Closantel-containing products – Changes to authorised withdrawal periods for oral suspensions for sheep

The HPRA monitors reports of adverse events to veterinary medicinal products as part of our role in the post-authorisation safety monitoring of veterinary medicinal products in Ireland. 

In 2024, the HPRA became aware of a limited number of reports where residues of closantel above the Maximum Residue Limit (MRL) were detected post slaughter from treated livestock. Residues pose a threat to food safety and result in condemnation of carcases, financial losses, as well as reputational risk.

At that time, the HPRA published a notice advising users of closantel-containing products for sheep, and veterinary medicines generally, to ensure administration of the correct dose, avoid over-dosing and respect the withdrawal period of the product to be administered. As an additional measure to ensure consumer safety and to avoid non-compliant residues, the HPRA has, in recent weeks, agreed with relevant marketing authorisation holders that the withdrawal periods of selected closantel-containing products intended for use in sheep and currently marketed in Ireland be increased from 42 days to 56 days. 

The products in question are:

• Flukiver 50 mg / ml Oral Suspension for sheep and lambs (VPA22020/001/001, Elanco GmbH)
• Solantel 50 mg / ml Oral Suspension for Sheep (VPA22664/128/001, Norbrook Laboratories (Ireland) Limited)

Users are asked to respect the new withdrawal period (56 days for sheep) with immediate effect pending the availability of new stock with updated labelling reflecting the revised withdrawal period.

Problem or issue

To ensure the safety of consumers of food and food products derived from animals treated with veterinary medicines containing closantel, the European Commission has set maximum residue limits (MRLs) for closantel in the edible tissues of animals. In order for closantel-derived residues to deplete below the MRLs, a sufficient time (withdrawal period) between treatment and slaughter must be observed and which takes into account the dose rate and route of administration approved for the concerned products. 

If the time between treatment and slaughter is insufficient, closantel-derived residues may be detected in sheep tissues. Further, unless care is taken to accurately assess the bodyweight of animals to be treated, they can be over-dosed and this may lead to residues in excess of the MRL being present at time of slaughter. The risk of overdosing increases when the bodyweight of animals to be treated is not accurately assessed, or when animals are grouped for dosing but the range of individual bodyweights within the group differs significantly, resulting in lighter-weight animals receiving a higher than recommended dose. The risk is further increased where users dose to a standard bodyweight, irrespective of whether there are mixed weights of animals in the group. 

Residues pose a threat to food safety and result in condemnation of carcases, financial losses, as well as reputational risk.

Background information

Withdrawal periods are set by the HPRA on the basis of residue depletion studies submitted with applications for marketing authorisations and are usually specific to each formulation and product. Closantel has slow and limited metabolism and it takes a relatively long time for it to be eliminated from tissues. 

Withdrawal periods (available from your prescription or the product datasheet) must be respected to protect human health and to avoid non-compliant residues which may result in condemnation of carcasses and financial losses. 

Approved withdrawal periods are adequate to avoid non-compliant residues provided that the concerned medicines are used correctly i.e. dosed in accordance with the approved dose rate. 

The HPRA in cooperation with MAHs will continue to closely monitor for reports of residue violations. 

All antiparasitic products for food animals are designated by the HPRA as ‘POM’ (Prescription Only). From 1st December 2025, such products can only be supplied to farmers on foot of a veterinary prescription. 

Actions to be taken

For Flukiver and Solantel, users are asked to respect the new withdrawal period (56 days for sheep) with immediate effect.

To ensure administration of the correct dose, bodyweight should be determined as accurately as possible before dosing.

Accuracy of any dosing device should be checked.

If animals are to be treated collectively rather than individually, they should be grouped according to their bodyweight and dosed accordingly in order to avoid over-dosing.

Do not exceed the recommended dose.

Always read the label and package leaflet before use.

For advice on the use of veterinary medicines and on parasite control in general, consult your veterinary practitioner.

All suspected adverse events, including reports of residue violations should be reported immediately, preferably to the marketing authorisation holder, or alternatively to the HPRA.