Pharmacokinetics of a new, microencapsulated erythromycin base after repeated oral doses

Serum erythromycin levels in pregnancy

Erythromycin is the recommended therapy for pregnant women with chlamydial infection. Despite the fact that this drug has been available since 1952, relatively little is known about its pharmacokinetic behavior in pregnant women, and no investigations have been conducted in women who were in the third trimester of pregnancy. In this study, 10 women were treated with erythromycin for chlamydial infection during pregnancy; 7 of these women were in the third trimester of pregnancy, and 3 were in the second trimester. Serum samples were obtained at 0.5, 1, 2, 3, and 4 hours after a 500-mg oral dose of erythromycin base and were analyzed to determine absorption and peak serum levels of erythromycin. Results indicated that absorption was delayed and serum levels were diminished in comparison with values reported in the literature for patients in the second trimester of pregnancy. In 2 women, erythromycin serum levels were not detectable at any time during the 4 hours of the study; these 2 women also experienced the most severe gastrointestinal symptoms. Although the size of our study population was small and certainly not definitive, the data suggest that in patients in the third trimester of pregnancy, severe adverse gastrointestinal events may forewarn of subtherapeutic plasma concentrations of erythromycin, which could have consequences for the treatment outcome.

Pharmacokinetic advantages of erythromycin estolate over ethylsuccinate as determined by high-pressure liquid chromatography

The pharmacokinetics of erythromycin estolate (500 mg) and erythromycin ethylsuccinate (600 mg) were compared in 12 healthy volunteers after single doses and after repeated oral doses (every 8 h). High-pressure liquid chromatography with electrochemical detection was used to determine concentrations in plasma and urine of estolate, ethylsuccinate, and erythromycin base. The maximum concentration of drug in the serum, the half-life, and the area under the curve for erythromycin estolate were significantly greater than those of erythromycin ethylsuccinate after both regimens. After single and multiple doses, the respective areas under the curve of erythromycin base generated by estolate formulation were 3 and 1.6 times greater (P less than 0.05) than those of ethylsuccinate. The lower percentage of hydrolysis of erythromycin estolate (41 versus 69%) combined with its longer half-life (5.47 versus 2.72 h) and its larger area under the curve (30.61 versus 4.68 micrograms/h/ml, after multiple doses) could explain these differences. This study underscores the need for a specific high-pressure liquid chromatography assay and the importance of wide variability, rate-limited processes, changes with multiple doses, and the appearance of a second peak when one studies the pharmacokinetics of erythromycin esters. The pharmacokinetic data presented in this study reinforce the clinical advantages of erythromycin estolate over erythromycin ethylsuccinate.

Effect of concomitant food intake on absorption kinetics of erythromycin in healthy volunteers

The steady state absorption of erythromycin from enteric-coated pellets of erythromycin base was compared with that from enteric-coated tablets in a randomized, two-way cross-over study in 24 healthy adult volunteers. A higher mean individual peak concentration (p less than 0.01), and a greater mean area under the serum concentration-time (0-8 h) curve (AUC, p less than 0.01) was produced by the enteric-coated pellets, when the preparations were administered 1 hour before breakfast. No significant differences in the kinetic parameters between the two preparations were observed when they were taken during a non-standardized breakfast, as concomitant food intake was found to reduce both the peak levels and the AUC-values (p less than 0.01) produced by the pelleted preparation.

Erythromycin absorption in healthy volunteers from single and multiple doses of enteric-coated pellets and tablets

The absorption of erythromycin from two different enteric-coated preparations was evaluated in three groups of healthy volunteers. After a single dose, taken after an overnight fast, absorption was significantly better from enteric-coated pellets than from tablets; both the mean peak serum concentration and the peak mean level were higher (p less than 0.01) in all three groups, and the mean area under the serum concentration-time curve (AUC) was at least 65% larger. Eight out of 23 subjects showed no or only a very low serum concentration after the enteric-coated tablets. In a follow-up study, 250 mg doses were given 6-hourly for 3 days, and again the mean maximum serum concentration was significantly higher (p less than 0.05) after the pellets. In conclusion, enteric-coated pellets led to more regular and predictable absorption of erythromycin than did coated tablets.

Dose-related pharmacokinetics after oral administration of a new formulation of erythromycin base

1 Erythromycin concentrations in serum and urine were determined in 24 healthy male, fasting subjects after oral administration of 250, 500, or 1000 mg of erythromycin base (250 mg capsules containing enteric-coated pellets). The subjects also received a film-coated erythromycin stearate tablet (equivalent to 500 mg base). 2 The mean +/- s.d. maximal serum erythromycin concentrations were 1.9 +/- 0.8, 3.8 +/- 1.4, 6.5 +/- 2.9 and 2.9 +/- 1.7 mg/l for 250, 500, or 1000 mg base and 500 mg stearate, respectively. The serum peaks usually occurred after 2 h irrespective of dosage form given. 3 The mean +/- s.d. areas under the serum concentration v time curves (AUC0-infinity) were 4.5 +/- 1.7, 11.2 +/- 4.3, 27.2 +/- 10.6 and 7.5 +/- 3.4 mg l -1 . h after 250, 500, or 1000 mg base, and 500 mg stearate, respectively. 4 The urinary recoveries were 5.0, 6.7, 8.6% of the base doses given and 4.4% of the stearate dose given. 5 Dose-dependent excretion of erythromycin occurred. The increase in AUC was larger than multiples of the lowest base dose.