What Is Emodepside? Definition and What Research Reports

Definition

Emodepside is a semisynthetic cyclic octadepsipeptide anthelmintic — a macrocyclic molecule built from alternating amino-acid and hydroxy-acid (ester-linked) residues — that is used in registered veterinary deworming products and that has been investigated as a candidate treatment for parasitic nematode infections in humans. It is not a therapeutic peptide in the conventional sense of a linear chain of amino acids acting on a hormone receptor; instead it belongs to the depsipeptide family of fungal-derived natural products, and its best-characterised molecular target is an ion channel in the nematode neuromuscular system. In glossaries and reference lists, emodepside is therefore usually filed under "cyclodepsipeptides" or "peptide-like natural products" rather than under peptide hormones or growth factors.

What Class of Molecule It Is and Where It Comes From

Emodepside was developed as a chemically modified version of PF1022A, a cyclooctadepsipeptide isolated from a fungus. Structurally, the molecule is a closed ring of eight residues; the "depsi-" prefix signals that at least one peptide (amide) bond in the backbone has been replaced by an ester bond. That substitution matters pharmacologically, because ester-containing macrocycles behave differently from ordinary peptides in terms of conformational rigidity and resistance to the proteases that rapidly clear linear peptides.

Two features make emodepside a recurring example in discussions of peptide-adjacent chemistry:

• Non-ribosomal origin. Like many fungal and bacterial depsipeptides, its parent compound is assembled by enzymatic machinery rather than by ribosomal translation, which allows unusual residues and ring closure.
• Cyclisation and ester bonds. The macrocyclic scaffold is frequently cited as an illustration of how cyclic peptide-like architectures can reach intracellular or membrane-embedded targets that linear peptides generally do not.

Quick reference

How the Term Is Used in Research Writing

In the published literature, "emodepside" appears in three fairly distinct contexts. First, as a pharmacological tool: invertebrate neuroscientists use it to probe the function of SLO-1-type potassium channels, and the 2012 perspective titled "Worms take to the slo lane" framed the compound explicitly around that channel-centred mode of action (PMID 22539031). Second, as an anthelmintic agent in veterinary and human parasitology. Third, as a chemistry exemplar for cyclodepsipeptides, where it is cited to illustrate that a peptide-derived macrocycle can be optimised into an orally active drug-like molecule.

Because of that last usage, the term drifts into "peptide" vocabulary even though emodepside is not a signalling peptide. Readers encountering it in a peptide glossary should note the distinction: the molecule is peptide-derived in its biosynthetic ancestry and its backbone chemistry, not in its pharmacology.

Mechanism as Described in the Literature

Reviews of emodepside converge on the SLO-1 channel — a large-conductance, calcium-activated potassium channel — as the key site of action in nematodes, with a 2012 review concluding that SLO-1 is required for the compound's characteristic effects on worm motility and pharynx function (PMID 21910990). The same channel-based model was examined in a companion perspective, which discussed how channel opening produces inhibitory effects on nematode neuromuscular signalling (PMID 22539031). A more recent review covering both mode of action and toxicity revisited these mechanisms and discussed how the same channel family in mammals is relevant to the compound's toxicological profile (PMID 39817180). Earlier work on a latrophilin-type receptor as an additional or upstream element is also discussed within these reviews rather than as a settled alternative mechanism.

What the Published Literature Reports

Preclinical parasitology: a 2019 evaluation in laboratory models of human helminth infections tested emodepside across rodent models and reported activity against several intestinal nematode species while reporting a lack of comparable activity against schistosomes, and the study framed those findings as support for further development against soil-transmitted helminths (PMID 31088525). Researchers in that work used oral administration in rodent hosts and assessed worm burden reduction as the primary readout (PMID 31088525).

Filarial disease: a 2021 paper described the industrial–academic collaboration that repositioned emodepside from a veterinary product toward a possible adulticidal (macrofilaricidal) treatment for human onchocerciasis, and reported that the compound's activity against adult filarial worms was the property that drove that development programme (PMID 34293063).

Clinical research: a 2023 report in The New England Journal of Medicine described a dose-finding trial of single oral doses of emodepside in people with Trichuris trichiura or hookworm infection, and researchers reported cure rates that increased with ascending dose levels alongside a comparator arm (PMID 37195942). That trial is the most frequently cited human dataset for the compound, and the published account paired the efficacy findings with dose-level safety monitoring (PMID 37195942).

Emodepside Safety Signals: What Studies Report

Safety and toxicity are discussed explicitly in the review literature: the 2024 review was titled around "mode of action and toxicity" and examined mammalian toxicology alongside the nematode pharmacology, discussing how effects on conserved channel targets inform the compound's toxicological assessment (PMID 39817180). In the clinical setting, the 2023 dose-finding trial in Trichuris trichiura and hookworm infection recorded adverse events by dose level as part of its reported outcomes (PMID 37195942), and the 2021 development account described the safety and tolerability work required to move a veterinary compound into human studies for onchocerciasis (PMID 34293063). Readers comparing these sources should note that the reviews and the trial report use different endpoints and populations, so their safety descriptions are not interchangeable.

Regulatory and Research-Status Context

Emodepside's established regulatory footprint is in veterinary medicine, where it is a component of licensed deworming products for companion animals. Its use in humans remains investigational; the 2021 development paper described the collaboration structure through which a veterinary anthelmintic was progressed toward human onchocerciasis indications (PMID 34293063), and the 2023 clinical report represents the kind of dose-finding study that such programmes generate (PMID 37195942). Nothing in the cited literature establishes an approved human indication.

Related Terms

• Cyclodepsipeptide / octadepsipeptide — the structural class to which emodepside belongs.
• PF1022A — the fungal natural product that served as the chemical starting point.
• SLO-1 — the calcium-activated potassium channel identified as emodepside's principal nematode target in review articles (PMID 21910990).
• Anthelmintic — the functional drug category under which emodepside is classified.
• Soil-transmitted helminths — the infection group addressed in the rodent-model evaluation (PMID 31088525) and the human dose-finding trial (PMID 37195942).

This page is for educational purposes only and is not medical advice; consult a licensed physician about any medical condition, medication or treatment decision. It summarises what published studies report and does not describe how any compound should be obtained or used.

References

• Emodepside: the anthelmintic's mode of action and toxicity (Frontiers in Parasitology, 2024)
• Emodepside for Trichuris trichiura and Hookworm Infection (The New England Journal of Medicine, 2023)
• Development of emodepside as a possible adulticidal treatment for human onchocerciasis—The fruit of a successful industrial-academic collaboration (PLoS Pathogens, 2021)
• Evaluation of emodepside in laboratory models of human intestinal nematode and schistosome infections (Parasites & Vectors, 2019)
• Worms take to the slo lane: a perspective on the mode of action of emodepside (Invertebrate Neuroscience, 2012)
• Emodepside and SLO-1 potassium channels: a review (Experimental Parasitology, 2012)