Meloxicam

(meloxicam)

Brands

Metacam, Mobic

Availability

Tablets: 7.5 mg and 15 mg
Suspension: 0.5 mg/ml and 1.5 mg/ml
Also available in 10 ml dropper bottle (0.1 mL = 2 drops= 0.2 mg)

Pharmacology

Meloxicam, an oxicam derivative, belongs to a newer family of NSAIDs (nonsteroidal anti-inflammatory drugs) called COX-2 inhibitors that block the enzyme cyclooxygenase-2, which is thought to trigger pain and inflammation in the body. A related enzyme, but somewhat different, is cyclooxygenase-1 (COX-1). It produces biochemicals needed to maintain normal blood supply to the kidneys and GI tract. Previous NSAIDs were unable to inhibit cyclooxygenase-2 without also inhibiting cyclo-oxygenase-1, hence they produced unpleasant side effects.
Meloxicam has shown, at therapeutic dosing, to selectively inhibit COX-2 over COX-1. Meloxicam is closely related to piroxicam though structurally different, and unlike piroxicam it has fewer gastrointestinal side effects.

It is interesting to note that some forms of cancer such as carcinomas (e.g. Squamous Cell Carcinoma) 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.

Like other NSAIDs, meloxicam acts to inhibit prostaglandin synthesis thereby exerting an anti-inflammatory, analgesic, anti-exudative and antipyretic effect. It is able to reduce leukocyte infiltration into inflamed tissue.

Meloxicam is slowly, but well absorbed orally with a long serum half-life. It has a duration of action, in most species of animals, from 24 to 48 hours. It is distributed into blood, liver, kidneys an synovial fluid, and is believed to cross placental barrier. It is metabolized in the liver and excreted in both feces and urine. It has also been found in the milk of lactating rats.

Indications

Used for relief of inflammation and pain where the side effects of a corticosteroid is not acceptable. Also used as an analgesic following surgery, as a supplement to opioids in major surgery where pain is anticipated ²⁷, and during palliative care for inoperable tumors.

Drug Interactions or Contraindications

Not recommended to be given to pregnant or lactating animals.
Since many NSAIDs have the potential to produce gastrointestinal ulceration and bleeding avoid concomitant use of meloxicam (Metacam) with other nonsteroidal anti-inflammatory drugs or corticosteroids.
Do not use on animals with history of asthma, or suffering from gastrointestinal irritation and hemorrhage, impaired hepatic, cardiac, or renal functions.
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

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

GU: renal papillary necrosis, renal failure, albuminuria, frequent urination

Hepatic: elevated liver enzymes

Hematologic: anemia, elevated BUN and creatinine

Skin: pruritus (itching)

Metabolic: dehydration

Other: edema

Use cautiously in dehydrated, hypovolemic or hypotensive animals due to the potential for increased risk of renal toxicity. ²⁷

Dosage Recommendations

*Note: dosages should be adjusted to the lowest effective dose by veterinarian, when needed, to treat chronic conditions.

0.2 mg/kg, PO or SQ, once daily. ²⁷

or

0.5 mg/kg, PO or SQ, daily. ²⁶

or

0.3 mg/kg to 0.6 mg/kg, PO or SQ, q24hr (may be given in severe respiratory illness if the rat is in discomfort) ²⁹. *Note: do not give if a corticosteroid is already in use.

or

1.0 mg/kg, PO or SQ, daily. ⁵^, ¹⁷^, ⁴¹^, ⁴⁴

or

1.0 mg/kg to 2.0 mg/kg, PO or SQ, q24hrs ²⁶^, ³⁴^, ³⁵^, ⁴¹^, ⁴²^, ⁴³^, ⁴⁴:Analgesic

Considerations

*Note: nonsteroidal anti-inflammatory medicines may mask clinical signs of infection. When deciding to use NSAIDs or steroids in rats’ long term, it may become necessary to add a broad-spectrum antibiotic as part of the treatment regimen.
Prevent dehydration by providing juicy types of fruit in addition to fresh water.
Shake suspensions well before use.
Give med at same time every day.
May give with or without food.
Report increase swelling, changes in stool (black), urinary changes, or weight gain to the vet.
Store in a closed container, in a dry area, at room temperature.

References

Gallo, O., Franchi, A., Magnelli, L., Sardi, I., Vannacci, A., Boddi, V., Chiarugi, V., & Masini, E. (2001). Cyclooxygenase-2 pathway correlates with VEGF expression in head and neck cancer. Implications for tumor angiogenesis and metastasis. Neoplasia, 3(1), 53-61. Retrieved November 16, 2008, from http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1505025.
Iwase, N., Higuchi, T., Gonda, T., Kobayashi, H., Uetake, H., Enomoto, M., & Sugihara, K. (2007). The effect of meloxicam, a selective COX-2 inhibitor, on the microvasculature of small metastatic liver tumors in rats. Japanese Journal of Clinical Oncology, 37(9), 673-678. Retrieved November 16, 2008, from http://jjco.oxfordjournals.org/cgi/content/short/37/9/673?rss=1.
Metacam. (2005). Retrieved November 16, 2008, from https://www.fda.gov/cvm/Documents/N141213pi.pdf.
Veterinary Non-Steroidal Anti-Inflammatory Drugs (NSAIDs). (2008). Retrieved November 16, 2008, from https://www.fda.gov/cvm/nsaids.htm.