Pharmacokinetics and efficacy of a ketorolac-loaded ocular coil in New Zealand white rabbits.

Eye drops are considered standard practice for the delivery of ocular drugs. However, low patient compliance and low drug levels compromise its effectiveness. Our group developed a ketorolac-loaded ocular coil for sustained drug delivery up to 28 days. The aim of this study was to gain insight into the pharmacokinetics and efficacy of the ocular coil. The pharmacokinetics of the ketorolac-loaded ocular coil versus eye drops were tested in New Zealand White rabbits by repetitive sampling for 28 days. Efficacy of the ocular coil was also tested in New Zealand White rabbits. Ocular inflammation was induced where after the ocular coil was inserted, or eye drops, or no treatment was provided. The total protein concentration and cytokine levels were measured in tears, aqueous humor, and plasma at 4 h, 8 h, 24 h, 4 d, 7 d, 14 d, 21 d, and 28 d. Four h after inserting the ocular coil in the eye, ketorolac levels in aqueous humor and plasma were higher in the ocular coil group than in the eye drop group. Ketorolac released from the ocular coil could be detected up to 28 d in tears, up to 4 d in aqueous humor and up to 24 h in plasma. After inducing inflammation, both the ocular coil and eye drops were able to suppress prostaglandin E2, TNFα and IL-6 levels in aqueous humor and plasma as compared to the group that received no treatment. To conclude, the ocular coil facilitated a sustained release of the drug and showed similar therapeutic benefit in suppressing post-operative inflammation as eye drops.

Antinociceptive Interaction and Pharmacokinetics of the Combination Treatments of Methyleugenol Plus Diclofenac or Ketorolac.

Although nonsteroidal anti-inflammatory drugs (NSAIDs) are one of the main types of drugs used to treat pain, they have several adverse effects, and such effects can be reduced by combining two analgesic drugs. The aim of this study was to evaluate the nociceptive activity of methyleugenol combined with either diclofenac or ketorolac, and determine certain parameters of pharmacokinetics. For the isobolographic analysis, the experimental effective dose 30 (ED30) was calculated for the drugs applied individually. With these effective doses, the peak plasma concentration (Cmax) was found and the other parameters of pharmacokinetics were established. Methyleugenol plus diclofenac and methyleugenol plus ketorolac decreased licking behavior in a dose-dependent manner in phase II, with an efficacy of 32.9 ± 9.3 and 39.8 ± 9.6%, respectively. According to the isobolographic analysis, the experimental and theoretical ED30 values were similar for methyleugenol plus diclofenac, suggesting an additive effect, but significantly different for methyleugenol plus ketorolac (3.6 ± 0.5 vs. 7.7 ± 0.6 mg/kg, respectively), indicating a probable synergistic interaction. Regarding pharmacokinetics, the only parameter showing a significant difference was Cmax for the methyleugenol plus diclofenac combination. Even with this difference, the combinations studied may be advantageous for treating inflammatory pain, especially for the combination methyleugenol plus ketorolac.

Blood-Brain Barrier Is the Major Site for a Rapid and Dramatic Prostanoid Increase upon Brain Global Ischemia.

We and others have demonstrated a rapid and dramatic increase in brain prostanoids upon decapitation-induced brain global ischemia and injury. However, the mechanism for this induction, including the cell types involved, are unknown. In the present study, we have validated and applied a pharmacological approach to inhibit prostanoid synthesis in the blood-brain barrier including endothelial cells. Our results indicate that a nonspecific cyclooxygenase (COX) inhibitor, ketorolac, does not pass the blood-brain barrier and does not enter red blood cells but penetrates endothelial cells. Ketorolac treatment did not affect basal prostanoid levels but completely prevented prostanoid induction upon global ischemia. These data indicate that basal prostanoids are synthesized in brain parenchyma cells, while inducible prostanoids are synthesized in the blood-brain barrier, most likely in endothelial cells. However, future studies with cell and COX isoform-specific gene ablation are needed to further validate this conclusion. These findings identify endothelial cells as a possible target for the development of pharmacological approaches to selectively attenuate inducible prostanoid pools without affecting basal levels under brain ischemia, trauma, surgery, and other related conditions.

Population Pharmacokinetics of Periarticular Ketorolac in Adult Patients Undergoing Total Hip or Total Knee Replacement Surgery.

BACKGROUND: Ketorolac tromethamine has been used for joint infiltration by the orthopedic surgeons as a part of postoperative multimodal analgesia. The objective of this study is to investigate the pharmacokinetic properties of S (-) and R (+) enantiomers of ketorolac in adult patients undergoing total hip (THA) and knee arthroplasty (TKA). METHODS: Adult patients with normal preoperative renal function received a periarticular infiltration of 30 mg of ketorolac tromethamine along with 100 mL of 0.2% ropivacaine and 1 mg of epinephrine at the end of their THA or TKA surgery. Blood samples were taken from a venous cannula at various time points after infiltration. Pharmacokinetic modeling was performed using PMetrics 1.5.0. RESULTS: From 18 participants, 104 samples were analyzed. The peak plasma concentration for S (-) ketorolac was found to be lower than that of R (+) ketorolac, for both THA (0.19-1.22 mg/L vs 0.39-1.63 mg/L, respectively) and TKA (0.28-0.60 mg/L vs 0.48-0.88 mg/L, respectively). The clearance of the S (-) ketorolac enantiomer was higher than R (+) ketorolac (4.50 ± 2.27 vs 1.40 ± 0.694 L/h, respectively). CONCLUSIONS: Our study demonstrates that with periarticular infiltration, S (-) ketorolac was observed to have increased clearance rate and highly variable volume of distribution and lower peak plasma concentration compared to R (+) ketorolac.

Pharmacokinetics and four-week repeated-dose toxicity of hyaluronic acid and ketorolac combination following intra-articular administration in normal rats.

Intra-articular (IA) injection of hyaluronic acid (HA) in combination with nonsteroidal anti-inflammatory drugs, such as ketorolac (KL), have been clinically investigated to provide more rapid and profound pain relief in patients with osteoarthritis. However, its safety, local tolerance, and potential for pharmacokinetic interaction have not been assessed. In this study, the pharmacokinetics and toxicity of a combination of HA and KL were evaluated in normal rats following four-week repeated-dose injection. Rats received HA or KL alone at 4 mg/kg or 16 mg/kg, respectively, or HA/KL combination at 4/4 mg/kg, 4/8 mg/kg, or 4/16 mg/kg on a weekly basis. The rats exhibited temporal, reversible changes in hematology, serum chemistry, and urinalysis caused primarily by KL treatment. No deleterious effects were observed on the joint following repeated IA HA/KL administration, which showed only minimal to mild levels of temporary inflammatory changes in synovial membrane. The plasma KL level following IA injection rose as fast as that of intra-muscular injection, with no alteration with the co-administered HA. In conclusion, repeated IA administration of HA/KL combination was tolerated well in normal rats, encouraging future studies of IA injection of HA/KL combination on osteoarthritis-induced animal models and even patients.

Pharmacokinetics of ketorolac in wild Eastern box turtles (Terrapene carolina carolina) after single intramuscular administration.

Ketorolac is a nonsteroidal anti-inflammatory drug that possesses potent analgesic activity comparable to morphine. The opioid shortage in the United States has led to an unreliable supply of opioids for use in rehabilitation facilities, thus underscoring the need for research on the safe and effective use of nonopioid alternatives. The goal of this study was to determine the pharmacokinetics of ketorolac after a single 0.25 mg/kg intramuscular injection administered to injured Eastern box turtles (Terrapene carolina carolina). A sparse blood sampling protocol was used to collect samples from 32 wild turtles that presented to the Turtle Rescue Team at North Carolina State University for traumatic injuries. Blood was collected from 0 to 24 hr after injection and analyzed via high-pressure liquid chromatography (HPLC). A nonlinear mixed-effects (NLME) model was fitted to the data to obtain typical values for population parameters. Using this approach, we identified a long half-life (T1/2 ) of 9.78 hr and a volume of distribution (Vss ) of 0.26 L/kg. We have concluded that this long T1/2 for a dose of 0.25 mg/kg ketorolac-injected IM provides plasma levels above a previously published target level for 24-hour analgesia to allow for once daily dosing.

Magnetic field distribution modulation of intrathecal delivered ketorolac iron-oxide nanoparticle conjugates produce excellent analgesia for chronic inflammatory pain.

BACKGROUND: Nanoparticles have become one of the most promising among the potential materials used for biomedical applications. However, few researchers have focused on their effects on analgesia. Despite the fact that various nanoparticles have been evaluated for drug delivery and MRI imaging contrast enhancement in clinical settings, no reports have investigated the in vivo synergy of ketorolac iron-oxide nanoparticle conjugates to improve the analgesic effect. METHODS: Ketorolac conjugated magnetic iron oxide nanoparticles (Keto-SPIO) were synthesized via two-stage additions of protective agents and chemical co-precipitation. ICR mice were used to develop inflammatory pain models induced by Complete Freund's adjuvant (CFA) injection in the hind paw. Different magnet field strengths and polarities were applied to the spinal cord after injecting Keto-SPIO into the theca space. Analgesia behavior was evaluated with the up-down method via von Frey microfilament measurement. Spinal cord tissues were harvested at the end analgesia time point upon induction of the inflammatory pain. The presence of the two cyclooxygenases (COX) in the spinal cord was examined via Western blotting to quantify the changes after intra-thecal Keto-SPIO administration. RESULTS: Intrathecal Keto-SPIO administration demonstrated a magnetic field-dependent analgesia effect in CFA pain model with a significant reduction in COX expression. CONCLUSIONS: Our results indicated that intrathecal administration of the Keto-SPIO combined magnet field modulated delivery significantly promoted an analgesia effect with suppression of COX in the mice inflammatory pain model.

The pharmacokinetics of intravenous ketorolac in children aged 2 months to 16 years: A population analysis.

BACKGROUND: Intravenous ketorolac is commonly administered to children for the control of postoperative pain. An effect site EC50 for analgesia of 0.37 mg. L-1 is described in adults. AIMS: The aim of this study was to review age- and weight-related effects on ketorolac pharmacokinetic parameters in children and current dosing schedules. METHODS: Pooled intravenous ketorolac (0.5 mg. kg-1 ) concentration-time data in children aged 2 months to 16 years were analyzed using nonlinear mixed-effects models. Allometry was used to scale to a 70 kg person. RESULTS: There were 64 children aged 2 months to 16 years (641 plasma concentrations) available for analysis. A two-compartment mammillary model was used to describe pharmacokinetics. Clearance was 2.53 (CV 45.9%) L. h-1. 70 kg-1 and intercompartment clearance was 4.43 (CV 95.6%) L. h-1. 70 kg-1 . Both central (V1) and peripheral (V2) volumes of distribution decreased with age over the first few years of postnatal life to reach V1 6.89 (CV 30.3%) L. 70 kg-1 and V2 5.53 (CV 47.6%) L. 70 kg-1 . CONCLUSION: Clearance, expressed as L. h-1. kg-1 , decreased with age from infancy. A dosing regimen of 0.5 mg. kg-1 every 6 hours maintains a trough concentration larger than 0.37 mg. L-1 in children 9 months to 16 years of age. This dosing regimen is consistent with current recommendations.

Enantiomer-specific ketorolac pharmacokinetics in young women, including pregnancy and postpartum period.

Racemic ketorolac clearance (CL) is significantly higher at delivery, but S-ketorolac disposition determines the analgesic effects. The aim of this study was to investigate the effect of pregnancy and postpartum period on enantiomer-specific (S and R) intravenous (IV) ketorolac pharmacokinetics (PKs). Data in women shortly following cesarean delivery (n=39) were pooled with data in a subgroup of these women that was reevaluated in the later postpartum period (postpartum group, n=8/39) and with eight healthy female volunteers. All women received single IV bolus of 30 mg ketorolac tromethamine. Five plasma samples were collected at 1, 2, 4, 6, and 8 hours and plasma concentrations were determined using high performance liquid chromatography. Enantiomer-specific PKs were calculated using PKSolver. Unpaired analysis showed that distribution volume at steady state (Vss, L/kg) for S- and R-ketorolac was significantly higher in women shortly following cesarean delivery (n=31) compared to postpartum group (n=8) or to healthy female volunteers (n=8). CL, CL to body weight, and CL to body surface area (CL/BSA) for S- and R-ketorolac were also significantly higher in women following delivery. In addition, S/R-ketorolac CL/BSA ratio was significantly higher at delivery. Paired PK analysis in eight women shortly following delivery and in postpartum group showed the same pattern. Finally, the simultaneous increase in CL and Vss resulted in similar estimates for elimination half-life in both unpaired and paired analysis. In conclusion, pregnancy affects S-, R-, and S/R-ketorolac disposition. This is of clinical relevance since S-ketorolac (analgesia) CL is even more increased compared to R-ketorolac CL, and S/R-ketorolac CL ratio is higher following delivery compared to postpartum period or to healthy female volunteers.

The enantioselective population pharmacokinetics of intravenous ketorolac in children using a stereoselective assay suitable for microanalysis.

OBJECTIVE: To describe the effect of age and body size on enantiomer selective pharmacokinetic (PK) of intravenous ketorolac in children using a microanalytical assay. METHODS: Blood samples were obtained at 0, 15 and 30 min and at 1, 2, 4, 6, 8 and 12 h after a weight-dependent dose of ketorolac. Enantiomer concentration was measured using a liquid chromatography tandem mass spectrometry method. Non-linear mixed-effect modelling was used to assess PK parameters. KEY FINDINGS: Data from 11 children (1.7-15.6 years, weight 10.7-67.4 kg) were best described by a two-compartment model for R(+), S(-) and racemic ketorolac. Only weight (WT) significantly improved the goodness of fit. The final population models were CL = 1.5 × (WT/46)(0.75) , V1 = 8.2 × (WT/46), Q = 3.4 × (WT/46)(0.75) , V2 = 7.9 × (WT/46), CL = 2.98 × (WT/46), V1 = 13.2 × (WT/46), Q = 2.8 × (WT/46)(0.75) , V2 = 51.5 × (WT/46), and CL = 1.1 × (WT/46)(0.75) , V1 = 4.9 × (WT/46), Q = 1.7 × (WT/46)(0.75) and V2 = 6.3 × (WT/46)for R(+), S(-) and racemic ketorolac. CONCLUSIONS: Only body weight influenced the PK parameters for R(+) and S(-) ketorolac. Using allometric size scaling significantly affected the clearances (CL, Q) and volumes of distribution (V1 , V2 ).

Evaluation of a Pharmacy-Managed Pharmacokinetic Dosing Program.

PURPOSE: The objective of this study was to determine the impact of a pharmacy-managed pharmacokinetic dosing program on appropriate dosing of famotidine, enoxaparin, and ketorolac. METHODS: A large community teaching hospital implemented a pharmacy-managed pharmacokinetic dosing program for famotidine, enoxaparin, and ketorolac. Subjects were included if they received famotidine and had a creatinine clearance (CrCl) of <50 mL/min; received therapeutic enoxaparin and had a CrCl of <30 mL/min; or received ketorolac and had a CrCl <30 mL/min, age > 65 years or weight <50 kg. RESULTS: One hundred and forty-six patients were included in the preimplementation group (famotidine [n = 50], enoxaparin [n = 46], and ketorolac [n = 50]) and 143 patients were included in the postimplementation group (famotidine [n = 50], enoxaparin [n = 43], and ketorolac [n = 50]). In all, 66% of patients were dosed appropriately in the preimplementation group (famotidine 28%, enoxaparin 85%, and ketorolac 86%) compared to 94% in the postimplementation group (famotidine 92%, enoxaparin 95%, and ketorolac 94%), P < .001. CONCLUSION: Implementation of a pharmacy-managed pharmacokinetic dosing program significantly improved appropriate dosing of famotidine, enoxaparin, and ketorolac. These findings could justify expansion of pharmacist autonomy through institution-approved, pharmacy-managed programs for other medications to improve appropriate dosing. Analyses specifically evaluating patient-oriented or financial outcomes may provide additional support for expansion.

Pharmacokinetics of intravenous ketorolac in cats undergoing gonadectomy.

AIM: To determine the pharmacokinetics of ketorolac tromethamine (0.5 mg/kg) when administered I/V to cats undergoing gonadectomy. METHODS: Ketorolac was administered to nine female and three male shorthair domestic cats as an I/V bolus of 0.5 mg/kg after intubation, and 20 minutes prior to ovariectomy or orchiectomy. Intra-operative cardiorespiratory variables were monitored and blood samples were collected over 24 hours. Concentrations of ketorolac in serum were determined by high-performance liquid chromatography to establish pharmacokinetic parameters. RESULTS: During surgery, mean end tidal isoflurane concentration was 1.63 (SD 0.24)% and normocapnia and spontaneous ventilation were maintained in all animals. The kinetics of ketorolac was described by a two-compartment model. The distribution and elimination half-lives were 0.09 (SD 0.06) and 4.14 (SD 1.18) hours, respectively. The body clearance was 56.8 (SD 33.1) mL/h/kg. The volume of distribution at steady-state and the mean residence time were 323.9 (SD 115.7) mL/kg and 6.47 (SD 2.86) hours, respectively. CONCLUSION AND CLINICAL RELEVANCE: On the basis of the results, concentrations of ketorolac in serum in cats were above the human effective concentrations for 5-6 hours postoperatively. However, other studies including a control group are advocated to further investigate the ketorolac kinetics and the analgesic efficacy in this species.

Pharmacokinetics and analgesic effect of ketorolac floating delivery system.

OBJECTIVES: The efficacy of ketorolac tromethamine (KT) floating alginate beads as a drug delivery system for better control of KT release was investigated. The formulation with the highest drug loading, entrapment efficiency, swelling, buoyancy, and in vitro release would be selected for further in vivo analgesic effect in the mice and pharmacokinetics study in rats compared to the tablet dosage form. METHODS: KT floating alginate beads were prepared by extrusion congealing technique. KT in plasma samples was analyzed using a UPLC MS/MS assay. RESULTS: The percentage yield, drug loading and encapsulation efficiency were increased proportionally with the hydroxypropylmethyl cellulose (HPMC) polymer amount in the KT floating beads. A reverse relationship was observed between HPMC amount in the beads and the KT in vitro release rate. F3-floating beads were selected, due to its better in vitro results (continued floating for >8 h) than others. A longer analgesic effect was observed for F3 in fed mice as compared to the tablets. After F3 administration to rats, the Cmax (2.2 ± 0.3 µg/ml) was achieved at ∼2 h and the decline in KT concentration was slower. F3 showed a significant increase in the AUC (1.89 fold) in rats as compared to the tablets. CONCLUSION: KT was successfully formulated as floating beads with prolonged in vitro release extended to a better in vivo characteristic with higher bioavailability in rats. KT in floating beads shows a superior analgesic effect over tablets, especially in fed mice.

An ex vivo investigation into the transurothelial permeability and bladder wall distribution of the nonsteroidal anti-inflammatory ketorolac.

Transurothelial drug delivery continues to be an attractive treatment option for a range of urological conditions; however, dosing regimens remain largely empirical. Recently, intravesical delivery of the nonsteroidal anti-inflammatory ketorolac has been shown to significantly reduce ureteral stent-related pain. While this latest development provides an opportunity for advancing the management of stent-related pain, clinical translation will undoubtedly require an understanding of the rate and extent of delivery of ketorolac into the bladder wall. Using an ex vivo porcine model, we evaluate the urothelial permeability and bladder wall distribution of ketorolac. The subsequent application of a pharmacokinetic (PK) model enables prediction of concentrations achieved in vivo. Ketorolac was applied to the urothelium and a transurothelial permeability coefficient (Kp) calculated. Relative drug distribution into the bladder wall after 90 min was determined. Ketorolac was able to permeate the urothelium (Kp = 2.63 × 10(-6) cm s(-1)), and after 90 min average concentrations of 400, 141 and 21 µg g(-1) were achieved in the urothelium, lamina propria and detrusor respectively. An average concentration of 87 µg g(-1) was achieved across the whole bladder wall. PK simulations (STELLA) were then carried out, using ex vivo values for Kp and muscle/saline partition coefficient (providing an estimation of vascular clearance), to predict 90 min in vivo ketorolac tissue concentrations. When dilution of the drug solution with urine and vascular clearance were taken into account, a reduced ketorolac concentration of 37 µg g(-1) across the whole bladder wall was predicted. These studies reveal crucial information about the urothelium's permeability to agents such as ketorolac and the concentrations achievable in the bladder wall. It would appear that levels of ketorolac delivered to the bladder wall intravesically would be sufficient to provide an anti-inflammatory effect. The combination of such ex vivo data and PK modeling provides an insight into the likelihood of achieving clinically relevant concentrations of drug following intravesical administration.

Ketorolac as an analgesic agent for infants and children after cardiac surgery: safety profile and appropriate patient selection.

Ketorolac has been used safely as an analgesic agent for children following cardiac surgery in selected populations. Controversy exists among institutions about the risks involved with this medication in this patient group. This article reviews the current literature regarding the safety of ketorolac for postoperative pain management in children after cardiac surgery. Specifically, concerns about renal dysfunction and increased bleeding risk are addressed. Additionally, the article details pharmacokinetics and potential benefits of ketorolac, such as its opioid-sparing effect. The literature reflects that the use of this medication is not well studied in certain pediatric cardiac patients such as neonates and those with single-ventricle physiology, and the safety of this medication in regards to these special populations is reviewed. In conclusion, ketorolac can be used in specific pediatric patients after cardiac surgery with minimal risk of bleeding or renal dysfunction with appropriate dosing and duration of use.

Development of an enantiomer selective microsampling assay for the quantification of ketorolac suitable for paediatric pharmacokinetic studies.

BACKGROUND: Ketorolac, a potent nonsteroidal anti-inflammatory drug used for pain control in children, exists as a racemate of inactive R (+) and active S (-) enantiomers. AIM: To develop a microsampling assay for the enantioselective analysis of ketorolac in children. METHODS: Ketorolac enantiomers were extracted from 50 µl of plasma by liquid­liquid extraction and separated on a ChiralPak AD-RH. Detection was by a TSQ quantum triple quadrupole mass spectrometer with an electrospray ionisation source operating in a positive ion mode. Five children (age 13.8 (1.6) years, weight 52.7 (7.2) kg), were administered intravenous ketorolac 0.5mg/kg (maximum 10mg) and blood samples were taken at 0, 0.25, 0.5, 1, 2, 4, 6, 8 and 12 h post administration. CL, VD and t1/2 were calculated based on non-compartmental methods. RESULTS: The standard curves for R (+) and S (-) ketorolac were linear in the range 0­2000 ng/ml. The LLOQs of the method were 0.15 ng on column and 0.31 ng on column for R (+) and S (-) ketorolac, respectively. The median (range) VD and CL of R (+) and S (-) ketorolac were 0.12 l/kg (0.07­0.17), 0.017 l/h/kg (0.12­0.29) and 0.17 (0.09­0.31) l/kg, 0.049 (0.02­0.1) l/h/kg, p = 0.043), respectively. The median (range) elimination half-life (t1/2) of the R (+) and S (-) ketorolac was 5.0 h (2.5­5.8) and 3.1 h (1.8­4.4), p = 0.043), respectively. CONCLUSION: The development of a simple, rapid and reliable ketorolac assay suitable for paediatric PK studies is reported.

Enantioselective disposition after single dose I.V administration of ketorolac in male Wistar rats.

Ketorolac, a commonly used anti-inflammatory and analgesic agent, was studied in male wistar rats. The plasma samples were analysed using chiral AGP column with UV detection. The experimental data was analysed for probable fit in the compartmental and non-compartmental models using WinNolin software. The data of (+)-R-Ketorolac and (-)-S-Ketorolac was found to fit into the compartmental as well as non compartmental model. There was a difference between the plasma concentrations of (+)-R-Ketorolac and (-)-S-Ketorolac; the plasma concentrations of (+)-R-Ketorolac were higher than those of (-)-S-Ketorolac throughout the time course of the study. The area under the curve (AUC) of time vs. concentration profile of (+)-R-Ketorolac was found to be higher than (-)-S-Ketorolac. Volume of distribution and clearance was found to be higher for (-)-S-Ketorolac.

Pharmacokinetics and perioperative efficacy of intravenous ketorolac in dogs.

Ketorolac (KET) is a nonsteroidal anti-inflammatory drug approved for the use in humans that possesses a potent analgesic activity, comparable to morphine, and could represent a useful tool to control acute pain also in animals. The clinical efficacy and pharmacokinetic profile of intravenous (IV) ketorolac tromethamine (0.5 mg/kg) were studied in 15 dogs undergoing gonadectomy. Intra-operative cardiorespiratory variables were monitored, and post-operative pain was assessed using a subjective pain score (0-24) in all dogs, whereas the pharmacokinetic profile of the drug was determined in 10 animals. During surgery, mean minimal alveolar concentration of isoflurane was 1.69 ± 0.11%, and normocapnia and spontaneous ventilation were maintained in all animals. During pain assessment, no significant differences between males and females were found, and in no case rescue analgesia was necessary. No adverse effects were reported. Serum samples were purified by solid-phase extraction and analysed by HPLC with UV-Vis detection. A large variability was observed in serum concentrations. The kinetics of ketorolac was described by a noncompartmental analysis. The elimination half-life (t½λz ) and ClB were 10.95 ± 7.06 h and 92.66 ± 84.49 mL/h/kg, respectively, and Vdss and Vz were 1030.09 ± 620.50 mL/kg and 1512.25 ± 799.13 mL/kg, respectively. AUC(0→last) and MRT(0→last) were 6.08 ± 3.28 h × µg/mL and 5.59 ± 2.12 h, respectively. The results indicate that ketorolac possess good post-operative analgesic effects until about 6 h after administration in dogs undergoing moderately painful surgery.