Sileo

Sileo is a veterinary medicine that contains dexmedetomidine hydrochloride. It is available as an oromucosal gel (a gel applied to the lining of the mouth).

Sileo is used in dogs to reduce acute anxiety and fear associated with noise. Typical signs of anxiety and fear in dogs include panting, trembling, pacing, seeking people, hiding or trying to escape, refusal to eat and inappropriate urination or defaecation. Sileo is applied to the lining of the dog’s mouth between the cheek and gum from the pre-filled oral syringe. An initial dose is given either when the dog first shows signs of anxiety or when the owner detects a typical stimulus such as the sound of fireworks or thunder. The dose to be given depends on the dog’s bodyweight. If the noise continues and the dog shows signs of anxiety and fear again, further doses can be given at intervals of two hours, up to a total of 5 times during each event.

The active substance in Sileo, dexmedetomidine hydrochloride, is a type of sedative medicine called an alpha-2 adrenoceptor agonist. It works by preventing the release of the neurotransmitter noradrenaline from nerve cells in the body.

Neurotransmitters are chemicals that allow nerve cells to communicate with each other. Since noradrenaline is involved in maintaining alertness and arousal, reducing its release reduces the severity of acute anxiety and fear associated with noise.

The effectiveness of Sileo was investigated in a field study involving dogs exposed to fireworks noise at New Year’s Eve. Sileo was given to 89 dogs and 93 dogs received a dummy treatment. The two main measures of effectiveness were the owner’s assessment of the dog’s behaviour at least two hours after the last dose compared to the previous year and the score given by the owner for signs of anxiety and fear after treatment.

72% (64 of 89) of the Sileo-treated dogs were scored excellent or good for behaviour compared to 37% (34 of 93) of the group given dummy treatment. Score good for behaviour indicated only mild and short-lived signs of fear and anxiety shown by the dog whilst score excellent for behaviour indicated no signs shown.

Sileo-treated dogs also had significantly lower scores for signs of anxiety and fear than the dogs given dummy treatment.

Short-lived paleness of the lining of the mouth and gums at the application site may occur in less than 10 in 100 dogs due to a temporary localised narrowing of the blood vessels. Sedation, vomiting and urinary incontinence may also occur in less than 10 in 100 dogs.

Sileo must not be used in dogs with severe disorders of the heart and blood vessels, with severe disease such as kidney or liver failure or in dogs if unexpectedly sedated from a previous dose.

For a full list of all restrictions and side-effects reported with Sileo, see the package leaflet.

If Sileo is accidentally ingested or if there is prolonged contact with the eyes, lips or the inside of the mouth or nostrils medical advice should be sought immediately and the package leaflet or the label shown to the doctor. The affected person should not drive as sedation and changes in blood pressure may occur.

Contact with skin, eye, lips or the inside of the mouth or nostrils should be avoided. Impermeable disposable gloves should be worn when handling Sileo.

In case of skin contact the exposed skin should be washed immediately after exposure with large amounts of water and contaminated clothes should be removed. In case of contact with the eye or inside of the mouth, the area should be rinsed abundantly with fresh water. If symptoms occur, the advice of a doctor should be sought.

Pregnant women should avoid contact with the product as uterine contractions and reduced blood pressure of the unborn baby may occur after exposure to dexmedetomidine.

The oral syringe should be returned to the outer carton immediately after each use for child safety.

The CVMP concluded that the benefits of Sileo exceed the risks for the approved indication and recommended that Sileo be given a marketing authorisation. The benefit-risk balance may be found in the scientific discussion module of this EPAR.

The European Commission granted a marketing authorisation valid throughout the European Union, for Sileo on 10 June 2015. Information on the prescription status of this product may be found on the label/outer package.