First Equine-Specific Metered Dose Inhaler Approved by FDA

If you’ve ever been diagnosed with asthma or chronic bronchitis, you’ve probably been prescribed a convenient inhaler that delivers your medication into your airway. For the first time, horses with recurrent airway obstruction can be treated with a specially designed equine inhaler with medication. Boehringer-Ingelheim Vetmedica recently received Food and Drug Administration (FDA) approval for Torpex, a product that combines albuterol sulfate with an equine-specific metered dose inhaler (MDI) designed by 3M. The device should be available to veterinarians by May 2002.


COURTESY BOB STENBOM, DVM

Administering Torpex.

"Torpex will give veterinarians and horse owners an easy, convenient, and efficient way to administer an inhaled bronchiodilator to horses,” said Bob Stenbom, DVM, a veterinarian at Boehringer. "Torpex actively delivers a high percentage of the drug dose directly into the inhaled airstream with minimal wastage and predictable results."

Devices currently used in horses to deliver airway medication include masks in combination with human MDIs, water vaporizers, and nebulizers (atomizers equipped to produce an extremely fine spray for deep penetration of medication into the lungs). An advantage of these devices is that they can be used with a variety of medications, some of which are inexpensive. While some veterinarians have had success with these delivery devices, others have questioned wastage of drug, cost of the equipment, and efficacy.

"Use of MDIs designed for people usually result in a passive delivery of drug to the horse’s inhaled airstream, resulting in large portions of the dose being wasted," said Stenbom.

Torpex allows the drug to be delivered from a pressurized, non-removable, non-interchangeable aluminum canister through a disposable hand-held metered dose actuator with a patented, anatomically correct bulb that is inserted into the horse’s left nostril for aerosol administration. The actuator has an airflow-direction vane, which helps determine when to deliver a puff to the horse (administering inhaled medications is most effective when the horse inhales). Boehringer has a video to instruct veterinarians and their clients on administration and use of Torpex.

The advantage to using an drug delivery device specifically designed for the horse is that the medication begins working faster than systemically administered medications, and the effect on the target tissues (lungs) is maximized while minimizing the effects on the horse’s entire system.

To gain FDA approval, Torpex underwent a number of studies to determine the effective dose and the duration of the medication’s effect. Additionally, researchers examined the drug for safety to the horse, possible side effects, safety to the administrator, and tolerance. Most of the research was done by individuals in the Pulmonary Laboratory at Michigan State University, and by scientists at Washington State University. Through their studies, researchers designed each actuation--or puff--on the canister valve to release 120 micrograms (mcg) of the drug. The recommended dose is three puffs, but for horses which don’t respond, the dose can be repeated for a total of six puffs. Each canister contains sufficient medication to provide 200 puffs to the horse.

Researchers found that the onset of action ranged from five to 15 minutes, and the minimum duration of the effect from a single treatment of the drug is one hour. However, the effects might persist for up to seven hours. The horse can have up to four doses a day for a maximum of five days.

In a more informal study of 144 horses, 64% showed perfect compliance on the first day of administration, 82% showed compliance by the second day, and 92% showed compliance by the seventh day.

The only real maintenance required for the Torpex device is cleaning. The bulb that fits in the horse’s nostril is easily removed and can be rinsed or washed in soap and water. Torpex is a prescription drug/device combination only available to veterinarians, who can get more information about the product by contacting Boehringer-Ingelheim Vetmedica, Inc., at 800/325-9167.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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