Piroxicam is not commonly used as an anti-inflammatory in the US because it isn't labelled or approved for this use, but - interestingly - when it is used, it is used for situations like yours. People are currently studying it to see if it is particularly effective for tumor-based inflammation. While experimental, it could be a really good choice in your situation.
I'll attach the prescribing information below, in case your vet hasn't read this yet.
- Non-Steroidal Antiinflammatory (NSAID), Anti-Tumor
- NSAID primarily used for its antitumor (indirect) activity. There are safer and/or approved NSAIDs available for pain/inflammation for dogs & cats.
- Low dose metronomic (continuous) therapy with cyclophosphamide shows promise for preventing sarcoma recurrence in dogs with fewer adverse effects then high dose treatment.
- Contraindications: Hypersensitivity or severely allergic to aspirin or other NSAIDs. Extreme Caution: Active, or a history of GI ulcer disease or bleeding disorders. Caution: Severely compromised cardiac function.
- Use in cats is controversial; use with caution.
- Adverse Effects: GI ulceration & bleeding, renal papillary necrosis, & peritonitis.
In dogs and cats, piroxicam’s primary use is as adjunctive treatment of bladder transitional cell carcinoma. It may also be of benefit in squamous cell carcinomas, mammary adenocarcinoma, and transmissible venereal tumor (TVT). Piroxicam may be beneficial in reducing the pain and inflammation associated with degenerative joint disease, but there are safer alternatives available.
Like other non-steroidal antiinflammatory agents, piroxicam has antiinflammatory, analgesic, and antipyretic activity. The drug’s antiinflammatory activity is thought to be primarily due to its inhibition of prostaglandin synthesis, but additional mechanisms (e.g., superoxide formation inhibition) may be important. As with other NSAIDs, piroxicam can affect renal function, cause GI mucosal damage, and inhibit platelet aggregation.
Piroxicam’s antitumor effects are believed to be due to its action on the immune system and not because of direct effects on tumor cells.
After oral administration, piroxicam is well absorbed from the gut. While the presence of food will decrease the rate of absorption, it will not decrease the amount absorbed. It is not believed that antacids significantly affect absorption.
In dogs, piroxicam has high oral bioavailability (100%) with peak plasma levels reached ≈ 3 hours after dosing. Volume of distribution is ≈ 0.3 L/kg; total body clearance is 0.066 L/hour and elimination half-life is ≈ 40 hours (Galbraith et al. 1991).
After single oral doses in cats, piroxicam is well absorbed with an oral bioavailability of ≈ 80%. Peak levels occur in ≈ 3 hours. Elimination half-life after intravenous or oral dosing is ≈ 12-13 hours.
Piroxicam is highly bound to plasma proteins. In humans, synovial levels are ≈ 40% of those found in plasma. Maternal milk concentrations are only ≈ 1% of plasma levels.
In humans, piroxicam has a very long plasma half-life (≈ 50 hours). The drug is principally excreted as metabolites in the urine after hepatic biotransformation.
Piroxicam is contraindicated in patients hypersensitive to it or that are severely allergic to aspirin or other NSAIDs. It should be used only when its potential benefits outweigh the risks in patients with active or history of GI ulcer disease or bleeding disorders. Because peripheral edema has been noted in some human patients, it should be used with caution in patients with severely compromised cardiac function.
Piroxicam has not been evaluated for use in cats. It must be used with extreme caution, if at all, in this species.
Do not confuse piroxicam with PARoxetine.
Like other NSAIDs used in dogs, piroxicam has the potential for causing significant GI ulceration and bleeding. The therapeutic window for the drug is very narrow, as doses as low as 1 mg/kg given daily have caused significant GI ulceration, renal papillary necrosis, and peritonitis. Other adverse effects reported in humans and potentially possible in dogs include: CNS effects (headache, dizziness, etc.), otic effects (tinnitus), elevations in hepatic function tests, pruritus and rash, and peripheral edema. Renal papillary necrosis has been seen in dogs at post-mortem but, apparently, clinical effects have not been noted with these occurrences.
In cats, GI effects (vomiting, anorexia, diarrhea) may be seen, particularly early in therapy. There are anecdotal reports of piroxicam decreasing hematocrits in cats when dosed daily for 7-14 days. Renal toxicity is possible if used for prolonged periods.
Animal studies have not demonstrated any teratogenic effects associated with piroxicam. The drug is excreted into milk in very low concentrations (≈ 1% found in maternal plasma). In humans, the FDA categorizes this drug as category C for use during pregnancy (Animal studies have shown an adverse effect on the fetus, but there are no adequate studies in humans; or there are no animal reproduction studies and no adequate studies in humans.) If using in the third trimester or near delivery in humans, the FDA categorizes all NSAIDs as category D for use during pregnancy (There is evidence of human fetal risk, but the potential benefits from the use of the drug in pregnant women may be acceptable despite its potential risks.)
Most NSAIDs are excreted in maternal milk; use with caution in nursing patients.
There is limited information available, but dogs may be more sensitive to the drugs ulcerative effects than are humans.
There were 63 exposures to piroxicam reported to the ASPCA Animal Poison Control Center (APCC) during 2008-2009. In these cases 58 were dogs with 12 showing clinical signs and 5 were cats with 1 showing clinical signs. Common findings in dogs recorded in decreasing frequency included vomiting, and bloody vomitus.
As with any NSAID, overdosage can lead to gastrointestinal and renal effects. Decontamination with emetics and/or activated charcoal is appropriate. For doses where GI effects are expected, the use of gastrointestinal protectants is warranted. If renal effects are also expected, fluid diuresis is should be considered. Patients ingesting significant overdoses should be monitored carefully and treated supportively.
The following drug interactions have either been reported or are theoretical in humans or animals receiving piroxicam and may be of significance in veterinary patients. Unless otherwise noted, use together is not necessarily contraindicated, but weigh the potential risks and perform additional monitoring when appropriate.
- Aminoglycosides (gentamicin, amikacin, etc.): Increased risk for nephrotoxicity.
- Anticoagulants (heparin, LMWH, warfarin, etc.): Increased risk for bleeding possible.
- Aspirin: When aspirin is used concurrently with piroxicam, plasma levels of piroxicam could decrease and an increased likelihood of GI adverse effects (blood loss) could occur. Concomitant administration of aspirin with piroxicam cannot be recommended.
- Bisphosphonates (alendronate, etc.): May increase risk for GI ulceration.
- Cisplatin: Piroxicam may potentiate the renal toxicity of cisplatin when used in combination.
- Corticosteroids: Concomitant administration with NSAIDs may significantly increase the risks for GI adverse effects.
- Furosemide: Piroxicam may reduce the saluretic and diuretic effects of furosemide.
- Highly Protein Bound Drugs (e.g., phenytoin, oral anticoagulants, other antiinflammatory agents, salicylates, sulfonamides, and thesulfonylurea antidiabetic agents): Because piroxicam is highly bound to plasma proteins (99%), it potentially could displace other highly bound drugs; increased serum levels and duration of actions may occur. Although these interactions are usually of little clinical concern, use together with caution.
- Methotrexate: Serious toxicity has occurred when NSAIDs have been used concomitantly with methotrexate; use together with extreme caution.
- Piroxicam may cause falsely elevated blood glucose values when using the glucose oxidase and peroxidase method using ABTS as a chromogen.
- As an adjunctive therapy of neoplastic diseases (extra-label): 0.3 mg/kg PO with food once a day (preferred, if tolerated) or once every other day (q48h). Adding misoprostol may be considered in dogs that do not tolerate NSAID’s GI effects.
- For adjunctive treatment of idiopathic lymphoplasmacytic rhinitis (LPR): Long-term administration of antibiotics having immunomodulatory effects (doxycycline 3 – 5 mg/kg PO q12h; or azithromycin 5 mg/kg PO q24h) combined with NSAIDs can be helpful in some dogs. Piroxicam 0.3 mg/kg PO q24h is recommended. If clinical improvement is observed within 2 weeks, daily piroxicam therapy is continued but the frequency of administration of doxycycline is reduced to once daily or azithromycin reduced to twice weekly. Therapy will likely be required for a minimum of 6 months, if not indefinitely. (Kuehn 2007b)
- As adjunctive therapy for neoplasia (extra-label): For adjunctive therapy of transitional cell carcinomas: 0.3 mg/kg PO q24-72h. Most will use q48h (every other day) dosing interval.
- As an antiinflammatory/analgesic (extra-label): 1 mg per cat PO q24h for a maximum of 7 days. (Note: After compounding, drug is stable for 10 days). (Gaynor 2008), (Rochette 2007)
- Idiopathic chronic rhinosinusitis (extra-label): Some cats’ clinical signs can be reduced with piroxicam at 0.3 mg/kg PO once daily or every other day. (Kuehn 2007a)
- For neoplastic diseases (extra-label):
- From a case report treating mucocutaneous squamous cell carcinoma: 80 mg (per horse) PO once daily; lip lesion resolved completely over 3 months, but patient developed colic signs twice. Dose was eventually reduced to every other day or every third day. (Moore et al. 2003)
- From a case report treating a squamous cell carcinoma of the third eyelid after surgical excision: 80 mg (per horse) PO once daily. (Iwabe et al. 2009)
Rabbits, Rodents, Small Mammals:
- Rabbits for fracture associated limb swelling (extra-label): 0.1 – 0.2 mg/kg PO q8h for 3 weeks. (Ivey et al. 2000)
- Adverse Effects (particularly GI bleeding).
- Liver function and renal function tests should be monitored occasionally with chronic use.
- Best given with food to reduce the chance for stomach upset.
- Gastrointestinal (stomach) ulcers and bleeding and kidney problems (especially in cats) are possible.
An oxicam derivative non-steroidal antiinflammatory agent, piroxicam occurs as a white, crystalline solid. It is sparingly soluble in water. Piroxicam is structurally not related to other non-steroidal antiinflammatory agents.
Piroxicam may also be known as: CP-16171, piroxicamum or PIRO; many trade names are available.
Capsules should be stored at temperatures <30°C in tight, light-resistant containers. When stored as recommended, capsules have an expiration date of 36 months after manufacture.
Dosage Forms/Regulatory Status
Veterinary-Labeled Products: None.
The ARCI (Racing Commissioners International) has designated this drug as a class 4 substance. See the appendix for more information.
Piroxicam Oral Capsules: 10 mg & 20 mg; Feldene®, generic; (Rx)
Monograph revised/updated May 2014.