Fate of single oral doses of erythromycin acistrate, erythromycin stearate and pelleted erythromycin base analysed by mass-spectrometry in plasma of healthy human volunteers

Efficacy of a new cream formulation of mupirocin: comparison with oral and topical agents in experimental skin infections

A new cream formulation of mupirocin developed to improve patient compliance was compared with systemic and topical antibiotics commonly used to treat primary and secondary skin infections. A mouse surgical wound model infected with Staphylococcus aureus or Streptococcus pyogenes was used. Topical treatment was applied at 4 and 10 h postinfection or oral treatment at a clinically relevant dose was administered 4, 8, and 12 h postinfection; treatments were continued three times daily for a further 3 days. Mupirocin cream was significantly more effective than (P < 0.01; two of eight studies) or not significantly different from (six of eight studies) mupirocin ointment in reducing bacterial numbers. Mupirocin cream was similar in efficacy to oral flucloxacillin but significantly more effective (P < 0.001) than oral erythromycin. It was also similar in efficacy to cephalexin against S. pyogenes but superior against S. aureus (P < 0.01). Mupirocin cream had a similar efficacy to fusidic acid cream against S. aureus but was significantly superior against S. pyogenes (P < 0.01). A hamster impetigo model infected with S. aureus was also used. Topical or oral treatment was administered at 24 and 30 h postinfection (also 36 h postinfection for oral therapy) and then three times daily for a further 2 days. On day 5, mupirocin cream was significantly more effective than mupirocin ointment in one study (P < 0.01) and of similar efficacy in the other two studies. Mupirocin cream was not significantly different from fusidic acid cream or neomycin-bacitracin cream, but it was significantly superior (P < 0.01) to oral erythromycin and cephalexin. Mupirocin cream was as effective as, or superior to, oral and other topical agents commonly used for skin infections.

Bioavailability of erythromycin acistrate from hard gelatin capsules containing sodium bicarbonate

Erythromycin acistrate is a new prodrug of erythromycin. Its bioavailability from hard gelatin capsules containing the drug with or without sodium bicarbonate was studied in healthy volunteers. The plasma levels of erythromycin, anhydroerythromycin, and acetylerythromycin were measured using an HPLC method. Addition of sodium bicarbonate to the capsule markedly enhanced the plasma level of the microbiologically active substance, erythromycin, doubling the Cmax and AUC values (P less than 0.05). At the same time, the lag time in the absorption curve was shortened to one-third. No changes in the plasma levels of the inactive metabolite anhydroerythromycin were noted. It is concluded that adding sodium bicarbonate to an erythromycin acistrate formulation enhances its bioavailability.

Penetration of erythromycin into periapical lesions after repeated doses of erythromycin acistrate and erythromycin stearate: a pilot study

In 26 patients who had undergone apicectomy and extirpation of granulomas (n = 9) or radicular cysts (n = 17), concentrations of erythromycin, 2'-acetyl erythromycin, and their anhydro forms were determined with a novel chemical method in plasma and periapical lesions after at least 2 days of treatment with erythromycin acistrate (EA) (400 mg three times daily, n = 11) or erythromycin stearate (ES) (500 mg three times daily, n = 15). Oral surgery was performed 2 1/2 to 3 hours after the last dose. Blood samples were collected at the time of operation, and immediately before antibiotic treatment, and 1, 2, and 6 hours after treatment. At all time points EA produced at least twice the total antibiotic (2'-acetyl erythromycin plus erythromycin) concentrations in plasma as ES. Erythromycin levels in plasma were at least as high after EA treatment as after ES. In periapical lesions erythromycin concentration after EA was three times higher (1.34 +/- 0.28 micrograms/gm) than after ES treatment (0.40 +/- 0.17 micrograms/gm). Although the total drug concentration in periapical lesions was about the same after EA (2.64 micrograms/ml) and ES (3.41 micrograms/ml), most of the drug recovered after ES was antimicrobially inactive anhydroerythromycin (3.01 micrograms/gm). The concentration of anhydroerythromycin in plasma was approximately the same as that of erythromycin after ES throughout the dose interval. After EA treatment both plasma and the periapical lesion samples contained hardly detectable amounts of anhydroerythromycin. Hence EA has a good bioavailability essential for treatment and prophylaxis of bacterial infections in dentistry.

Effect of erythromycin on the oro-caecal transit time in man

Erythromycins often cause gastrointestinal side-effects due to an increase in motility or to change in the intestinal bacterial flora. In order to evaluate the effect of erythromycin on gastrointestinal motility. 11 healthy volunteers were given placebo, erythromycin stearate (ES) 1000 mg or a therapeutically equivalent single dose of erythromycin acistrate (EA.2'-acetyl erythromycin stearate) 800 mg in a double-blind trial. The oro-caecal transit time was measured using the hydrogen breath test with lactulose as the substrate. The transit time was estimated from the H2-peak (ppm) in end-expiratory breath by two methods, t1 representing the "front" and t2 the "bulk" of lactulose reaching the colon. t1 was 51 min in the placebo group, 38 min in the EA and 31 min in the ES group (p less than 0.05, ES vs placebo). t2 was 74 min, 64 min, and 46 min, respectively (p less than 0.05, ES vs placebo). The difference between EA and ES was also significant. Six subjects in the ES group but none in the EA group recorded adverse gastrointestinal effects attributable to medication. It was concluded that erythromycin shortens the oro-caecal transit time in man and that EA effects the transit time slightly less than ES.

Effect of Lactobacillus GG yoghurt in prevention of antibiotic associated diarrhoea

The efficacy of Lactobacillus GG yoghurt in preventing erythromycin associated diarrhoea was studied. Sixteen healthy volunteers were given erythromycin acistrate 400 mg t.i.d for a week. The volunteers were randomly assigned into two groups taking twice daily 125 ml of either Lactobacillus GG fermented yoghurt or pasteurized regular yoghurt as placebo during the drug treatment. Subjects receiving Lactobacillus GG yoghurt with erythromycin had less diarrhoea than those taking pasteurized yoghurt. Other side effects of erythromycin, such as abdominal distress, stomach pain and flatulence, were less common in the GG yoghurt group than in the placebo yoghurt group. The subjects receiving Lactobacillus GG yoghurt were colonized with these bacteria even during erythromycin treatment as measured by faecal counts of total Lactobacillus GG. No Lactobacillus GG was found in the faecal samples of volunteers in the group taking pasteurized yoghurt.

Concentrations of erythromycin, 2'-acetyl erythromycin, and their anhydro forms in plasma and tonsillar tissue after repeated dosage of erythromycin stearate and erythromycin acistrate

The concentrations of erythromycin, 2'-acetylerythromycin (2'-AE) and their anhydro forms in plasma and tonsillar tissue were analyzed after a 3-day repeated-dosage regimen of erythromycin stearate (ES; 500 mg twice a day [b.i.d]) and erythromycin acistrate (EA), a new erythromycin prodrug, at two doses (400 and 500 mg b.i.d.). The tonsils of 40 patients were removed at 112 to 329 min after intake of the last dose. Blood samples were collected at the time of tonsillectomy and at 0, 2, and 6 h after the last dose. At all time points, EA produced severalfold more total antibiotic (erythromycin + 2'-AE) concentrations in plasma compared with ES. There were two nonabsorbers in the ES group, but none in the two EA groups. The mean total antibiotic levels in tonsillar tissue after EA treatment exceeded the levels after treatment with ES by a factor of 3 (for EA at 400 mg b.i.d.) and 4.5 (for EA at 500 mg b.i.d.). The ratios of erythromycin concentration in tonsil to that in plasma at the time of tissue removal were quite similar for all groups (means, 0.51 to 0.54). In the EA groups, 2 of 26 (8%) patients had no measurable erythromycin in the tonsillar tissue samples, whereas in the ES group, 3 of 14 (21%) patients had no measurable erythromycin in the same tissue. The degree of hydrolysis of 2'-AE to erythromycin was about 25% in plasma at the time of tonsillectomy for both EA groups and about 40% in tonsillar tissue. There were negligible amounts of anhydro forms in plasma after EA administration, whereas in the ES group, anhydroerythromycin levels were, from time to time, even higher than erythromycin levels. Very high levels of anhydro forms were detected in tonsillar tissue after ES treatment, whereas only low levels were found after EA administration.