victims of drug interactions because of P450 enzyme induction. Reports for other antibiotics acting as victims in drug interactions are scarce.

Oral Flucloxacillin for Staphylococcal Osteomyelitis: Obsolete or Underused?

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Probenecid and food effects on flucloxacillin pharmacokinetics and pharmacodynamics in healthy volunteers

OBJECTIVES

To measure the effect of probenecid, fasting and fed, on flucloxacillin pharmacokinetic and pharmacodynamic endpoints.

METHODS

Flucloxacillin 1000 mg orally was given to 11 volunteers alone while fasting ('flucloxacillin alone'), and with probenecid 500 mg orally while fasting ('probenecid fasting') and with food ('probenecid fed'). Flucloxacillin pharmacokinetic and pharmacodynamic endpoints were compared.

RESULTS

Probenecid, fasting and fed, increased free plasma flucloxacillin area under the concentration-time curve (zero to infinity) ∼1.65-fold (p < 0.01) versus flucloxacillin alone. Probenecid fed prolonged time to peak flucloxacillin concentrations ∼2-fold versus the other two regimens (p < 0.01). Probenecid fasting or fed increased free flucloxacillin concentrations exceeding 30%, 50% and 70% of the first 6, 8 and 12 h post-dose by 1.58- to 5.48-fold compared with flucloxacillin alone. As an example of this pharmacodynamic improvement, the probability of target attainment of free concentrations above the minimum inhibitory concentration for Staphylococcus aureus (0.5 mg/L) for 50% of a 6-hour dose interval was > 80% for flucloxacillin plus probenecid (fasting or fed) and < 20% for flucloxacillin alone.

CONCLUSIONS

Probenecid increased flucloxacillin exposure, with predicted pharmacodynamic effects greater than pharmacokinetic effects because of the altered shape of the concentration-time curve. Probenecid may improve the applicability of oral flucloxacillin regimens.

In healthy volunteers, taking flucloxacillin with food does not compromise effective plasma concentrations in most circumstances

It is usually recommended that flucloxacillin is given on an empty stomach. The aim of this study was to compare total and free flucloxacillin concentrations after oral flucloxacillin, given with and without food, based on contemporary pharmacokinetic and pharmacodynamic targets. Flucloxacillin 1000 mg orally was given to 12 volunteers, after a standardised breakfast and while fasting, on two separate occasions. Flucloxacillin concentrations over 12 hours were measured by liquid chromatography-tandem mass spectrometry. Pharmacokinetic parameters, and pharmacodynamic endpoints related to target concentration achievement, were compared in the fed and fasting states. For free flucloxacillin, the fed/fasting area under the concentration-time curve from zero to infinity (AUC0-∞) ratio was 0.80 (p<0.01, 90% CI 0.70-0.92), the peak concentraton (Cmax) ratio 0.51 (p<0.001, 0.42-0.62) and the time to peak concentration (Tmax) ratio 2.2 (p<0.001, 1.87-2.55). The ratios for total flucloxacillin concentrations were similar. The mean (90% CI) fed/fasting ratios of free concentrations exceeded for 30%, 50% and 70% of the first 6 hours post-dose were 0.74 (0.63-0.87, fed inferior p<0.01), 0.95 (0.81-1.11, bioequivalent) and 1.15 (0.97-1.36, fed non-inferior), respectively. Results for 8 hours post-dose and those predicted for steady state were similar. Comparison of probability of target attainments for fed versus fasting across a range of minimum inhibitory concentrations (MICs) were in line with these results. Overall, this study shows that food reduced the AUC0-∞ and Cmax, and prolonged the Tmax of both free and total flucloxacillin concentrations compared with the fasting state, but achievement of free concentration targets associated with efficacy was in most circumstances equivalent. These results suggest that taking flucloxacillin with food is unlikely to compromise efficacy in most circumstances.

Inhibition of flucloxacillin tubular renal secretion by piperacillin

AIMS

To explore the extent, time course, site(s), mechanism and possible clinical relevance of the pharmacokinetic (PK) interaction between piperacillin and flucloxacillin.

METHODS

A single-dose, randomized, six-way crossover study in 10 healthy volunteers where all subjects received all of the following as 5-min intravenous infusions: (i) 1.5 g piperacillin, (ii) 0.5 g flucloxacillin, (iii) 1.5 g piperacillin + 0.5 g flucloxacillin, (iv) 3 g piperacillin, (v) 1 g flucloxacillin, and (vi) 3 g piperacillin + 1 g flucloxacillin. Drug concentrations in plasma and urine were determined by high-performance liquid chromatography. WinNonlin was used for PK modelling and statistics.

RESULTS

Piperacillin significantly decreased the renal clearance of flucloxacillin from 5.44 to 2.29 l h(-1) (medians, P < 0.01) and the nonrenal clearance of flucloxacillin from 2.67 to 1.80 l h(-1) (P < 0.01). The renal clearance of flucloxacillin was reduced to 45% (point estimate, 90% confidence interval 40 to 50%) and the nonrenal clearance to 66% (59, 73). The extent of interaction was larger at the higher doses. Competitive inhibition of tubular secretion by piperacillin was identified as the most likely mechanism for the decreased renal clearance of flucloxacillin. Piperacillin had a 15-times higher affinity for the renal transporter than flucloxacillin based on the molar ratio. Piperacillin PK was only slightly affected by flucloxacillin.

CONCLUSIONS

Piperacillin inhibits renal and nonrenal elimination of flucloxacillin. This interaction seems clinically significant, as total clearance was reduced by a factor of 1.5 for the lower and 2.1 for the higher doses. PK interactions, especially with piperacillin, are likely to occur also with other beta-lactam combinations and might be useful to improve the effectiveness of antibacterial treatment.

Pharmacokinetics and bioavailability of flucloxacillin in elderly hospitalized patients

The pharmacokinetics and oral bioavailability of flucloxacillin were studied in five female and two male patients (age 68-87 yr) who had been hospitalized for orthopedic surgeries. A single dose of intravenous or oral flucloxacillin sodium (500 mg) was administered in random order on different occasions separated by at least 2 days. Blood and urine samples were taken up to 24 hours after drug administration and levels of flucloxacillin and 5-hydroxymethylflucloxacillin (5-HMF), a major metabolite, were measured by high-performance liquid chromatography. Flucloxacillin elimination, but not oral absorption, was reduced in the elderly, compared with data from young healthy subjects reported elsewhere. Total clearance, renal clearance, and volume of distribution were 0.083 +/- 0.013 L/kg/hr, 0.038 +/- 0.01 L/kg/hr, and 0.184 +/- 0.034 L/kg, respectively. Regression of flucloxacillin renal clearance (Clr) on estimated creatine clearance (CLcr) gave the relationship: Clr = 0.755 (CLcr) + 10.6 (r = 0.91; P = 0.004). Terminal half-lives for flucloxacillin and 5-HMF were 2.21 +/- 0.51 hr and 3.0 +/- 0.75 hr, respectively after intravenous administration. Flucloxacillin was absorbed rapidly after oral administration with a mean absorption time of 0.95 +/- 0.34 hr, and time to reach peak concentration of 1.20 +/- 0.29 hr. The absolute bioavailability of flucloxacillin from capsules was 54.4 +/- 18.8%.

Should probenecid be used to reduce the dicloxacillin dosage in orthopaedic infections? A study of the dicloxacillin-saving effect of probenecid

Reduction in the dosage of dicloxacillin from 500 mg to 250 mg 3 times a day would mean lowering of costs and less side-effects in orthopaedic infections. In this cross-over study, the serum concentrations of dicloxacillin were measured in 9 patients after administration of dicloxacillin 500 mg 3 times a day (dicloxacillin 500 mg) and after co-administration of 250 mg dicloxacillin and 250 mg probenecid 3 times per day (dicloxacillin 250 mg+probenecid 250 mg). Concentrations were measured every hour after the tablet intake. The mean maximum serum concentrations of dicloxacillin were 17.1 micrograms/ml (dicloxacillin 500 mg) and 12.2 micrograms/ml (dicloxacillin 250 mg+probenecid 250 mg), respectively (P < 0.05). Serum concentrations above 3 micrograms/ml were obtained during 285 min. in both regimes, but the individual variations were biggest during in the dicloxacillin 250 mg+probenecid 250 mg treatment. Serum concentrations above 5 micrograms/ml were in mean measured during 228 min. (dicloxacillin 500 mg) and 190 min. (dicloxacillin 250 mg+probenecid 250 mg), respectively (P < 0.05). The clinical significance of these findings is being discussed. In theory, treatment with dicloxacillin 250 mg+probenecid 250 mg may be as sufficient as dicloxacillin 500 mg.

Oral absorption of flucloxacillin in infants and young children

The bioavailability of flucloxacillin (Heracillin) following oral administration was determined in infants and children. After a dose of 12.5 mg/kg, peak concentrations were achieved at 60 min. which declined rapidly and were low in older children only 4 hours afterwards. Infants below 6 months of age showed a better absorption when given the mixture than older children. Older children achieved higher plasma concentrations when given tablets than when given equal doses of the mixture. There was no difference in the concentration when the dose was given to the subject when fasting, or with breakfast.

Treatment and prevention of recurrent staphylococcal furunculosis: clinical and bacteriological follow-up

Various therapeutic and preventive methods were evaluated in 80 patients with recurrent staphylococcal furunculosis. The most appropriate treatment was peroral antibiotics for 10-14 days, mainly flucloxacillin twice daily. Fusidic acid ointment was used for prevention of relapses. Patients and healthy family members who carried the patient strain applied the ointment in nares twice daily every 4th week during 4-15 months. The method had a permanent effect in 80%. Implantation of strain 502 A was less effective when evaluated during a 2-3 yr period. 40-80 patients were checked up to 8 yr after their last furuncle. Three still had furuncles, in 2 of these cases the original strain was found in nares. 37 patients, now healthy after a mean observation time of 4.5 yr, showed either new nasal strains or negative cultures. A significantly lower frequency of phage group II strains in nares was noted in comparison to the previous findings during active furunculosis.

Pharmacokinetics and distribution of flucloxacillin in pacemaker patients

The pharmacokinetics of flucloxacillin in plasma and tissue fluid after i.v. infusion of 1 g was analyzed according to an open two-compartment model in 19 patients with bradyarrhythmias (mean age 70.8 years) admitted for implantation or replacement of a permanent pacemaker system. After the first infusion of flucloxacillin (5 min), the distribution phase was rapid (t 1/2 alpha = 0.13 h). The plasma half-life of elimination (t 1/2 beta) was 1.51 h, which is almost twice as long as reported in healthy volunteers. Total plasma clearance (93.1 ml/min) was also lower than is usually found in healthy individuals, due to low renal clearance of flucloxacillin (60.2 ml/min). The total apparent volume of distribution during the beta-phase (Vdarea) was 0.172 l/kg and distribution in the central compartment (Vc) 0.064 1/kg. In each patient plasma protein binding and drug distribution to plasma water, proteins and blood cells in whole blood were determined. Binding in plasma to proteins was 91.0% and distribution to blood cells in whole blood 13.8%. The mean distribution volume of free flucloxacillin during the beta-phase (Vd beta free) was 2.18 1/kg, which exceeds total body water, suggesting possible intracellular distribution and substantial tissue binding. Plasma concentrations of flucloxacillin after the fourth dose (1 g t.i.d.) were very similar to those obtained after the first infusion and those predicted from the single dose kinetics. The concentration of flucloxacillin in fluid from the pacemaker pockets in 5 patients averaged 12.1 micrograms/ml and 9.5 micrograms/ml at 1 and 5 h, respectively, which was more than ten times the MIC-values for Staphylococcus aureus and S. epidermidis.(ABSTRACT TRUNCATED AT 250 WORDS)

Oral therapy for orthopedic infections in children and adults

Literature and clinical experience in the treatment of both adult and pediatric osteomyelitis by oral antibiotics is reviewed. Antibiotics achieving adequate penetration into joint fluid and bone are listed. Particular discussion is given to penicillins, cephalosporins, and non-β-lactam antibiotics. Techniques for monitoring therapeutic effectiveness and patient compliance are noted.