Furosemide is a diuretic agent that is widely used in the veterinary practice setting. Some of the more common indications for the use of this drug include treatment of patients with congestive heart failure, pulmonary edema, hypercalcemia, and acute, oliguric kidney failure.
Furosemide has a rapid onset of action, and it is this characteristic that makes it the drug of choice for managing the emergent patient with respiratory distress associated with cardiogenic or pulmonary edema. Drug formularies and other references cite dosages for furosemide - administered by the intravenous (IV) and intramuscular (IM) routes - for treating patients with acute cardiogenic or pulmonary edema. Although there are references for administering this drug subcutaneously (SC), it is not generally listed as a suggested route of administration for patients with acute, severe pulmonary edema.
The effect of a drug - regardless of how it is administered - is dependent on how well it is absorbed, effectively distributed to its target tissue, and metabolized. Some of the factors that determine the route by which a drug can be administered include its pH, lipid solubility, and protein binding. Whereas drugs administered intravenously typically have a very rapid effect, drugs administered subcutaneously are typically thought to have a slower rate of absorption and onset of effect. Intramuscular injections can be painful, elicit more stress, and drugs given by this route are typically absorbed more rapidly than those given subcutaneously due to the increased vascularity of the tissue.
Dyspneic patients with acute cardiogenic or pulmonary edema require prompt medical intervention. Providing oxygen and minimizing stress to the patient is key to successful management. Because placement of an intravenous catheter and painful IM injections (i.e. for administering furosemide) can exacerbate the stress and cause them to rapidly deteriorate, animals in respiratory distress are often first placed into an oxygen cage - to help improve their oxygenation and alleviate the distress associated with their dyspnea - prior to IV catheter placement.
This week's Evidence Based Update reveals the findings of a study that compared the diuretic effects of furosemide - when administered subcutaneously - to other routes of administration including a constant rate infusion, as well as the intravenous, intramuscular, and oral routes. View this Evidence Based Update - it's available for On Demand viewing (running time 9 mins; Approved for CE credit in New York and by the NJVMA, pending approval for CE credit by AAVSB RACE).
