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PubMed1991

Quantitative analysis of erythromycin by reversed-phase liquid chromatography using column-switching.

A column-switching technique is described for LC of erythromycin. The method allows, in about 1 h, the separation of erythromycin A from all its known potential impurities, except erythromycin D, which is a minor impurity. The switching technique combines two columns (7.5 cm x 4.6 mm and 25.0 cm x 4.6 mm) both packed with RSil C 18 LL 10 microns. The mobile phase is acetonitrile-tetrabutylammonium sulphate (0.2 M, pH 6.0)-ammonium phosphate buffer (0.2 M, pH 6.0)-water (24:5:5:66, v/v/v/v). Temperature was 35 degrees C, flow rate was 1.5 ml min-1, detection was by UV at 210 nm. Results for a number of commercial samples of various origin are reported.

Acetonitriles↗
PubMed1985

Disc diffusion method to screen for high-level resistance to clindamycin and erythromycin in the Bacteroides fragilis group.

High-level clindamycin resistance in Bacteroides species was investigated by measuring zone sizes surrounding 2 micrograms clindamycin and 60 micrograms erythromycin discs, using a nonstandardized disc diffusion method, and by determining minimal inhibitory concentrations (MIC). The absence of a zone of inhibition surrounding either disc was predictive for all isolates having high-level resistance to both antibiotics (MIC greater than 256 micrograms/ml), characteristic of macrolide-lincosamide-streptogramin (MLS) cross-resistance. Although zone size could not be used as an absolute predictor of MIC, a clindamycin zone diameter of less than 17 mm was suggestive of strains with a moderate level of clindamycin resistance (MIC greater than or equal to 8 micrograms/ml), regardless of erythromycin zone size. Disc diffusion testing using a combination of clindamycin and erythromycin discs can be a useful screening method for detection of clindamycin-resistant Bacteroides species, occurring either alone or as part of the MLS resistance phenotype.

Bacteroides fragilis↗
PubMed1986

Susceptibility of Haemophilus influenzae to amoxicillin/clavulanic acid, erythromycin, cefaclor, and trimethoprim/sulfamethoxazole.

A total of 126 strains of Haemophilus influenzae were examined for susceptibility to amoxicillin/clavulanic acid, trimethoprim/sulfamethoxazole, cefaclor, and erythromycin by an agar dilution procedure. Fifty strains (eight type B, 42 non-type B), all with ampicillin minimal inhibitory concentrations (MIC) of greater than or equal to 6.2 micrograms/ml, produced beta-lactamase. The remaining 76 strains (18 type B, 59 non-type B) were beta-lactamase-negative. All of these strains had ampicillin MICs of less than or equal to 0.8 micrograms/ml. The combination of amoxicillin and clavulanic acid (2:1) was highly active against all strains tested. With the exception of two strains with amoxicillin/clavulanic acid MICs of 1.6/0.8 ug/ml, all strains were inhibited by concentrations of less than or equal to 0.8/0.4 ug/ml. Trimethoprim/sulfamethoxazole was also found to be highly active (MICs uniformly less than or equal to 0.1/1.9 ug/ml). Cefaclor and erythromycin were the least active of the agents tested. Fourteen strains (10.6%) had cefaclor MICs of greater than 32 ug/ml. Forty-seven strains (35.6%) had erythromycin MICs of greater than 8 micrograms/ml. With the exception of amoxicillin/clavulanic acid beta-lactamase production did not seem to influence the activity of any of the antimicrobials tested. Minimum inhibitory concentrations of amoxicillin/clavulanic acid, although still well within achievable serum levels, were approximately one twofold dilution higher with beta-lactamase-producing H. influenzae type B strains than with beta-lactamase-negative strains.

Amoxicillin↗
PubMed1994

Validation of NCCLS macrolide (azithromycin, clarithromycin, and erythromycin) interpretive criteria for Haemophilus influenzae tested with the Haemophilus test medium. National Committee for Clinical Laboratory Standards.

Some recently marketed macrolide antimicrobial agents possess physiochemical, antimicrobial, and pharmacokinetic advantages that enable their wider clinical use against Haemophilus influenzae infections. A five-laboratory study assessed the validity of existing or proposed azithromycin, clarithromycin, and erythromycin interpretive criteria for tests with H. influenzae isolates. National Committee for Clinical Laboratory Standards (NCCLS) methods, criteria, and quality-control guidelines were used. A total of 350 H. influenzae strains were processed, including fresh clinical isolates (250 strains) and replicate tests of 100 stock cultures sampling strains isolated from 1984 to 91. Azithromycin interpretive criteria (susceptible at < or = 4 micrograms/ml, > or = 12 mm) produced a 99.8% absolute agreement between the minimum inhibitory concentrations and disk diffusion results (0.2% false-susceptible error). Clarithromycin breakpoint criteria (susceptible at < or = 8 micrograms/ml, > or = 13 mm; and resistant at > or = 32 micrograms/ml, < or = 10 mm) produced high minor interpretive error, but < or = 1% combined false-susceptible and false-resistant discrepancies. Erythromycin interpretive guidelines were initially proposed for susceptible at < or = 0.5 microgram/ml, > or = 26 mm. This categorizes nearly all H. influenzae strains as resistant to this older macrolide. The NCCLS should consider the proposed erythromycin criteria for publication in appropriate tables, and a class drug should also be selected (azithromycin) that would best predict macrolide-class susceptibility for those agents indicated by the US Food and Drug Administration for H. influenzae infection chemotherapy (azithromycin and clarithromycin). No serious interpretive problems were observed with the current NCCLS criteria using Haemophilus test medium.

Anti-Bacterial Agents↗
PubMed1996

Antimicrobial activity and spectrum of sparfloxacin tested against erythromycin-resistant Streptococcus pneumoniae isolates.

Recognition of a worldwide increase of penicillin-resistant Streptococcus pneumoniae and cross-resistance to other classes of antimicrobials have placed a great urgency on the need for new antimicrobial agents. Sparfloxacin, a novel pyridone carboxylic acid fluoroquinolone derivative was evaluated and compared to six other compounds for antimicrobial activity against erythromycin-resistant pneumococci (50 strains). The Etest susceptibility testing method was used to inoculate Mueller-Hinton agar supplemented with 5% sheep blood. There was extensive cross-resistance between erythromycin, clarithromycin (94%), and azithromycin (100%), but no cross-resistance was detected between macrolides/azalides and sparfloxacin (all strains susceptible at < or = 1.0 mu g/ml). Sparfloxacin (MIC90, 1 mu g/ml) was four-fold more active than ciprofloxacin and ofloxacin (MIC90, 4 mu g/ml). Sparfloxacin appears to possess excellent in vitro activity against erythromycin-resistant S. pneumoniae that were often highly resistant to beta-lactams, and further studies are recommended to investigate its in vivo efficacy against these multi-resistant organisms.

Anti-Bacterial Agents↗
PubMed2004

Synthesis and antimicrobial activity of erythromycin-A oxime analogs.

A series of erythromycin-A oxime ether as well as esters have been synthesized. Ether derivatives were synthesized through the epoxy ether intermediate of erythromycin-9-oxime, followed by opening of the epoxy linkage through various amines, whereas esters have been prepared through DCC mediated protocol. These derivatives have been evaluated for antibacterial activity and found to be as active as erythromycin-A.

Anti-Bacterial Agents↗
PubMed2005

Design, synthesis, and biological evaluation of BODIPY-erythromycin probes for bacterial ribosomes.

BODIPY-erythromycin probes of bacterial ribosomes were designed and synthesized by attaching a BODIPY fluorophore to the 4''- and 9-positions of the erythromycin structure. The probes exhibited excellent binding affinity to bacterial ribosomes and competed with erythromycin and other drugs whose binding sites are in the same vicinity of the 50S subunit. The synthetic fluorescent probe 5 was successfully adapted in our ultra high-throughput screening (uHTS) to identify novel ribosome inhibitors.

Anti-Bacterial Agents↗
PubMed2004

Identification of impurities in erythromycin by liquid chromatography-mass spectrometric detection.

A simple, isocratic liquid chromatographic (LC) method using volatile mobile phase constituents for the identification of related substances in erythromycin samples is described. For method development, evaporative light scattering detection (ELSD) was used. An XTerra RP18 column was used at 70 degrees C with a mobile phase consisting of acetonitrile-isopropanol-0.2M ammonium acetate pH 7.0-water (165:105:50:680). Mass spectral data were acquired on an ion trap mass spectrometer equipped with an electrospray interface operated in the positive ion mode. First, a library was created using MS/MS and MS(n) spectra of reference substances available in the laboratory. Using these reference spectra as interpretative templates, eight novel related substances in erythromycin samples were identified: N-demethylerythromycin E, erythromycin E N-oxide, anhydroerythromycin C, N-demethylerythromycin B, anhydro-N-demethylerythromycin A, pseudoerythromycin E enol ether, EF lacking the neutral sugar and EA lacking the neutral sugar.

Chromatography, Liquid↗
PubMed2006

Viridans group streptococci in blood culture isolates in a Swedish university hospital: antibiotic susceptibility and identification of erythromycin resistance genes.

One hundred and twenty-nine isolates of viridans group streptococci in blood cultures from patients with septicaemia or endocarditis isolated between 1998 and 2003 were tested for antibiotic susceptibility to penicillin, ciprofloxacin, clindamycin, dalbavancin, daptomycin, erythromycin, linezolid, tigecycline, trimethoprim/sulphamethoxazole and vancomycin. Reduced susceptibility to penicillin (minimum inhibitory concentration (MIC) > or =0.25 microg/mL) was found in 18% of the isolates, and 4% of the strains were resistant to penicillin (MIC> or =4.0 microg/mL). Nineteen percent of the isolates had reduced susceptibility to erythromycin (MIC> or =0.5 microg/mL), among which ermB and mefA were found in 40% and 80%, respectively. Strains sequenced as Streptococcus mitis by rnpB had a high degree of non-susceptibility to erythromycin (32%) and penicillin (21%). The level of penicillin resistance in this Swedish study was lower compared with studies from other countries where the antibiotic pressure might be higher than in Sweden. Susceptibility to newer antibiotics was high; all strains were susceptible to dalbavancin, daptomycin, linezolid and vancomycin.

Blood↗
PubMedDate not supplied

A motilin agonist, erythromycin, decreases circulating growth hormone levels in normal subjects but not in diabetic subjects.

Erythromycin (EM) is a common antibiotic known to be a specific agonist of motilin receptors. We have previously reported that administration of EM improves glycemic control in type 2 diabetes patients. In the present study, we tested the effect of EM on growth hormone (GH) secretion in normal and type 2 diabetic subjects. Erythromycin (300 mg) was administered orally in fasted type 2 diabetic (n=12) and normal (n=10) subjects. Blood samples were obtained before and 2 h after the administration. Blood glucose, plasma insulin, somatostatin (SS), and GH levels were determined. The same fasted groups received intravenous erythromycin infusion (10 mg/kg per hour) for 60 min. Blood samples were collected just prior to the infusion and at 15, 30, 45 and 60 min, and plasma GH and somatostatin levels during the infusion were determined. Oral EM administration increased insulin levels and decreased blood glucose levels. GH levels were significantly decreased, while SS levels did not change in normal subjects. In diabetic subjects, there was an increase in insulin levels, but no change in blood glucose, SS, and GH levels. Intravenous EM infusion resulted in a marked decrease in GH levels, while no change in SS levels occurred in normal subjects. There were no changes in SS and GH levels in diabetic subjects during the infusion. When diabetic subjects were divided into two groups with and without autonomic neuropathy, no changes in GH levels were seen in either group. We conclude that EM decreases GH levels in normal subjects while not changing SS levels. This effect was not observed in type 2 diabetic subjects.

Blood Glucose↗
PubMed2006

Construction of universal quantitative models for determination of roxithromycin and erythromycin ethylsuccinate in tablets from different manufacturers using near infrared reflectance spectroscopy.

Universal quantitative models using NIR reflectance spectroscopy were developed for the analysis of API contents (active pharmaceutical ingredient) in roxithromycin and erythromycin ethylsuccinate tablets from different manufacturers in China. The two quantitative models were built from 78 batches of roxithromycin samples from 18 different manufacturers with the API content range from 19.5% to 73.9%, and 66 batches erythromycin ethylsuccinate tablets from 36 manufacturers with the API content range from 28.1% to 70.9%. Three different spectrometers were used for model construction in order to have robust and universal models. The root mean square errors of cross validation (RMSECV) and the root mean square errors of prediction (RMSEP) of the model for roxithromycin tablets were 1.84% and 1.45%, respectively. The values of RMSECV and RMSEP of the model for erythromycin ethylsuccinate tablets were 2.31% and 2.16%, respectively. Based on the ICH guidelines and characteristics of NIR spectroscopy, the quantitative models were then evaluated in terms of specificity, linearity, accuracy, precision, robustness and model transferability. Our study has shown that it is feasible to build a universal quantitative model for quick analysis of pharmaceutical products from different manufacturers. Therefore, the NIR method could be used as an effective method for quick, non-destructive inspection of medicines in the distribution channels or open market.

Anti-Bacterial Agents↗
PubMed2004

Azithromycin and erythromycin ameliorate the extent of colonic damage induced by acetic acid in rats.

Ulcerative colitis is a common inflammatory bowel disease (IBD) of unknown etiology. Recent studies have revealed the role of some microorganisms in the initiation and perpetuation of IBD. The role of antibiotics in the possible modulation of colon inflammation is still uncertain. In this study, we evaluated the effects of two macrolides, namely azithromycin and erythromycin, at different doses on the extent and severity of ulcerative colitis caused by intracolonic administration of 3% acetic acid in rats. The lesions and the inflammatory response were assessed by histology and measurement of myeloperoxidase (MPO) activity, nitric oxide synthetase (NOS) and tumor necrosis factor alpha (TNFalpha) in colonic tissues. Inflammation following acetic acid instillation was characterized by oedema, diffuse inflammatory cell infiltration and necrosis. Increase in MPO, NOS and TNFalpha was detected in the colonic tissues. Administration of either azithromycin or erythromycin at different dosage (10, 20 and 40 mg/kg orally, daily for 5 consecutive days) significantly (P < 0.05) reduced the colonic damage, MPO and NOS activities as well as TNFalpha level. This reduction was highly significant with azithromycin when given at a dose of 40 mg/kg. It is concluded that azithromycin and erythromycin may have a beneficial therapeutic role in ulcerative colitis.

Acetic Acid↗
PubMed2005

Antibiotics in the human food chain: establishing no effect levels of tetracycline, neomycin, and erythromycin using a chemostat model of the human colonic microflora.

A chemostat model of the healthy human large bowel ecosystem was used to establish no effect levels for tetracycline, neomycin, and erythromycin. For each compound, the equivalent to four oral doses (0, 1.5, 15, and 150 mg/60 kg person/d) was studied. Concentrations of the test compounds in the chemostat medium were intended to simulate fecal levels that might be expected following consumption of food containing antibiotic residue and were based on published oral doses and fecal levels. We monitored the following parameters: short chain fatty acids, bile acids, sulfate reduction, azoreductase and nitroreductase activities, beta-glucosidase and beta-glucuronidase activities, a range of bacterial counts and, lastly, the susceptibility among sentinel bacteria to each test compound. Neomycin and erythromycin reduced bile acid metabolism. Neomycin elevated propionate levels and caused a marginal diminution in azoreductase activity. Based on our results, the no observed effect level (NOEL) of both tetracycline and erythromycin was 15 mg/60 kg person/d. The NOEL for neomycin was 1.5 mg/60 kg person/d.

Adult↗
PubMed1998

Effects of erythromycin or rifampin on losartan pharmacokinetics in healthy volunteers.

BACKGROUND: Losartan is metabolized by CYP2C9 and CYP3A4 to an active metabolite, E3174, which has greater antihypertensive activity than the parent compound. Coadministered drugs that inhibit or induce metabolic processes may therefore alter the pharmacokinetics and pharmacologic response of losartan and E3174. OBJECTIVE AND METHODS: Ten healthy volunteers were studied to assess the effects of CYP3A4 inhibition and nonspecific P450 enzyme induction on the pharmacokinetics of losartan and E3174. Subjects completed three 1-week phases separated by 6 days: 50 mg losartan every morning, losartan plus 500 mg erythromycin four times a day, and losartan plus 300 mg rifampin (INN, rifampicin) twice a day. On the eighth day of each phase, serial plasma concentrations of losartan and E3174 were obtained over 32 hours and steady-state pharmacokinetics were determined. RESULTS: Rifampin decreased the area under the concentration-time curve from time zero to 24 hours after the dose (AUC[0-24]) of losartan by 35% (349 +/- 246 versus 225 +/- 130; p = 0.0001) and decreased the AUC(0-24) of E3174 by 40% (1336 +/- 445 versus 792 +/- 302; p < 0.005). Losartan oral clearance was increased by 44% (p = 0.0001). The half-life values of both compounds were decreased by 50% (p < 0.005). In contrast, erythromycin did not significantly affect the AUC(0-24) or half-life of either losartan or E3174. CONCLUSIONS: Rifampin is a potent inducer of losartan and E3174 elimination. Given the magnitude of the effect, this interaction is likely to be clinically significant. On the basis of the minimal inhibitory effects observed with erythromycin, CYP3A4 appears to play a minor role in the in vivo metabolism of losartan to E3174. Further studies are needed to define the contribution of other isozymes, particularly CYP2C9, to the pharmacokinetics of losartan and E3174.

Adult↗
PubMed1999

Failure of erythromycin breath test to correlate with midazolam clearance as a probe of cytochrome P4503A.

BACKGROUND: Cytochrome P4503A (CYP3A) activity exhibits considerable interindividual variability, and an in vivo probe to measure such differences would serve several purposes. The erythromycin breath test (ERBT) is an established approach that has proven useful in this regard, but it has several limitations. More recently, the hydroxylation of midazolam has been suggested as an alternative in vivo probe approach, because it is possible to estimate CYP3A activity in the intestinal epithelium as well as in the liver. The purpose of this study was to investigate the relationship, if any, between the ERBT and midazolam's CYP3A-mediated metabolism. METHODS: Twenty healthy, medication-free young (24 to 46 years) European Americans (10 women) each received on separate days, in random order, either 3 microCi [14C-N-methyl]-erythromycin intravenously, 1 mg midazolam intravenously, or 2 mg midazolam orally. An ERBT value was determined 60 minutes after administration, and clearances were estimated after midazolam administration. In addition, an endogenous 0- to 4-hour urinary 6beta-hydroxycortisol/cortisol ratio was measured. RESULTS: All three measured drug trait values varied approximately threefold to fivefold, whereas the endogenous phenotype measure exhibited far greater variability (>100-fold). No statistically significant (P < .05) correlations existed between any of the trait values, including the ERBT value, obtained after intravenous administration of the radiolabeled probe and the systemic clearance of midazolam, expressed in terms of either total or unbound drug, or on an absolute or a body weight-corrected basis (r = 0.03 to r = 0.24; P = .08 to P = .90). Substratification according to sex generally did not improve such relationships. CONCLUSION: Although both erythromycin N-demethylation and the metabolism of midazolam by hydroxylation are mediated by CYP3A, the phenotypic trait measures associated with these two in vivo probe drugs do not provide the same information about the catalytic activity of the enzyme. An indirect measure such as the ERBT may reflect CYP3A activity and be useful for some purposes, but the estimation of the oral and intravenous clearance of midazolam has additional advantages, and they may be more applicable and have broader usefulness as quantitative estimates of CYP3A activity.

Adult↗
PubMed2003

Electrophysiological effects of erythromycin, but lack of mechanical effects, in airway smooth muscle.

The antibiotic erythromycin has been shown to modulate a variety of electrophysiological and mechanical responses in many cell types. We investigated whether it did so in airway smooth muscle using standard patch clamp, fura-2 fluorimetric and organ bath techniques. Erythromycin (10(-4) M) evoked a small transient inward current with reversal potential and time-course similar to that of the Ca2+-dependent Cl- currents seen in these cells. Unlike its effects in other cell types, however, it did not alter basal [Ca2+]i, voltage-dependent Ca2+ currents, nor mechanical tone at rest, nor the corresponding responses to cholinergic stimulation (membrane currents; release of internally sequestered Ca2+, nor contractions evoked by neural stimulation or exogenously added cholinergic agonist). In conclusion, erythromycin does exert interesting electrophysiological actions in airway smooth muscle, but does not alter mechanical activity as it has been shown to do elsewhere.

Animals↗
PubMed1996

Depression of the N-demethylation of erythromycin, azithromycin, clarithromycin and clindamycin in murine Toxoplasma infection.

The N-demethylation of macrolides was studied in a murine model of infection. Mice were infected with a cystogenic strain of Toxoplasma gondii (20 or 40 cysts/mouse) and microsomes were prepared from liver homogenates and jejunum villus tip enterocytes on day 10 post-infection. The rate of N-demethylation of the anti-Toxoplasma macrolides azithromycin, clarithromycin and clindamycin was investigated and compared to that of the macrolide erythromycin, a marker of activity of the cytochrome P-450 3A (CYP3A) mono-oxygenases. In infected mice (20 cysts/mouse), the rate of N-demethylation fell in the liver and jejunum for erythromycin (-25% and -35%, respectively), azithromycin (-12% and -10%, respectively), clarithromycin (-23% and -21%, respectively) and clindamycin (-20% and -28%, respectively). The degree of hepatic depression was more marked in mice receiving a 40-cysts burden: for erythromycin (-54%), azithromycin (-29%), clarithromycin (-49%) and clindamycin (-47%).

Animals↗