Out-of-date adder antivenom: to use or not to use?

I am not going to go into any detail here suffice to say that when it comes to treating envenomation by the common adder (common European adder, Vipera berus), antivenom is the only therapy shown to have a beneficial impact on progression and outcome. It is true that mortality in dogs and cats from bites by this snake is (very) low but antivenom use can significantly reduce severity and duration of morbidity which attenuates suffering and saves pet carers money too! As I say, I am not going to get into any more about the treatment here – except to say NO STEROIDS and NO EMPIRICAL ANTIBIOTICS!

I have been following the current availability of adder antivenom saga with interest because of its key importance in treating these cases. The Institute of Immunology in Zagreb, Croatia which has been the source for most of the adder antivenom used in veterinary medicine in the UK in recent times is no longer manufacturing the product. Antivenom can however now be sourced from Biomed in Warsaw, Poland (European Viper Antiserum) via application to the Veterinary Medicines Directorate (VMD); in urgent cases the antivenom may be supplied, purchased and used prior to the Special Treatment Certificate being obtained from VMD under a special dispensation made for this condition. ViperaTab (Flynn Pharma) is also available and used for people but is likely to be too expensive for veterinary use. An organisation in Wales is working on manufacturing a veterinary adder antivenom product that should hopefully be available in the next few months to a year (this is second-hand information though so timing may not be quite right).

In June a veterinary surgeon in practice, Alan Sim, wrote a letter to The Veterinary Record (BVA, June 7, 2014, vol 174, p 589) in which he said:

“Some years ago, during a period when the antivenom was not available, the Liverpool School of Tropical Medicine supplied the practice with time-expired stocks of antivenom. It was known that the cold chain had been maintained for this antivenom at all times. With the owners' consent, these supplies were administered to dogs that had been bitten by adders…

Approximately 30 animals were treated in this way. No loss of efficacy or increase in side effects of the time-expired antivenom was noted despite it being, in some cases, 11 years out of date. Accordingly, with the snake bite season upon us, I would urge practices to retain any antivenom that has become time-expired until the current issues of supply are resolved.

The fact that European snake antivenom retained its potency for a considerable time after its expiry date may be of significance elsewhere in the world where people more commonly suffer snake bites. If the cold chain has been maintained, it could be the case that a time-expired antivenom may still be efficacious, if no other supplies are available.”

Two weeks letter in the same publication (June 21, 2014, vol 174, p 639) Nicola Bates and Nick Edwards, representatives of the Veterinary Poisons Information Service (VPIS, www.vpisuk.co.uk) wrote:

“An antivenom for dogs is currently in development [the one being developed in Wales] but until this becomes available, we would agree with Mr Sim that the use of out of data antivenom is probably acceptable, at the discretion of the veterinary surgeon, provided the antivenom has been stored appropriately.”

Which brings us to the latest issue of The Veterinary Record (July 12, 2014, vol 175, p 52) in which there is a letter from Denise Burge of the VMD Legislation Team in which she writes:

“Further to the letters from Alan Sim (VR, June 7, 2014, vol 174, p 589) and Nicola Bates and Nick Edwards (VR, June 21, 2014, vol 174, p 639) following the supply problems for European snake antivenom, the Veterinary Medicines Directorate (VMD) would like to remind veterinary surgeons that veterinary medicines that have passed their expiry date should not be supplied or administered. The Veterinary Medicines Regulations 2013 make it an offence, under Regulation 7(2), to supply or administer a medicine that has passed its expiry date. This is because their quality and hence safety and efficacy may not be maintained beyond the authorised shelf life and, as a result, they could be harmful to the animal or fail to work effectively.”

Personally with the information I have available to date, I would be quite happy and indeed keen to use expired Croatian adder antivenom in my own dog as long as I could be (reasonably) sure that it had been stored appropriately throughout with the cold chain being maintained but it seems like that would be to commit an offence. Thoughts?