Roxithromycin. An update of its antimicrobial activity, pharmacokinetic properties and therapeutic use

Aptamer-free upconversion nanoparticle/silk biosensor system for low-cost and highly sensitive detection of antibiotic residues

The detection of antibiotics is crucial for safeguarding the environment, ensuring food safety, and promoting human health. However, developing a rapid, convenient, low-cost, and sensitive method for antibiotic detection presents significant challenges. Herein, an aptamer-free biosensor was successfully constructed using upconversion nanoparticles (UCNPs) coated with silk fibroin (SF), based on Förster resonance energy transfer (FRET) and the charge-transfer effect, for detecting roxithromycin (RXM). A synergistic FRET efficiency was achieved by utilizing alizarin red and RXM complexes as energy acceptors, with UCNP as the energy donor, and immobilizing an ultrathin SF protein corona within 10 nm. The biosensor detects RXM in deionized water with high sensitivity primarily through monolayer adsorption, with a detection range of 1.0 nM-141.6 nM and a detection limit as low as 0.68 nM. The performance of this biosensor was compared with the ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS) method for detecting antibiotics in river water separately and a strong correlation between the two methods was observed. The biosensor exhibited long-term stability in aqueous solutions (up to 60 d) with no attenuation of fluorescence intensity. Furthermore, the biosensor's applicability extended to the highly sensitive detection of other antibiotics, such as azithromycin. This study introduces a low-cost, eco-friendly, and highly sensitive method for antibiotic detection, with broad potential for future applications in environmental, healthcare, and food-related fields.

Analyzing atomic scale structural details and nuclear spin dynamics of four macrolide antibiotics: erythromycin, clarithromycin, azithromycin, and roxithromycin

The current investigation centers on elucidating the intricate molecular architecture and dynamic behavior of four macrolide antibiotics, specifically erythromycin, clarithromycin, azithromycin, and roxithromycin, through the application of sophisticated solid-state nuclear magnetic resonance (SSNMR) methodologies. We have measured the principal components of chemical shift anisotropy (CSA) parameters, and the site-specific spin-lattice relaxation time at carbon nuclei sites. To extract the principal components of CSA parameters, we have employed 13C 2DPASS CP-MAS SSNMR experiments at two different values of magic angle spinning (MAS) frequencies, namely 2 kHz and 600 Hz. Additionally, the spatial correlation between 13C and 1H nuclei has been investigated using 1H-13C frequency switched Lee-Goldburg heteronuclear correlation (FSLGHETCOR) experiment at a MAS frequency of 24 kHz. Our findings demonstrate that the incorporation of diverse functional groups, such as the ketone group and oxime group with the lactone ring, exerts notable influences on the structure and dynamics of the macrolide antibiotic. In particular, we have observed a significant decrease in the spin-lattice relaxation time of carbon nuclei residing on the lactone ring, desosamine, and cladinose in roxithromycin, compared to erythromycin. Overall, our findings provide detailed insight into the relationship between the structure and dynamics of macrolide antibiotics, which is eventually correlated with their biological activity. This knowledge can be utilized to develop new and more effective drugs by providing a rational basis for drug discovery and design.

Progress in approved drugs from natural product resources

Natural products (NPs) have consistently played a pivotal role in pharmaceutical research, exerting profound impacts on the treatment of human diseases. A significant proportion of approved molecular entity drugs are either directly derived from NPs or indirectly through modifications of NPs. This review presents an overview of NP drugs recently approved in China, the United States, and other countries, spanning various disease categories, including cancers, cardiovascular and cerebrovascular diseases, central nervous system disorders, and infectious diseases. The article provides a succinct introduction to the origin, activity, development process, approval details, and mechanism of action of these NP drugs.

Delivering macrolide antibiotics to heal a broken heart - And other inflammatory conditions

Drug carriers to deliver macrolide antibiotics, such as azithromycin, show promise as antibacterial agents. Macrolide drug carriers have largely focused on improving the drug stability and pharmacokinetics, while reducing adverse reactions and improving antibacterial activity. Recently, macrolides have shown promise in treating inflammatory conditions by promoting a reparative effect and limiting detrimental pro-inflammatory responses, which shifts the immunologic setpoint from suppression to balance. While macrolide drug carriers have only recently been investigated for their ability to modulate immune responses, the previous strategies that deliver macrolides for antibacterial therapy provide a roadmap for repurposing the macrolide drug carriers for therapeutic interventions targeting inflammatory conditions. This review describes the antibacterial and immunomodulatory activity of macrolides, while assessing the past in vivo evaluation of drug carriers used to deliver macrolides with the intention of presenting a case for increased effort to translate macrolide drug carriers into the clinic.

Pharmacokinetic evaluation of roxithromycin and ciprofloxacin in treating complicated avian mycoplasmosis in broiler chickens

The use of roxithromycin along with ciprofloxacin is having potential to be a promising antimicrobial therapy to treat complicated avian mycoplasmosis in broiler chickens. The present research was undertaken to study the influence of roxithromycin (20 mg/kg body weight) and ciprofloxacin (10 mg/kg body weight) on the oral pharmacokinetics of each other, when both drugs are concomitantly administered in eight healthy male broiler chickens (n=8) and to establish their therapeutic dosage regimens. Their plasma concentrations were assayed by validated ultra high performance liquid chromatography (UHPLC) methods using UV detector. Oral pharmacokinetic parameters were calculated from plasma concentration versus time data based on non-compartmental analysis. Statistically, plasma roxithromycin concentration was significantly higher at one time point only (0.5 h) and plasma ciprofloxacin concentration was significantly lower at the time point of 2 h only when used in combination, in comparison to their respective values obtained after their alone administrations. The pharmacokinetic parameters of roxithromycin and ciprofloxacin showed no significant effect on values of either drug when given in combination and there was a lack of pharmacokinetic interaction between the two antimicrobials. The predicted effective oral dose rate of roxithromycin was 20 mg/kg body weight, every 12 h, and that of ciprofloxacin was 10 mg/kg body weight, every 24 h, to treat complicated avian mycoplasmosis in broiler chickens.

Chemoinformatic Screening for the Selection of Potential Senolytic Compounds from Natural Products

Cellular senescence is a cellular condition that involves significant changes in gene expression and the arrest of cell proliferation. Recently, it has been suggested in experimental models that the elimination of senescent cells with pharmacological methods delays, prevents, and improves multiple adverse outcomes related to age. In this sense, the so-called senoylitic compounds are a class of drugs that selectively eliminates senescent cells (SCs) and that could be used in order to delay such adverse outcomes. Interestingly, the first senolytic drug (navitoclax) was discovered by using chemoinformatic and network analyses. Thus, in the present study, we searched for novel senolytic compounds through the use of chemoinformatic tools (fingerprinting and network pharmacology) over different chemical databases (InflamNat and BIOFACQUIM) coming from natural products (NPs) that have proven to be quite remarkable for drug development. As a result of screening, we obtained three molecules (hinokitiol, preussomerin C, and tanshinone I) that could be considered senolytic compound candidates since they share similarities in structure with senolytic leads (tunicamycin, ginsenoside Rb1, ABT 737, rapamycin, navitoclax, timosaponin A-III, digoxin, roxithromycin, and azithromycin) and targets involved in senescence pathways with potential use in the treatment of age-related diseases.

Interventions for preventing ophthalmia neonatorum

BACKGROUND

Ophthalmia neonatorum is an infection of the eyes in newborns that can lead to blindness, particularly if the infection is caused by Neisseria gonorrhoeae. Antiseptic or antibiotic medication is dispensed into the eyes of newborns, or dispensed systemically, soon after delivery to prevent neonatal conjunctivitis and potential vision impairment.

OBJECTIVES

1. To determine if any type of systemic or topical eye medication is better than placebo or no prophylaxis in preventing ophthalmia neonatorum. 2. To determine if any one systemic or topical eye medication is better than any other medication in preventing ophthalmia neonatorum.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, LILACS, and three trials registers, date of last search 4 October 2019. We also searched references of included studies and contacted pharmaceutical companies.  SELECTION CRITERIA: We included randomised and quasi-randomised controlled trials of any topical, systemic, or combination medical interventions used to prevent ophthalmia neonatorum in newborns compared with placebo, no prophylaxis, or with each other.

DATA COLLECTION AND ANALYSIS

We used standard methods expected by Cochrane. Outcomes were: blindness or any adverse visual outcome at 12 months, conjunctivitis at 1 month (gonococcal (GC), chlamydial (CC), bacterial (BC), any aetiology (ACAE), or unknown aetiology (CUE)), and adverse effects.  MAIN RESULTS: We included 30 trials with a total of 79,198 neonates. Eighteen studies were conducted in high-income settings (the USA, Europe, Israel, Canada), and 12 were conducted in low- and middle-income settings (Africa, Iran, China, Indonesia, Mexico). Fifteen of the 30 studies were quasi-randomised. We judged every study to be at high risk of bias in at least one domain. Ten studies included a comparison arm with no prophylaxis. There were 14 different prophylactic regimens and 12 different medications in the 30 included studies. Any prophylaxis compared to no prophylaxis  Unless otherwise indicated, the following evidence comes from studies assessing one or more of the following interventions: tetracycline 1%, erythromycin 0.5%, povidone-iodine 2.5%, silver nitrate 1%. None of the studies reported data on the primary outcomes: blindness or any adverse visual outcome at any time point. There was only very low-certainty evidence on the risk of GC with prophylaxis (4/5340 newborns) compared to no prophylaxis (5/2889) at one month (risk ratio (RR) 0.79, 95% confidence interval (CI) 0.24 to 2.65, 3 studies). Low-certainty evidence suggested there may be little or no difference in effect on CC (RR 0.96, 95% CI 0.57 to 1.61, 4874 newborns, 2 studies) and BC (RR 0.84, 95% CI 0.37 to 1.93, 3685 newborns, 2 studies). Moderate-certainty evidence suggested a probable reduction in risk of ACAE at one month (RR 0.65, 95% 0.54 to 0.78, 9666 newborns, 8 studies assessing tetracycline 1%, erythromycin 0.5%, povidone-iodine 2.5%, silver nitrate 1%, colostrum, bacitracin-phenacaine ointment). There was only very low-certainty evidence on CUE  (RR 1.75, 95% CI 0.37 to 8.28, 330 newborns, 1 study). Very low-certainty evidence on adverse effects suggested no increased nasolacrimal duct obstruction (RR 0.93, 95% CI 0.68 to 1.28, 404 newborns, 1 study of erythromycin 0.5% and silver nitrate 1%) and no increased keratitis (single study of 40 newborns assessing silver nitrate 1% with no events).    Any prophylaxis compared to another prophylaxis Overall, evidence comparing different interventions did not suggest any consistently superior intervention. However, most of this evidence was of low-certainty and was extremely limited.

AUTHORS' CONCLUSIONS

There are no data on whether prophylaxis for ophthalmia neonatorum prevents serious outcomes such as blindness or any adverse visual outcome. Moderate-certainty evidence suggests that the use of prophylaxis may lead to a reduction in the incidence of ACAE in newborns but the evidence for effect on GC, CC or BC was less certain. Comparison of individual interventions did not suggest any consistently superior intervention, but data were limited. A trial comparing tetracycline, povidone-iodine (single administration), and chloramphenicol for GC and CC could potentially provide the community with an effective, universally applicable prophylaxis against ophthalmia neonatorum.

Correlated quantification using microbiological and electrochemical assays for roxithromycin determination in biological and pharmaceutical samples

Microbiological and electrochemical assays, applying the cylinder-plate and differential pulse voltammetry as techniques, are reported for the quantitative determination of roxithromycin in serum and solid pharmaceutical form. The microbiological assay is based upon the inhibitory effect of this drug on the strain Bacillus subtilis ATCC 9372 used as the test microorganism. Linearity of the calibration curve was observed over the concentration range of 8.37-83.70 μg mL^-1, with relative standard deviation values less than 5.0%. The electrochemical behavior of roxithromycin was studied at a graphite screen-printed electrode modified with graphene by using cyclic voltammetry and differential pulse voltammetry. The current value of the oxidative peak obtained for roxithromycin at 0.65 V vs. Ag/AgCl in 0.03 mol L^-1 phosphate buffer solution (pH 7.0) with a scan rate of 0.1 V^-1 is a linear function of the concentration in a range of 4.19-83.70 μg mL^-1 (5-100 μmol L^-1). A comparative study was carried out and both methods were applied for the determination of roxithromycin in solid dosage forms and spiked serum. The bioassay results of human serum samples were in accordance with the electrochemical ones (R² = 0.988, P < 0.001), and the Bland-Altman method also showed good agreement between the values obtained by both procedures. Moreover, the statistical comparison indicated that there was no significant difference between the proposed techniques regarding both accuracy and precision.

Conducting Polymers, Hydrogels and Their Composites: Preparation, Properties and Bioapplications

This review is focused on current state-of-the-art research on electroactive-based materials and their synthesis, as well as their physicochemical and biological properties. Special attention is paid to pristine intrinsically conducting polymers (ICPs) and their composites with other organic and inorganic components, well-defined micro- and nanostructures, and enhanced surface areas compared with those of conventionally prepared ICPs. Hydrogels, due to their defined porous structures and being filled with aqueous solution, offer the ability to increase the amount of immobilized chemical, biological or biochemical molecules. When other components are incorporated into ICPs, the materials form composites; in this particular case, they form conductive composites. The design and synthesis of conductive composites result in the inheritance of the advantages of each component and offer new features because of the synergistic effects between the components. The resulting structures of ICPs, conducting polymer hydrogels and their composites, as well as the unusual physicochemical properties, biocompatibility and multi-functionality of these materials, facilitate their bioapplications. The synergistic effects between constituents have made these materials particularly attractive as sensing elements for biological agents, and they also enable the immobilization of bioreceptors such as enzymes, antigen-antibodies, and nucleic acids onto their surfaces for the detection of an array of biological agents. Currently, these materials have unlimited applicability in biomedicine. In this review, we have limited discussion to three areas in which it seems that the use of ICPs and materials, including their different forms, are particularly interesting, namely, biosensors, delivery of drugs and tissue engineering.

Population-based meta-analysis of roxithromycin pharmacokinetics: dosing implications of saturable absorption and protein binding

Objectives

The macrolide antibiotic roxithromycin has seen widespread clinical use for several decades; however, no population pharmacokinetic analysis has been published. Early studies indicated saturation of protein binding and absorption at doses within the approved range, which may impact pharmacodynamic target attainment since regimens of 150 mg twice daily and 300 mg once daily are used interchangeably in clinical practice. This study aimed to develop a population-based meta-analysis of roxithromycin pharmacokinetics, and utilize this model to inform optimal dosing regimens.

Methods

Following an extensive search, roxithromycin pharmacokinetic data were collected or digitized from literature publications. Population pharmacokinetic modelling was undertaken with ADAPT. Dosing simulations were performed to investigate differences in exposure and pharmacodynamic target attainment between dosing regimens.

Results

A two-compartment model with saturable absorption described the data ( n  =   63); changes in free drug exposure were simulated using a saturable protein binding model. Simulations indicated that a 300 mg daily regimen achieves a 37% and 53% lower total or free AUC ( f AUC), respectively, compared with 150 mg twice daily. These pharmacokinetic differences translated to significantly lower target attainment ( f AUC/MIC ratio >20) with a 300 mg daily regimen at MICs of 0.5 and 1 mg/L (51% and 7%) compared with patients receiving 150 mg twice daily (82% and 54%).

Conclusions

Roxithromycin displays saturable absorption and protein binding leading to lower exposure and lower target attainment at MICs ≥0.5 mg/L with widely used once-daily dosing regimens, indicating that twice-daily regimens may be preferable for pathogens less susceptible to roxithromycin.

Titrimetric and Spectrophotometric Assay of Ganciclovir in Pharmaceuticals Using Cerium(IV) Sulphate as the Oxidimetric Agent

Titrimetric and spectrophotometric assay of ganciclovir (GNC) is described using cerium(IV) sulphate as the oxidimetric reagent. The methods are based on the oxidation of GNC with a measured excess of cerium(IV) sulphate in acid medium followed by determination of the unreacted oxidant by two different reaction schemes. In titrimetry, the unreacted oxidant was determined by back titration with ferrous ammonium sulphate (FAS) in sulphuric acid medium, and spectrophotometry involves the reaction of residual cerium(IV) with p-DMAB to form brownish-coloured p-dimethylamino quinoneimine whose absorbance was measured at 460 nm. In both methods, the amount of cerium(IV) sulphate reacted corresponds to GNC concentration. Titrimetry is applicable over 3–10 mg range where as, in spcetrophotometry, the calibration graph is linear over the range of 2–10 μg mL−1 and the calculated molar absorptivity value is  L mol−1 cm−1. The validity of the proposed methods was tested by analyzing pure and dosage forms containing GNC. Statistical treatment of the results reflects that the proposed procedures are precise, accurate, and easily applicable for the determination of GNC pure form and in pharmaceutical formulations.

Pathological studies on the protective effect of a macrolide antibiotic, roxithromycin, against sulfur mustard inhalation toxicity in a rat model

Macrolide antibiotics have been shown to protect airway epithelial cells and macrophages from sulfur mustard (SM)-induced cytotoxicity. In the current study, the efficacy of roxithromycin in ameliorating SM-induced respiratory injury was further evaluated in a rat model. Anesthetized rats (N = 8/group) were intratracheally exposed to SM by vapor inhalation. For the drug treatment groups, rats were orally given 10, 20, or 40 mg/kg roxithromycin one hr prior to exposure and every twenty-four hr thereafter. After one, three, or seven days of treatment, sections of the lung were examined and scored for histopathological parameters. Treatment with roxithromycin ameliorated many of the symptoms caused by SM in some animals. In particular, treatment at 40 mg/kg for three days showed significant improvements (p < .05) over the untreated group. When the evaluation was focused on trachea, treatment with roxithromycin for three days showed a trend of dose-dependent protection; moreover, the groups treated with 20 or 40 mg/kg of roxithromycin were statistically different (p < .001 and p < .05, respectively) from the untreated group. These results suggest that roxithromycin protects against some damages associated with SM injury in the lung, particularly in the upper respiratory tract.

Impact of pharmaceutical dosage form on stability and dissolution of roxithromycin

The behavior of dispersible tablets containing enteric-coated pellets and oral suspension, both containing roxithromycin, was investigated using dissolution tests in different media. The dissolution test was performed under different pH conditions. For both dosage forms investigated, the test was conducted at pH 1.2, 4.5, and 6.8. Additionally, for dispersible tablets, the test involving increasing pH was performed at pH 1.2 (acid stage) and afterwards at pH 6.8 (buffer stage). The extent of dissolution was measured using high-performance liquid chromatography (HPLC). In all cases tested, roxithromycin underwent rapid degradation at pH 1.2. Dispersible tablets displayed the features of modified release preparations with a non-complete dissolution during the test times in all media. Conversely, the oral suspension behaved as an immediate release preparation, with degradation at pH 1.2. However, the dissolution of the oral suspension at pH 4.5 and 6.8 was rapid and complete. The role of enteric-coated pellets is to mask the bitter taste of the active substance upon administration. However, the coating showed lack of resistance to media at pH 1.2. Therefore, dispersible tablets containing enteric-coated pellets are not pharmaceutically equivalent to the immediate-release oral suspension.

Extraction and mechanism investigation of trace roxithromycin in real water samples by use of ionic liquid-salt aqueous two-phase system

The ionic liquid, as a green solvent, has several advantages over the organic solvents in traditional liquid-liquid extraction. Aqueous two-phase system (ATPS) consisting of a hydrophilic ionic liquid (1-butyl-3-methylimidazolium tetrafluoraborate, [Bmim]BF(4)) and Na(2)CO(3), which is a novel, simple, non-toxic and effective sample pretreatment technique coupled with molecular fluorescence spectrophotometry, was developed for the simultaneous separation, enrichment and rapid analysis of roxithromycin. The extraction yield of roxithromycin in [Bmim]BF(4)-Na(2)CO(3) aqueous two-phase system is influenced by the types of salts, concentrations of Na(2)CO(3) and [Bmim]BF(4), as well as the extracting temperature. Under the optimum conditions, the average extraction efficiency is up to 90.7%. The mechanism of ionic liquid-salt ATPS formation was discussed by hydration theory, and the extraction mechanism of the [Bmim]BF(4)-salt ATPS was investigated by FT-IR spectroscopy and UV-vis spectroscopy. The results demonstrate that no chemical (bonding) interactions are observed between ionic liquid and roxithromycin, while the nature properties of the roxithromycin are not altered. This method was practical when applied to the analysis of roxithromycin in real water samples with the detection limit of 0.03 microg mL(-1), relative standard deviation (RSD) of 1.9% (n=13), and linear ranges of 1.00-20.00 microg mL(-1). The proposed extraction technique will be promising in the separation of other small biomolecules.

Fetal outcome following roxithromycin exposure in early pregnancy

OBJECTIVE

Because very little information exists on the fetal safety of roxithromycin, we aimed to extend the knowledge on fetal outcome in pregnant women who were exposed to roxithromycin in early pregnancy.

METHODS

Twenty pregnant women inadvertently exposed to roxithromycin during early pregnancy were identified and prospectively followed-up. For comparison, 170 pregnant women matched by age and gravidity, not being exposed to any potential teratogenic agent during pregnancy, were recruited as controls. All gestations were confirmed by ultrasound examination, and participants were followed-up until delivery. Newborns were examined by a neonatologist.

RESULTS

Of 20 pregnant women exposed to roxithromycin during early pregnancy, information was obtained from 17 cases. The median dose of roxithromycin to which pregnant women were exposed was 300 mg/day (range 300-450 mg/day) and exposure occurred at a mean of 4.0 (range 2.8-17.6) weeks. Mean gestational age at delivery was 39.2 weeks in the exposed group and 39.4 in the controls (p = 0.6). Birth weight of babies exposed in utero to roxithromycin was not different to controls. We did not observe any major malformation in the exposed group whereas three (1.8%) occurred in the control group.

CONCLUSIONS

. Despite the limitations of the study due to the small sample size, roxithromycin appears not to be a major teratogen.

Determination of roxithromycin in human plasma by HPLC with fluorescence and UV absorbance detection: application to a pharmacokinetic study

A selective HPLC method with fluorescence detection for the determination of roxithromycin (ROX) in human plasma was described. After solid-phase extraction (SPE), ROX and erythromycin (internal standard, I.S.) were derivatized by treatment with 9-fluorenylmethyl chloroformate (FMOC-Cl). Optimal resolution of fluorescence derivatives of ROX and I.S. was obtained during one analytical run using reversed phase, C(18) column. The mobile phase was composed of potassium dihydrogenphosphate solution, pH 7.5 and acetonitrile. Fluorescence of the compounds was measured at the maximum excitation, 255 nm and emission, 313 nm, of ROX derivatives. Validation parameters of the method were also established. After SPE, differences in recoveries of ROX and erythromycin from human plasma were observed. The linear range of the standard curve of ROX in plasma was 0.5-10.0 mg/l. The validated method was successfully applied for pharmacokinetic studies of ROX after administration of a single tablet of ROX.

Pharmacokinetic/pharmacodynamic modelling of roxithromycin for the inhibitory effect of tumour necrosis factor-alpha and interleukin-6 production in dogs

The objective of the present study was to determine and characterize the relationship between the plasma concentration of roxithromycin, and its inhibitory effect on cytokine production, in order to predict its possible clinical relevance. Six healthy beagle dogs received a single intravenous dose of 20-mg roxithromycin per kg body weight. Blood samples were obtained at different time points. The plasma was analysed with respect to roxithromycin, tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). The concentration-effect relationship was explored by modelling the data using two compartmental model and an indirect response model with an E(max) concentration-effect relationship. The estimated pharmacokinetic parameters (geometric mean) were as follows: V(c) = 2.59 l; k(10) = 0.08/h; k(12) = 0.26/h; k(21) = 0.40/h. The pharmacodynamic parameters (geometric mean) for the inhibitory effect on cytokine production induced by heat-killed Staphylococcus aureus (HKSA) were for TNF-alpha (k(in) = 1.42 microg/h; k(out) = 1.10 microg/h; EC(50) > 5.69 mg/l) and for IL-6 (k(in) = 2.31 microg/h; k(out) = 2.04 microg/h; EC(50) = 21.07 mg/l) production, respectively. The inhibitory effect of roxithromycin on production can be adequately described by the indirect response model with an E(max) concentration-effect relationship.

Trachoma control in Southern Zambia--an international team project employing the SAFE strategy

PURPOSE

To determine the prevalence of trachoma and to measure the impact of the SAFE strategy (World Health Organization GET 2020 strategy) for treating trachoma in the Gwembe District of Southern Zambia.

DESIGN

This is an observational study of the introduction of the SAFE strategy employing a collaborative approach and its impact on trachoma in the area.

PARTICIPANTS

Three thousand eight hundred ninety two persons in communities at 26 well sites in the Gwembe district of Southern Zambia were included in this study.

METHODS

New, clean water wells were drilled under local supervision for each of 26 identified villages. All people living in villages near the wells were screened for trachoma and then treated with antibiotic if required. Education on personal and environmental hygiene was provided by trained volunteers. Patients affected by trichiasis and corneal scarring received surgery, locally if possible. Attempts to control fly populations by cleaning villages, penning livestock, and digging latrines were undertaken. This was performed under advisement and consultation with local villagers and government officials. Data was collected on variables normally associated with trachoma and others relating to demographics, water quality, environment and hygiene.

MAIN OUTCOME MEASURES

Prevalence of trachoma in the area at two years post introduction of SAFE strategy.

RESULTS

The overall prevalence of trachoma in the area was 47% in 2001; however, the prevalence was 55% among children under 10 years. At two years post intervention, the overall prevalence of trachoma reduced to 7.6%, and decreased to 10.6% in children under 10 years, and 5.9% among adults.

CONCLUSIONS

Continued monitoring and risk factors will need to continue to be addressed in order to sustain this trachoma control project in this area of Zambia.

Drug interactions during therapy with three major groups of antimicrobial agents

This review focuses on drug-drug interactions with three major groups of antimicrobial agents: macrolides (including azalides and ketolides), quinolones, which are widely used for the treatment of bacterial infections, and azoles, which are used for antifungal therapy. Macrolides and the ketolide telithromycin are potent inhibitors of CYP3A4 and thus interfere with the pharmacokinetics of many other drugs that are metabolised by this enzyme. In contrast, although closely related, azithromycin is not a cytochrome inhibitor. All quinolones form complexes with di- and trivalent cations and, therefore, the absorption of quinolones can be dramatically reduced when given concomitantly with mineral antacids, zinc or iron preparations. Ciprofloxacin exhibits an inhibitory potential for the cytochrome isoenzyme 1A2, resulting in an inhibition of theophylline metabolism. Other quinolones, such as levofloxacin or moxifloxacin, do not interfere with theophylline metabolism. The systemic azoles, such as ketoconazole, itraconazole, fluconazole and voriconazole, are inhibitors of CYP isoenzymes, such as CYP3A4, CYP2C9 and CYP2C19, to varying degrees. In addition, some are substrates of the MDR-1 gene product, P-glycoprotein. These features are the basis for most of the interactions occurring during azole therapy (e.g., in severely ill patients in the hospital who are treated with multiple drugs).

Stochastic resonance is applied to quantitative analysis for weak chromatographic signal of roxithromycin in beagle dog plasma

Based on the theory of stochastic resonance, the signal to noise ratio (SNR) of HPLC/UV chromatographic signal of roxithromycin is enhanced by cooperation of signal, noise and nonlinear system. A simple new method for the determination of low concentration of roxithromycin in beagle dog plasma is presented. Using signal enhancement by stochastic resonance, this method extends the limit of quantitation from the reported 0.5 to 0.1 microg/ml. During validation of the new method, HPLC/MS was used as a comparison technique. The results indicate that the recovery and low concentrations of roxithromycin in beagle dog plasma were equivalent between the two methods (P>0.05). Stochastic resonance may be a promising tool for improving detection limits in trace analysis.

Impact of pharmaceutical dosage forms on the pharmacokinetics of roxithromycin in healthy human volunteers

OBJECTIVES

The impact of two different pharmaceutical preparations on the pharmacokinetics of roxithromycin was investigated in healthy human volunteers.

METHODS

The degradation kinetics and products of roxithromycin were investigated in simulated gastric fluid and simulated intestinal fluid. Two oral dosage forms of roxithromycin were employed: enteric-coated pellets and dispersible tablets.

RESULTS

The degradation half-time of roxithromycin in simulated gastric fluid was 0.23 h, and three main degradation products were characterized. In contrast, roxithromycin was stable in simulated intestinal fluid and remained unchanged after a 1.00 h incubation. The roxithromycin enteric-coated pellets exhibited higher bioavailability and a more potent serum antibacterial activity than the dispersible tablets.

CONCLUSIONS

The type of oral dosage forms of roxithromycin altered its pharmacokinetics. Whether or not this affects the in vivo antibacterial efficacy requires further study.

pH-dependent geometric isomerization of roxithromycin in simulated gastrointestinal fluids and in rats

The biotransformation of roxithromycin in simulated gastrointestinal fluids at 37 degrees C and in rats was investigated by using liquid chromatography-tandem mass spectrometry. Roxithromycin degraded to its Z-isomer and decladinose derivative in simulated gastrointestinal fluids in vitro at pH </= 3, and followed pseudo first-order degradation with a rate constant (+/-SD, standard derivation) of 0.1066 min(-1) (+/-0.0014) at pH 1.0, 0.0994 min(-1) (+/-0.0031) at pH 1.2, 0.0400 min(-1) (+/-0.0003) at pH 1.3, 0.0136 min(-1) (+/-0.0008) at pH 1.8, and 0.0022 min(-1) (+/-0.0002) at pH 3.0, respectively. The ratio of Z-roxithromycin to roxithromycin (+/-SD) was 0.21 (+/-0.01) at pH 1.0, 0.19 (+/-0.03) at pH 1.2, 0.18 (+/-0.01) at pH 1.3, 0.15 (+/-0.01) at pH 1.8, and 0.08 (+/-0.02) at pH 3.0, respectively. Pepsin and NaCl added to gastric fluid had no effect on the transformation of roxithromycin. Roxithromycin underwent four metabolic routes such as geometric isomerization, demethylation, dealkylation, and hydrolysis of cladinose in rats after oral administration. The geometric isomerization in rats was neither observed after an intravenous dose, nor after an oral dose with Na(2)CO(3) alkalization. The geometric isomerization between roxithromycin and its Z-isomer took place in gastric fluid both in vitro and in vivo. It was interconvertible and pH-dependent. The isomerization of roxithromycin to its Z-isomer was less than that of Z- to E-configuration both in vitro and in vivo.

International guidelines for the treatment of community-acquired pneumonia in adults: the role of macrolides

The significance of community-acquired pneumonia (CAP) has led to the publication of guidelines from numerous international organisations. Because the macrolide class of antimicrobials is active against most of the key pathogens associated with CAP, agents from this class are commonly included in recommendations from these guidelines. However, there are differences among the various guidelines concerning the positioning of the macrolides for empirical therapy. An important factor concerning the use of macrolides for CAP is the emergence of resistance of Streptococcus pneumoniae over the past decade. The rate of S. pneumoniae resistance to macrolides ranges from 4 to 70% of strains in worldwide surveillance studies. The most common mechanisms of resistance include methylation of a ribosomal target encoded by the erm gene and efflux of the macrolides by a cell membrane protein transporter, encoded by the mef gene. S. pneumoniae strains with the mef gene are resistant at a lower level (with minimum inhibitory concentration [MIC] values generally 1-16 microg/ml) than erm resistant strains; and it is possible that such strains may be inhibited if sufficiently high levels of macrolide can be obtained at the infected site. Currently mef-associated resistance predominates in North America, whereas erm predominates in Europe. Until recently, reports of failure of treatment of CAP with macrolides has been rare, particularly for patients with low-risk for drug-resistant strains. However, since 2000, several patients treated with an oral macrolide who have subsequently required admission to the hospital for macrolide-resistant S. pneumoniae (MRSP) bacteraemia have been reported in the literature. Major issues, which are fundamental to the use of the macrolides as recommended in the various guidelines, include the importance of providing therapy for 'atypical' pathogens and the clinical significance of MRSP. Presently, the macrolides are more prominently recommended in the North American guidelines than in other parts of the world. The difference in the emphasis placed on the importance of the atypical pathogens as well as the expression of MRSP in North America compared with Europe partly explains this variance.

Quantitative comparison of the cytocidal effect of seven macrolide antibiotics on human periodontal ligament fibroblasts

The cytocidal effect of seven macrolide antibiotics on human periodontal ligament fibroblasts (Pel cells) was studied. Pel cells were exposed for 48 h to erythromycin (EM), clarithromycin (CAM), roxithromycin (RXM), azithromycin (AZM), josamycin (JM), midecamycin (MDM), and rokitamycin (RKM), and allowed to form colonies. The cytocidal effect of the macrolides was measured as a decrease in colony-forming efficiency and was found to increase with the concentration. To obtain a quantitative measure of the cytocidal effect, the LD50, i.e. the concentration that decreases colony-forming efficiency 50% relative to control cells, was extrapolated from the concentration-response curves. The rank of the macrolides according to their cytocidal effect (LD50) was RKM > RXM > CAM > AZM > JM > MDM approximately EM. RKM, RXM, CAM, AZM, and JM were at least 1.7-12.2 times more cytocidal than MDM or EM. When extrapolated from the concentration-response curves, the relative survival of the Pel cells exposed to each of the macrolides at the MIC90 concentrations for periodontopathic bacteria was estimated to be: > or = 53.8% for RKM, > or = 92.7% for RXM, > or = 94.6% for CAM, > or = 97.1% for AZM, and > or = 86.2% for EM. The effect of the antibiotics on the mRNA expression of alkaline phosphatase (ALP) and type I procollagen (COL) was examined in Pel cells exposed for 48 h to RXM, CAM, AZM, and EM, which exhibited strong, moderate, and weak cytocidal activity. The constitutive levels of both ALP and COL mRNA were retained in cells exposed to RXM at < or = 3 microM, CAM at < or = 10 microM, and AZM or EM at < or = 3 microM. The MIC90 against periodontopathic bacteria is < or = 4.8 microM for RXM, 5.3 microM for CAM, 2.7 microM for AZM, and 21.8 microM for EM. These results suggest that topical administration of CAM or AZM to the gingival crevice at their MIC90 concentration for periodontopathic bacteria would have little adverse effect on the growth and differentiation of the periodontal ligament. It is important to note, however, that these findings have yet to be extrapolated to in vivo conditions.

Determination of roxithromycin residues in the flounder muscle with electrospray liquid chromatography-mass spectrometry

A highly sensitive and specific method for the determination of roxithromycin in the flounder muscle by LC-MS was developed and validated. A dichloromethane extract of the sample was separated on C18 reversed-phase column with acetonitrile-50 mM ammonium acetate (80:20, v/v) as the mobile phase and analyzed by LC-MS via atmospheric pressure ionization/electrospray ionization interface. The limit of detection and limit of quantitation were 0.01 and 0.1 ng/g, respectively. Mean recoveries from spiked muscles were 81.1% (ranged from 71.0 to 90.3%) for roxithromycin. The method has been successfully applied to determine roxithromycin in the flounder muscle.

The transplacental transfer of the macrolide antibiotics erythromycin, roxithromycin and azithromycin

OBJECTIVE

To investigate the transplacental transfer of the macrolide antibiotics erythromycin, roxithromycin and azithromycin.

METHODS

Twenty-one term placentas were obtained with maternal consent immediately after delivery and a two-hour nonrecirculating perfusion of a single placental cotyledon was performed. Erythromycin (2 microg/mL), roxithromycin (2 microg/mL) and azithromycin (0.3 microg/mL) were infused to the maternal inflow at a constant rate, with antipyrine as a reference compound, and their appearance in the fetal circulation was followed. Drug concentrations were measured by high performance liquid chromatography for 120 min.

RESULTS

The mean transplacental transfers (TPT(SS)) for erythromycin, roxithromycin and azithromycin were 3.0%, 4.3% and 2.6%, respectively, calculated as the ratio between the steady state concentrations in fetal venous and maternal arterial sides. Similar results were obtained when the TPT was calculated as the absolute amount of drug transferred across the placenta during 2-hour perfusion (TPT(A)). No significant differences were found among the three macrolides in TPT(SS) (P = 0.39) or TPT(A) (P = 0.35). The TPT(SS) of erythromycin, roxithromycin and azithromycin were 41%, 35% and 32% of the freely diffusable reference compound antipyrine, respectively. Steady state was reached in 60 minutes in each perfusion indicating sufficient perfusion time.

CONCLUSION

The limited transplacental transfer of erythromycin, roxithromycin and azithromycin suggests compromised efficacy in the treatment of fetal infections. On the other hand, the placenta seems to produce an effective barrier reducing the fetal exposure when these three macrolides are used to treat maternal infections.

Pharmacokinetic considerations in the eradication of Helicobacter pylori

As Helicobacter pylori plays an important role in the aetiopathogenesis of peptic ulcer, therapeutic strategies aimed at maintaining long term remission have shifted from the control of intragastric pH to targeting H. pylori. According to recent international guidelines the clinical goals--rapid ulcer healing and prevention of relapse--can be best accomplished by combination therapy consisting of an antisecretory drug (proton pump inhibitor or ranitidine) and 2 antimicrobial agents (preferable amoxicillin, clarithromycin or metronidazole). When applying such multidrug regimens, possible synergy between the agents suggests that pharmacokinetic considerations might help to improve H. pylori eradication rates, which should be above 85 to 90% on an intention-to-treat basis. The present review summarises the pharmacokinetic properties and interaction potential of all drugs presently used in the various H. pylori eradication regimens, with emphasis on particular patient populations such as the elderly and those with renal impairment. The drugs considered are omeprazole, lansoprazole, pantoprazole, rabeprazole, ranitidine and ranitidine bismutrex, bismuth salts, amoxicillin, clarithromycin, azithromycin, roxithromycin, metronidazole, tinidazole and tetracycline. When addressing the clinically important questions of the efficacy, safety and costs of the recommended regimens, the impact of drug disposition on H. pylori eradication should not be neglected.

Determination of roxithromycin in human plasma by high-performance liquid chromatography with spectrophotometric detection

A simple and reproducible method for the determination of roxithromycin in human plasma is presented. This method is based on liquid-liquid extraction with hexane-isoamylalcohol (98:2, v:v) and reversed-phase chromatography with spectrophotometric detection at 220 nm. The mobile phase consists of methanol-15 mM dihydrogen potassium phosphate (70:30, v:v), pH of the aqueous part of the mobile phase is 6.0. The column is operated at 60 degrees C. Clarithromycin is used as the internal standard. The limit of quantitation is 0.5 microg/ml and the calibration curve is linear up to 30 microg/ml. Within-day and between-day precision expressed by relative standard deviation is less than 5% and inaccuracy does not exceed 9%. The assay was used for pharmacokinetic studies.

Lack of association between first myocardial infarction and past use of erythromycin, tetracycline, or doxycycline

To evaluate the association of prior treatment with antibiotics active against Chlamydia pneumoniae with the risk for incident myocardial infarction, we conducted a population-based case-control study. We found that use of erythromycin, tetracycline, or doxycycline during the previous 5 years was not associated with risk for first myocardial infarction. These results suggest little or no association between the use of these antibiotics and the risk for first myocardial infarction in the primary prevention setting.

Eradication of Helicobacter pylori with lansoprazole, roxithromycin and metronidazole--an open pilot study

BACKGROUND

The most extensively studied Helicobacter pylori eradication regimen comprises omeprazole, clarithromycin and metronidazole. Macrolide antibiotics other than clarithromycin should achieve similar efficacy, but they have not yet been thoroughly tested.

AIM

To determine the efficacy and safety of a triple therapy regimen using lansoprazole, roxithromycin, and metronidazole on the basis of multicentre outpatient care in an open pilot study.

METHODS

163 patients with duodenal ulcer and proven H. pylori infection received lansoprazole 30 mg b.d., roxithromycin 300 mg b.d. and metronidazole 500 mg b.d. for 7 days followed by another 7 days of lansoprazole 30 mg once daily. H. pylori status was determined by urease quick test, histology, microbiology and 13C-urea breath test before starting and at least 4 weeks after completing treatment.

RESULTS

150 patients were available for evaluation; H. pylori was successfully eradicated in 84.7% (127/ 150) as determined by urease quick test, 78.0% (117/150) by histology, 81.3% (109/134) by 13C-urea breath test; and in 75.3% (113/150), at least two tests were negative. Side-effects were reported in 34 patients (most commonly diarrhoea and changes in liver function tests), in two cases the study medication was interrupted. Prior to treatment, 23% of the H. pylori isolates were resistant against metronidazole and 3.4% against roxithromycin. After unsuccessful treatment, 84% of the isolates were resistant against metronidazole and 21% against roxithromycin. Primary resistance to metronidazole increased the chance of treatment failure approximately sevenfold (7% vs. 53%).

CONCLUSIONS

For H. pylori eradication, the combination of lansoprazole, roxithromycin and metronidazole proved to be as safe as other current triple therapy regimens, while a comparison of efficacy rates yet remains to be assessed in prospective controlled trials. The metronidazole-resistant H. pylori is not rare in Germany and, in the present study, has strongly influenced treatment success.

Comparative in vitro and in vivo efficacy of roxithromycin and erythromycin against a strain of methicillin-susceptible Staphylococcus epidermidis

The in vitro and in vivo efficacy of roxithromycin was compared with that of erythromycin, against a methicillin-susceptible strain of Staphylococcus epidermidis. We performed standard in vitro testing (MIC, MBC, and time-kill kinetics) for roxithromycin, erythromycin, and rifampin. Both macrolides were bacteriostatic in vitro. There was no significant difference in microbial survival between erythromycin and roxithromycin groups in the time-kill kinetics (p = 0.3). For the in vivo experiments, using the rabbit experimental endocarditis model, roxithromycin was found to be inferior to erythromycin in decreasing the microbial burden of the endocardial vegetations (p < 0.05). Rifampin was highly effective, both in vitro and in vivo. In conclusion, the efficacy of roxithromycin was poor and inferior to erythromycin against a strain of methicillin-susceptible S. epidermidis.

Metabolism of roxithromycin in the isolated perfused rat liver

Roxithromycin is a macrolide antibiotic with high clinical potency. N-Demethylation is considered to be one of the main pathways of roxithromycin metabolism in rats. We have studied the hepatic metabolism of roxithromycin in the isolated perfused rat liver. After addition of roxithromycin (30 microM) to the perfusion medium the parent compound and one major metabolite were detected in bile by high-performance liquid chromatography. The metabolite was identified as monodesmethylated roxithromycin by mass spectrometric analysis. Onset of biliary excretion of native roxithromycin was fast, reaching a maximum (130.52 +/- 43.88 pmol g(-1) min(-1)) after only 10 min, whereas excretion of the metabolite was delayed (maximum 75.83 +/- 11.92 pmol g(-1) min(-1) at 30 min). The cumulative excretion of roxithromycin and its metabolite into bile during the 60 min of application amounted to only 1.09 +/- 0.30 and 0.64 +/- 0.22% of the roxithromycin cleared from the perfusate during the same time. The liver content was 0.48 micromol (g liver)(-1), indicating high retention within the organ. No release of the metabolite into the perfusate was detected. In conclusion, this study has demonstrated the importance of phase-I metabolism for the biliary excretion of roxithromycin in rat liver. These findings might be predictive of roxithromycin biotransformation and biliary excretion in man.

Periodontal tissue disposition of azithromycin

The tissue penetration of azithromycin, the prototype of a new class of macrolide antibiotics named azalides, was studied in patients undergoing surgery for third-molar removal. Drug concentrations in plasma, saliva, and periodontal tissues were evaluated in 28 patients treated with azithromycin 500 mg/day per os for 3 consecutive days. Samples of blood, saliva, gingiva, and alveolar bone were collected during oral surgery, 12 hours, and 2.5, 4.5, and 6.5 days after the last dosing, and the azithromycin concentration was measured microbiologically by using Micrococcus luteus NCTC 8440 as the reference organism. The highest concentrations of azithromycin were observed 12 hours after the last dose in plasma, saliva, gingiva, and bone (0.33 +/- 0.04 mg/l, 2.14 +/- 0.30 mg/l, 6.47 +/- 0.57 mg/kg, and 1.86 +/- 0.15 mg/kg, respectively) and then declined gradually. However, consistent levels of the drug in saliva and periodontal tissues could be detected up to 6.5 days, indicating that azithromycin was retained in target tissues and fluids for a long time after the end of treatment. Among the samples examined, the highest concentration of azithromycin was found in the gingiva at each time studied. Moreover, the ratios of salivary or periodontal tissue levels versus plasma concentrations remained nearly unmodified from 12 hours up to 6.5 days. Overall, these results indicate a favorable disposition of azithromycin into saliva and periodontal tissues and suggest that this macrolide antibiotic represents a valuable option in the pharmacologic treatment of odontogenic infections.

In vitro antimicrobial susceptibility of periodontopathic Actinobacillus actinomycetemcomitans to roxithromycin and erythromycin

The in vitro minimal inhibitory concentrations (MIC) and minimal bactericidal concentration (MBC) of roxithromycin and erythromycin against Actinobacillus actinomycetemcomitans were evaluated. Sixty-seven different A. actinomycetemcomitans isolated from periodontal pockets of 101 subjects with different forms of early-onset and adult periodontitis and three reference strains of A. actinomycetemcomitans (ATCC 29522, ATCC 29523, and NCTC 9710) were included in this study. Erythromycin showed poor in vitro activity against A. actinomycetemcomitans; roxithromycin, on the contrary, exhibited good in vitro activity. Moreover, roxithromycin showed the best in vitro antimicrobial activity against 17 serotype a and 12 serotype c subpopulations of A. actinomycetemcomitans; against 38 serotype b subpopulation of A. actinomycetemcomitans, roxithromycin was consistently active. Roxithromycin exhibited MBC values usually equal to, or one-fold higher than MIC values. All the MBC values of erythromycin were three- to four-fold higher than the respective MIC result. Since roxithromycin is characterized by high concentrations in serum and good penetration and diffusion into gingival tissue, it could be expected to pass into the gingival crevicular fluid at levels sufficiently high to inhibit A. actinomycetemcomitans in vivo. These data indicate that roxithromycin might be a potential candidate for therapeutic trials in patients with A. actinomycetemcomitans-associated periodontitis.

Clarithromycin. A review of its efficacy in the treatment of respiratory tract infections in immunocompetent patients

Clarithromycin is a broad spectrum macrolide antibacterial agent active in vitro and effective in vivo against the major pathogens responsible for respiratory tract infections in immunocompetent patients. It is highly active in vitro against pathogens causing atypical pneumonia (Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella spp.) and has similar activity to other macrolides against Staphylococcus aureus. Streptococcus pyogenes, Moraxella catarrhalis and Streptococcus pneumoniae. Haemophilus influenzae is susceptible or intermediately susceptible to clarithromycin alone, but activity is enhanced when the parent drug and metabolite are combined in vitro. Absorption of clarithromycin is unaffected by food. More than half of an oral dose is systemically available as the parent drug and the active 14-hydroxy metabolite. Pharmacokinetics are nonlinear, with plasma concentrations increasing in more than proportion to the dosage. First-pass metabolism results in the rapid appearance of the active metabolite 14-hydroxy-clarithromycin in plasma. Clarithromycin and its active metabolite are found in greater concentrations in the tissues and fluids of the respiratory tract than in plasma. Dosage adjustments are required for patients with severe renal failure, but not for elderly patients or those with hepatic impairment. Drug interactions related to the cytochrome P450 system may occur with clarithromycin use. In addition to the standard immediate-release formulation for administration twice daily, a modified-release formulation of clarithromycin is now available for use once daily. In dosages of 500 to 1000 mg/day for 5 to 14 days, clarithromycin was as effective in the treatment of community-acquired upper and lower respiratory tract infections in hospital and community settings as beta-lactam agents (with or without a beta-lactamase inhibitor), cephalosporins and most other macrolides. Clarithromycin was similar in efficacy to azithromycin in comparative studies and is as effective as and better tolerated than erythromycin. Adverse events are primarily gastrointestinal in nature, but result in fewer withdrawals from therapy than are seen with erythromycin. Clarithromycin provides similar clinical and bacteriological efficacy to that seen with beta-lactam agents, cephalosporins and other macrolides. It offers a cost-saving alternative to intravenous erythromycin use in US hospitals and is available in both once-daily and twice-daily formulations. The spectrum of activity of clarithromycin against common and emerging respiratory tract pathogens may make it suitable for use in the community as empirical therapy of respiratory tract infections in both children and adults.

Macrolide antibiotics in paediatric infectious diseases

Erythromycin and other macrolides have enjoyed a renaissance in the 1970s, 1980s and 1990s secondary to the discovery of "new' pathogens such as Chlamydia, Legionella, Campylobacter and Mycoplasma spp. Erythromycin is an important therapeutic agent in the paediatric age group for several reasons: (a) it exhibits proven efficacy for a wide range of infections (upper and lower respiratory tract infections, skin/skin structure infections, prophylaxis of endocarditis/acute rheumatic fever/ophthalmia neonatorum and pre-colonic surgery, campylobacteriosis, chlamydial and ureaplasmal infections, diphtheria, whooping cough, streptococcal pharyngitis) and gastrointestinal (GI) dysmotility states; (b) intravenous formulations are widely available; and (c) it is available in a number of formulations as a generic product, which is likely to result in significant cost savings. Nevertheless, erythromycin and similar earlier macrolides are characterised by a number of drawbacks including a narrow spectrum of antimicrobial activity, unfavourable pharmacokinetic properties and poor GI tolerability. Newer macrolides such as clarithromycin and azithromycin are useful in serving the needs of paediatric patients who are erythromycin-intolerant or who have infections caused by organisms that are intrinsically erythromycin-resistant, or for which a high percentage of strains are resistant (e.g. Haemophilus influenzae, Helicobacter pylori, Mycobacterium avium complex). In addition, these newer macrolides may be considered as alternatives to oral amoxicillin-clavulanic acid, second or third generation cephalosporins, or erythromycin plus sulphonamide in this patient population. Selection between specific macrolides and between macrolides and other antibiotics in the paediatric population is likely to depend, at least for the immediate future, on separate comparisons of product availability, cost, effectiveness and tolerability profiles.