Voltaren gel (generic name: diclofenac gel 1%) is a nonsteroidal anti-inflammatory drug (NSAID) that is used to treat joint pain caused by osteoarthritis (OA) of the hands, wrists, elbows, knees, ankles, or feet. It is the first prescription topical gel approved to treat joint pain secondary to OA.
FDA Approval and Indications
Novartis was granted regulatory approval by the US Food and Drug Administration for Voltaren gel—the first topical treatment that patients can apply directly to their skin to relieve pain associated with osteoarthritis. As per FDA guidelines, it is only approved for “relief of the pain of osteoarthritis of joints amenable to topical treatment.” That statement elucidates that Voltaren gel may not work in areas covered with thick muscle, but that does not stop physicians from prescribing the drug to be used in areas other than the approved indications. Though it’s not illegal to use a drug off-label, medical providers should discuss the pros and cons of using the gel with patients.
How Does it Work?
NSAIDs are non-narcotic drugs with analgesic (pain relieving), antipyretic (fever reducing), and anti-inflammatory effects. The term “non-steroidal” is used to differentiate these drugs from steroids, which have a similar anti-inflammatory activity. There are several types of NSAIDs, and diclofenac belongs to the arylalkanoic acid type.
A signaling molecule called eicosanoid controls inflammation and immunity in the body. NSAIDs downregulate the production of eicosanoid, particularly prostaglandin, by inhibiting the enzyme cyclooxygenase (COX). Diclofenac inhibits both COX-1 and COX-2 enzymes. This enzyme converts arachidonic acid to prostaglandin and thromboxane. Prostaglandin is one of the four families of eicosanoid and is produced at the site of tissue damage or infection. This causes pain, inflammation, and fever, which are all part of the natural healing process.
The inhibition of COX can provide inflammation and pain relief. NSAIDs like ibuprofen, aspirin, and diclofenac are powerful agents that can slow down or stop even inflammation or pain arising from the nervous system. However, the action of NSAIDs is a double-edged sword. While it can provide potent pain relief, it is also associated with adverse gastrointestinal irritation. Utilizing diclofenac in a topical gel form eliminates the risks associated with its oral use. The active ingredient is delivered directly to the site of pain, while sparing the gastrointestinal tract from irritation and bleeding. It is proven to be effective in treating pain of the hands and knees. However, it may not be effective for spine, hip, or shoulder pain.
Safety and Efficacy
Voltaren gel is effective for acute muscle and skeletal pain, as well as chronic conditions like knee OA. Due to minimal systemic absorption, it is associated with lower risks of side effects compared to oral diclofenac. A systemic review and network meta-analysis examined the efficacy of NSAIDs for arthritis pain, and found that diclofenac, ibuprofen, naproxen, celecoxib, and etoricoxib were more effective than placebo. However, patients who use NSAIDs for longer periods have a three times greater risk for adverse gastrointestinal events compared to non-users.  In a randomized, three-way crossover study by Dr. Kienzler and Dr. Gold, diclofenac sodium gel 1% inhibited COX-1 and COX-2 less than oral diclofenac, but systemic exposure was five-to 17-fold lower. Side effects were also mild and temporary.
Good Candidates for Treatment
Voltaren gel is recommended for osteoarthritic patients who want to reduce their risk for gastrointestinal tract toxicity and hepatic problems. What’s more, some individuals respond poorly to diclofenac when taking it orally. Voltaren gel improves tolerability and reduces systemic exposure to the drug.
Warnings and Contraindications
- NSAID use is associated with potentially fatal cardiovascular thrombotic events, heart attack, and stroke. Apply the lowest possible dose in patients with a known heart problem or history of heart disease.
- Voltaren gel, like most NSAIDs, can cause gastrointestinal side effects such as inflammation, bleeding, perforation, and ulceration.
- Discontinue the use of topical gel if abnormal liver tests continue or worsen.
- Long-term application of diclofenac gel can result in kidney necrosis and other kidney injuries.
- Blood pressure should be monitored during treatment, as NSAIDs may cause hypertension.
- Dermal side effects include exfoliative dermatitis, toxic epidermal necrolysis, and other adverse events that can be fatal.
- Do not use Voltaren gel with aspirin, as this could potentially increase side effects, including gastrointestinal bleeding.
- Do not use Voltaren gel in patients who are set to undergo coronary artery bypass graft surgery.
- Avoid using this with other topical products, such as sunscreen, lotions, cosmetics, and insect repellants, as it may cause skin reactions.
How to use Voltaren gel
The daily dose for topical Voltaren should not exceed 32g. For upper extremities, apply at least 2g to the affected area four times a day. For lower extremities, apply 2g of gel to the affected joint four times daily. Patients should not double their dose without permission from a medical professional. There is a dosing card included with every purchase of Voltaren gel to help patients apply the drug to the affected joints.