Absorption of erythromycin acistrate and erythromycin base in the fasting and non-fasting state

Erythromycin for myotonic dystrophy type 1: a multicentre, randomised, double-blind, placebo-controlled, phase 2 trial

Background

Myotonic dystrophy type 1 (DM1) is a devastating multisystemic disorder caused by a CTG repeat expansion in the DMPK gene, which subsequently triggers toxic RNA expression and dysregulated splicing. In a preclinical study, we demonstrated that erythromycin reduces the toxicity of abnormal RNA and ameliorates the aberrant splicing and motor phenotype in DM1 model mice.

Methods

This multicentre, randomised, double-blind, placebo-controlled, phase 2 trial was conducted at three centres in Japan to translate preclinical findings into practical applications in patients with DM1 by evaluating the safety and efficacy of erythromycin. Between Nov 29, 2019, and Jan 20, 2022, a total of 30 adult patients with DM1 were enrolled and randomly assigned in a 1:2:2 ratio to receive either placebo or erythromycin at two daily doses (500 mg or 800 mg) for 24 weeks. The primary outcome included the safety and tolerability of erythromycin. The secondary efficacy measures included splicing biomarkers, 6-min walk test results, muscle strength, and serum creatinine kinase (CK) values. This trial is registered with the Japan Registry of Clinical Trials, jRCT2051190069.

Findings

Treatment-related gastrointestinal symptoms occurred more frequently in the erythromycin group, but all adverse events were mild to moderate and resolved spontaneously. No serious safety concerns were identified. The CK levels from baseline to week 24 decreased in the overall erythromycin group compared with the placebo group (mean change of -6.4 U/L [SD 149] vs +182.8 [SD 228]), although this difference was not statistically significant (p = 0.070). Statistically significant improvements in the overall erythromycin treated groups compared to placebo were seen for two of the eleven splicing biomarkers that were each evaluated in half of the trial sample. These were MBNL1 (p = 0.048) and CACNA1S (p = 0.042).

Interpretation

Erythromycin demonstrated favourable safety and tolerability profiles in patients with DM1. A well-powered phase 3 trial is needed to evaluate efficacy, building on the preliminary findings from this study.

Funding

Japan Agency for Medical Research and Development.

Pharmacokinetic drug interactions of antimicrobial drugs: a systematic review on oxazolidinones, rifamycines, macrolides, fluoroquinolones, and Beta-lactams

Like any other drug, antimicrobial drugs are prone to pharmacokinetic drug interactions. These drug interactions are a major concern in clinical practice as they may have an effect on efficacy and toxicity. This article provides an overview of all published pharmacokinetic studies on drug interactions of the commonly prescribed antimicrobial drugs oxazolidinones, rifamycines, macrolides, fluoroquinolones, and beta-lactams, focusing on systematic research. We describe drug-food and drug-drug interaction studies in humans, affecting antimicrobial drugs as well as concomitantly administered drugs. Since knowledge about mechanisms is of paramount importance for adequate management of drug interactions, the most plausible underlying mechanism of the drug interaction is provided when available. This overview can be used in daily practice to support the management of pharmacokinetic drug interactions of antimicrobial drugs.

Pharmacokinetics of EDP-420 after multiple oral doses in healthy adult volunteers and in a bioequivalence study

EDP-420 (also known as EP-013420, or S-013420) is a first-in-class bridged bicyclolide currently in clinical development for the treatment of respiratory tract infections (RTI) and has previously shown favorable pharmacokinetic (PK) and safety profiles after the administration of single oral doses of a suspension to healthy volunteers. Here we report its PK profile after the administration of multiple oral doses of a suspension to healthy adults. Bioequivalence between suspension and capsule formulations, as well as the effect of food, is also reported. The most important PK features of EDP-420 observed in these clinical studies are its long half-life of 17 to 18 h and its high systemic exposure, which support once-daily dosing and treatment durations potentially shorter than those of most other macrolide antibiotics. EDP-420 is readily absorbed following oral administration in both suspension and capsule formulations. In the multiple-oral-dose study, steady state was achieved on day 1 by using a loading dose of 400 mg/day, followed by 2 days of 200 mg/day. A high-fat meal had no effect on the bioavailability of EDP-420 administered in a capsule formulation. EDP-420 was well tolerated, with no serious or severe adverse events reported, and no subject was discontinued from the study due to an adverse event. Based on its human PK and safety profiles, together with its in vitro/in vivo activities against common respiratory pathogens, EDP-420 warrants further development, including trials for clinical efficacy in the treatment of RTI.

Pharmacokinetics of EDP-420 after ascending single oral doses in healthy adult volunteers

EDP-420 (EP-013420, S-013420) is a first-in-class bicyclolide (bridged bicyclic macrolide) currently in clinical development for the treatment of respiratory tract infections. It has good preclinical pharmacokinetic properties across multiple species and potent in vitro and in vivo activity against respiratory tract infection pathogens, including Haemophilus influenzae, atypical organisms (e.g., Chlamydia pneumoniae, Mycoplasma pneumoniae, and Legionella pneumophila), and multidrug-resistant streptococci. The safety, tolerability, and pharmacokinetics of an orally administered EDP-420 suspension in 40 healthy adult subjects were assessed in a randomized, double-blind, placebo-controlled, ascending single-dose study. Eligible subjects were sequentially randomized into one of five study groups (i.e., 100-, 200-, 400-, 800-, or 1,200-mg dosing groups) consisting of eight subjects (six active and two placebo) each. EDP-420 was well tolerated. There were no serious adverse events reported, nor were there any dose-limiting clinical or laboratory adverse events reported. EDP-420 was rapidly absorbed after a single oral dose. The mean plasma terminal half-life ranged from 15.6 to 20.1 h with low clearance. At the 400-mg dose, the area under the curve was 14.4 microg x h/ml, which well exceeded the required area under the concentration-time curve to cover common respiratory tract infection pathogens based on preclinical pharmacokinetic/pharmacodynamic modeling. The long half-life and high systemic exposure of EDP-420 support once-daily dosing and may allow for shorter treatment durations compared to other macrolide antibiotics. Based on its human pharmacokinetic profiles, taken together with its in vitro/in vivo activity against common respiratory pathogens, EDP-420 warrants efficacy trials for the treatment of respiratory tract infections.

Dental anxiety and the absorption of orally administered erythromycin stearate

Erythromycin stearate is an acid labile antibiotic, therefore fear and apprehension, which are known to affect gastric motility, may produce erratic absorption resulting in lower serum levels. The mean (SD) serum erythromycin concentration 75 minutes after a 1.5 gm oral dose of erythromycin stearate to 45 patients was 8.7 (4.8) mg/L and ranged widely from 0.4 to 20.5 mg/L. The serum concentration of erythromycin was below therapeutic levels (1.0 mg/L) in two patients. No significant association was found between anxiety and serum levels of erythromycin when age, gender, and gastric distress were taken into account. It is concluded that dental anxiety may indirectly influence the uptake of oral erythromycin stearate; but this relationship is complex, and there is no evidence from this study that increased dental anxiety decreases the uptake of the drug.