Trial reportBritish journal of clinical pharmacology2014
Systemic exposure of topical erythromycin in comparison to oral administration and the effect on cytochrome P450 3A4 activity.
Trial report in British journal of clinical pharmacology, 2014. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
2 citing papers in PubMed, 10 citations in OpenAlex.
- Optimization of In Vitro CYP3A4 TDI Assay Conditions and Use of Derived Parameters for Clinical DDI Risk Assessment Using Static and Dynamic Models.The AAPS journal · 2025Article
- The Use of Microdosing for In vivo Phenotyping of Cytochrome P450 Enzymes: Where Do We Stand? A Narrative Review.European journal of drug metabolism and pharmacokinetics · 2024Review
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
6 authors at 2 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
aimsErythromycin is a macrolide antibiotic, which is frequently used as a topical formulation for the treatment of acne. It is also known as an inhibitor of the cytochrome P450 (CYP) isoenzyme 3A4. In this study, the systemic availability of topical erythromycin, hence the influence on the activity of CYP3A, is evaluated in comparison to orally administered erythromycin.
methodsSixteen healthy volunteers received consecutively topical (two applications of 800 mg) and oral erythromycin (two dose groups, 250 and 1000 mg, with n = 8) to assess erythromycin pharmacokinetics. A microdose of midazolam (3 μg orally) was used to determine the effect on CYP3A activity.
resultsAfter topical administration, erythromycin was detected in the plasma of every participant without causing a statistically significant alteration of CYP3A activity. After oral administration, the dose-normalized erythromycin exposure (AUC∞ ) was 1335 h ng ml(-1) after 250 mg and 3-fold higher after the 1000 mg dose (4051 h ng ml(-1); P < 0.01), suggesting nonlinear pharmacokinetics of erythromycin. Both oral doses inhibited CYP3A activity; midazolam clearance was decreased to 61% (250 mg) and 21% (1000 mg). The relationship between erythromycin exposure and CYP3A activity (Hill equation) revealed a 50% reduction of CYP3A activity by an erythromycin AUC∞ of 2106 h ng ml(-1).
conclusionsTopical erythromycin did not cause clinically relevant CYP3A alterations, although low systemic availability of erythromycin was observed. This supports the assumption that treatment with topical erythromycin is not critical in terms of CYP3A inhibition. Furthermore, substantial nonlinearity of erythromycin pharmacokinetics after two different oral doses was observed, possibly due to autoinhibition.
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