(piroxicam)

Brand

Feldene

Availability

• Capsules: 10 mg, 20 mg
• Suspension: 1 mg/mL

Pharmacology

Piroxicam, an oxicam derivative is a non-selective inhibitor of COX-1 and COX-2. It is thought to act by inhibiting prostaglandin synthesis, and inhibit superoxide formation, thereby exerting an anti-inflammatory, analgesic, anti-exudative and antipyretic effect.
Though similar, piroxicam is not structurally related to other nonsteroidal anti-inflammatory drugs ²⁷.

It is interesting to note that some forms of cancer such as carcinomas (e.g., Squamous Cell Carcinoma and mammary adenocarcinoma) appear to exhibit COX-2 activity. Studies suggest that these types of NSAIDs may have anti-tumor effects, besides their anti-inflammatory effects. This may make them useful in palliative care where tumors are inoperable.

Piroxicam is rapidly and well absorbed by the gut, and is distributed into synovial fluid as well as plasma. It has an extensive serum half-life greater than that of meloxicam.
Piroxicam goes through biotransformation in the liver and excretes metabolites in urine.
It has not been found to have teratogenic effects in animals, and has only exhibited minimal concentration in breast milk.

Indications

Used for degenerative joint disease, and spondylosis of the vertebrae in rats. It is also used to treat certain neoplasia’s (e.g., squamous cell carcinoma and mammary adenocarcinoma) expressing COX (cyclooxygenase) receptors.

Drug Interactions or Contraindications

• Due to the potential of peripheral edema; use cautiously in those with history of cardiac problems.
• Can inhibit platelet aggregation and cause GI erosion, avoid concomitant use if giving aspirin, phenylbutazone, corticosteroids or other NSAIDs.
• Not recommended if gastrointestinal irritation and hemorrhage, or impaired hepatic, cardiac, or renal function present.
• Caution when using with aminoglycosides (e.g., gentamicin, amikacin); may increase risk of nephrotoxicity.
• Can decrease the antihypertensive effect of ACE inhibitors.
• May reduce the diuretic effect of furosemide (Lasix).
• Can increase serum levels of digoxin.

Adverse Reactions

CNS: restlessness or lethargy, tinnitus

GI: loss of appetite, GI ulceration, fecal occult blood

GU: renal papillary necrosis

Hematologic: anemia, may falsely elevate blood glucose levels

Hepatic: elevated liver enzymes

Metabolic: dehydration

Skin: pruritus (itching)

Other: peripheral edema

Dosage Recommendations

3 mg/kg, PO, q24hr.  ¹¹ (anti-inflammatory analgesia)

Due to the extensive half-life of piroxicam and potential for GI ulceration, when choosing to use for long term treatment in specific disorders, lower dose adjustments and extended frequency of dosing to every other day should be a consideration of the veterinarian.

0.1 mg/kg to 0.3 mg/kg, PO, every other day (maintenance, long term use)  ¹²

*Note: because of the potential for GI ulceration with long term use of piroxicam it is recommended that an anti-ulcer agent (e.g., sucralfate) be used concurrently.

Considerations

• Give med at same time every day.
• May give with food.
• Prevent dehydration by providing juicy types of fruit in addition to fresh water.
• Report increase swelling, changes in stool (black), urinary changes, or weight gain to the vet.
• *Note: nonsteroidal anti-inflammatory medicines may mask clinical signs of infection. When deciding to use NSAIDs or steroids in rat’s long term, it may become necessary to add a broad-spectrum antibiotic as part of the treatment regimen.
• Store capsules in dry area in a closed container, at room temperature.
• If made up as suspension, refrigerate.