The U.S. Food and Drug Administration announced on February 17, 2017, the approval of Diroban (melarsomine dihydrochloride), the first generic drug to treat heartworm disease in dogs. Diroban must be prescribed by a licensed veterinarian because professional expertise is needed to correctly diagnose the severity of a dog’s heartworm disease and administer the drug as part of a treatment plan.
Heartworm disease is caused by a thread-like parasitic worm called Dirofilaria immitis. The worms are called heartworms because the adult worms live in the heart, lungs, and associated blood vessels of an infected animal. In dogs, the disease results in heart failure, severe lung disease, other organ damage, and death. Heartworm disease is only spread through the bite of a mosquito; it cannot be transmitted directly from one dog to another.
Diroban is administered by deep injection into the back muscles. It is used to treat dogs with stabilized class 1 (no symptoms), class 2 (mild to moderate respiratory symptoms), and class 3 (severe respiratory symptoms) heartworm disease, but should not be used in dogs with class 4 (extremely severe respiratory symptoms) heartworm disease. Side effects of treatment may include pain, swelling, or tenderness at the injection site, coughing/gagging, decrease in activity level, lack of appetite, fever, and vomiting. Dogs should be closely monitored by a veterinarian during treatment. Following treatment, dogs should have restricted exercise for up to six weeks because active dogs are at risk for blood clots in the lungs.