Clonac - Dosage instructions | Interactions

This article was medically reviewed by M.Pharm, Marko Tanaskovic on August 12, 2018. To read more about an author, click here.

Clonac is a drug that contains active ingredient called diclofenac-sodium and belongs to the family of drugs known as non-steroidal-anti-inflammatory drugs (NSAIDs). Its mechanism of action is based on non-selective inhibition of cyclooxygenase - an enzyme responsible for releasing of inflammatory mediators (prostaglandins). It exerts anti-inflammatory, anti-pyretic and analgesic effects, therefore it is used for the treatment of rheumatic diseases, various types of pain and for lowering body temperature.


It is well known that all NSAIDs exhibit toxic effects on gastric mucosa which often leads to abdominal pain, stomach bleeding and to the occurrence of gastric ulcer. Among all NSAIDs, Clonac and diclofenac-sodium, respectively, has lowest potential for gastrointestinal toxicity.

However, this drug must not be used in patient who have gastric or duodenal ulcer. If you notice blood in stool, changed stool color (black-colored), you should inform your doctor immediately.

Clonac is contraindicated in patients who have difficulty breathing or respiratory disease. Inhibition of cyclooxygenase can lead to bronchoconstriction and narrowing of bronchi which lead to difficult breathing.

If you have ever had allergic reaction due to NSADs use (e.g. difficulty breathing, edema, skin rash or increased nose secretion), than you should not use this drug.

It is also contraindicated in last trimester of pregnancy.


Inhibition of cyclooxygenase can exert inhibitory effect on platelet aggregation and for that reason patients who are already taking acetylsalicylic acid or other inhibitors of platelet aggregation have to consult with the doctor prior starting the treatment. For that reason, this medication must be catiously used in patients who have coagulation disorders, high blood pressure, thrombosis or cardiac diseases.

Most of this medication is metabolized and excreted by the kidneys and liver, because of which it exerted potential for nephrotoxicity and hepatotoxicity. Therefore, this drug should be avoided in patients who already have impaired renal or hepatic function.

It must be used with extra precaution in patients above the age of 65, because elderly are more sensitive to Clonac's effects and therefore more prone to adverse effects.

Clonac use during pregnancy and breastfeeding

Use of Clonac during last trimester of pregnancy can lead to fetal anomalies. Because of that, use of this medication during pregnancy must be avoided. There are adequate analgesics that are proven to be safe for use during pregnancy (such as Paracetamol).

Women who are breastfeeding should not take Clonac because of an increased risk of Rey's syndrome.

Dosage instructions

Usual dose is 100 mg once daily. Maximum daily dose is 150 mg.

Swallow the tablet whole with sufficient liquids during the meal.

Patients above the age of 65 should take lower dose (not more than 50 mg daily).


According to Patient Information Leaflet, Clonac should not be used concurrently with following drugs:

Drug Result of an interaction
Lithium (anti-psychotic) Increased concentration of lithium in the blood and consequently increased risk of adverse effects
Digoxin (drug used for the treatment cardiac insufficiency) Increased concentration of digoxin in the blood and consequently increased risk of adverse effects
Blood thinners (warfarin, heparin and acenocoumarol) Increased concentration of blood thinners and consequently increased risk of bleeding
Oral hypoglycemic drugs Changed effects of oral hypoglycemic drugs
Hinolone antibiotics (ciprofloxacin, norfloxacin and ofloxacin) Increased risk for convulsions
Cyclosporine Increased risk of Cyclosporine toxic effects
Methotrexate Increased risk of Methotrexate toxic effects
Corticosteroids Increased risk of gastrointestinal bleeding
ACE inhibitors (cilazapril, quinapril, captopril, lisinopril, enalapril, ramipril and others), beta blockers (carvedilol, metoprolol, atenolol, propranolol, bisoprolol and others), water pills (spironolactone, furosemide, amiloride, hydrochlorothiazide and others) Decreased anti-hypertensive effects of these drugs
Other NSAIDs (ibuprofen, ketoprofen, acetylsalicylic acid and others) Increased risk of gastrointestinal bleeding

Side effects

Possible side effects of Clonac are given bellow:

  • Bronchoconstriction and consequent difficult breathing
  • Pneumonia
  • Impaired renal function
  • Gastrointestinal bleeding (severe pain in the stomach, presence of blood in the stool and black-colored stool)
  • Impaired hepatic function (severe pain in right upper abdomen, loss of appetite and jaundice)
  • Fluid retention (edema)
  • Impaired sense of touch
  • Chest pain
  • Hypertension
  • Congestive heart failure
  • Alopecia
  • Pancreatitis
  • Photosensitivity
  • Hearing loss
  • Tremor
  • Double vision
  • Amnesia
  • Heartburn
  • Allergic reactions

Information on this website are provided for educational purposes only and are not intended for medical advice, diagnosis or treatment.

If you have any concerns or questions about your health, you should always consult with a physician or other health-care professional.

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