FDA approves extended-release Proin for dogs

April 2, 2019

New formulation offers once-daily dosing option for the control of urinary incontinence resulting from urethral sphincter hypotonus in veterinary patients.

K. Thalhofer / stock.adobe.comThe FDA has announced the approval of Proin ER (phenylpropanolamine hydrochloride extended-release) tablets for the control of urinary incontinence due to urethral sphincter hypotonus in dogs, an age-associated condition in which urethral muscles weaken and lose the ability to hold back urine.

Proin Chewable Tablets, already approved for use in dogs, are given twice daily for a total daily dose of 2 to 4 mg/kg. The approval of Proin ER, which is dosed once daily at the same total dose rate, gives veterinarians and pet owners an easier option for managing this condition, according to an FDA release.

Data confirming the effectiveness of Proin ER come courtesy of a multiclinic field study involving 119 client-owned dogs whose urinary incontinence was being controlled by Proin Chewable Tablets. For the first week of the study, owners recorded the number of urinary accidents per day and whether the dog received its two daily doses of Proin Chewable Tablets. Dogs were then transitioned to Proin ER, and owners continued to record the number of urinary accidents for 28 days.

To determine the drug's effectiveness, the number of urinary accidents during the fourth week of Proin ER administration was compared with the number of accidents during the initial week on the original formulation. Data from the 104 dogs that completed the study showed that once-daily Proin ER was just as effective as twice-daily Proin:

75 of the 104 dogs had no urinary accidents during either the first week on Proin tablets or the fourth week after they were transitioned to Proin ER.

19 dogs had fewer urinary incontinence incidents with Proin ER than with the original Proin formulation.

10 dogs had more urinary accidents while on Proin ER than on the original formulation.

To assess drug safety, the dogs continued to receive Proin ER for a total of 180 days. The most common adverse reactions during the study period were vomiting, weight loss, hypertension and diarrhea. In some cases adverse effects resolved quickly on their own; in others the effects continued to occur intermittently throughout the study.

Manufactured by Pegasus Laboratories Inc. (Pensacola, Florida) and available by prescription only, Proin ER is available in 18-, 38-, 74-, or 145-mg tablets. It should not be used in dogs weighing less than 10 lb.