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EUROPEAN MEDICINES AGENCY

SCIENCE MEDICINES HEALTH

EMEA/V/C/136

EPAR summary for the public

Improvac

Gonadotropin

This document is a summary of the European Public Assessment Report. Its purpose is to explain how the assessment done by the Committee for Medicinal Products for Veterinary Use (CVMP) on the basis of the documentation provided, led to the recommendations on the conditions of use.

This document cannot replace a face-to-face discussion with your veterinarian. If you need more information about your animal's medical condition or treatment, contact your veterinarian. If you want more information on the basis of the CVMP recommendations, read the Scientific Discussion (also part of the EPAR).

What is Improvac?

Improvac is an immunological product intended for male pigs that contains a gonadotropin releasing factor (GnRF) analogue-protein conjugate as the active substance. It is available as a solution for injection.

What is Improvac used for?

Improvac is used to reduce 'boar taint' in the meat obtained from male pigs. Boar taint is an offensive smell or taste in pork or pork products derived from non-castrated male pigs (boars) that have reached puberty. Boar taint is caused by compounds such as androstenone, which is produced by the testicles of male pigs and skatole, a substance produced in the intestine of all pigs but which tends to accumulate in the fat of uncastrated males. Improvac is used as an alternative to physical castration (removal of the testicles) to reduce the presence of these compounds.

Improvac is given to young male pigs as two doses, with at least a 4 week interval. The first dose is given as early as eight weeks of age and the second at four to six weeks before slaughter. The product is given as an injection in the neck just behind the ear.

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How does Improvac work?

Improvac is an immunological product which has an action mode similar to that of a vaccine (stimulates the immune system to produce antibodies). The active substance in the product is an analogue of gonadotropin releasing factor (GnRF) linked to a carrier protein obtained from the bacterium Corynebacterium diphtheriae. GnRF is responsible for maintaining the activity of the testicles in male pig. When Improvac is given to male pigs it causes their immune systems to recognise the synthetic GnRF as 'foreign' and produce antibodies against it. These antibodies are then able to attach to natural GnRF and stop it from having its effect. As a result, the product reduces the production of sex hormones including androstenone in the testicles. Androstenone is one of the main substances responsible for boar taint. The reduction in the level of sex hormones also allows the liver to cleanse the pig's system of skatole more effectively, reducing its levels in the body. Skatole is the second main substance that is responsible for boar taint. Improvac also contains an adjuvant (a chemical derived from the sugar dextran). The carrier protein and the adjuvant both help to stimulate a better response.

How has Improvac been studied?

The efficacy of Improvac was studied in numerous laboratory and field studies. Pivotal studies included five trials. One of these was carried out under laboratory conditions and the remaining four were carried out under typical commercial field conditions for pig production in Europe. The studies looked at the effectiveness of Improvac in triggering an immune response by measuring the levels of antibodies against GnRF and the levels of testosterone (the male sex hormone) in the pigs' blood at several time points before slaughter. They also assessed the effectiveness of the product in controlling boar taint by checking that the levels of skatole and androstenone in fat samples from the pigs were below a threshold level that would be detectable by a human consumer. In all of the studies, the immunised pigs were compared with pigs that were castrated.

The safety of Improvac was studied in laboratory and field safety studies. Results of these studies showed that pigs immunised with Improvac showed little reaction to the act of injection. Injection site reactions and other post-immunisation effects are relatively mild and adequately described in the SPC.

What benefit has Improvac shown during the studies?

Immunisation with Improvac resulted in a temporary reduction in the activity of the testicles. During this period, concentrations of skatole and androstenone were below the threshold levels associated with the risk of boar taint. The studies showed that the first injection has a limited effect, but the second injection is followed by the production of antibodies against GnRF. The levels of these antibodies decline with time but are still high enough to be reliably effective four to six weeks after the second injection.

What is the risk associated with Improvac?

The most common side effect with Improvac is swelling at the site of the injection.

Improvac must not be used in female pigs or in male pigs intended for breeding.

Improvac

What are the precautions for the person who gives the medicine or comes into contact with the animal?

No special precautions are required for persons coming into contact with immunised animals. Accidental self-injection of Improvac may produce similar effects in people to those seen in pigs. These may include a temporary reduction in sex hormone levels and reduced ability to reproduce in men and in women, including problems with pregnancy. The risk of these effects occurring is greater after a second or subsequent accidental injection than after a first injection. Special care should be taken to avoid accidental self-injection. The product must only be used with a safety device including a needle guard and a mechanism to prevent accidental operation of the trigger. Improvac must not be given to pigs by women who are or who may be pregnant.

In case of eye contact, rinse immediately with lots of water. In case of skin contact, wash immediately with soap and water.

What is the time to allow before the animal can be slaughtered and the meat used for human consumption (withdrawal period)?

The withdrawal period is zero days.

Why has Improvac been approved?

The Committee for Medicinal Products for Veterinary Use (CVMP) concluded that the benefits of Improvac exceeded the risks for the reduction of boar taint caused by the key boar taint compound, androstenone, in entire male pigs following the onset of puberty. Another key contributor to boar taint, skatole, may also be reduced as an indirect effect. Therefore the CVMP recommended that Improvac should be given a marketing authorisation. The benefit-risk balance may be found in module 6 of this EPAR.

Other information about Improvac:

The European Commission granted a marketing authorisation valid throughout the European Union for Improvac on 11 May 2009. Information on the prescription status of this product may be found on the label/outer package.

This summary was last updated in May 2013.

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