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Piroxicam

Drug Reference 9 min 1649

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Created On: 27/09/2019

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Introduction

Piroxicam is a cyclooxygenase inhibitor, non-steroidal anti-inflammatory agent (NSAID) that is well established in treating rheumatoid arthritis and osteoarthritis and used for musculoskeletal disorders, and postoperative pain. It is used to treat the symptoms of pain and inflammation. Its long half-life enables it to be administered once daily. It may block certain substances in the body that are linked to inflammation.

Pharmacological Class: NSAID

Indications

Osteoarthritis
Rheumatoid arthritis
Postoperative pain
Acute musculoskeletal disorders
Postoperative pain

Pharmachologic action

Piroxicam is used to reduce pain, inflammation, and stiffness caused by rheumatoid arthritis and osteoarthritis. It shows reversible inhibition of cyclooxygenase, causing peripheral inhibition of prostaglandin synthesis. Prostaglandins are produced by an enzyme called as cyclooxygenase-1 (COX-1). Piroxicam blocks the COX-1 enzyme, resulting into reduced production of prostaglandins. Piroxicam also inhibits the migration of leukocytes into inflammation sites and prevents the formation of thromboxane A2, an aggregating agent, by the platelets.

Dosage

Adult dose for

Rheumatoid arthritis : 20 mg orally, daily as a single dose
Acute musculoskeletal disorders : 40 mg orally, daily given for 2 days
Postoperative pain : 40 mg orally, daily given for 2 days
Osteoarthritis: 20 mg orally once a day

Pediatric dose for

Pain: 0.2 to 0.3 mg/kg orally once a day

Pharmacokinetics

Piroxicam is well absorbed after oral administration. The volume of distribution is found to be 0.11 l/kg and plasma protein binding is 95%. Piroxicam and its biotransformation products are excreted in urine and feces, with about twice as much appearing in the urine as in the feces. Approximately 5% of a piroxicam dose is excreted unchanged. A substantial portion of piroxicam elimination occurs by hepatic metabolism. Piroxicam is excreted into human milk. and plasma half life is 30 to 86 hours.

Contraindications

In patients with known hypersensitivity to piroxicam
In patients who have experienced asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs. Severe, rarely fatal, anaphylactic-like reactions to NSAIDs have been reported in such patients
Contraindicated in treating peri-operative pain in setting of coronary artery bypass graft (CABG) surgery

Drug interaction

NSAIDs competitively inhibit methotrexate accumulation, thus they could enhance methotrexate toxicity.
NSAIDs diminish the antihypertensive effect of ACE-inhibitors.
NSAIDs produced an elevation of plasma lithium levels and reduction in renal lithium clearance. The mean minimum lithium concentration increased 15% and the renal clearance was decreased by approximately 20%. These effects have been attributed to renal prostaglandin synthesis inhibition by NSAID.
Effects of warfarin and NSAIDs on gastro interstinal (GI) bleeding are synergistic, such that users of both drugs together have a risk of serious GI bleeding higher than users of either drug alone.

Side effects

Common (affecting between 1 in10 to 1 in 100)

Diarrhea
Dizziness
Headache
Heartburn

Uncommon (affecting 1 in 100 to 1 in 1000)

Skin rash
Itching or hives
Swelling of Face, Lips, or Tongue
Tiredness
Pain in the upper part of stomach
Itching

Very rare (affecting less than 1 in 10,000)

Chest pain
Shortness of breath
Weakness on one side of body
Slurred speech
Decreased urination
Unusual weight gain
Skin redness and blisters

Precautions

In patients with history of high blood pressure, blood disorders, bleeding problems, heart disease and allergy
Patients taking other medications, during pregnancy and breastfeeding
Do not drive or operate machinery, as drug causes drowsiness

Clinical evidence

Piroxicam is a chemically unique, long-acting, potent anti-inflammatory/analgesic now available for the treatment of arthritis and other inflammatory diseases. Extensive clinical trials in over 66,000 patients have demonstrated the high efficacy and excellent toleration of piroxicam in rheumatoid arthritis, osteoarthritis, various musculoskeletal disorders and pain of varied etiology. Patient preference and compliance has consistently been higher for patients on piroxicam therapy. Piroxicam has been known as a useful addition to physicians’ armamentarium.¹
Piroxicam is recommended 40 mg once daily for 2 days and 20 mg once daily thereafter. Statistically significant improvement from baseline in pain was evident within 1 hour of the initial dose, an effect which was enhanced over a 12-hour period and which lasted for 24 hours. After 3 days of intramuscular injections, pain, tenderness, morning stiffness and back elongation were markedly improved. Subsequent treatment with either intramuscular or oral piroxicam further improved these symptoms and most patients recovered their normal physical activity within a week. Toleration was regarded as excellent or good in about 84% of the patients. Results indicated that piroxicam can provide rapid and effective therapy with good toleration in treating acute musculoskeletal disorders.²