diclofenac potassium

di·clo·fen·ac potassium (dkl-fnk)

n.

A nonsteroidal anti-inflammatory drug used to treat pain.

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diclofenac potassium,

the potassium salt of diclofenac, administered orally in the treatment of rheumatoid arthritis, osteoarthritis, ankylosing spondylitis, a variety of nonrheumatic inflammatory conditions, pain, and dysmenorrhea.

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diclofenac potassium

Cataflam, Novo-Difenac-K (CA), Novo-Difenac-SR (CA)

Pharmacologic class: Cyclooxygenase inhibitor, nonsteroidal anti-inflammatory drug (NSAID)

Therapeutic class: Nonopioid analgesic, antiarthritic

Pregnancy risk category C

FDA Boxed Warning

• Drug may increase risk of serious cardiovascular thrombotic events, myocardial infarction, and stroke. Risk may increase with duration of use. Patients with cardiovascular disease or risk factors for it may be at greater risk.
• Drug increases risk of serious GI adverse events, including bleeding, ulcers, and stomach or intestinal perforation. These events can occur at any time during use and without warning. Elderly patients are at greater risk.
• Drug is contraindicated for treatment of perioperative pain in setting of coronary artery bypass graft surgery.

Action

Unclear. Thought to block activity of cyclooxygenase, thereby inhibiting inflammatory responses of vasodilation and swelling and blocking transmission of painful stimuli.

Availability

Tablets: 50 mg, 75 mg

Tablets (delayed-release): 25 mg, 50 mg, 75 mg

Tablets (extended-release): 100 mg

⊘Indications and dosages

➣ Analgesia; dysmenorrhea

Adults: Initially, 100 mg P.O., then 50 mg t.i.d. as needed

➣ Rheumatoid arthritis

Adults: Initially, 50 mg P.O. three to four times daily. After initial response, reduce to lowest dosage that controls symptoms. Usual maintenance dosage is 25 mg t.i.d.

➣ Osteoarthritis

Adults: Initially, 50 mg P.O. two to three times daily. After initial response, reduce to lowest dosage that controls symptoms.

➣ Ankylosing spondylitis

Adults: 25 mg P.O. four to five times daily. After initial response, reduce to lowest dosage that controls symptoms.

Dosage adjustment

• Renal impairment
• Elderly patients

Off-label uses

• Post-radial keratotomy symptoms
• Dental pain

Contraindications

• Hypersensitivity to drug or its components, other NSAIDs, or aspirin
• Active GI bleeding or ulcer disease

Precautions

Use cautiously in:
• severe cardiovascular, renal, or hepatic disease; bleeding tendency
• history of porphyria or asthma
• concurrent anticoagulant use
• elderly patients
• pregnant or breastfeeding patients
• children.

Administration

• Give on empty stomach 1 hour before or after a meal.
• If drug causes GI upset, give with milk or meals.
• Make sure patient swallows extended-release form whole without chewing or crushing.

Route	Onset	Peak	Duration
P.O.	10 min	1 hr	8 hr
P.O. (delayed)	30 min	2-3 hr	8 hr
P.O. (extended)	Unknown	5-6 hr	Unknown

Adverse reactions

CNS: dizziness, drowsiness, headache

CV: hypertension

EENT: tinnitus

GI: diarrhea, abdominal pain, dyspepsia, heartburn, peptic ulcer, GI bleeding, GI perforation

GU: dysuria, frequent urination, hematuria, proteinuria, nephritis, acute renal failure

Hematologic: prolonged bleeding time

Hepatic: hepatotoxicity

Skin: eczema, photosensitivity, rash, contact dermatitis, dry skin, exfoliation

Other: allergic reactions (including edema), anaphylaxis

Interactions

Drug-drug. Anticoagulants, antiplatelet agents, cephalosporins, plicamycin, thrombolytics: increased risk of bleeding

Antihypertensives, diuretics: decreased efficacy of these drugs

Antineoplastics: increased risk of hematologic adverse reactions

Colchicine, corticosteroids, other NSAIDs: additive adverse GI effects

Cyclosporine, probenecid: increased risk of diclofenac toxicity

Digoxin, lithium, methotrexate, phenytoin, theophylline: increased levels of these drugs, greater risk of toxicity

Potassium-sparing diuretics: increased risk of hyperkalemia

Drug-diagnostic tests. Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, blood urea nitrogen, creatinine, electrolytes, lactate dehydrogenase, urine uric acid: increased values

Bleeding time: prolonged

Hematocrit, hemoglobin, platelets, serum uric acid, urine electrolytes, white blood cells: decreased values

Drug-herbs. Anise, arnica, chamomile, clove, dong quai, fenugreek, feverfew, garlic, ginger, ginkgo, ginseng, and others: increased risk of bleeding

Drug-behaviors. Alcohol use: increased risk of adverse GI effects

Patient monitoring

• Monitor hepatic and renal function.
• Observe for and report signs and symptoms of bleeding.
• Assess for hypertension.
• Monitor sodium and potassium levels in patients receiving potassium-sparing diuretics.
• Weigh patient to detect fluid retention. Report gain of more than 2 lb in 24 hours.

Patient teaching

• Instruct patient to take drug on empty stomach 1 hour before or after a meal.
• Advise patient not to lie down for 15 to 30 minutes after taking drug, to minimize esophageal irritation.
• Instruct patient to stop taking drug and contact prescriber promptly if he experiences ringing or buzzing in ears, dizziness, GI discomfort, or bleeding.
• Caution patient not to take over-the-counter analgesics during diclofenac therapy.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, herbs, and behaviors mentioned above.