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Diclofenac

Generality

Diclofenac is a non-steroidal anti-inflammatory drug (NSAID), used in the treatment of inflammatory and painful conditions of various kinds.

Diclofenac - Chemical Structure

Diclofenac is available in numerous pharmaceutical formulations, suitable for different administration routes (oral, parenteral, ocular, rectal and cutaneous).

From a chemical point of view, diclofenac belongs to the category of acetic acid derivatives.

Examples of medicinal specialties containing Diclofenac

  • Deflamat ®
  • Dicloreum ®
  • Flector ®
  • Solaraze ®
  • Voltaren Emulgel ®

Indications

For what it uses

The use of diclofenac is indicated for the symptomatic treatment of inflammation and / or pain caused by:

  • Rheumatoid arthritis;
  • Osteoarthritis;
  • Ankylosing spondylitis;
  • periarthritis;
  • bunions;
  • Tendinitis;
  • myositis;
  • sciatica;
  • Gout;
  • Injuries, fractures or traumas;
  • Stretching, bruising or distortions;
  • Orthopedic surgical interventions;
  • Kidney stones.

Furthermore, diclofenac can be used for the symptomatic treatment of primary dysmenorrhoea (oral administration) and for the treatment of inflammation (on a non-infectious basis) of the anterior segment of the eye, in particular after cataract surgery (administration by eye).

Warnings

Before starting diclofenac therapy for oral, rectal or parenteral use, you must inform your doctor if you are in any of the following conditions:

  • If you have a smoking habit;
  • If you have diabetes;
  • If you suffer from cardiovascular diseases (angina, hypertension, blood clots);
  • If you suffer from hypercholesterolemia and / or hypertriglyceridemia;
  • If you have a history of gastrointestinal ulceration, perforation and / or bleeding;
  • If you suffer from ulcerative colitis or Crohn's disease;
  • If you have a history of kidney and / or liver disease;
  • If you suffer - or have suffered in the past - from blood disorders;
  • If you are suffering from systemic lupus erythematosus;
  • If you suffer - or have suffered in the past - from asthma, chronic obstructive pulmonary disease (COPD), nasal polyps or allergic rhinitis;
  • If you are planning to become pregnant, as diclofenac may adversely affect female fertility.

Diclofenac administered orally, rectally or parenterally may cause gastrointestinal ulceration, perforation and / or bleeding. Therefore, should any gastrointestinal symptom appear, it is necessary to immediately inform the doctor. Furthermore, diclofenac administered via these routes may also cause an increased risk of myocardial infarction or stroke, especially when used at high doses and for long periods.

Diclofenac for skin use should only be applied to intact skin and never to injured skin.

Patients wearing soft contact lenses should avoid contact lenses with diclofenac for ocular use, as the drug exerts bleaching action on them.

Diclofenac administered orally, rectally or parenterally could cause side effects that can alter the ability to drive and / or use machinery, so great care should be taken.

Interactions

At the moment there are no known drug interactions between diclofenac for dermal use and for ocular use and other drugs.

Instead, before starting diclofenac therapy for oral, rectal or parenteral use - due to the drug interactions that could occur - you need to tell your doctor if you are already taking any of the following medications:

  • Other NSAIDs, including selective COX-2 inhibitors (such as, for example, celecoxib and etoricoxib);
  • Antidiabetic drugs;
  • Anticoagulant drugs, such as warfarin or heparin;
  • Antiplatelet agents ;
  • Diuretics ;
  • Lithium salts, used in the treatment of bipolar disorder;
  • Phenytoin, an antiepileptic;
  • Cardioactive glycosides, such as, for example, digoxin;
  • Quinolones, antibiotic drugs;
  • Cyclosporine and tacrolimus, immunosuppressive drugs;
  • Methotrexate and pemetrexed, anticancer drugs;
  • Corticosteroids ;
  • Colestipol and cholestyramine, drugs used to decrease cholesterol levels too high;
  • Voriconazole, an antifungal;
  • Antihypertensive drugs;
  • SSRIs (selective serotonin reuptake inhibitors), antidepressant drugs;
  • Anxiolytic drugs;
  • Deferasirox (Exjade ®), a drug given to patients subjected to frequent blood transfusions;
  • Sulfinpyrazone, a drug used in the treatment of hyperuricemia and gout;
  • Zidovudine, used in the treatment of HIV.

In any case - regardless of the route of administration used - it is however advisable to inform the doctor if you are taking, or have recently been, any type of medication, including over-the-counter medicines and herbal and homeopathic products.

Side effects

Diclofenac can cause several side effects, although not all patients experience them. This depends on the sensitivity that each individual has towards the drug.

Listed below are some of the side effects that may occur during diclofenac therapy.

Blood and lymphatic system disorders

Diclofenac-based therapy can lead to:

  • Aplastic anemia;
  • Hemolytic anemia;
  • agranulocytosis;
  • Leukopenia;
  • Thrombocytopenia.

Allergic reactions

Diclofenac can trigger allergic reactions in sensitive individuals. These reactions can occur in the form of hypotension, angioedema and anaphylactic shock.

Gastrointestinal disorders

Treatment with diclofenac may cause:

  • Nausea and vomit;
  • Diarrhea or constipation;
  • Hemorrhagic diarrhea;
  • Melena;
  • Hematemesis;
  • Abdominal pain;
  • Flatulence;
  • Anorexia;
  • Gastritis;
  • Gastrointestinal ulceration, perforation and / or bleeding;
  • Colitis;
  • Exacerbation of ulcerative colitis and Crohn's disease in patients suffering from it;
  • Pancreatitis.

Nervous system disorders

Diclofenac therapy may cause:

  • Headache;
  • dizziness;
  • Drowsiness;
  • paresthesia;
  • Tremors;
  • Alterations in the sense of taste;
  • Convulsions;
  • Aseptic meningitis.

Psychiatric disorders

During treatment with diclofenac disorientation, excitement, depression, irritability, insomnia, nightmares, anxiety and psychotic reactions may occur.

Cardiovascular disorders

Diclofenac can promote the onset of hypertension, vasculitis, palpitations, heart failure and myocardial infarction.

Hepatobiliary disorders

Treatment with diclofenac may cause an increase in blood transaminase levels and promote the onset of liver failure, hepatitis and jaundice.

Kidney and urinary tract disorders

Diclofenac therapy may cause acute renal failure, hematuria, proteinuria, interstitial nephritis, nephrotic syndrome and renal papillary necrosis.

Skin and subcutaneous tissue disorders

Treatment with diclofenac may cause:

  • Skin rash;
  • Urticaria;
  • Eczema;
  • Erythema;
  • Erythema multiforme;
  • Stevens-Johnson syndrome;
  • Toxic epidermal necrolysis;
  • Exfoliative dermatitis;
  • Alopecia;
  • Photosensitivity reactions;
  • Bullous dermatitis;
  • Purple or allergic purple;
  • Itch.

Other side effects

Other adverse reactions that may occur during diclofenac therapy are:

  • Asthma;
  • Vision disorders;
  • Tinnitus;
  • Worsening of hearing;
  • Dizziness;
  • Asthma;
  • Edema;
  • Reactions at the injection site (when the drug is given parenterally);
  • Itching, redness, burning of the eye (when diclofenac is administered via the eye).

Overdose

If overdoses of diclofenac are taken, the following may occur:

  • He retched;
  • Diarrhea;
  • dizziness;
  • Tinnitus;
  • Gastrointestinal hemorrhage;
  • Convulsions.

Since there is no specific antidote, in case of overdosage, the treatment is only symptomatic and supportive.

In any case, if you suspect a diclofenac overdose, you must contact your doctor immediately or go to the nearest hospital.

Action mechanism

Diclofenac exerts its anti-inflammatory and analgesic action by inhibiting cyclooxygenase (or COX).

Cyclooxygenase is an enzyme of which three different isoforms are known: COX-1, COX-2 and COX-3.

COX-1 is a constitutive isoform, normally present in cells and involved in the mechanisms of cellular homeostasis.

COX-2, on the other hand, is an inducible isoform that is produced by inflammatory cells (inflammatory cytokines) activated. The task of these enzymes is to convert arachidonic acid into prostaglandins, prostacyclines and thromboxanes.

Prostaglandins - in particular, prostaglandins G2 and H2 - are involved in inflammatory processes and mediate pain responses.

Therefore, with the inhibition of cyclooxygenase 2, diclofenac hinders the production of prostaglandins responsible for pain and inflammation.

However, it is worth remembering that diclofenac is not a selective COX-2 inhibitor, therefore, it is also able to inhibit COX-1. This latter inhibition is at the origin of some of the side effects typical of all non-selective NSAIDs.

Mode of Use - Posology

Diclofenac is available for:

  • Oral administration in the form of hard capsules, oral solution, tablets, granules for oral solution and soluble tablets.
  • Rectal administration in the form of suppositories.
  • Parenteral administration (intramuscular or subcutaneous) as a solution for injection.
  • Dermal administration in the form of gel, skin foam, dermatological solution and medicated plasters.
  • Ocular administration in the form of eye drops.

To avoid the occurrence of dangerous side effects, during treatment with the drug, it is very important to follow the instructions provided by the doctor, both as regards the amount of diclofenac to be taken, and as regards the duration of the treatment itself.

In the following, however, some indications are given on diclofenac doses usually administered in therapy.

However, to know the exact dosage of each pharmaceutical formulation, see the illustrative leaflets of the individual medicinal products.

Elderly patients may need to adjust the diclofenac doses usually used.

Oral administration

When administered orally, the dose of diclofenac usually used is 50-100 mg per day, depending on the severity of the symptoms presented by the patients. The dose can be increased up to a maximum of 150 mg of drug per day.

Rectal administration

When diclofenac is used rectally, the recommended dose is 50 mg 1-3 times a day, or 100 mg 1-2 times a day.

Parenteral administration

When administered intramuscularly, the diclofenac dose usually used is 25-75 mg per day, depending on the severity of the symptoms presented by the patients. If the doctor deems it necessary, he can decide to increase the daily dose up to a maximum of 150 mg.

Cutaneous administration

When using diclofenac-based gel, it is recommended to carry out 3-4 applications a day.

When using skin foam, however, it is advisable to apply 1-3 applications a day.

In the case of the medicated plaster, it is advisable to apply 1-2 patches and to replace it / them every 12-24 hours, according to medical prescription.

Ocular administration

Diclofenac-based eye drops are used to treat inflammation of the anterior segment of the eye (on a non-infectious basis) and, in particular, following cataract surgery. The dosage of the drug must be established by the doctor on an individual basis.

Pregnancy and breastfeeding

During the first and second trimester of pregnancy, diclofenac should only be used if the doctor considers it absolutely necessary.

In the third trimester of pregnancy, however, the drug is contraindicated due to the damage it can cause to the fetus (cardiopulmonary toxicity, renal dysfunction and prolonged bleeding time at birth) and to the mother (inhibition of uterine contractions with consequent delay or prolongation of the labor and increased bleeding time).

Furthermore, the use of diclofenac is also contraindicated in breastfeeding mothers.

Contraindications

The use of diclofenac by oral, rectal or parenteral route is contraindicated in the following cases:

  • In patients with known hypersensitivity to the same diclofenac (even when the drug is administered dermal or ocular);
  • In patients with known hypersensitivity to acetylsalicylic acid, to other NSAIDs or to analgesic-antipyretics (even when the drug is administered via the dermal route);
  • In patients who have had asthma attacks, urticaria or acute rhinitis following the administration of other NSAIDs (even when the drug is administered via the skin or eye);
  • In patients with ongoing gastrointestinal ulceration, perforation and / or bleeding;
  • In patients who have suffered from perforation or gastrointestinal bleeding after taking other NSAIDs;
  • In patients with impaired bone marrow function;
  • In patients undergoing intensive diuretic therapy;
  • In patients with coagulation disorders;
  • In patients suffering from cardiovascular diseases;
  • In patients with severe hepatic and / or renal insufficiency;
  • In the last trimester of pregnancy (even when the drug is administered via the skin and eye);
  • During lactation (even when the drug is administered via the skin and eye).

Furthermore, the use of diclofenac is contraindicated in children and adolescents under 14 years of age when the drug is administered orally, rectally or dermally, in adolescents under 16 years old when using the medicated diclofenac-based patch and in adolescents under 18 years of age when the drug is given parenterally.

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