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.