4 minute read
Herd Health
Several sustained release products are on the Canadian market for use in cattle. These are setting a new standardfor the way we treat pneumonic calves in Canadian feedlots. Time will tell how they fit into our treatment protocols. This article will give you the facts about one which has been around for a few years.
This product is called Draxxin, which is short for “duration of action”. It was developed by the pharmaceutical company Pfizer. There seemed a need to develop a very long acting product as multiple doses of long duration products like Nuflor or Micotil were sometimes given in feedlots. The active ingredientis Tulathromycin. It has an extremely long half-life, which means the time it takes for half the product to still remain in the animal’s system. The half life is 184 hours in the lungs allowing it at recommended dosage (1.25 cc per 50 kg or 1.1cc per 100 lbs) to maintain activity against specific bacteria ten days or longer. This was an unheard of length of time in the animal health industry until it was launched.
This antibiotic was discovered October 31, 1996. You may wonder why it took this long to get to market (10 years), but various trials both for efficacy and safety were necessary and with such long duration it had to be proven there were no harmful effects on good bacteria or that resistance would not develop on organisms harmful to humans such as salmonella or ecoli. All this took about six years to prove and then the regulatory process took an additional four years. Most of the regulatory work happened in 2006, which is why the product was out in the European Union in 2003 and in the USA last year. This regulatory process is painfully slow in Canada and costs the whole industry money, but enough said.
The compound in Draxxin has some very good qualities especially for our Canadian climate. It is very syringeable having the consistency of water yet is very stable and will not freeze until well below –15C. It will come in a clear bottle since UV light does not affect it as well. It has an affinity for lung tissue so concentrates there making it effective on pneumonias. It is absorbed very quickly from the site (within 30 minutes) with only minor swelling evident occasionally. It is given subcutaneously and has been proven very safe. When tested in rats after 60 days there was no significant effect on reproductive rate so should be very safe as well on calves destined as breeding stock. It is totally safe when given to pigs and pigs surprisingly enough are test models for humans. If given intravenously there are no deleterious effects. Accidental injections should be safe in humans but that is no excuse for being careless. In most cases dirty needles and the size of the needle is what commonly causes the problem in accidental human injections. We should be careful with any product we handle or inject and use the one-handed technique to inject wherever possible.
The withdrawal for slaughter is 44 days. In Canada they arrive at a safe level of the drug in meat bearing in mind our testing procedures now can measure out into parts per trillion. That amount is calculated back to a 60 kg human (small person) eating 500 grams of muscle daily which is a lot of meat every single day. All this in the interests of being very safe. In the United States they use the same calculations but base it on only eating 300 grams of muscle and the detectable levels are slightly higher. That is why the same product in the States at the same dosage and delivery has a withdrawal of only 18 days.
With any new products these days’ specific things are mentioned on the label. Baytril a potent drug for pneumonia must only be given as the second drug of choice as in a relapse situation. With Draxxin it can be given in a group situation when a diagnosis of pneumonia has been made or the calves are highly stressed and likely to contract pneumonia as determined by your veterinarian. We call this giving it metaphylactically just before an outbreak of respiratory disease is suspected.
In the trial work to prove effectiveness against pneumonia very sick cattle were treated. This product did prove statistically significant in the relapse rate as well as the overall death loss compared to some very good antibiotics. Although not on the label it also shows effectiveness against the mycoplasma organism if given early enough.
The total cost to get a product approved in Canada now approaches 100 million dollars, so there is no wonder why it is expensive, but very comparable or cheaper to contemporary’s on a per treatment day basis. Applications for a patent must be made before submission to the regulatory authorities. The clock then starts ticking. Patents last twenty years so if products take half that or better to get to market it is no wonder they are expensive as companies try and recoup their development costs.
One always asks the questions with all these apparently superior drugs on the market why do morbidity and continued on page 35
