Diclofenac available as a topical (external use, applied to the skin) patch is non-steroidal anti-inflammatory for the treatment of the acute pain due to strains, sprains, contusions, and trauma. As a patch the drug is supplied as the epolamine salt, other forms include Diclofenac potassium in tablet form as Cataflam (50mg tablets) and Zipsor (25mg liquid filled capsules).

The 1.3% patch contains 180mg of the active drug, applied twice daily to the most painful area involved. Orally the dosage for pain, fever, and inflammation is 50mg three times daily or the 25mg capsule four times daily after meals in patients 18 and older.

Diclofenac patches should be applied only to intact skin and should be avoided in patients with a history of asthma, are allergic to aspirin or other NSAIDs, have undergone coronary artery bypass graft t surgery (CABG). Whether topical or oral, the drug may aggravate gastrointestinal pathology with increased risks of GI (stomach) ulceration, bleeding and perforation.

Cardiac reactions may include serious and fatal thrombotic(blood clotting) events, myocardial infarction,(heart attack) CVA(stroke ) Effects on the liver may be detected with increased liver function test results, Minor blood pressure rises may also occur. Those patients who retain fluids or have compromised heart function must use diclofenac with caution due to possibility of increasing fluid retention. The long term application or oral use of diclofenac may cause papillary necrosis and other renal diseases(kidney diseases).

Skin reactions such as TEN (topical epidermal necrosis, Stevens - Johnson syndrome (SJS) and exfoliative (severe peelingn) dermatitis may occur. The drug is avoided in pregnant patients past 30 weeks of gestation. Diclofenac should not be used in conjunction with other NSAIDs and the used patches should be disposed of properly to avoid accidentally poisoning of pets or young children Bleeding may occur due to its anti-platelet effect preventing adhesion. To avoid the possibility of anemia,(reduced red blood cells) patients should have routine labs including hemoglobin and hematocrit, and the drug may be discontinued if platelet function is compromised. This effect is reversible upon discontinuation of drug, much faster then aspirin. Other adverse reactions include he possibility of abdominal discomfort, bloating, constipation or diarrhea, indigestion with nausea, headache, dizziness, pruritis (itching), and tinnitus (ringing in the ear)

Diclofenac mechanism of action is the inhibition of prostaglandin synthesis.

Possible drug interactions may occur as with other NSAIDs to various medications.

When co-administered with aspirin, the protein binding of diclofenac is reduced and decreased therapeutic response may occur. Given with anticoagulants a

synergistic(additive) response my lead to GI (stomach) bleeding, the antihypertensive effects of ACE-inhibitors may be diminished with doses with diclofenac.

Reduced diuretic effects of the loop(section in the kidney) (furosemide) and thiazide (hydrochlorothiazide) may occur with diclofenac which necessitate monitoring with laboratory renal studies.

Lithium carbonate levels may be elevated with diclofenac, producing increased concentration by as much a 15% which may produce lithium toxicity.

The use of diclofenac in the elderly, especially with reduced renal function should be used cautiously and monitored regularly with renal function testing.

The application of any drug in patch formulation also has the additional possibility of skin reaction due to the direct patch application of the material and /or the delivery system, causing sometimes burning , tingling, dryness, formation of local vesicles or bulla(blisters), irritation of the skin, redness( erythema) discoloration, hyperhydrosis(increase moisture). These can generally be reversed or addressed with the discontinuation of the patch and local treatment.

REFERENCES

MPR, Monthly Prescribing Reference, 2011 Edition, Pain Management

The Medication Guide, King Pharmaceuticals, Inc., February 2011

Personal use in my practice as Podiatrist has found favorable results, When prescribed for ankle sprains and overuse tendonitis, with adjunct treatment, and proper application significant pain relief in most instances is reported in two to three days. It is easily applied and compliance is usually excellent.

ADDITIONAL REFERENCES

Mayo Clinic

MedlinePlus

Medscape

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