Choosing the right macrolide antibiotic. A guide to selection

Breaking boundaries: the advancements in transdermal delivery of antibiotics

Transdermal drug delivery systems (TDDS) for antibiotics have seen significant advances in recent years that aimed to improve the efficacy and safety of these drugs. TDDS offer many advantages over other conventional delivery systems such as non-invasiveness, controlled-release pattern, avoidance of first-pass metabolism. The objective of this review is to provide an overview on the recent advances in the TDDS of different groups of antibiotics including β-lactams, tetracyclines, macrolides, and lincosamides, utilized for their effective delivery through the skin and to explore the challenges associated with this field. The majority of antibiotics do not have favorable properties for passive transdermal delivery. Thus, novel strategies have been employed to improve the delivery of antibiotics through the skin, such as the use of nanotechnology (nanoparticles, solid-lipid nanoparticles, nanoemulsions, vesicular carriers, and liposomes) or the physical enhancement techniques like microneedles and ultrasound. In conclusion, the transdermal delivery systems could be a promising method for delivering antibiotics that have the potential to improve patient outcomes and enhance the efficacy of drugs. Further research and development are still needed to explore the potential of delivering more antibiotic drugs by using various transdermal drug delivery approaches.

Erythromycin infusion prior to emergency endoscopy for acute upper gastrointestinal bleeding: a systematic review

AIM: To determine the efficacy and safety of erythromycin infusion prior to emergency endoscopy for acute upper gastrointestinal bleeding.

METHODS: A computer-based search of the Cochrane library, Medline, PubMed and China Journal Full-text database and a manual search of Gastroenterology Week and the American Gastroenterological Association Conference Proceedings to identify relevant controlled trials, regardless of language. The references were manually retrieved according to reference index. The randomized controlled trials that evaluated the use of erythromycin in endoscopy for acute upper gastrointestinal bleeding were included in our study. A meta-analysis was conducted using the method for Cochrane systematic review.

RESULTS: Three trials involving 245 patients were included in the systematic review. The meta-analysis showed that erythromycin was superior to placebo in gastric emptying and second-look endoscopy (OR = 5.10 and 0.48; 95%CI: 1.96-13.27 and 0.27-0.88; P = 0.0008 and 0.02, respectively), but no more effective than placebo in mean duration of endoscopy, mean blood transfusion volume and mean hospital stay (P = 0.84, 0.07 and 0.36, respectively). No complications were observed in all patients.

CONCLUSION: Erythromycin infusion is effective and safe in improving endoscopic view in patients with acute upper gastrointestinal bleeding.

Polymerase chain reaction--restriction fragment length polymorphism analysis of clarithromycin-resistant Helicobacter pylori infection in children using stool sample

BACKGROUND

To analyze clarithromycin-resistant Helicobacter pylori infection in children, we developed a method of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis using stool samples.

MATERIALS AND METHODS

Twenty-three children without significant upper abdominal symptoms were included (mean age 7.0 years). Of these, 18 and five were diagnosed as H. pylori-positive and -negative, respectively, by the H. pylori stool antigen test (HpSA). The DNA from the stool samples was purified using the QIAamp DNA Stool Minikit (QIAGEN). The PCR was performed on the purified DNA using oligonucleotide primers designed to amplify the 23S rRNA gene of H. pylori. The PCR products were reacted with restriction enzymes MboII, BceAI, and BsaI to detect mutations A2142G, A2142C, and A2143G, respectively.

RESULTS

Sixteen of the 18 HpSA-positive samples were PCR-positive, and all five HpSA-negative samples were PCR-negative. Thus, the PCR had 89% sensitivity and 100% specificity, with 91% accuracy in reference to HpSA. Of the 16 PCR-positive samples, one and four were digested with MboII and BsaI, respectively, indicating 31% prevalence of CAM-resistance.

CONCLUSIONS

We conclude that the PCR-RFLP using stool samples is a rapid and reliable method to noninvasively detect clarithromycin-resistant H. pylori infection in children. It may be useful before choosing regimens of H. pylori eradication.

[Guidelines for the management of community pneumonia in adult who needs hospitalization]

Community acquired pneumonia is still an important health problem. In Spain the year incidence is 162 cases per 100,000 inhabitants with 53,000 hospital admission costing 115 millions of euros per year. In the last years there have been significant advances in the knowledge of: aetiology, diagnostic tools, treatment alternatives and antibiotic resistance. The Spanish Societies of Intensive and Critical Care (SEMICYUC), Infectious Diseases and Clinical Microbiology (SEIMC) and Pulmonology and Thoracic Surgery (SEPAR) have produced these evidence-based Guidelines for the management of community acquired pneumonia in Adults. The main objective is to help physicians to make decisions about this disease. The different points that have been developed are: aetiology, diagnosis, treatment and prevention.

Pharmacokinetics and lung tissue concentrations of tulathromycin in swine

The absolute bioavailability and lung tissue distribution of the triamilide antimicrobial, tulathromycin, were investigated in swine. Fifty-six pigs received 2.5 mg/kg of tulathromycin 10% formulation by either intramuscular (i.m.) or intravenous (i.v.) route in two studies: study A (10 pigs, i.m. and 10 pigs, i.v.) and study B (36 pigs, i.m.). After i.m. administration the mean maximum plasma concentration (C(max)) was 616 ng/mL, which was reached by 0.25 h postinjection (t(max)). The mean apparent elimination half-life (t(1/2)) in plasma was 75.6 h. After i.v. injection plasma clearance (Cl) was 181 mL/kg.h, the volume of distribution at steady-state (V(ss)) was 13.2 L/kg and the elimination t(1/2) was 67.5 h. The systemic bioavailability following i.m. administration was >87% and the ratio of lung drug concentration for i.m. vs. i.v. injection was > or =0.96. Following i.m. administration, a mean tulathromycin concentration of 2840 ng/g was detected in lung tissue at 12 h postdosing. The mean lung C(max) of 3470 ng/g was reached by 24 h postdose (t(max)). Mean lung drug concentrations after 6 and 10 days were 1700 and 1240 ng/g, respectively. The AUC(inf) was 61.4 times greater for the lung than for plasma. The apparent elimination t(1/2) for tulathromycin in the lung was 142 h (6 days). Following i.m. administration to pigs at 2.5 mg/kg body weight, tulathromycin was rapidly absorbed and highly bioavailable. The high distribution to lung and slow elimination following a single dose of tulathromycin, are desirable pharmacokinetic attributes for an antimicrobial drug indicated for the treatment of respiratory disease in swine.

Nursing home-acquired pneumonia: an emergency department treatment algorithm

Nursing home-acquired pneumonia (NHAP) is a leading cause of morbidity, hospitalization, and mortality among older nursing home residents. Too often, these patients are erroneously grouped with cases of community-acquired and hospital-acquired pneumonia. Yet, they differ in terms of most common pathogens, significant underlying disease, impaired functional and cognitive status, and poor nutrition. The NHAP emergency department treatment algorithm presented here shows that an important decision for initial care in the emergency department (ED) is whether the patient should return to the nursing home. This decision often is based on the facility's ability to administer parenteral antibiotics, and care for co-morbidities and complications. Cephalosporins are the foundation of initial treatment of NHAP in the ED, and are combined with other antibiotics in anticipation of the most likely pathogens and treatment variables discussed here. It is hoped the NHAP treatment algorithm will contribute to improved outcomes.

Tissue reparative effects of macrolide antibiotics in chronic inflammatory sinopulmonary diseases

It is well established that macrolide antibiotics are efficacious in treating sinopulmonary infections in humans. However, a growing body of experimental and clinical evidence indicates that they also express distinct salutary effects that promote and sustain the reparative process in the chronically inflamed upper and lower respiratory tract. Unlike the anti-infective properties, these distinct effects are manifested at lower doses, usually after a relatively prolonged period (weeks) of treatment, and in the absence of an identifiable, viable pathogen. Long-term, low-dose administration of macrolide antibiotics has been used most commonly for sinusitis, diffuse panbronchiolitis, asthma, bronchiectasis, and cystic fibrosis. It is associated with down-regulation of nonspecific host inflammatory response to injury and promotion of tissue repair. Although large-scale trials are lacking, the prolonged use of these drugs has not been associated with emergence of clinically significant bacterial resistance or immunosuppression. Long-term, low-dose administration of 14- and 15-membered ring macrolide antibiotics may represent an important adjunct in the treatment of chronic inflammatory sinopulmonary diseases in humans.

The evolution and role of macrolides in infectious diseases

Two of the most significant changes in the field of infectious disease management during the last few decades are the emergence of atypical and/or new pathogens that may have devastating consequences and the re-emergence of well-recognised organisms that have acquired antimicrobial resistance through a variety of mechanisms. Erythromycin, the prototype macrolide, was originally marketed approximately five decades ago as a useful alternative agent in the treatment of patients allergic to beta-lactam antibiotics. While clinically useful, its pharmacokinetic and adverse-event profile limited the use of erythromycin to these individuals. Enhancements of the macrolide structure circumvented many of the limitations of erythromycin and resulted in the development of azithromycin and clarithromycin. The clinical uses of clarithromycin and azithromycin are substantially wider than erythromycin due to the wide spectra of activity against the atypical and newer pathogens. In addition, these agents are well-tolerated and have a pharmacokinetic profile that allows once- or twice-daily administration. Studies also indicate that the more common of the two mechanisms of macrolide resistance in the US and Canada imparts only low-level resistance. The multitude of studies substantiating clinical as well as bacteriological success with these two agents indicates that, when used appropriately, they will stand the test of time and continue to be useful antimicrobial agents.

Erythromycin intravenous bolus infusion in acute upper gastrointestinal bleeding: a randomized, controlled, double-blind trial

BACKGROUND & AIMS

Emergency endoscopy may be difficult in upper gastrointestinal bleeding when blood obscures the visibility. Erythromycin, a motilin agonist, induces gastric emptying. We investigated whether an intravenous bolus infusion of erythromycin would improve the yield of endoscopy in these patients.

METHODS

Patients admitted within 12 hours after hematemesis were randomly assigned to erythromycin (250 mg) or placebo, 20 minutes before endoscopy. The primary end point was endoscopic yield, as assessed by objective and subjective scoring systems and endoscopic duration. Secondary end points were the need for a second look, endoscopy-related complications, blood units transfused, and length of hospital stay.

RESULTS

Fifty-one patients received erythromycin and 54 received placebo. A clear stomach was found more often in the erythromycin group (82% vs. 33%; P < 0.001). This difference remained significant in patients with cirrhosis. Erythromycin shortened the endoscopic duration (13.7 vs. 16.4 minutes in the placebo group; P = 0.036) and reduced the need for second-look endoscopy (6 vs. 17 cases; P = 0.018). Length of hospital stay and blood units transfused did not significantly differ between the 2 groups. No complications were noted.

CONCLUSIONS

Erythromycin infusion before endoscopy in patients with recent hematemesis makes endoscopy shorter and easier, thereby reducing the need for a repeat procedure.

Review of macrolides and ketolides: focus on respiratory tract infections

The first macrolide, erythromycin A, demonstrated broad-spectrum antimicrobial activity and was used primarily for respiratory and skin and soft tissue infections. Newer 14-, 15- and 16-membered ring macrolides such as clarithromycin and the azalide, azithromycin, have been developed to address the limitations of erythromycin. The main structural component of the macrolides is a large lactone ring that varies in size from 12 to 16 atoms. A new group of 14-membered macrolides known as the ketolides have recently been developed which have a 3-keto in place of the L-cladinose moiety. Macrolides reversibly bind to the 23S rRNA and thus, inhibit protein synthesis by blocking elongation. The ketolides have also been reported to bind to 23S rRNA and their mechanism of action is similar to that of macrolides. Macrolide resistance mechanisms include target site alteration, alteration in antibiotic transport and modification of the antibiotic. The macrolides and ketolides exhibit good activity against gram-positive aerobes and some gram-negative aerobes. Ketolides have excellent activity versus macrolide-resistant Streptococcus spp. Including mefA and ermB producing Streptococcus pneumoniae. The newer macrolides, such as azithromycin and clarithromycin, and the ketolides exhibit greater activity against Haemophilus influenzae than erythromycin. The bioavailability of macrolides ranges from 25 to 85%, with corresponding serum concentrations ranging from 0.4 to 12 mg/L and area under the concentration-time curves from 3 to 115 mg/L x h. Half-lives range from short for erythromycin to medium for clarithromycin, roxithromycin and ketolides, to very long for dirithromycin and azithromycin. All of these agents display large volumes of distribution with excellent uptake into respiratory tissues and fluids relative to serum. The majority of the agents are hepatically metabolised and excretion in the urine is limited, with the exception of clarithromycin. Clinical trials involving the macrolides are available for various respiratory infections. In general, macrolides are the preferred treatment for community-acquired pneumonia and alternative treatment for other respiratory infections. These agents are frequently used in patients with penicillin allergies. The macrolides are well-tolerated agents. Macrolides are divided into 3 groups for likely occurrence of drug-drug interactions: group 1 (e.g. erythromycin) are frequently involved, group 2 (e.g. clarithromycin, roxithromycin) are less commonly involved, whereas drug interactions have not been described for group 3 (e.g. azithromycin, dirithromycin). Few pharmacoeconomic studies involving macrolides are presently available. The ketolides are being developed in an attempt to address the increasingly prevalent problems of macrolide-resistant and multiresistant organisms.

[Phlebitis due to intravenous administration of macrolide antibiotics. A comparative study of erythromycin versus clarithromycin]

BACKGROUND

To know and to compare the incidence of phlebitis due to intravenous administration of macrolide antibiotics erythromycin and clarithromycin.

PATIENTS AND METHOD

Non-randomized prospective study of consecutive patients who were diagnosed of community pneumonia and treated with intravenous macrolides (19 with erythromycin and 25 with clarithromycin).

RESULTS

The cumulative incidence of phlebitis in patients treated with erythromycin was 78.9% (incidence rate of 0.40 episodes/patient-day) and in those treated with clarithromycin 76% (incidence rate of 0.35 episodes/patient-day).

CONCLUSIONS

The risk of phlebitis is high and similar with intravenous administration of both macrolides.

A time-kill evaluation of clarithromycin and azithromycin against two extracellular pathogens and the development of resistance

OBJECTIVE

To determine the activity of clarithromycin, its metabolite (14-hydroxyclarithromycin), and azithromycin against Haemophilus influenzae and Staphylococcus aureus using time-kill methodology and to evaluate the susceptibility of the organisms following exposure to various concentrations of the azalide macrolides.

DATA SOURCES AND METHODS

Clinical isolates of H. influenzae and S. aureus were obtained from the Clinical Microbiology Laboratory at University Hospital, San Antonio, Texas. Susceptibility testing was performed according to National Committee for Clinical Laboratory Standards guidelines. 14-Hydroxyclarithromycin was added to clarithromycin solutions used for H. influenzae. Time-kill studies were performed using antimicrobial concentrations of 0.25-8x minimum inhibitory concentration (MIC) and an initial inoculum of approximately 10(5) CFU/mL. Samples were plated onto solid agar at 0, 4, 8, 12, and 24 hours. At 0, 12, and 24 hours, samples were then plated onto solid agar incorporated with antibiotic. After incubating plates at 35 degrees C for 24 hours, colony counts were determined.

RESULTS

The MICs of clarithromycin and clarithromycin plus 14-hydroxyclarithromycin for H. influenzae were 4 and 2 microg/mL, respectively. For S. aureus, the MIC of clarithromycin was 0.25 microg/mL, and the MIC of azithromycin for both organisms was 1 microg/mL. H. influenzae developed resistance to both macrolides within 12 hours when exposed to sub-MICs of clarithromycin plus 14-hydroxyclarithromycin. However, when exposed to concentrations less than or equal to the MIC of azithromycin, resistance was not conferred to clarithromycin. S. aureus, on the other hand, became resistant to azithromycin and less susceptible to clarithromycin following exposure to sub-MICs of either macrolide.

CONCLUSIONS

Clarithromycin and azithromycin elicited a concentration-independent bacteriostatic effect against H. influenzae and S. aureus at concentrations at least two times the MIC. In addition, concentrations maintained above the MIC prevented changes in the susceptibility of H. influenzae and S. aureus to both macrolides.

Erythromycin

ERYTHROMYCIN, A MACROLIDE ANTIBIOTIC, HAS BEEN USED widely in pediatrics to treat a number of infections. Initially given as an alternative to penicillin because of that drug’s potential for allergic reactions, erythromycin was first introduced in 1952.1 Erythromycin is currently used in neonatal settings for treatment of infections caused by Chlamydia, Ureaplasma, and Mycoplasma.1,2 Prophylaxis for ophthalmia neonatorum and treatment of otitis media are often managed with erythromycin. Erythromycin is the only drug currently proven effective for both prophylaxis and treatment of Bordetella pertussis (not a common pathogen in neonatal intensive care units, however).

[New macrolides]

INTRODUCTION

Following their use for a few years, the place of new macrolides can be assessed.

CURRENT KNOWLEDGE AND KEY POINTS

"New macrolides", ie, roxithromycin, clarithromycin, azithromycin and dirithromycin, are derivated from erythromycin and defined by different pharmacokinetic parameters: longer half time with better oral administration and shorter duration of treatment, better tissue concentrations with reduction of dosages and better tolerance, high cellular concentration with good activity. However, new macrolides and erythromycin do not show major differences in their antibacterial spectrum against usual pyogenic strains. Clinical use of new macrolides extends to opportunistic infections, such as atypical mycobacterial infections or toxoplasmosis, occurring in the course of HIV infection. New macrolides are also recommended for the treatment of Helicobacter pylori-related gastroduodenal ulcer.

FUTURE PROSPECTS AND PROJECTS

New macrolides have opened new avenues in the development of anti-infectious strategies. Due to their good efficacy against Chlamydia pneumoniae which is suspected of inducing vascular diseases, the upcoming use of ketolids and the development of their non-antibiotic effects, the future of macrolides is favorable.