Zipsor is a prescription analgesic (pain reliever) approved by the FDA in June 2009. The active ingredient in Zipsor is 25 mg diclofenac potassium, formulated for immediate release in a soft gelatin capsule. It may be taken up to four times per day.
Diclofenac is a non-steroidal anti-inflammatory drug (NSAID). Like all NSAIDs, Zipsor is non-narcotic and non-addicting. These features makes it a useful choice in managing mild to moderate acute pain. NSAIDs can have mild or serious side effects, especially with long-term use, so many are only available by prescription. Zipsor is not available over-the-counter, although in some European companies diclofenac is available without a prescription.
New Formulation of Diclofenac
While the FDA approved the ingredient diclofenac in 1998, Zipsor is the only diclofenac product in the U.S. that contains 25 mg of the drug for immediate release. The only other immediate-release formulations are for 50 mg. The new lower dose is important because experts recommend that the lowest effective dose be used for all NSAIDs due to their potential side effects. Before Zipsor, patients could only obtain the 25 mg dose in a delayed-release form.
How It Works
Zipsor works by inhibiting an enzyme called cyclooxygenase (COX). COX is needed to produce prostaglandins, hormones that trigger pain and inflammation. This mechanism of action is the same as for other NSAIDs, such as ibuprofen.
Diclofenac may be used as a salt of either sodium or potassium. Diclofenac potassium, the form used in Zipsor, is removed from the body more slowly than diclofenac sodium. Therefore, it may be effective for a longer period.
The label for Zipsor comes with two “black box” warnings from the FDA. NSAIDs can increase the risk of severe cardiovascular problems including stroke, clots (thromboses), and heart attack. They also are known to irritate the stomach and can cause ulceration and even perforation of the stomach.
Both types of problems can have a sudden onset, occur without warning symptoms, and be fatal. These dangers are the reason for the recommendation that patients use the lowest effective dose of NSAIDs.
NSAIDs are also associated with severe, potentially fatal skin reactions such as Steven-Johnsons syndrome. They can cause allergic reactions, including anaphylaxis. (Find out what to do in an anaphylaxis emergency.) With long-term use, they can cause kidney damage. Fortunately, these side effects are rare.
Other possible side effects of NSAIDs, including Zipsor, include:
- Liver dysfunction
- High blood pressure, fluid retention, and/or edema (swelling)
- Gastrointestinal problems, including abdominal pain, nausea, vomiting, diarrhea, bleeding, stomach ulcers, and stomach perforation (a hole in the stomach wall)
For more information about side effects, including your risk of serious side effects, ask the person who prescribed the drug or your pharmacist.
- FDA drug label for Zipsor
- Omudhome Ogbru, Pharm. D. “Diclofenac.” MedicineNet.com.
- Ahmad M, Iqbal M, Murtaza G. Comparison of bioavailability and pharmacokinetics of diclofenac sodium and diclofenac potassium in normal and dehydrated rabbits. Yao xue xue bao = Acta pharmaceutica Sinica. 2009 Jan;44(1):80-4.