Diclofenac is a type of medicine that belongs to the group known as NSAIDs (non-steroidal anti-inflammatory drugs). NSAIDs relieve pain and reduce the inflammation and fever produced by the body's immune system. Diclofenac is considered safe, is faster acting than ibuprofen, and remains effective longer than paracetamol. Dilcofenic is a relatively potent NSAID. It is a phenylacetic or benzeneacetic acid derivative with the chemically designation 2-(2,6-dichlorophenyl)amino phenylacetic acid or benzeneacetic acid, monosodium or monopotassium salt. Diclofenac sodium was first synthesised by Ciba-Geigy of Switzerland in 1965 and was launched as Voltaren in 1988.Voltaren Emulgel contains diclofenac sodium, as diclofenac diethylammonium, and Voltaren Rapid contains diclofenac potassium as their respective active ingredients. In Voltaren Rapid, the potassium ion is used to replace the sodium ion but the active ingredient remains the same. The sodium salt and potassium salt used are biologically equivalent, with both being protonated by the acid in the stomach. One difference is that diclofenac potassium is slightly more soluble in water than diclofenac sodium. Diclofenac has analgesic, antirheumatic, antipyretic and anti-inflammatory properties. It is a non-selective COX inhibitor. It works by blocking an enzyme in the body known as cyclo-oxygenase (COX). Cyclo-oxygenase is involved in the production of numerous chemicals in the body, including those known as prostaglandins. Prostaglandins are produced by the body in response to the presence of injury or disease and they make the nerves more sensitive to pain impulses. They produce pain, inflammation, and fever because they are hyperalgesic, pro-inflammatory, and pyretic. By reducing the amount of prostaglandin produced and inhibiting its biosynthesis by the body, diclofenac is able to relieve each of these symptoms. The analgesic properties of diclofenac make it effective in cases of moderate to severe pain where rapidly relief is required. Diclofenac is used to treat a wide range of musculoskeletal disorders, including muscular aches, sprains, strains, tendonitis (tendon inflammation), bursitis, bruises, fractures and dislocations. It is effective in the treatment of joint disorders, including arthritis, osteoarthritis (a degenerative joint condition), rheumatoid arthritis (inflammation of the joints), ankylosing spondylitis (an inflammation of the vertebrae, also called Bechterew's disease), and pyrophosphate arthropathy (crystal deposits in the joints). Diclofenac in gel form is particularly useful for alleviating the pain and inflammation of muscle, joint, tendon and ligament injuries, and soft tissue rheumatism because it is applied topically to the skin. Diclofenac is also used to provide relief for those who suffer from acute gout, lower back pain, migraine headache, menstrual pain and dysmenorrhoea. It can alleviate the discomfort associated with inflammatory infections of the ear, nose, or throat, post-operative pain or inflammation due to trauma following dental, orthopaedic, or other minor surgery.The absorption process begins immediately after the tablets are taken, with pain relief usually occurring within 15 to 30 minutes. With Voltaren Rapid oral tablets, the diclofenac potassium is quickly released into the blood stream to provide fast relief from pain. Approximately half of the diclofenac is metabolised during its first passage through the liver. About 60% of the administered dose will be excreted through the urine, via the kidneys, with less than 1% of that which is excreted remaining unchanged. The rest of the dose will be eliminated as metabolites through bile and in the faeces. The pharmacokinetic behaviour of diclofenac will not change after repeated doses and diclofenac will not accumulate in the body provided that the dosages are taken at regular intervals.The biotransformation of diclofenac occurs partly because of the glucuronidation of the intact molecule, but it is mostly the result of single and multiple hydroxylation and methoxylation. This creates several phenolic metabolites, most of which are converted to glucuronide conjugates.Diclofenac enters the synovial fluid, where the maximum concentrations will be measured 2 to 4 hours after peak plasma levels are reached. Two hours after reaching peak plasma levels, the concentration of diclofenac will be higher in the synovial fluid than in the plasma. The terminal half-life for diclfenac in plasma is 1 to 2 hours, while the half-life for the elimination from the synovial fluid is 3 to 6 hours.