How diclofenac works
Diclofenac is a so-called non-steroidal anti-inflammatory drug (NSAID). The active ingredient inhibits the formation of so-called prostaglandins by blocking the enzymes responsible for them (cyclooxygenase 1 and 2).
Prostaglandins are tissue hormones that are involved in inflammatory processes, pain mediation and the development of fever. By inhibiting prostaglandin synthesis, diclofenac thus has an analgesic, anti-inflammatory and antipyretic effect.
Absorption, degradation and excretion
The analgesic is metabolized by the liver and most of it is excreted by the kidneys. The time for the body to excrete half of the active ingredient is about one to three hours.
However, diclofenac accumulates in tissues with acute inflammatory response and mediates its effects at the affected site until about six hours after ingestion.
When is diclofenac used?
It is also given long-term in low doses for the treatment of diseases such as osteoarthritis, arthritis, gout, and for pain after operations and injuries.
Diclofenac eye drops are available for the prevention and treatment of inflammatory and painful processes in the eye (e.g. after cataract surgery).
How Diclofenac is used
Diclofenac gel, diclofenac ointment or diclofenac spray are usually used to treat pain and inflammation of muscles, tendons or joints. These topical dosage forms have the advantage that they achieve a high concentration of active ingredient, especially in localized pain conditions.
Diclofenac suppositories are particularly suitable for children and patients with swallowing difficulties. The active ingredient is also available as an injection solution and adhesive patches.
For long-term treatment, tablets, active ingredient patches and delayed-release capsules (diclofenac retard capsules) are frequently used. Especially with patches and sustained-release tablets, it is easy to achieve constant levels of the active ingredient in the blood.
Frequency of use
The frequency of use depends on the dosage form and the dose strength.
For oral preparations, the following applies: over-the-counter medicines containing diclofenac – just like other over-the-counter painkillers – should not be taken for more than three days in a row and not more often than ten days a month without a doctor’s advice.
Prescription drugs containing Diclofenac are used according to the doctor’s instructions. The dosage is determined individually.
While topical diclofenac preparations (such as ointments, gels and patches) are available without a prescription in Germany, Austria and Switzerland, this only applies to Germany and Switzerland for low-dose tablets. In Austria, diclofenac tablets in any dosage require a prescription.
What are the side effects of Diclofenac?
- Nausea
- Diarrhea
Frequently (in one to ten percent of users) develop:
- Abdominal pain
- Increase in liver enzyme levels
- Itching @
- Dizziness
If severe side effects occur (especially adverse effects in the gastrointestinal tract), you should inform a doctor immediately.
What should be considered when using Diclofenac?
Contraindications
In principle, diclofenac should not be used in combination with other painkillers from the class of non-steroidal anti-inflammatory drugs or if there is an intolerance to this class of drugs. In addition to diclofenac, the non-steroidal anti-inflammatory drugs include, for example, acetylsalicylic acid (ASA), ibuprofen and naproxen.
Other contraindications include:
- Gastrointestinal ulcers
- Blood formation disorders
- ischemic heart disease (coronary artery disease)
- peripheral arterial disease and vascular disease in the brain (cerebrovascular disease)
- severe renal and hepatic dysfunction
In other cases, the analgesic should be used only with caution and in consultation with a doctor, such as in:
- inflammatory bowel disease (Crohn’s disease, ulcerative colitis)
- asthma (risk of severe asthma attacks and other consequences)
Drug interactions
When used concomitantly, diclofenac may increase blood levels of lithium (in mental illness), digoxin (in heart disease), and phenytoin (in epilepsy). Blood levels of these agents should therefore be monitored.
Because of possible interactions, caution should also be exercised with concomitant use of:
- ACE inhibitors (e.g., for high blood pressure, cardiac insufficiency)
- glucocorticoids (“cortisone”)
- Diuretics (dehydrating agents)
- drugs that damage the kidneys (such as tacrolimus, ciclosporin, methotrexate)
- fluoroquinolones (antibiotics)
- oral diabetes medications
- strong CYP2C9 inhibitors such as voriconazole (antifungals)
Those who take alcohol in addition to diclofenac place a double burden on their liver, because the detoxification organ must break down both substances. An increase in the bleeding tendency is also discussed when diclofenac and alcohol are taken simultaneously.
Age restriction
The age at which use of over-the-counter and prescription preparations containing diclofenac is permitted depends on the particular dosage form (tablet, suppository, gel) and may vary between products.
After a doctor’s prescription, use is possible even in childhood.
Pregnancy and lactation
Diclofenac should be used cautiously in the first and second trimesters and only after better studied analgesics such as paracetamol or ibuprofen have been exhausted. In the last trimester, diclofenac is contraindicated.
How to get medicines with Diclofenac
Medicines containing diclofenac can be obtained only through pharmacies. Certain dosage forms are available over-the-counter, i.e., without a prescription. In Germany, Austria and Switzerland, this applies to topical dosage forms (such as diclofenac gel, ointment, spray).
Single-dose forms (such as tablets, soft capsules, suppositories) with a maximum active ingredient content of 25 milligrams are available without a prescription in Germany and Switzerland, but not in Austria.
How long has diclofenac been known?
Diclofenac was systematically developed from older pain-relieving agents of the non-steroidal anti-inflammatory class. It was launched on the market in 1974 and is now a component of numerous medications.
