What are diclofenac tablets?
DICLOFENAC (Voltaren®) is an anti-inflammatory drug. Diclofenac reduces the joint pain, stiffness, inflammation, or swelling caused by rheumatoid arthritis (rheumatism) and osteoarthritis. Generic diclofenac delayed-release tablets are available.
What should I tell my health care provider before I take this medicine?
They need to know if you have any of these conditions:
• asthma, especially aspirin sensitive asthma
• bleeding problems or taking medicines that make you bleed more easily such as anticoagulants ('blood thinners')
• cigarette smoker
• coronary artery bypass graft (CABG) surgery within the past 2 weeks
• dental disease
• drink more than 3 alcohol-containing beverages a day
• heart or circulation problems like angina, high blood pressure, heart failure, heart rhythm problems, history of heart attack, history of blood clots, or leg edema (fluid retention)
• kidney disease
• liver disease
• stomach or duodenal ulcers
• history of stroke
• systemic lupus erythematosus
• ulcerative colitis
• an unusual or allergic reaction to diclofenac, aspirin, other salicylates, other NSAIDs, other medicines, foods, dyes or preservatives
• pregnant or trying to get pregnant
How should I take this medicine?
Take diclofenac tablets by mouth. Follow the directions on the prescription label. Swallow tablets whole with a full glass of water; take tablets in an upright or sitting position. Do not crush or chew tablets. Taking a sip of water first, before taking the tablets, may help you swallow them. It is better to take diclofenac with food. Take your doses at regular intervals. Do not take your medicine more often than directed.
Contact your pediatrician or health care professional regarding the use of this medicine in children. Special care may be needed.
What if I miss a dose?
If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.
What drug(s) may interact with diclofenac?
• aspirin and aspirin-like medicines
• drospirenone; ethinyl estradiol (Yasmin®)
• herbal products that contain feverfew, garlic, ginger, or ginkgo biloba
• medicines for high blood pressure
• medicines that affect platelets
• medicines that treat or prevent blood clots such as warfarin and other 'blood thinners'
• other antiinflammatory drugs (such as ibuprofen or prednisone)
• water pills (diuretics)
Tell your prescriber or health care professional about all other medicines you are taking, including non-prescription medicines, nutritional supplements, or herbal products. Also tell your prescriber or health care professional if you are a frequent user of drinks with caffeine or alcohol, if you smoke, or if you use illegal drugs. These may affect the way your medicine works. Check with your health care professional before stopping or starting any of your medicines.
What side effects may I notice from taking diclofenac?
Elderly patients are at increased risk for developing side effects.
Side effects that you should report to your prescriber or health care professional as soon as possible:
• signs of bleeding from the stomach - black tarry stools, blood in the urine, unusual tiredness or weakness, vomiting blood or vomit that looks like coffee grounds
• signs of an allergic reaction - difficulty breathing or wheezing, skin rash, redness, blistering or peeling skin, hives, or itching, swelling of eyelids, throat, lips
• change in the amount of urine passed
• difficulty swallowing, severe heartburn or burning, pain in throat
• pain or difficulty passing urine
• stomach pain or cramps
• swelling of feet or ankles
• yellowing and/or itching of eyes or skin, upper right abdominal/chest tenderness, fatigue
Side effects that usually do not require medical attention (report to your prescriber or health care professional if they continue or are bothersome):
• constipation or diarrhea
• gas or heartburn
• nausea, vomiting
What should I watch for while taking diclofenac?
Let your prescriber or health care professional know if your pain continues, do not take with other pain-killers without advice. If you get flu-like symptoms (fever, chills, muscle aches and pains), call your prescriber or health care professional; do not treat yourself.
To reduce unpleasant effects on your throat and stomach, take diclofenac with a full glass of water and never just before lying down. If you notice black, tarry stools or experience severe stomach pain and/or vomit blood or what looks like coffee grounds, notify your health care prescriber immediately.
If you are taking medicines that affect the clotting of your blood, such as aspirin or blood thinners such as Coumadin®, talk to your health care provider or prescriber before taking this medicine.
You may get dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how diclofenac affects you. Do not sit or stand up quickly, especially if you are an older patient. This reduces the risk of dizzy or fainting spells.
Do not smoke cigarettes or drink alcohol; these increase irritation to your stomach and can make it more susceptible to damage from diclofenac.
If you are going to have surgery, tell your prescriber or health care professional that you are taking diclofenac. Diclofenac can cause you to bleed more easily. Problems can arise if you need dental work, and in the day to day care of your teeth. Try to avoid damage to your teeth and gums when you brush or floss your teeth.
It is especially important not to use diclofenac during the last 3 months of pregnancy unless specifically directed to do so by your health care provider. Diclofenac may cause problems in the unborn child or complications during delivery.
Where can I keep my medicine?
Keep out of the reach of children in a container that small children cannot open.
Store at room temperature below 30 degrees C (86 degrees F). Protect from moisture. Keep container tightly closed. Throw away any unused medicine after the expiration date.
Diclofenac is used to treat pain, inflammatory disorders, and dysmenorrhea.
Inflammatory disorders may include musculoskeletal complaints, especially arthritis, rheumatoid arthritis, polymyositis, dermatomyositis, osteoarthritis, dental pain, TMJ pain, spondylarthritis, ankylosing spondylitis, gout attacks, and pain management in cases of kidney stones and gallstones. An additional indication is the treatment of acute migraines. Diclofenac is used commonly to treat mild to moderate postoperative or post-traumatic pain, in particular when inflammation is also present, and is effective against menstrual pain and endometriosis.
As long-term use of diclofenac and similar NSAIDs predisposes for peptic ulcer, many patients at risk for this complication are prescribed a combination (Arthrotec) of diclofenac and misoprostol, a synthetic prostaglandin (PGE1) analogue, to protect the gastric mucosa.
An external, gel-based formulation containing 3% of diclofenac (Solaraze) is available for the treatment of facial actinic keratosis caused by overexposure to sunlight. Some countries have also approved the external use of diclofenac 1% gel to treat musculoskeletal conditions.
In many countries, eye drops are sold to treat acute and chronic nonbacterial inflammations of the anterior part of the eyes (e.g., postoperative states). A common brand name is Voltaren-ophtha.
- Hypersensitivity against diclofenac
- History of allergic reactions (bronchospasm, shock, rhinitis, urticaria) following the use of aspirin or another NSAID
- Third-trimester pregnancy
- Active stomach and/or duodenal ulceration or gastrointestinal bleeding
- Inflammatory intestinal disorders such as Crohn's disease or ulcerative colitis
- Severe insufficiency of the heart (NYHA III/IV)
- Patients recovering from heart surgery
- Severe liver insufficiency (Child-Pugh Class C)
- Severe renal insufficiency (creatinine clearance <30 ml/min)
- Caution in patients with pre-existing hepatic porphyria, as diclofenac may trigger attacks
- Caution in patients with severe, active bleeding such as cerebral hemorrhage
- NSAIDs in general should be avoided during dengue fever, as it induces (often severe) capillary leakage and subsequent heart failure.
- Diclofenac is among the better-tolerated NSAIDs. Though 20% of patients on long-term treatment experience side effects, only 2% have to discontinue the drug, mostly due to gastrointestinal complaints.
Mechanism of action
The exact mechanism of action is not entirely known, but the primary mechanism responsible for its anti-inflammatory, antipyretic, and analgesic action is thought to be inhibition of prostaglandin synthesis by inhibition of cyclooxygenase (COX). It also appears to exhibit bacteriostatic activity by inhibiting bacterial DNA synthesis.
Inhibition of COX also decreases prostaglandins in the epithelium of the stomach, making it more sensitive to corrosion by gastric acid. This is also the main side effect of diclofenac. Diclofenac has a low to moderate preference to block the COX2-isoenzyme (approximately 10-fold) and is said to have, therefore, a somewhat lower incidence of gastrointestinal complaints than noted with indomethacin and aspirin.
The action of one single dose is much longer (6 to 8 hr) than the very short half-life of the drug indicates. This could be partly because it persists for over 11 hours in synovial fluids.
Diclofenac may also be a unique member of the NSAIDs. Some evidence indicates it inhibits the lipoxygenase pathways, thus reducing formation of the leukotrienes (also pro-inflammatory autacoids). It also may inhibit phospholipase A2 as part of its mechanism of action. These additional actions may explain its high potency - it is the most potent NSAID on a broad basis.
Marked differences exist among NSAIDs in their selective inhibition of the two subtypes of cyclooxygenase, COX-1 and COX-2. Much pharmaceutical drug design has attempted to focus on selective COX-2 inhibition as a way to minimize the gastrointestinal side effects of NSAIDs such as aspirin. In practice, use of some COX-2 inhibitors with their adverse effects has led to massive numbers of patient family lawsuits alleging wrongful death by heart attack, yet other significantly COX-selective NSAIDs, such as diclofenac, have been well tolerated by most of the population.
Besides the well-known and often-cited COX-inhibition, a number of other molecular targets of diclofenac possibly contributing to its pain-relieving actions have recently been identified. These include:
- Blockage of voltage-dependent sodium channels (after activation of the channel, diclofenac inhibits its reactivation also known as phase inhibition)
- Blockage of acid-sensing ion channels (ASICs)
- Positive allosteric modulation of KCNQ- and BK-potassium channels (diclofenac opens these channels, leading to hyperpolarization of the cell membrane)
This article uses material from the Wikipedia article Diclofenac, which is released under the Creative Commons Attribution-Share-Alike License 3.0.