# Monepantel: veterinary dose and monograph

> Monepantel is a veterinary antiparasitic. An amino-acetonitrile derivative (AAD) — a NOVEL anthelmintic class (the "orange" drench) developed specifically to combat MULTIDRUG-RESISTANT gastrointestinal nematodes in SHEEP. Indications include gastrointestinal nematodes of sheep — including benzimidazole/ML/levamisole-resistant strains (Haemonchus, Teladorsagia, Trichostrongylus, etc.); quarantine ("knock-out") drench for incoming sheep to prevent importing resistant worms; refractory parasitism where other classes have failed. This monograph lists 1 reference dose for sheep, each with route, frequency and source, plus meat and milk withdrawal periods for food animals.

Source: https://vetmasterji.com/drugs/monepantel · Last reviewed: 2026-10-01

## At a glance

- **Drug class:** Antiparasitic
- **Also known as:** Zolvix
- **Species with doses:** Sheep
- **General dose range:** 2.5 mg/kg PO single dose (repeat per cycle) — check the species tables for the indication
- **Routes:** PO
- **Last reviewed:** 1 October 2026

## Indications

- Gastrointestinal nematodes of sheep — including benzimidazole/ML/levamisole-resistant strains (Haemonchus, Teladorsagia, Trichostrongylus, etc.)
- Quarantine ("knock-out") drench for incoming sheep to prevent importing resistant worms
- Refractory parasitism where other classes have failed

## Monepantel dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

### Goats

*Monepantel doses for goats*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| No reference dose for this species | Not established in Papich 5e or Plumb’s 10e — do not extrapolate from another species | — | — | — | — |

- No reference dose for this species: Neither Papich 5e nor Plumb’s has a monepantel monograph, and the previous goat dose was an unsourced extrapolation.

### Sheep

*Monepantel doses for sheep*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| GI nematodes (incl. multidrug-resistant) | 2.5 mg/kg | PO | single dose | — | 7d slaughter |

- GI nematodes (incl. multidrug-resistant): Label-sourced — neither Papich 5e nor Plumb’s has a monepantel monograph. Zolvix label: 2.5 mg/kg oral drench; follow the local label withdrawal; not for sheep producing milk for human consumption. Reserve for resistant worms / quarantine drenching.

## Contraindications

Known hypersensitivity. Routine sole/over-use (preserve the novel class — resistance can develop). Observe meat/milk withdrawal. Off-label use in goats requires dose/withdrawal verification. Lambs below the label minimum age/weight.

## Species-specific warnings

> **Caution:** Goats: Off-label in goats — higher dose needed and withdrawal not established; extend meat/milk withdrawal conservatively.

## Adverse effects

- Very well tolerated at label dose
- Wide safety margin
- No notable host toxicity reported at therapeutic use

## Drug interactions

- No clinically important host drug interactions
- No cross-resistance with older anthelmintic classes (its key feature)

## Pregnancy and lactation

Considered safe in breeding/pregnant sheep at label doses.

## Monitoring

- Faecal egg count reduction test (confirm efficacy and detect emerging resistance)
- Quarantine-drench protocols for incoming stock
- Meat/milk withdrawal compliance
- Refugia/resistance-management practices to preserve the class

## Toxicity and overdose

Very wide safety margin in sheep — no significant host toxicity at therapeutic or modestly supratherapeutic doses. The real "risk" is ecological/economic: over-reliance selects for monepantel resistance (already documented on some farms), eroding a last-line class.

Management: Supportive only; no specific antidote needed (wide margin).

## Clinical pearls

- A NOVEL-class drench that kills multidrug-resistant sheep worms — invaluable where benzimidazole/ML/levamisole resistance has accumulated
- Use it strategically (quarantine "knock-out" drench, refractory cases) and with refugia/rotation — monepantel resistance has already emerged where overused
- Unique mode of action = no cross-resistance, but that advantage is finite — steward it
- Goats need a higher dose (faster metabolism) with conservative withdrawal

## Mechanism of action

An amino-acetonitrile derivative that acts on a NEMATODE-SPECIFIC subunit of the nicotinic acetylcholine receptor (the DEG-3/MPTL-1 family, e.g. MPTL-1/ACR-23), causing sustained receptor activation, hypercontraction/paralysis and death of the worm. Because this target is distinct from those of all older anthelmintic classes, monepantel retains activity against nematodes resistant to benzimidazoles, macrocyclic lactones, imidazothiazoles (levamisole) and tetrahydropyrimidines (pyrantel).

## Formulations and products

- Oral drench 25 mg/mL (2.5 %, Zolvix)
- Zolvix (Elanco) — 25 mg/mL (2.5 %) oral drench, Oral drench

## Storage

Drench: 15–30 °C, protect from light; shake before use.

## Before you use this dose

> **Caution:** Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

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## Frequently asked questions

### Can Monepantel be given to goats?

Not established in Papich 5e or Plumb’s 10e — do not extrapolate from another species (No reference dose for this species).

### What is the dose of Monepantel for sheep?

Reference doses for Monepantel in sheep: 2.5 mg/kg PO single dose (GI nematodes (incl. multidrug-resistant)). Confirm against the label and the patient before use.

### What is the withdrawal period for Monepantel?

Sheep, PO (GI nematodes (incl. multidrug-resistant)): 7d slaughter. Follow the product label and national regulations where they differ.

### When should Monepantel not be used?

Known hypersensitivity. Routine sole/over-use (preserve the novel class — resistance can develop). Observe meat/milk withdrawal. Off-label use in goats requires dose/withdrawal verification. Lambs below the label minimum age/weight.

### What are the side effects of Monepantel in animals?

Very well tolerated at label dose; Wide safety margin; No notable host toxicity reported at therapeutic use.

## Sources

- Plumb's Veterinary Drug Handbook
- Merck Veterinary Manual, 11th edition
- Papich, Papich Handbook of Veterinary Drugs, 5th edition

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VetMasterJi is a clinical decision-support and education platform for veterinary professionals and students. It does not provide veterinary advice, diagnosis or treatment for specific animals. All drug doses, calculators and differentials are references that must be independently verified before clinical use; the attending registered veterinarian remains solely responsible for every clinical decision.