Recent developments in nonsteroidal antiinflammatory drugs in cats

PHARMACOKINETIC EVALUATION OF MELOXICAM AFTER INTRAVENOUS AND INTRAMUSCULAR ADMINISTRATION IN NILE TILAPIA (OREOCHROMIS NILOTICUS)

Critically evaluating the pharmacokinetic behavior of a drug in the body provides crucial information about how to effectively treat a patient. Pharmacokinetic studies that exist in fish have primarily focused on drugs used to treat infectious disease, with minimal attention given to analgesic drugs. The objective of this study was to determine the pharmacokinetics of meloxicam (1 mg/kg) in Nile tilapia ( Oreochromis niloticus ) (n = 12). A single dose of meloxicam was administered either i.v. or i.m. Blood samples were obtained at predetermined times after drug injection. Plasma meloxicam concentrations were determined by a validated liquid chromatography/mass spectrometry method, and noncompartmental pharmacokinetic analysis was performed. The mean peak plasma concentration after i.m. injection was 1.95 μg/ml. The mean terminal half-life of meloxicam after i.v. and i.m. administration was 1.36 and 1.8 hr, respectively. The area under the plasma concentration-versus-time curve extrapolated to infinity was 11.26 hr·μg/ml after i.v. administration and 5.72 hr·μg/ml after i.m. administration. Bioavailability of meloxicam after i.m. administration was approximately half that of i.v. administration. Elimination was rapid in both the i.m. and i.v. routes of administration, suggesting that maintaining clinically relevant plasma concentrations may be difficult using this dose. This study represents the first pharmacokinetic evaluation of a nonsteroidal anti-inflammatory drug in a fish species, and further studies evaluating efficacy are needed.

The pharmacokinetics and in vitro/ex vivo cyclooxygenase selectivity of parecoxib and its active metabolite valdecoxib in cats

Parecoxib (PX) is an injectable prodrug of valdecoxib (VX, which is a selective cyclo-oxyganase-2 (COX-2)) inhibitor licensed for humans. The aim of the present study was to evaluate pharmacokinetics and in vitro/ex vivo cyclooxygenase selectivity of PX and VX in cats. In a whole blood in vitro study, PX did not affect either COX enzymes whereas VX revealed a COX-2 selective inhibitory effect in feline whole blood. The IC50 values of VX for COX-2 and COX-1 were 0.45 and 38.6 µM, respectively. Six male cats were treated with 2.5 mg/kg of PX by intramuscular injection. PX was rapidly converted to VX with a relatively short half-life of 0.4 h. VX achieved peak plasma concentration (2.79 ± 1.59 µg/mL) at 7 h following PX injection. The mean residence times for PX and VX were 0.43 ± 0.15 and 5.94 ± 0.88 h, respectively. In the ex vivo study, PX showed a COX-2 inhibition rate of about 70% in samples taken at 1, 2, 4 and 10 h after injection, with a significant difference compared to the control. In contrast, COX-1 was slightly inhibited, ranging from 0.7% to 9.7% of the control inhibition rate without any significant difference for 24 h after PX administration. The preliminary findings of the present research appear promising and encourage further studies to investigate whether PX can be successfully used in feline medicine.

ISFM and AAFP consensus guidelines: long-term use of NSAIDs in cats

NSAIDS AND CATS: Non-steroidal anti-inflammatory drugs (NSAIDs) are an important class of drug in feline medicine, having analgesic, anti-inflammatory and antipyretic activity. While most published data on their use in this species relate to short-term (often perioperative) therapy, there is increasing evidence of the value of these drugs in treating chronic pain in cats (for example, that associated with degenerative joint disease), and some NSAIDs have now become licensed for long-term use in cats in some geographies. Most of our knowledge of therapeutic mechanisms or adverse drug reactions associated with NSAIDs is extrapolated from work in other species, and there is a paucity of published data relating to cats.

GUIDELINES

These guidelines have been drawn together by an expert panel, which have reviewed the current literature on long-term NSAID use in cats and other species, and developed guidance on their use based on this information. The aim is to provide practical information for veterinarians to encourage appropriate NSAID therapy whenever cats will benefit from the use of these drugs.

Evaluation of adverse events in cats receiving long-term piroxicam therapy for various neoplasms

The role of cyclo-oxygenase 2 (COX-2) and prostaglandins (PG) in carcinogenesis has been documented in many species. Piroxicam has shown efficacy against several neoplasms and is frequently prescribed for chronic use. There are no studies investigating chronic piroxicam administration in cats and the chronic use of non-steroidal anti-inflammatory agents in this species has long been cautioned against. This retrospective study aimed to evaluate adverse effects in cats receiving long-term daily piroxicam. Seventy-three cats received daily piroxicam at doses of 0.13-0.41mg/kg. Treatment duration ranged from 1 to 38 months. Treatment with piroxicam was found to significantly increase frequency of vomiting during the first month of therapy, though this was most significant for cats receiving concurrent chemotherapy. Piroxicam administration was not significantly associated with hematologic, renal or hepatic toxicities. Adverse events were not correlated with dosage. Adverse events were reported in 29% of cats, and were generally mild and transient. Eight percent discontinued piroxicam due to adverse reaction, and 4% due to difficult administration. This study indicates that long-term daily piroxicam is generally well tolerated in cats at conventional doses.

Perioperative administration of vedaprofen, tramadol or their combination does not interfere with platelet aggregation, bleeding time and biochemical variables in cats

A randomized double blind and placebo controlled design was used to investigate the hemostatic, biochemical, gastrointestinal and behavioral effects of pre- and postoperative administration of vedaprofen 0.5mg/kg PO (V), tramadol 2mg/kg SC (T), their association (VT) or placebo (P) in 40 adult female cats (3.0+/-0.32kg; 1.8+/-0.7 years) distributed in groups of 10. Platelet aggregation and bleeding time were measured before and 52h after ovariohysterectomy. Serum urea, creatinine, alanine aminotransferase, alkaline phosphatase and gamma-glutamyl transferase concentrations were measured before and 7 days postoperatively. The occurrence of vomiting, frequency and consistency of feces, and behavior were observed for 7 days postoperatively. Morphine (0.5mg/kg, IM) was used as rescue analgesic. Laboratory variables did not change. Vomiting was observed only after morphine administration. Mild euphoria was observed in T and VT. The perioperative use of vedaprofen and/or tramadol did not modify the hemostatic, biochemical and gastrointestinal function in cats.

Pain mechanisms and their implication for the management of pain in farm and companion animals

Over the last two decades there has been a dramatic increase in the literature relating to the mechanisms and management of pain in domestic animals. Understanding the mechanisms of pain is crucial for its effective management. This review highlights the current understanding of the neurophysiology of nociception and the plastic changes involved in chronic pain states. Additionally, we describe a range of novel molecules and pathways that offer opportunities for the development of mechanism-based analgesic therapies. Pain management in animals is limited by pain assessment which remains highly subjective, with clinicians relying on indirect measures of pain, using rating scales and (less frequently) quantifiable physiological and behavioural parameters. The need for a systematic approach which would assess different pain components is well justified. Species-specific issues on pain assessment and management in mammalian companion and farm animals are addressed in the later part of this review.

A NINE-DAY ACCELERATED RADIATION PROTOCOL FOR FELINE SQUAMOUS CELL CARCINOMA

Nine cats with oral squamous cell carcinoma were treated with an accelerated radiation protocol (14 fractions of 3.5 Gy in 9 days). Radiation was administered twice daily with a 6hour break between treatments. Median overall survival was 86 +/- 110 days. Median survival for cats with a partial response (n=6) was 60 +/- 7 days, while median survival for cats with a complete response (n=3) was 298 +/- 187 days (P = 0.0639). The accelerated protocol was well tolerated and toxicity in the early and late period was manageable in all cats. Further modification of the protocol is warranted to extend survival.