Physiologically Based Pharmacokinetic Modeling of Renally Cleared Drugs in Pregnant Women

BACKGROUND

Since pregnant women are considerably underrepresented in clinical trials, information on optimal dosing in pregnancy is widely lacking. Physiologically based pharmacokinetic (PBPK) modeling may provide a method for predicting pharmacokinetic changes in pregnancy to guide subsequent in vivo pharmacokinetic trials in pregnant women, minimizing associated risks.

OBJECTIVES

The goal of this study was to build and verify a population PBPK model that predicts the maternal pharmacokinetics of three predominantly renally cleared drugs (namely cefazolin, cefuroxime, and cefradine) at different stages of pregnancy. It was further evaluated whether the fraction unbound (f _u) could be estimated in pregnant women using a proposed scaling approach.

METHODS

Based on a recent literature review on anatomical and physiological changes during pregnancy, a pregnancy population PBPK model was built using the software PK-Sim^®/MoBi^®. This model comprised 27 compartments, including nine pregnancy-specific compartments. The PBPK model was verified by comparing the predicted maternal pharmacokinetics of cefazolin, cefuroxime, and cefradine with observed in vivo data taken from the literature. The proposed scaling approach for estimating the f _u in pregnancy was evaluated by comparing the predicted f _u with experimentally observed f _u values of 32 drugs taken from the literature.

RESULTS

The pregnancy population PBPK model successfully predicted the pharmacokinetics of cefazolin, cefuroxime, and cefradine at all tested stages of pregnancy. All predicted plasma concentrations fell within a 2-fold error range and 85% of the predicted concentrations within a 1.25-fold error range. The f _u in pregnancy could be adequately predicted using the proposed scaling approach, although a slight underestimation was evident in case of drugs bound to α₁-acidic glycoprotein.

CONCLUSION

Pregnancy population PBPK models can provide a valuable tool to predict a priori the pharmacokinetics of predominantly renally cleared drugs in pregnant women. These models can ultimately support informed decision making regarding optimal dosing regimens in this vulnerable special population.

[Microcalorimetric investigation of two cephalosporins on colon bacteria activity]

The effects of cephradinum and ceftazidime on the metabolism of Escherichia coli (E. coli) DH5alpha was determined by microcalorimetry. The microbial activity was recorded as power-time curves through an ampoule method with a TAM Air Isothermal Microcalorimeter at 37 degrees C. The parameters such as the growth rate constant (k), inhibitory ratio (I), the maximum power output (Pm) and the time (tm) corresponding to the maximum power output were calculated. The results show that the ceftazidime has a better inhibitory effect on E. coli DH5alpha than cephradinum.

A study of the chemiluminescence behavior of cephalosporins with luminol and its analytical application

The chemiluminescence intensity of luminol-dissolved oxygen was decreased when cephalosporins were mixed with luminol. The decrease chemiluminescence intensity was linear with the logarithm of cephalosporins concentration over the range from nanogram to microgramme level, with the limits of detection at nanogram level. The sensitivities of determination for cephalosporins were in the order of cefoperazone > ceftriaxone > cefuroxime > cefaclor > cefalexin > cefradine. The proposed method was applied to monitor the excretion of cefradine in human urine after taken cefradine capsules. The possible chemiluminescence mechanism and relationship between the determination sensitivities and generations of cephalosporins were also discussed.

Pharmacokinetic study of cephradine in Pakistani healthy male volunteers

To observe and discuss the difference in the pharmacokinetics of cephradine in Pakistani population with the reported data of other ethnic origins. A Single group pharmacokinetic study was conducted having six healthy male volunteers of 20-24 years of age. Blood samples were collected at appropriate times up to 7 hours. Plasma concentrations of cephradine was determined by HPLC technique and pharmacokinetic parameters were determined by both compartmental and noncompartmental methods using Kinetica ver 4.4.1 and Winnonlin ver 5.01. Peak plasma concentration was 11.49+/-1.73 microg/ ml achieved at 0.76+/-0.12 hr, after the administration of 250 mg cephradine to fasting volunteers. Area under the serum concentration-time curve was found to be 16.4+/-1.71 g.hr/ ml. Absorption, distribution, disposition and elimination half lives were calculated as 0.183 +/- 0.038 hr, 0.248 +/- 0.143 hr, 2.126 +/- 0.341 hr and 0.441+/-0.193 hr respectively where as the volume of central compartment and total body clearance were found to be 9.65+/-3.78 L and 15.4+/-1.89 L/hr. The plasma concentration time curves showed the absorption rate constant was 3.968 +/- 0.05 hr(-1), disposition rate constant was 0.333+/-0.05 hr(-1), distribution rate constant was 3.64+/-2.18 hr(-1) and elimination rate constant was 1.738+/-0.468 hr(-1). The value of micro-constants i.e. K(12) (central to peripheral compartment) and K(21) (peripheral to central compartment) were found to be 1.529+/- 1.499 hr(-1) and 0.704 +/- 0.44 hr(-1) respectively, where as MRT and AUMC were calculated as 2.04+/-0.09 hr and 35.92+/-1.86 hr(2) microg/ ml. The findings showed that the results of Pakistani subjects are slightly different when compared with the reported data of other ethnic origin.

Controlled drug delivery system based on magnetic hollow spheres/polyelectrolyte multilayer core-shell structure

A novel controlled drug delivery system was fabricated by coating chitosan/PAA multilayer onto magnetic hollow spheres via a "Layer-by-Layer" (LBL) assembly approach. Cefradine was used as a model drug to evaluate the drug release characteristics of this core-shell hollow structure and the results show that it exhibits a sustained release of the drug and the release rate can be regulated by the pH environment of release medium. It is believed that this core-shell hollow structure, which combines the advantage of controlled delivery as well as magnetic targeting, has commendable potential in drug delivery therapeutics.

Preparation and characterization of uniform nanosized cephradine by combination of reactive precipitation and liquid anti-solvent precipitation under high gravity environment

In this work, a novel direct method, which was combined with reactive precipitation and liquid anti-solvent precipitation under high gravity environment, had been developed to prepare nanosized cephradine with narrow particle size distribution. Compared with commercial crude cephradine, the prepared cephradine showed a significant decrease in particle size, a significant increase in the specific surface area and shorter dissolving time when used for injection. The characteristic particle size was between 200-400 nm. The specific surface area increased from 2.95 to 10.87 m2/g after micronization. When the amount of L-arginin decreased from 0.25 to 0.18 g, the mixture of nanosized cephradine and L-arginine could still dissolve in 1 min. The X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) analysis indicated that the physical characteristics and molecular states remained unchanged after the recrystallization process. This method had potential application in industrial fields because of its low cost, efficient processing and the ease of scaling-up.

Properties and active substance release kinetics from gelatin-alginate matrices

The aim of the study was to evaluate the effect of composition and technological processing on pharmaceutical availability of active substance as well as on the properties of porous gelatin-alginate matrices. The active substance carrier included glycerol or peanut oil apart from gelatin and sodium alginate, and some matrices were additionally modified with calcium lactate. The obtained matrices were characterized by good sorption properties and high resistance to proteolytic enzymes. The release of the model antibiotic followed the pattern of first order kinetics, while half-release time in vitro (in the experimental conditions) was 1.5 to 3 hrs.

Preparation and characterization of porous hollow silica nanoparticles for drug delivery application

Porous hollow silica nanoparticles (PHSNP) with a diameter of 60-70 nm and wall thickness of approximately 10nm were synthesized by using CaCO(3) nano-particles as the inorganic template. The characterization of PHSNP by TEM and BET indicated that PHSNP were uniform spherical particles with good dispersion, and had a specific surface area of 867 m(2)/g. The as-synthesized PHSNP were subsequently employed as drug carrier to investigate in vitro release behavior of cefradine in simulated body fluid. UV-spectrometry and TG analyses were performed to determine the amount of cefradine entrapped in the carrier. The BJH pore size distribution of PHSNP before and after entrapping cefradine was examined. Cefradine release profile from PHSNP followed a three-stage pattern and exhibited a delayed release effect.

An interrupted time series analysis of parenteral antibiotic use in Colombia

A University-based hospital in Bogotá, Colombia, developed and implemented an educational intervention to complement a new structured antibiotic order form. This intervention was performed after assessing the appropriateness of the observed antibiotic prescribing practices using a quasi-experimental study. An application of interrupted time series intervention analysis was conducted in three antibiotic groups (aminoglycosides, cephradine/cephalothin, and ceftazidime/cefotaxime) and their hospital weekly rate of incorrect prescriptions before and after the intervention. A fourth time series was defined on prophylactic antibiotic use in elective surgery. Preintervention models were used in the postintervention series to test for pre-post series level differences. An abrupt constant change was significant in the first, third, and fourth time series indicating a 47, 7.3, and 20% reduction of incorrect prescriptions after the intervention. We conclude that a structured antibiotic order form, coupled with graphic and educational interventions can improve antibiotic use in a university hospital.

Treatment of breast abscesses with sonographically guided aspiration, irrigation, and instillation of antibiotics

OBJECTIVE

We studied the feasibility of treating breast abscesses with sonographically guided aspiration, irrigation, and local instillation of antibiotics without placing indwelling catheters.

MATERIALS AND METHODS

Seventy-three patients with breast abscesses were seen from 1995 to 2001. Aspiration and irrigation were performed under sonographic guidance. Repeated aspiration was performed when deemed necessary. One gram of cephradine was injected into 29 abscesses measuring more than 25 mm.

RESULTS

Six patients refused further treatment after failure of the first aspiration and elected surgical drainage. Of the remaining 67 patients who completed treatment, 38 required one aspiration for cure, 18 required two aspirations, and eight required more than two aspirations. The treatment failed and surgical drainage was required in only three of the 67 patients completing treatment.

CONCLUSION

Ninety-six percent of patients completing treatment were cured with this procedure. Local instillation of antibiotics is probably beneficial.

A recirculatory model with enterohepatic circulation by measuring portal and systemic blood concentration difference

The present study describes a recirculatory model for the evaluation of pharmacokinetic characteristics of drugs possessing enterohepatic circulation (EHC). The advantage of the model is to separately define the extent and rate of absorption for the dosage and EHC after oral administration. Cephradine was used as a model drug and was intravenously or orally administered to rats. Portal and systemic bloods were simultaneously collected in order to estimate various local moments after defining the global moments obtained by non-compartment analysis. For the zero-order moments, bioavailability (BA), the hepatic recovery ratio (Fh), the sum of the local absorption ratio for the dosage and recirculatory local absorption ratio for EHC (F(a)po), and the recirculatory local absorption ratio for EHC (F(a)ehc) after oral administration were estimated to be 95.6, 77.9, 172, and 71.5%, respectively. These data indicate that a complete absorption and substantial EHC contribute high oral exposure of cephradine. For the first-order moments, the sum of the mean local absorption times for the dosage and EHC (t(a)po) and the mean transit time for a single pass of EHC (tc) were 2.50 and 0.117 hr, suggesting a rapid EHC of cephradine compared with the absorption from the dosage. With this model, the absorption rate-time profiles for the dosage and EHC were separately simulated by using a program of nonlinear least squares (MULTI) with fast inverse Laplace transform (FILT). The cumulative biliary excretion ratio (Fbile) calculated by the model was in good agreement with the experimental value obtained in the bile ductcannulated rats. These results suggest that the model proposed in this study would be useful for evaluating the extent and rate of ECH along with absorption from the dosage after oral administration of drugs.

Prolonged intestinal absorption of cephradine with chitosan-coated ethylcellulose microparticles in rats

Cephradine-containing ethylcellulose microparticles (MPC) were prepared by the solvent evaporation method. Chitosan-coated MPC (Chi-MPC) were prepared by doping MPC with viscous chitosan solution and subsequently drying. When fluorescein isothiocyanate (FITC)-labeled chitosan-coated ethylcellulose microparticles without drug were administered intraduodenally, they moved slowly in the intestine, that is, most of them were retained at the upper and middle parts of the small intestine for more than 8 h, which is considered due to mucoadhesive properties of coated chitosan. When MPC and Chi-MPC was incubated at 37 degrees C in the JP 14 second fluid, pH 6.8, both released the drug slowly with similar release rates. Cephradine solution and suspension, MPC and Chi-MPC were administered intraduodenally to investigate intestinal drug absorption. Only Chi-MPC suppressed the initial plasma level and maintained the plasma concentration for a long time up to 24 h, suggesting Chi-MPC would be useful for prolonged intestinal absorption of cephradine.

Update on prosthetic joints, dental treatment, and antibiotic prophylaxis

At this time, all dentists and physicians should be very familiar with the 1997 ADA/AAOS antibiotic prophylaxis recommendations for joint prosthesis patients who are undergoing dental treatment. The guidelines identify physical conditions that place joint replacement patients at the highest risk for joint sepsis. They also stratify dental procedures into higher-risk and lower-risk categories. Combining these two groupings clarifies the dentist's strategy for antibiotic prophylaxis protocols, which are greatly simplified over previous practices. Of notable importance is the elimination of posttreatment antibiotic dosing, the reduction of the loading dose of antibiotic, and the identification of a large group of joint replacement patients who do not require antibiotic prophylaxis prior to dental treatment. Every dentist must use clinical judgment, knowledge of the patient, and consultation with the attending physician to determine the appropriate treatment plan.

Comparison of local povidone-iodine antisepsis with parenteral antibacterial prophylaxis for prevention of infective complications of TURP: a prospective randomized controlled study

OBJECTIVE

To determine whether antisepsis with povidone-iodine solution applied at the external urethral meatus confers protection against infective complications following transurethral resection of the prostate (TURP) and compare that with antibacterial prophylaxis.

METHODS

A total of 167 patients with sterile urine undergoing TURP for benign prostatic hyperplasia (BPH) were prospectively randomized into three groups. Group A, had gauze soaked in saline applied at the urethral meatus (control group). In group B, the gauze was soaked in povidone-iodine instead of saline and group C had a single 1 g i.v. injection of cephradine at induction of anaesthesia with no treatment for the meatus. Bacteraemia, post-operative bacteriuria and other infective complications were compared in the three groups. Associations of bacteriuria at catheter removal and intra-operative bacteraemia with infective complications and with long term bacteriuria were also studied.

RESULTS

Bacteriuria rate at catheter removal was not significantly different in the three groups. However, intraoperative bacteraemia and bacterial growth at the external urethral meatus was significantly lower in group C. Bacteriuria at catheter removal was significantly associated with bacterial growth at the meatus but not with long term bacteriuria at 3 months. Bacteriuria at catheter removal could not accurately predict infective complications.

CONCLUSION

Post-TURP bacteriuria appears to be preceded by bacterial growth at the external urethral meatus. Antisepsis with povidone-iodine solution application at the meatus does not confer adequate protection against meatal bacterial growth as that obtained by prophylactic antibacterials. Nonetheless, neither antibacterial prophylaxis nor local antisepsis could reduce bacteriuria rate in this study.

Intraperitoneal ciprofloxacin and rifampicin versus cephradine as initial treatment of (C)APD-related peritonitis: a prospective randomized multicenter comparison (CIPPER trial)

OBJECTIVE

The initial treatment of peritonitis has evolved from single-agent to combination regimens. The initial response rates improved with these newer regimens but relapsing peritonitis continues to occur. For biofilm-embedded or intracellularly sequestrated bacteria, a combination of intracellularly- and biofilm-active agents such as ciprofloxacin and rifampicin might be beneficial. Many Dutch centers continue to use cephradine as initial treatment, claiming clinically adequate responses with this regimen. We compared the impact of these two regimens on outcome in patients who developed a new episode of peritonitis.

DESIGN

Prospective randomized open trial.

SETTING

Multicenter study including 14 Dutch dialysis units.

PATIENTS AND INTERVENTIONS

From October 1996 to October 1999, 367 patients from 14 centers were randomized to be treated with ciprofloxacin + rifampicin (CR; each 50 mg/L) or cephradine (C; 250 mg/L) in case of peritonitis. Of these 367 patients, 98 developed peritonitis, 44 of whom were treated with CR and 54 with C.

MAIN OUTCOME MEASURES

Clinical response, divided into early (during the 2 weeks of therapy) and late (including the following 4 weeks) response. Success was defined as disappearance of all signs and symptoms by days 4-6, through day 42. Bacteriological response was either success (eradication) or failure (persistence, superinfection, or eradication with relapse/reinfection).

RESULTS

The groups were comparable for age, sex, duration of continuous ambulatory/automated peritoneal dialysis, and occurrence of diabetes. Bacteriological cultures in both groups revealed predominantly gram-positive micro-organisms. Initial and late clinical successes were obtained in 27/54 and 20/54 episodes (50% and 37%) in the C group, and 33/44 and 28/44 episodes (75% and 63.6%) in the CR group (p = 0.021 and p = 0.019). Bacteriological success occurred in 29.6% in the C group, and in 59.1% in the CR group (p= 0.026), with failure in 46.3% and 18.2%, respectively. Peritonitis episodes were bacteriologically not evaluable in 24.1% of episodes in the C group and 22.7% of episodes in the CR group, due mostly to no growth in the initial culture.

CONCLUSION

The CIPPER Trial showed ciprofloxacin + rifampicin to be superior to cephradine as empiric treatment of peritonitis.

Labile conjugation of a hydrophilic drug to PLA oligomers to modify a drug delivery system: cephradin in a PLAGA matrix

The physical entrapment of a hydrophilic drug within degradable microspheres is generally difficult because of poor entrapment yield and/or fast release, depending on the microsphere fabrication method. In order to counter the effects of drug hydrophilicity, it is proposed to covalently attach the drug to lactic acid oligomers, with the aim of achieving temporary hydrophobization and slower release controlled by the separation of the drug from the degradable link within the polymer matrix. This strategy was tested on microspheres of the antibiotic cephradin. As the prodrug form, the entrapment of the drug was almost quantitative. The prodrug did degrade in an aqueous medium, modelling body fluids, but cleavage did not occur at the drug-oligomer junction and drug molecules bearing two lactyl residual units were released. When the prodrug is entrapped within a PLAGA matrix, no release was observed within the experimental time period. However, data suggest that conjugation via a bond more sensitive to hydrolysis than the main chain PLA ester bonds should make the system work as desired.

Topical antibiotics in neurosurgery: a re-evaluation of the Malis technique

We report the effect on the neurosurgical wound infection rate of a modification of the 'Malis' technique of antibiotic prophylaxis. In this a combination of antibiotics is given in the form of both parenteral administration and wound irrigation. A series of 1173 clean neurosurgical operations was compared with a historical control of 303 operations. Both treatment and control groups were operated on by the same surgeon, using similar surgical techniques. The control group received parenteral pre- and postoperative antibiotics (flucloxacillin and ampicillin). The treatment group (where the parenteral antibiotics used was cephradine) also received wound irrigation with a solution of gentamicin and flucloxacilin. The infection rate was 0.42% in the treatment group (five patients), in the control group it was 3.96% (12 patients). The difference was highly significant (p = 0.00006). We believe that the use of wound irrigation with antibiotics should receive further study.

A comparison of teicoplanin versus cephradine plus metronidazole in the prophylaxis of post-operative infection in vascular surgery

A total of 272 patients were enrolled into this prospective, unblinded, randomized comparison of single-dose teicoplanin vs three doses of cephradine plus metronidazole as prophylaxis for vascular surgery at St James's and Seacroft Hospitals, Leeds, UK. In all, 71.3% of patients (194/272) were enrolled at St James's University Hospital. Patients received either a single dose of teicoplanin, 6 mg/kg i.v., or cephradine, 1 g i.v. with metronidazole, 1 g rectally, at induction of anaesthesia followed by two further 1 g doses of cephradine and metronidazole 8 and 16 hours later. There were 136 patients in each treatment group. The most common operations were femoropopliteal grafts (96) and aortic aneurysm repairs (47). In the 'intention-to-treat' analysis, primary wound infections were seen in 4.4% of patients (6/136) receiving teicoplanin and 5.9% of patients (8/136) receiving cephradine plus metronidazole (95% CI -6.7%, +3.8%). Other disturbances to wound healing occurred in 23 patients (11 in the teicoplanin and 12 in the cephradine plus metronidazole group). Secondary respiratory tract infections occurred in 17 patients (8 receiving teicoplanin and 9 receiving cephradine plus metronidazole). In the evaluable patients analysis, primary wound infections occurred in 3.5% of patients (4/114) receiving teicoplanin and 5.1% of patients (6/117) receiving cephradine plus metronidazole. Staphylococcus aureus and Proteus sp. were the most common pathogens in primary wound infections. Despite the absence of Gram-negative cover in the teicoplanin group, Gram-negative infections occurred more often in the cephradine plus metronidazole group. Surgery of the lower extremities carried the highest risk of post-operative infection. Rates of infection were significantly higher at Seacroft Hospital (P = 0.001), and significantly higher for cephradine plus metronidazole between the two hospitals (P = 0.0008). Adverse events occurred in 40 patients receiving teicoplanin (29.4%) and 39 patients receiving cephradine plus metronidazole (28.7%). In 19 patients receiving teicoplanin (14%) and 15 receiving cephradine plus metronidazole (11%) these events were considered to be related to the study drugs. The most often reported events were infections, cardiac events and vascular phenomena (haematoma or emboli). Marked changes in haematological parameters and liver function tests were noted seven days after operation in patients in each treatment group, but these resolved quickly as the effects of the operation subsided. ESR remained elevated in both groups at the six-month follow-up assessment. It is concluded from this two-centre study that a single dose of teicoplanin shows similar efficacy to a three-dose regimen of cephradine plus metronidazole as prophylaxis for wound infection in vascular surgery. Both regimens were well tolerated, and there was an equal incidence of adverse events in the two regimens, which reflected the poor general health status of this elderly study population.

Cephradin-plaga microspheres for sustained delivery to cattle

In the field of controlled drug delivery, most of the reported work is aimed at introducing new systems, or at providing basic information on the critical parameters which affect release profiles in vitro and occasionally in vivo. The situation is totally different when one wants to fulfil the specific requirements imposed by the marketing of a sustained release device to be used in humans or in animals eaten by human beings. The control of the release characteristics is then a difficult challenge. In this work, attempts were made to combine cephradin, a hydrophilic beta-lactam antibiotic, and bioresorbable polymeric matrices of a poly(alpha-hydroxy acid) in the form of microspheres with the aim of delivering the antibiotic to cattle at a dose rate of 4-5 mg/kg/day over a 3-4 days period after i.m. injection. PLAGA aliphatic polyesters were selected because they are already FDA approved as matrices. The solvent evaporation technique using PVA as the emulsion stabilizer was selected because it is efficient and can be extended to an industrial scale. Various experimental conditions were used in order to obtain the highest encapsulation yields compatible with the desired specifications. Decreasing the volume of the aqueous phase and adding a water-miscible organic solvent/non-solvent of cephradin failed. In contrast, microspheres containing up to 30% cephradin were prepared after addition of sodium chloride to the aqueous dispersing phase. The amount of entrapped drug was raised to 40% by decreasing the temperature and the pressure. Preliminary investigations using dogs showed that 20% cephradin microspheres prepared under these conditions extended the presence of cephradin in the blood circulation up to 48 h. Increasing the load led to higher blood concentrations but shorter sustained release. The fact that the microspheres were for cattle limited the volume of the injection and thus the amount of microspheres to be administered. The other limiting factors were related to microsphere morphology.

Simplified treatment of acute staphylococcal osteomyelitis of childhood. The Finnish Study Group

OBJECTIVE

Recommendations on treatment of acute staphylococcal osteomyelitis of children, based mostly on retrospective analyses, comprise surgical drainage, up to 6 weeks fo antimicrobials guided by the erythrocyte sedimentation rate, and the possibility of switching to the oral route only if monitoring of serum bactericidal titer is guaranteed. A prospective study was conducted to test whether the treatment could be simplified.

DESIGN

Fifty pediatric cases of acute Staphylococcus aureus osteomyelitis were randomized to receive 150 mg/kg/day of cephradine divided in four doses, or 40 mg/kg/day in four doses of clindamycin. The treatment was initiated intravenously, but switched to oral administration mostly within 4 days, using the same doses. The peak antimicrobial serum inhibitory titer or bactericidal titer was not measured. The course of illness was monitored by blood leukocytes, erythrocyte sedimentation rate, and serum C-reactive protein. The follow-up was extended to 1 year posthospitalization.

SETTING

Eight tertiary pediatric-orthopedic hospitals in Finland.

MAIN OUTCOME MEASURE

Full recovery and remaining healthy at least 12 months from hospital discharge.

RESULTS

The lower and upper extremities were affected in 72% and 8% of patients, respectively. No surgery at all or needle aspiration only was performed in 62% and drilling in 38%. C-reactive protein and the sedimentation rate normalized within 9 days and 29 days, respectively. X-ray changes developed in 68% but had no prognostic significance. The mean hospitalization time was 11 days, and the total duration of antimicrobials was 23 days. No failure has occurred nor have long-term sequelae been observed in any patient.

CONCLUSIONS

Treatment of pediatric acute staphylococcal osteomyelitis can be simplified and costs reduced by keeping surgery at a minimum, shortening hospitalization and the course of antimicrobials, switching quickly to the oral route, and not monitoring serum bactericidal activity.

In vitro and in vivo studies on microcapsules and tabletted microcapsules of cephradine

Cephradine was microencapsulated by coacervation. Ethyl cellulose was used as the polymer and a core/wall ratio of 1:1 was selected. The repose angle, apparent and tapped density, particle size distribution of cephradine microcapsules (CM) and of cephradine powder were examined. Then flat-surfaced tablets of CM were prepared using Avicel PH 101 and magnesium stearate. In vitro and in vivo properties of CM and tabletted CM (both equivalent to 150 mg cephradine) were compared with commercial capsules (equivalent to 250 mg cephradine). The dissolution studies were carried out by the rotating basket method and the agar diffusion method was applied for quantitative determinations. Among the investigated kinetic models for the release of cephradine from CM and tabletted CM the best fit was found with the Higuchi model. In vivo studies were made in rabbits. Bioavailabilities of CM and their tabletted form were higher than that of the commercial capsules. In vitro/in vivo correlations between mean residence time (MRT) and mean dissolution time (MDT) for CM and tabletted CM were calculated. A good correlation was found between the in vitro and in vivo results.

Acute thyroiditis caused by Moraxella nonliquefaciens

A 43-year-old woman presented with thyroiditis caused by Moraxella nonliquefaciens. Antibiotic therapy resulted in complete recovery. The literature on M. nonliquefaciens and acute bacterial thyroiditis is reviewed. This is the first documented case of a thyroiditis caused by M. nonliquefaciens.

[Cephradine delivery into the eye with domestic collagen shield]

The author reports that enhancement by the native made collagen-shield on the permeation of cephradine into the eye is 1.5 times and 1.3 times versus controls when the corneal epithelium is intact or defect, and is 10 times versus frequent eyedrops instillation. On the other hand, the enhancement of the collagen-shield is about the same as that of the soft contact lens impregnated with cephradine solution, but the drug concentration in aqueous humor is increased by collagen-shield 1-2 times than that by the wet soft contact lens. These results indicate that the collagen-shield can effectively increase the drug concentration in aqueous humor.

Disposition kinetics of cephradine in normal and Escherichia coli infected goats

The pharmacokinetics of cephradine was studied following single and repeated intramuscular injections in normal and Escherichia coli infected goats. Bioavailability of cephradine was determined in normal goats after a single intramuscular dose. The serum concentrations of cephradine following a single and repeated intramuscular administration of 10 mg/kg b.wt. twice daily for five consecutive days, peaked 2 hours after each intramuscular dose with a lower significant value recorded in E. coli infected goats than in normal goats. The absorption half-lives (t0.5(ab)) following a single intramuscular injection of cephradine was significantly higher in E. coli infected goats (1.18 h) than in normal goats (0.64 h). The elimination half-lives (t0.5(beta)) of cephradine were significantly higher in E. coli infected goats than in normal goats following the administration of fifth and ninth doses. The urine and milk concentrations of cephradine were significantly lower in E. coli infected goats than in normal goats. The mean systemic bioavailability of cephradine following a single intramuscular injection in normal goats was 73.9%.

In vivo release of water-soluble drugs from stabilized water-in-oil-in-water (W/O/W) type multiple emulsions following intravenous administrations using rats

The in vivo release of four water-soluble drugs, cefadroxil, cephradine, antipyrine and 4-aminoantipyrine, from a stabilizing water-in-oil-in-water (W/O/W) type multiple emulsion was studied using rats. The W/O/W type multiple emulsion used in this study could be stabilized for 30 d after preparation at room temperature and also for 24 h in pH 7.4 isotonic phosphate buffer or in rat plasma at 37 degrees C. The cefadroxil and cephradine concentrations in rat plasma following intravenous administrations of their W/O/W type multiple emulsions containing drugs were considerably prolonged compared with those of respective aqueous solutions. Sustained-releasing properties of cefadroxil and cephradine from W/O/W type multiple emulsions could be explained by the mechanism underlying the long residence time of W/O/W type multiple emulsions and delay-release of drugs from the W/O/W type multiple emulsions circulated with rat blood stream. However, antipyrine and 4-aminoantipyrine decreased rapidly following W/O/W type multiple emulsions and these plasma profiles coincided precisely with those following intravenous administration of the aqueous solutions of drugs. These in vivo releasing data correlated with in vitro drug release observation stated in the previous papers.

Peptide carrier-mediated transport in intestinal brush border membrane vesicles of rats and rabbits: cephradine uptake and inhibition

The uptake kinetics of cephradine, an amino-beta-lactam antibiotic, were studied in rat and rabbit intestinal brush border membrane vesicles preparations using both the Ca2+ and the Mg2+ methods of preparation, in the presence of an inward proton gradient. The Ca2+ method demonstrated greater uptake of cephradine in intestinal brush border vesicles prepared from both rat and rabbit and was used for these studies. The transport was observed to be of Michaelis-Menten carrier-mediated type with a passive transport component. The kinetic parameters obtained were as follows: for rat and rabbit, respectively, Km, 1.6 and 1.9 mM; Jmax', 1.7 and 20.7 nmol/mg/min; Pc' (= Jmax'/Km), 1.1 and 10.9 microL/mg/min; and Pm', 0.4 and 0.8 microL/mg/min. The kinetic parameters for the rat vesicles are consistent with those from our previous perfusion study using a conversion factor of 0.71 cm2/mg protein. The rabbit vesicles exhibited a similar Michaelis constant and a 10-fold larger maximal transport velocity, suggesting a quantitative advantage for the study of carrier-mediated transport in the rabbit compared to rat vesicles from the intestine. Cephradine uptake was inhibited by phenylpropionylproline, a proline derivative, and enalapril, an ACE inhibitor, which do not have an alpha-amino group, as well as dipeptides, tripeptides, and amino-beta-lactam antibiotics in both rat and rabbit vesicles. These results support the suggestion that they share the same peptide carrier pathway for oral absorption and that the vesicles may be a useful tool in developing orally effective peptide-type drugs.

Copolymers of lysine and polyethylene glycol: a new family of functionalized drug carriers

Poly(PEG-Lys), a new, water-soluble poly(ether urethane), derived from L-lysine and poly(ethylene glycol) was investigated as a precursor for the preparation of polymeric drug conjugates. To facilitate a wide variety of coupling chemistries, the pendent carboxyl groups of poly(PEG-Lys) were converted to other reactive functional groups (amino, hydroxyl, active ester, and aldehyde) in high yield. These reactive pendent chains were then used as anchors for the covalent attachment of penicillin V and cephradine, two clinically used antimicrobial agents. Coupling to the carrier was achieved in good yields and the chemical versatility of this system was demonstrated by the preparation of conjugates having antibiotic ligands linked via biostable or biodegradable linkages to the carrier, either directly or via a spacer. Conjugate 4, poly(PEG-Lys-penicillin V ester), was obtained by linking penicillin V to the polymer backbone via hydrolytically labile ester bonds. This conjugate exhibited activity similar to that of the parent drug against three clinically important strains of bacteria. Drug activity coincided with the release of the drug from the carrier. Hydrolytically stable cephradine-containing conjugates were prepared by three different coupling methods but showed no antibiotic activity. 14C-labeled poly(PEG-Lys) was injected into mice and its biodistribution was monitored for 48 h. The carrier showed no preferential uptake by liver, spleen, or kidney. No signs of acute toxicity were evident in mice or rats when poly(PEG-Lys) was administered iv and ip at doses up to 10 g/kg. These results indicate that poly(PEG-Lys) is a promising precursor for the preparation of soluble drug conjugates.

[Preparation of stable W/O/W type multiple emulsion containing water-soluble drugs and in vitro evaluation of its drug-releasing properties]

The stable water-in-oil-in-water (W/O/W) multiple emulsion was prepared by a two-step procedure for emulsification using glyceryl tricaprylate (Panasate-800) as the oil phase. The water-soluble drugs such as cefadroxil, cephradine, 4-aminoantipyrine, and antipyrine were selected and entrapped separately in the inner aqueous phase of W/O/W multiple emulsion. In consideration of parenteral administration, pH 7.4 phosphate buffered saline was used in both inner and outer aqueous phases. Moreover, these multiple emulsions could be significantly stable for a month at room temperature by the addition of hydrophilic polymer like gelatin and of amino acid like lysine to the inner aqueous phase.

Pharmacokinetics of cefroxadine after infusion to healthy volunteers

The pharmacokinetics of cefroxadine in healthy human volunteers was studied in plasma and urine, after an infusion administration of 1 g of this drug for 0.5 h. Blood and urine samples were microbiologically quantified by diffusion on solid gelose using Bacillus Subtilis ATCC 6633 as the test organism. Plasma and urine profiles were fitted to a reduced two-compartment model not having inactivating biotransformation as a route of elimination. The parameters of distribution for this model show a rapid disposition (t1/2 alpha = 0.28 h) and an average volume of the central compartment of 0.15 +/- 0.04 l/kg (range 0.20-0.09). The dominant terminal half-life (beta-phase) was 1.17 +/- 0.26 h (range 0.90-1.67). The total body volume 0.41 +/- 0.09 l/kg (range 0.30-0.52) indicates that there is no diffusion of the antibiotic into intracellular fluids of poorly perfused tissues due to its high elimination rate.

[Lyell's syndrome--possibly drug-induced epidermal necrolysis in a 7-year-old boy]

In a 7-year-old child Lyell's syndrome was observed with extensive bullous epidermal necrolysis with a very severe clinical course. The disease could have been explained as a toxic-allergic reaction to sefril and aspirin taken for pharyngitis.

Pharmacokinetics of cephradine administered intravenously and orally to young and elderly subjects

The pharmacokinetics of IV and oral cephradine in healthy young male and female volunteers (ages 19 to 25, n = 10) were compared to those of older individuals (ages 65 to 81, n = 9). Subjects received 1 gram of cephradine by a 5-minute intravenous (IV) infusion followed the next day by a 1-gram oral dose. Serial serum and urine samples collected over a period of 12 hours after the dose were analyzed for cephradine concentration by a microbiologic assay. After IV administration, mean serum cephradine concentrations in the elderly group were significantly higher at both 6 hours (1.52 +/- 0.41 mcg/mL) and 8 hours (0.73 +/- 0.22 mcg/mL) than in the young group at 6 hours (0.43 +/- 0.11 mcg/mL). Total systemic clearance was significantly lower (2.64 +/- 0.34 vs. 4.81 +/- 0.59 ml/min/kg) and the elimination half-life was significantly longer (1.71 +/- 0.20 vs 1.12 +/- 0.13 hours) in the elderly group (P = .0001). Systemic cephradine clearance correlated positively with creatinine clearance (r2 = 0.34, P = .0110) and negatively with age (r2 = 0.79, P = .0052). The mean volume of distribution was not significantly different between the two groups. Mean renal clearance was significantly lower in the elderly group (P = .0001), but more than 80% of the dose was excreted in the urine within 6 hours in both groups. After oral administration, the mean peak concentration and time to peak concentration did not differ between groups. The relative oral bioavailability was approximately 94% in both groups. The mean serum concentrations in the elderly were higher at both 6 and 8 hours than in the young group at 6 hours. There were no differences in pharmacokinetic parameters between male and female subjects. Because of reduced cephradine clearance secondary to an age-related decline in renal function, administration of cephradine every 8 hours, rather than every 6 hours, may be sufficient in elderly patients.

Cephradine (Velosef) penetration of mandibular bone

The concentration of cephradine in serum and mandibular bone was assayed in 28 patients undergoing 3rd molar surgery following a single 1 g intravenous injection. Serum and cortical bone samples taken simultaneously, contained mean cephradine concentrations of 42.11 micrograms/ml and 2.61 micrograms/g respectively. These results, when compared with those reported for other bony sites including the femoral head and knee, show a reduced bone penetration with a bone-to-serum ratio of approximately 0.06:1.

In-vitro evaluation of a new oral cephalosporin, cefroxadine (CGP 9000)

The in vitro activity of cefroxadine was studied and found to be at least comparable to that previously reported for cefalexin and cefradine. The activity of cefroxadine was superior to that of amoxicillin against tested isolates. Time-killing studies showed that the addition of 4 X minimum inhibitory concentration (MIC) of cefroxadine to growing cultures reduced viable counts by 4 log units within a 3 h incubation. A diffusion test with a 30 microgram cefroxadine disk produced acceptable interpretive results with tentative zone size breakpoints of less than or equal to 14 mm for resistance and greater than or equal to 17 mm for susceptibility.

Toxic shock syndrome following diagnostic peritoneal lavage

We report the case of a 15-year-old girl who developed high fever, syncope, abdominal pain, nausea and vomiting, myalgia, pharyngitis, and a desquamating rash eight days after a diagnostic peritoneal lavage. The diagnostic peritoneal lavage wound was erythematous and tender. Incision of the site yielded 10 mL of exudate that cultured Staphylococcus aureus. The patient was treated with a first-generation cephalosporin and recovered without sequelae. To our knowledge, this is the first reported case of toxic shock syndrome following diagnostic peritoneal lavage.

Short-term cephradine prophylaxis in elective transurethral prostatectomy

A prospective randomized trial was conducted to assess the value of short-term antibiotic prophylaxis in elective transurethral resection of the prostate. Two hundred patients were randomized to receive 1.5g cephradine intramuscularly preoperatively and 1g cephradine orally before removal of the urethral catheter or to receive no antibiotic prophylaxis. Fifty-eight patients were excluded because of occult neoplasm or protocol violation. There was no difference in time to removal of catheter, incidence of pyrexial episodes, length of hospital stay or minor complication rate between the two groups. We conclude that a short-term antibiotic regime is of no value in the elective patient with sterile urine.

The penetration of antibiotics into the normal intervertebral disc

The role of antibiotics in the treatment of disc-space infection is controversial. This study assessed the tissue penetration of flucloxacillin and cephradine into the normal intervertebral disc after intravenous administration of a bolus dose of antibiotic. Twenty-five discs were removed from 12 adolescent patients having anterior spinal surgery to correct scoliosis; antibiotic had been administered between 30 minutes and four hours before operation. Despite high blood levels, no antibiotic could be detected by bioassay or by high-pressure liquid chromatography (h.p.l.c.) in any of the specimens from the nucleus pulposus or the annulus fibrosus.

One and two doses of cephradine in the prophylaxis of experimental streptococcal endocarditis

The efficacy of cephradine in the prophylaxis of rabbit Streptococcus sanguis endocarditis was investigated. Three days after cardiac catheterization and prior to challenge with S. sanguis, rabbits received either 1000 mg/kg (ten animals) or 500 mg/kg cephradine intramuscularly. Infective endocarditis was prevented in only 30% of the animals. The addition of a second dose of cephradine (100 mg/kg) 8 h after an initial dose of 400 mg/kg did not prevent streptococcal endocarditis in 80% of animals tested. In one or two dose regimens cephradine was found to be inferior to a single 400 mg/kg prophylactic dose of amoxycillin. Cephradine is not recommended for prophylaxis against streptococcal endocarditis.

Clinical pharmacokinetics of five oral cephalosporins in calves

The minimal inhibitory concentrations (MIC) of cephalexin, cephradine, cefaclor, cefatrizine and cefadroxil for Salmonella species, Escherichia coli and Pasteurella multocida isolated previously from young calves were determined. The MIC90 values for cephalexin, cephradine and cefadroxil ranged between 3.12 micrograms ml-1 and 12.5 micrograms ml-1, whereas those of cefatrizine and cefaclor were 3.12 micrograms ml-1 and 0.78 microgram ml-1, respectively. Each drug was administered intravenously and orally to groups of pre-ruminating calves and orally to early ruminating calves. Although the pharmacokinetic characteristics of the drugs after intravenous injection were similar to other beta-lactam antibiotics, significant differences between the cephalosporins examined were found in respect of certain kinetic parameters. The drugs showed rapid absorption into the systemic circulation after oral administration to pre-ruminating calves but the elimination half-life values (t1/2 beta) varied between three hours (cefaclor and cefadroxil) and nine hours (cefatrizine). The bioavailability of the drugs was about 35 per cent of the administered dose. Co-administration of probenecid with each antibiotic caused a twofold or greater increase in peak serum drug concentrations (Cmax) but the effect on t1/2 beta was variable. Cephalexin, cephradine and cefaclor given to the ruminating calves resulted in very low serum or plasma concentrations and their use should be restricted to younger calves. Cefadroxil was found to give the highest serum concentrations in this age group but had significantly lower bioavailability when compared with the unweaned calves. Provisional oral dosage regimens were computed for each cephalosporin on the basis of the MIC data and the kinetic parameters derived from intravenous and oral drug administration.

[A clinical study on cefroxadine in the treatment and recurrence of acute uncomplicated cystitis]

Cefroxadine (CXD) was administered to patients with acute uncomplicated cystitis (AUC) in a dose of 250 mg t.i.d. for 3-7 days. The patients were divided into 2 groups (less than 70 and greater than or equal to 70 years old) and clinical efficacy and incidents of recurrence were assessed. 1. Out of 83 patients treated, clinical efficacy was evaluated in 62 patients including 10 elder patients on the 3rd day and in 47 patients including 9 elder patients on the 7th day. In both groups clinical efficacy rates were 100% on the 3rd and 7th day. 2. Among 24 patients including 7 elder patients, who showed excellent response on the 7th day, recurrence was examined on the 14th day. The recurrence rate was 0% by the criteria proposed by the UTI committee in Japan. However, two patients (under 70 years of age) among them were considered as positive for recurrence by doctors in charge. Consequently, in both aged groups CXD showed excellent results in the treatment of AUC.

Comparison of the pharmacokinetics of cephradine and cefazolin in pregnant and non-pregnant women

The pharmacokinetics of cephradine, a cephalosporin with a low degree of protein binding, was studied in 12 women after oral and intravenous administration of the drug during and after pregnancy. Six of the 12 women also received a cephalosporin with a high degree of protein binding, cefazolin, intravenously during and after pregnancy. For both drugs most pharmacokinetic parameters were altered in pregnancy. The area under the plasma concentration-time curve (AUC) following intravenous administration was smaller for both drugs during as compared to after pregnancy (mean change 39% for cephradine and 31% for cefazolin). Half-lives of both drugs were significantly shorter during compared with after pregnancy (mean change 26% for cephradine and 35% for cefazolin). Consequently, total body clearance was increased during pregnancy. A significant negative correlation between length of gestation and total clearance per kg bodyweight was seen for cephradine. The bioavailability of oral cephradine did not differ significantly during compared with after pregnancy. It is concluded that the dosage of both cefazolin and cephradine should be increased when treating infections in pregnant women in order to obtain the same antibacterial effect as when treating non-pregnant women.

Bone levels of cephradine and cefuroxime after intravenous administration in patients undergoing total hip replacement

A randomised, comparative study is reported of single intravenous doses of cephradine 2 g or cefuroxime 1.5 g given as prophylactic cover for total hip replacements in 40 patients. The serum and bone levels of cephalosporin achieved were higher in the cephradine treated group in proportion to the higher dose employed. Both agents provided adequate bone levels on average, cephradine 25.34 mcg/g, cefuroxime 17.39 mcg/g, although bone penetration was more variable with cefuroxime.

[Influence of cefroxadine dry syrup on intestinal bacterial flora]

Influence of cefroxadine (CXD) dry syrup on intestinal bacterial flora was studied in mice infected with 4 species of bacteria, namely, Escherichia coli, Enterococcus faecalis, Bacteroides fragilis and Bifidobacterium breve, and in pediatric patients having infections in the respiratory tract and cutaneous/soft tissues. The results were summarized as follows: CXD dry syrup was administered for 5 consecutive days to mice infected with the 4 species. No considerable changes were observed in levels of bacteria in the feces and in different parts of digestive tracts. Eleven pediatric patients were orally administered with 30-54 mg/kg of CXD dry syrup a day for 7-15 consecutive days. Symptom of diarrhea was noted in 2 patients. Dominant species of the intestinal flora such as E. coli, Bifidobacterium, and Bacteroides sometimes decreased in patients treated with CXD dry syrup. In general, however, decreases in numbers of these bacteria were insignificant. Changes of intestinal flora in patients treated with CXD dry syrup were apparently smaller than those treated with ampicillin and were similar to those treated with cephalexin or amoxicillin.

Effect of inflammation on antibiotic penetration into the anterior segment of the rat eye

Bacterial infections were established in the right cornea of rats. Animals infected with Staphylococcus aureus were given cephradine intravenously (IV) (40 mg/kg) or topically (50 mg/ml) to both eyes. Animals infected with Pseudomonas aeruginosa were given gentamicin sulfate IV (40 mg/kg) or topically (10 mg/ml). Antibiotic concentrations in cornea and aqueous humor were measured for 4 hrs following dosing using bioassay and radioimmunoassay. In general, infection significantly increased the concentrations obtained soon after dosing. Topically applied cephradine passed through infected eyes more quickly than through normal eyes. Of the pharmacokinetic parameters derived, the permeability of the corneal epithelium to gentamicin in the rat more closely agrees with reported human values than does the rabbit, while the coefficient of elimination from aqueous in the rat is considerably greater than that for either humans or rabbits. This suggests that there are both advantages and disadvantages in using the rat for therapeutic studies of ocular disease.

Are preoperative antibiotics helpful in abdominal hysterectomy?

An open, randomized study to compare the effectiveness of triple-dose cefoxitin with the effectiveness of cephradine-tinidazole and with the result of nontreatment in patients undergoing abdominal hysterectomy was conducted from July 1983 to July 1984. One hundred ninety-nine patients were enrolled: 66 untreated control patients, 69 patients in the cephradine-tinidazole--treated group, and 64 patients in the cefoxitin-treated group. No significant differences were present in relation to age, pathologic condition, length of operation, blood loss, or length of hospital stay. That patients in both treatment groups had a lower incidence of postoperative febrile morbidity was not statistically significant.

The cephalosporin antibiotics in pediatric therapy

The cephalosporins have been available for clinical use for nearly 20 years and a large number is presently marketed, including drugs with a wide range of different pharmacokinetic and microbiologic properties. While some of these agents have certain specific uses in which they excel, the cephalosporins have not replaced older antibiotics but do provide the physician with a broader range of choices for the treatment of many infections, allowing greater individualization of therapy.

CAPD peritonitis: a prospective randomized trial of oral versus intraperitoneal treatment with cephradine

In a prospective randomized clinical trial 84 peritonitis episodes were treated with cephradine, either orally or intraperitoneally. No difference in treatment outcome between both groups could be demonstrated. In episodes caused by susceptible micro-organisms a good response was seen in 82% in the oral and 82% in the intraperitoneal groups. These clinical findings were supported by the demonstration of adequate cephradine concentrations in serum and dialysate after oral as well as after intraperitoneal administration. Altogether cephradine was given orally or intraperitoneally in 88 episodes of peritonitis as drug of first choice. In 52 a complete cure was obtained, in 36 another antibiotic was subsequently needed as soon as bacterial susceptibility was known. No patient deteriorated appreciably during the delay between the start of cephradine and the switch to another antibiotic. Of the 36 episodes 14, caused by methicillin-resistant Staphylococcus epidermidis, responded well initially to cephradine but relapsed later. Change to another antibiotic effected a complete recovery in all 14 cases. Of the remaining 22 episodes, 14 were cured by the other antibiotic, in eight the catheter had to be removed. Aminoglycosides could be avoided except for ten of the episodes. During peritonitis CAPD was continued, in 71% of the cases on an outpatient basis. Mortality due to peritonitis was absent. We conclude that oral cephradine can be used as drug of first choice in the initial treatment of CAPD peritonitis, because a good initial response was obtained in 66 (52 + 14) i.e. 75% of 88 episodes. However, complete cure by cephradine alone was achieved in only 60%.(ABSTRACT TRUNCATED AT 250 WORDS)