Pharmacokinetics of ketorolac tromethamine in humans after intravenous, intramuscular and oral administration

An Explanation of Why Dose-Corrected Area Under the Curve for Alternate Administration Routes Can Be Greater than for Intravenous Dosing

It is generally believed that bioavailability (F) calculated based on systemic concentration area under the curve (AUC) measurements cannot exceed 1.0, yet some published studies report this inconsistency. We teach and believe, based on differential equation derivations, that rate of absorption has no influence on measured systemic clearance following an oral dose, i.e., determined as available dose divided by AUC. Previously, it was thought that any difference in calculating F from urine data versus that from systemic concentration AUC data was due to the inability to accurately measure urine data. A PubMed literature search for drugs exhibiting F > 1.0 and studies for which F was measured using both AUC and urinary excretion dose-corrected analyses yielded data for 35 drugs. We show and explain, using Kirchhoff's Laws, that these universally held concepts concerning bioavailability may not be valid in all situations. Bioavailability, determined using systemic concentration measurements, for many drugs may be overestimated since AUC reflects not only systemic elimination but also absorption rate characteristics, which is most easily seen for renal clearance measures. Clearance of drug from the absorption site must be significantly greater than clearance following an iv bolus dose for F(AUC) to correctly correspond with F(urine). The primary purpose of this paper is to demonstrate that studies resulting in F > 1.0 and/or greater systemic vs urine bioavailability predictions may be accurate. Importantly, these explications have no significant impact on current regulatory guidance for bioequivalence testing, nor on the use of exposure (AUC) measures in making drug dosing decisions.

What is the analgesic ceiling dose of ketorolac for treating acute pain in the ED?

ABSTRACT

Recent research has suggested that ketorolac has an analgesic ceiling effect, meaning that despite increased dosages, the patient obtains no additional pain relief and is more likely to suffer adverse drug reactions. This article describes the outcomes of these studies and the recommendation to use the lowest possible dose for the shortest time when treating patients with acute pain.

Does Time of Administration of Intravenous Ketorolac Impact Pain-Related Outcomes in Dacryocystorhinostomy?

PURPOSE

An emerging body of evidence indicates that intravenous ketorolac (IVK) reduces pain scores and the requirement for opioid analgesics in a variety of oculofacial procedures. This study was performed to assess the impact of timing of IVK administration on these benefits after external dacryocystorhinostomy (DCR).

METHODS

Patients were randomized to receive IVK before (n = 50), during (n = 50), or after DCR (n = 50). An additional cohort of control patients did not receive the medication (n = 50). Postoperative pain was measured via a visual analog scale immediately after DCR on the first day after surgery (POD1). Additionally, the need for opioid analgesics to control pain was recorded. Statistical analyses were performed via a dedicated computerized software package.

RESULTS

Immediately after surgery, mean pain scores were 5.26 for control patients, and 2.30, 2.44, and 2.36 for patients that received IVK pre-, intra-, and post-operatively, respectively (p < .001 for each condition, as compared to controls). On POD1, mean pain scores were 3.52 for control patients and 1.38, 1.32, and 1.28 for patients that received IVK pre-, intra-, and post-operatively, respectively (p < .001 for each condition, as compared to controls). 28% of control patients required postoperative opioid analgesics, as compared to 6%, 4%, and 4% among patients that received IVK pre-, intra-, and postoperatively, respectively (p < .05 for each condition, as compared to controls).

CONCLUSIONS

IVK significantly reduces postoperative pain and the requirement for opioid analgesics after DCR, regardless of the timing of administration. This benefit appears to extend into the first postoperative day.

Effect of Timing of Intravenous Ketorolac Administration on Pain in Orbitotomy Surgery

PURPOSE

Intravenous ketorolac (IVK) is an effective and safe medication to reduce postoperative pain in the setting of oculofacial surgery. This study was undertaken to determine the impact of timing of IVK administration in orbital surgery on the reduction of postoperative pain score and opioid requirement.

METHODS

Patients either received IVK immediately before (n = 50), during (n = 50) or after (n = 50) orbital surgery or acted as controls (n = 50). Pain scores were assessed via an analog scale immediately after surgery and on the first postoperative day. The requirements for opioid analgesics were recorded. Statistical analyses were performed via a dedicated computerized software package.

RESULTS

One hundred fifty patients received IVK; 50 before incision (28 males, 22 females, mean age 52.2), 50 intraoperatively (20 males, 30 females, mean age 49.8) and 50 in the immediate postoperative period (26 males, 24 females, mean age = 55.3). Additionally, 50 patients acted as controls (26 males, 24 females, mean age 54). Immediately after surgery, administration of IVK resulted in statistically significant reduction in pain score regardless of the timing of dosing as compared with control patients (prior = 2.36, intraoperative = 2.34, postoperative = 2.46 vs. control 5.44, p < 0.0001). Eleven patients (22%) in the control group required opioids, whereas, in the IVK cohorts, only 2 (4%-preoperative), 1 (2%-intraoperative), and 1 (2%-postoperative) patients needed these medications (p = 0.0039).

CONCLUSIONS

In the setting of orbital surgery, IVK reduced pain scores and opioid requirement, regardless of the timing of administration, as compared with patients that did not receive the medication.

Ketorolac plus Lidocaine vs Lidocaine for pain relief following core needle soft tissue biopsy: A CONSORT-compliant double-blind randomized controlled study

BACKGROUNDS

The main objective of this study was to compare the pain control efficacy of local administration of Lidocaine with or without the nonsteroidal anti-inflammatory drug, Ketorolac, and local conventional Lidocaine injection in core needle biopsy of the musculoskeletal tumor.

METHODS

The current study was a randomized, double-blind controlled clinical trial that included 128 patients with suspected musculoskeletal tumors. Patients were randomly assigned to either the Ketorolac plus Lidocaine (n = 64) or Lidocaine group (n = 64). The Ketorolac - Lidocaine combination syringe contained 30 mg Ketorolac and 2% Lidocaine - adrenaline dosage, and the Lidocaine syringe contained 2% Lidocaine - adrenaline dosage. The level of pain after core needle biopsy was evaluated for each patient at 1, 6, 12, 24, 48, and >48 hours by a Visual Analog Scale (VAS). The mean VAS changes over time were compared between the Ketorolac plus Lidocaine and Lidocaine groups using a linear mixed model.

RESULTS

baseline information including mean age of patients in Lidocaine group (51.5 ± 19.4 years) and in Lidocaine - Ketorolac combination group (50.1 ± 18 years), diagnosis (malignant, benign, metastatic, infection), tumor location (upper and lower extremities, back), VAS score 1-hour post-operation (mild and moderate pain) were noted. The VAS score ratings were significantly lower in Lidocaine - Ketorolac combination group when compared to the Lidocaine group during the 1 to 24 hours post-operation time period.

CONCLUSION

Patients receiving Lidocaine - Ketorolac combination dosage had significantly lower VAS scores, and these results confirm that local injection of Lidocaine - Ketorolac combination had a superior pain-controlling effect during the first 24 hours after the biopsy procedure in comparison to Lidocaine injection alone, as measured by VAS score scale.

Pharmacokinetics of ketorolac in juvenile loggerhead sea turtles (Caretta caretta) after a single intramuscular injection

Ketorolac is a non-steroidal anti-inflammatory drug administered as an analgesic in humans. It has analgesic effects comparable to opioids but without adverse effects such as respiratory depression or restrictions because of controlled drug status. We designed this study to examine the potential of ketorolac as an analgesic for sea turtle rehabilitative medicine. Our objective was to determine the pharmacokinetics of a single 0.25 mg/kg intramuscular dose of ketorolac in a population of 16 captive-raised juvenile loggerhead sea turtles (Caretta caretta). A sparse sampling protocol was utilized, and blood samples were collected for 12 hours after administration of ketorolac. Samples were analyzed with high-pressure liquid chromatography (HPLC), and a nonlinear mixed effects model (NLME) was used to determine parameters for the population. With these methods, we identified a long elimination half-life (βT_1/2  = 11.867 hr) but a low maximum concentration (C_MAX  = 0.508 µg/mL) and concentrations were below the level proposed to be therapeutic in humans (EC₅₀  = 0.1-0.3 μg/mL) for most of the collection period. We conclude that ketorolac may not be an appropriate long-term analgesic for use in loggerhead sea turtles at this dose; however, it may have some benefit as a short-term analgesic.

Predicting the Human Hepatic Clearance of Acidic and Zwitterionic Drugs

Prospective predictions of human hepatic clearance for anionic/zwitterionic compounds, which are oftentimes subjected to transporter-mediated uptake, are challenging in drug discovery. We evaluated the utility of preclinical species, rats and cynomolgus monkeys [nonhuman primates (NHPs)], to predict the human hepatic clearance using a diverse set of acidic/zwitterionic drugs. Preclinical clearance data were generated following intravenous dosing in rats/NHPs and compared to the human clearance data (n = 18/27). Single-species scaling of NHP clearance with an allometric exponent of 0.50 allowed for good prediction of human clearance (fold error ∼2.1, bias ∼1.0), with ∼86% predictions within 3-fold. In comparison, rats underpredicted the clearance of lipophilic acids, while overprediction was noted for hydrophilic acids. Finally, an in vitro clearance assay based on human hepatocytes, which is routinely used in discovery setting, markedly underpredicted human clearance (bias ∼0.12). Collectively, this study provides insights into the usefulness of the preclinical models in enabling pharmacokinetic optimization for acid/zwitterionic drug candidates.

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.

Comparing the Efficacy of IV Ibuprofen and Ketorolac in the Management of Postoperative Pain Following Arthroscopic Knee Surgery. A Randomized Double-Blind Active Comparator Pilot Study

Introduction: Acute postoperative pain following knee arthroscopy is common in orthopedic surgeries. Managing pain postoperatively combines usage of opioids and non-steroidal anti-inflammatory drugs. The aim of this clinical study was to assess the efficacy of two different analgesic treatment regimens: intravenous (IV) ibuprofen and IV ketorolac for the treatment of postoperative pain pertaining to arthroscopic knee surgery. Methods: This was a single center, randomized, double-blind, parallel, active comparator clinical pilot study. Subjects were randomized to receive either IV ibuprofen, administered as two 800 mg doses or IV ketorolac, administered as a single 30 mg dose. Subjects in the ibuprofen group received 800 mg of IV ibuprofen within 2 h prior to surgery and a repeated second dose 4 h after the initial dose if they had not been discharged. Subjects in the ketorolac group received IV ketorolac 30 mg at the end of surgery, as per the manufacturer's recommendations. Pain assessments and opioid consumption data were collected up to 24 h postoperatively. Results: Of 53 randomized subjects, 51 completed the study. There were 20 subjects in the ibuprofen group and 31 subjects in the ketorolac group. The median (IQR) visual analog scale (VAS) pain score at resting upon post-anesthesia care unit (PACU) arrival was 33 (12, 52) vs. 9 (2, 25) (p = 0.0064) for the ketorolac and ibuprofen group, respectively. The median (IQR) visual analog scale (VAS) pain score at movement upon PACU arrival was 38 (20, 61) vs. 15 (6, 31) (p = 0.0018) for the ketorolac and ibuprofen group, respectively. Median VAS pain scores during movement taken at subsequent 30 min intervals in the ibuprofen group were less than half that of those reported in the ketorolac group for up to 90 min after arriving in PACU. The median VAS pain scores at rest and movement in the course of 120 min-24 h after PACU arrival was not statistically significant in both groups. Rescue opioid medication during PACU stay was required in 55.0% (N = 11) and 83.9% (N = 26), with a mean amount of narcotic consumption (oral morphine conversion) of 5.53 ± 5.89 mg vs. 19.92 ± 15.63 mg for the ibuprofen and ketorolac group, respectively (P < 0.001). However, opioid consumption during the first 24 h after PACU discharge was not statistically significant (p-value = 0.637). The mean time to first rescue medication was 77.62 ± 33.03 and 55.78 ± 35.37 for the ibuprofen and ketorolac group, respectively (p-value = 0.0456). There were no significant differences in patient satisfaction and documented adverse events during the first 24 h. Conclusion: This pilot study showed that the use of preemptive IV ibuprofen 800 mg could be considered to reduce postoperative pain and opioid consumption. Future prospective clinical trials using similar regimens should be conducted in order to gain a better understanding of how to best provide perioperative analgesic regimens. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT01650519.

An Evidence-Based Opioid-Free Anesthetic Technique to Manage Perioperative and Periprocedural Pain

Background

The epidemic of opioid abuse is increasing, and the number of deaths secondary to opioid overdose is also increasing. Recent attention has focused on opioid prescribing and management of chronic pain. However, opioid use in perioperative and periprocedural patients, whether they have chronic pain or exhibit new persistent opioid abuse after a procedure, has received little attention.

Methods

We present an evidence-based technique that combines subanesthetic infusions of lidocaine and dexmedetomidine supplemented with other intravenous agents and a low dose of inhaled anesthetic.

Results

Based on evidence of drug action and interaction, an opioid-free anesthetic can be delivered successfully. We present the cases of 2 patients in whom the opioid-free anesthetic technique was used with a successful outcome, adequate pain management, and avoidance of opioid drugs.

Conclusion

This anesthetic prescription can be useful for opioid-naïve patients as well as for patients with chronic pain that is managed with opioids.

Narrative review shows that the short-term use of ketorolac is safe and effective in the management of moderate-to-severe pain in children

In June 2013, the European Medicine Agency recommended limiting codeine use in paediatric patients, creating a void in managing moderate pain. We reviewed the literature published in English (1985-June 2017) on the pharmacokinetic, pharmacodynamic and safety profile of ketorolac, a possible substitute for codeine and opioids, for treating moderate-to-severe pain. We found that gastrointestinal side effects were mainly reported with prolonged use, significant bleeding was reported in adenotonsillectomy, and adverse renal effects appeared to be limited to patients with specific coexisting risk factors.

CONCLUSION

The short-term use of ketorolac appears to be safe for children in many situations.

Ketorolac, Oxymorphone, Tapentadol, and Tramadol: A Comprehensive Review

Pain remains a tremendous burden on patients and for the health care system, with uncontrolled pain being the leading cause of disability in this country. There are a variety of medications that can be used in the treatment of pain, including ketorolac, oxymorphone, tapentadol, and tramadol. Depending on the clinical situation, these drugs can be used as monotherapy or in conjunction with other types of medications in a multimodal approach. A strong appreciation of pharmacologic properties of these agents and potential side effects is warranted for clinicians.

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.

Efficacy of Ketorolac Buccal Infiltrations and Inferior Alveolar Nerve Blocks in Patients with Irreversible Pulpitis: A Prospective, Double-blind, Randomized Clinical Trial

INTRODUCTION

The purpose of this prospective, randomized, double-blind, placebo-controlled study was to determine whether ketorolac buccal infiltrations (BIs) helped to improve the success of inferior alveolar nerve blocks (IANBs) in patients with acute irreversible pulpitis (AIP).

METHODS

Forty adult volunteers with AIP in a mandibular molar were included in this study. Patients were instructed to evaluate their pain by using a Heft-Parker visual analog scale. They were randomly divided into 2 groups (n = 20). All patients received standard IANB injection and after that a BI of 4% articaine with 1:100,000 epinephrine. After 5 minutes, 20 patients received a BI of 30 mg/mL ketorolac, and the other received a BI of normal saline (control group). Endodontic access cavity preparation (ACP) was initiated 15 minutes after the IANB when the patient reported lip numbness and had 2 electric pulp tests with no responses. The patient's pain during caries and dentin removal, ACP, and canal length measurements (CLM) was recorded by using Heft-Parker visual analog scale. Successful anesthesia was defined as no or mild pain during any of these steps, without the need for additional injection. Data were statistically analyzed by using Mann-Whitney U and χ(2) tests.

RESULTS

Successful anesthesia after an IANB plus BI of articaine was obtained in 15% of patients in the control group at the end of CLM. Adding BI of ketorolac significantly increased the success rate to 40% (P < .05). Patient's pain during ACP and CLM was significantly lower in the ketorolac group (P < .05).

CONCLUSIONS

Ketorolac BI can increase the success rate of anesthesia after IANB and BI with articaine in patients with AIP.

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).

Ketorolac tromethamine - routes and clinical implications

Opioids have long been used for analgesic purposes for a wide range of procedures. However, the binding of these drugs to opiate receptors has created various challenges to the clinician due to unfavorable side effect profiles and the potential for tolerance and abuse. In 1989, ketorolac became an approved nonsteroidal inflammatory drug (NSAID) for injectable use as an analgesic. Over the last 20 years, numerous studies have been conducted involving ketorolac. These studies have provided additional information about various routes of administration and their effect on the efficacy and the side effect profile of ketorolac. Moreover, ketorolac has been compared with several widely used analgesics. This review evaluates both the potential benefits and potential drawbacks of ketorolac generally, and specifically discusses routes of administration, including their advantages and disadvantages when compared to several traditional analgesics in both inpatient and outpatient settings.

Pharmacokinetics and Safety of Ketorolac Following Single Intranasal and Intramuscular Administration in Healthy Volunteers

Ketorolac was administered to 15 healthy volunteers in a phase 1, single-dose, crossover, randomized study. Subjects received open-label randomized 15- and 30-mg intramuscular (i.m.) ketorolac and blinded randomized 15- and 30-mg intranasal (i.n.) ketorolac. The i.n. ketorolac was well tolerated; the only nasal symptoms were some instances of mild irritation. The i.n. ketorolac was rapidly and well absorbed (median tmax, 0.50-0.75 hours), and the half-life was approximately 5 to 6 hours, values that were similar to those following i.m. administration. Relative bioavailability of i.n. compared to i.m. administration at the same doses was approximately 67% to 75%. Dose proportionality was noted between the 15- and 30-mg i.n. and i.m. dose levels. Thus, i.n. ketorolac offers a therapeutic alternative to i.m. administration and may provide benefits in the clinical setting.

Recommendations of the national football league physician society task force on the use of toradol(®) ketorolac in the national football league

Ketorolac tromethamine (Toradol(®)) is a non-steroidal anti-inflammatory drug that has potent analgesic and anti-inflammatory properties. It can be administered orally, intravenously, intramuscularly, or via a nasal route. Ketorolac injections have been used for several years in the National Football League (NFL), in both the oral and injectable forms, to treat musculoskeletal injuries and to prevent post-game soreness. In an attempt to determine the appropriate use of this medication in NFL players, the NFL Team Physician Society appointed a Task Force to consider the best available evidence as to how ketorolac should be used for pain management in professional football players. These treatment recommendations were established based on the available medical literature taking into consideration the pharmacokinetic properties of ketorolac, its accepted indications and contraindications, and the unique clinical challenges of the NFL. The Task Force recommended that 1) ketorolac should only be administered under the direct supervision and order of a team physician; 2) ketorolac should not be used prophylactically as a means of reducing anticipated pain either during or after participation in NFL games or practices and should be limited to those players diagnosed with an injury or condition and listed on the teams' injury report; 3) ketorolac should be given in the lowest effective therapeutic dose and should not be used in any form for more than 5 days; 4) ketorolac should be given in its oral preparation under typical circumstances; 5) ketorolac should not be taken concurrently with other NSAIDs or by those players with a history of allergic reaction to ketorolac, other NSAIDs or aspirin; and 6) ketorolac should not be used by a player with a history of significant gastrointestinal bleeding, renal compromise, or a past history of complications related to NSAIDs.

Pulmonary and nasal deposition of ketorolac tromethamine solution (SPRIX) following intranasal administration

Ketorolac tromethamine is a racemic, non-steroidal, anti-inflammatory drug (NSAID). An intra-nasal (IN) formulation, SPRIX(®), is approved for the treatment of short term (up to 5 days) acute moderate to moderately severe pain. The primary objective of this study was to determine whether (99m)Tc-diethylenetriaminepenta acetic acid (DTPA) radiolabelled ketorolac tromethamine formulation (31.5 mg) was deposited in the lungs of healthy subjects (4 men and 9 women) following nasal inhalation of different intensities (gentle or vigorous sniff) and under different postural conditions (upright or semi-supine). The secondary objectives were to determine the deposition pattern of radiolabelled ketorolac solution in the nasal cavity and the clearance of the radiolabel over a 6h period post-administration. The nasal spray pump delivery device used showed a droplet size distribution with a volume mean diameter (VMD) of 50 μm and approximately 85% of the aerosol mass contained in droplets >10 μm diameter. The fraction of the dose recorded from the lung regions averaged <0.5%, and was considered to represent scattered radiation rather than true pulmonary deposition. This fraction was not affected by posture or by inhalation manoeuvre. The majority of the radiolabelled intranasal dose was deposited in the nasal cavity. The visual spread patterns within the nasal cavity were most uniform following administration in the upright position regardless of inhalation manoeuvre. Clearance from the nasal cavity was initially very rapid, with only 16-30% of the dose remaining after 10 min and 6-14% after 6 h. Retention was greatest following gentle inhalation.

Tips and traps analyzing pediatric PK data

Pharmacokinetic (PK) and pharmacodynamic (PD) modeling has elucidated aspects of developmental pharmacology of value to the anesthetic community. The increasing sophistication of modeling techniques is associated with pitfalls that may not be readily apparent to readers or investigators. While size and age are considered primary covariates for PK models, the impact of birth on clearance maturation is poorly documented, dose in obese children is poorly investigated, pharmacologic implications of physiologic changes poorly portrayed, disease progression on drug response poorly depicted and the impact of metabolites on effect poorly illustrated. This review identifies some of these pitfalls and suggests ideas to circumvent or investigate these hazards.

Effect of processing and sintering on controlled release wax matrix tablets of ketorolac tromethamine

The objective of present study was to evaluate the effect of processing methods and sintering condition on matrix formation and subsequent drug release from wax matrix tablets for controlled release. Ketorolac tromethamine and compritol were processed with appropriate diluent using either dry blending, spray drying, partial melt granulation or melt granulation.The tablets were then sintered at 80 degrees . The sintered tablets were characterized by their physical parameters and in vitro dissolution tests. The micro-morphology and wettability of the tablets was also investigated. It was evident that different processing methods for identical formulation significant impact the release profile of drug. Sintering further retarded drug release and its effect was related to the manufacturing processes. Scanning electron microscopy showed that heat treatment redistributed the wax and formed a film-like structure covering drug and excipient particle. The contact angle of tablets made by dry blending, spray drying and partial melt granulation methods increased after sintering, while that of tablets made by melt granulation remained constant. Drug release from the wax tablets with or without heat treatment was best described by the Higuchi equation. Different processing methods produced different matrix structures that resulted in different drug release rates. Sintering retarded drug release mainly by decreasing the porosity of the matrix. Contact angle measurement and SEM analysis indicated that heat treatment caused the wax to melt, redistribute, coat the drug and diluents and form a network structure. Differential scanning calorimetry studies ruled out the occurrence of solid solution of the drug during sintering condition.

Fatal adverse reaction to ketorolac tromethamine in asthmatic patient

A case of an asthmatic woman who collapsed within a few minutes after intramuscular ketorolac tromethamine (KT) injection is reported. Autopsy findings revealed anatomic evidence of a recent asthma attack. KT was found to be present in the blood at a concentration within the therapeutic range and consistent with the administered dose. Based on the timing of the collapse in relation to the KT administration, death was attributed to an adverse reaction to KT, resulting in acute bronchospasm and cardiac arrest, with asthma as an underlying contributing factor. In this case, asthma alone was not responsible for the death of the patient but only a contributing factor. Physicians have to be aware that in asthmatic patients bronchospasm can be induced by drugs among which aspirin or nonsteroidal anti-inflammatory drugs such as KT are the most common; therefore, death may have an iatrogenic cause. The paper also describes the pathogenic mechanism of an adverse reaction to such drugs and analytical methods for the isolation and detection of KT in postmortem blood.

Mechanistic evaluation of the effect of sintering on Compritol 888 ATO matrices

The present research studied the effect of sintering technique in the development of a controlled release formulation for ketorolac tromethamine. The method consisted of mixing drug and wax powder (Compritol 888 ATO) along with lactose as diluent and talc as lubricant followed by direct compression at room temperature. The compressed fluffy matrices were kept at 80 degrees C for 1, 2, and 3 h for sintering. The sintered tablets were characterized by their physical parameters and in vitro dissolution profile. The sintering time markedly affected the drug release properties of Compritol 888 ATO matrices. It is notable that the release rate of ketorolac tromethamine from matrices was inversely related to the time of sintering. This may be due to the increase in the extent and firmness of sintering which further compacts the mass so that drug release is affected. Contact angle measurement and scanning electron microscopy analysis indicated that heat treatment caused the wax to melt and redistribute. This redistributed wax formed a network-like structure in which the drug along with lactose is entrapped. This particular formed matrix is responsible for retarding the drug release. Fourier transform infrared spectroscopy results did not show any drug-wax interaction due to sintering. Differential scanning calorimetric and powder X-ray diffraction studies ruled out the occurrence of solid solution and polymorphic changes of the drug. Drug release from the wax tablets with or without sintering was best described by the Higuchi equation.

The use of drug metabolism for prediction of intestinal permeability (dagger)

The Biopharmaceutics Classification System (BCS), based on the aqueous solubility and intestinal permeability of a drug substance, has been widely used to predict the extent of drug absorption during the course of pharmaceutical development. Combined with product dissolution data, this system has gained a prominent role in regulatory process to determine if a drug formulated in an immediate release solid oral dosage form qualifies for waiver of in vivo bioequivalence studies. In parallel, the Biopharmaceutics Drug Disposition Classification System (BDDCS), using aqueous solubility and drug metabolism, takes on another venue to predict overall drug disposition. It has been suggested that the matrix of drug metabolism in BDDCS can be used to substantiate the classification of permeability by BCS. A total of 51 drugs were compiled in this study to examine the use of drug metabolism for predicting permeability. All compounds were classified as high permeability based on BCS, but only 73% of the compounds were found to exhibit extensive metabolism. Lipophilicity accounts for significant metabolism of many highly permeable drugs. Fourteen (14) out of 51 drugs have poor metabolism, suggesting that high permeability as defined by BCS does not necessarily dictate extensive metabolism. The drugs that have high permeability but poor metabolism are generally hydrophilic molecules with low molecular weight and are likely to be absorbed by active transport mechanisms. Based on the present data and literature information, it seems logical to predict that the extent of absorption is mostly complete (or > or =90%) if the drug is subject to a high degree of metabolism (e.g., > or =90%). The extent of drug metabolism may be useful in supporting permeability classification under certain circumstances.

The preemptive analgesic effect of ketorolac and propacetamol for adenotonsillectomy in pediatric patients

BACKGROUND

Both ketorolac and propacetamol are used postoperatively to control mild to moderate pain. This study compared the analgesic efficacy of ketorolac and propacetamol delivered either preoperatively or postoperatively, and assessed the preemptive analgesic effect of ketorolac and propacetamol for adenotonsillectomy.

METHODS

One hundred and two pediatric patients were divided randomly into four groups. The K1 and P1 groups received ketorolac 1 mg/kg or propacetamol 30 mg/kg after induction, respectively, whereas the K2 and P2 groups received each drug at the end of the operation, respectively. After adenotonsillectomy, we measured the NRS (Numerical Rating Scale), FPS (Faces Pain Scale) and OPS (Objective Pain scale) at 15, 30 and 60 min after arriving at the postanesthesia care unit.

RESULTS

There were no significant differences in the NRS, FPS and OPS between K1 and K2 and between P1 and P2 for 60 min after operation at the postanesthesia care unit.

CONCLUSIONS

These results suggest that both ketorolac (1 mg/kg) and propacetamol (30 mg/kg) have no preemptive analgesic effects during 1 hour after adenotonsillectomy.

Sensitization of central trigeminovascular neurons: blockade by intravenous naproxen infusion

We have previously observed that migraine attacks impervious to triptan therapy were readily terminated by subsequent i.v. administration of the non-steroidal anti-inflammatory drug (NSAID) ketorolac. Since such attacks were associated with periorbital allodynia--a symptom of central sensitization--we examined whether infusion of the NSAID naproxen can block sensitization of central trigeminovascular neurons in the medullary dorsal horn, using in vivo single-unit recording in the rat. Topical exposure of the cerebral dura to inflammatory soup (IS) for 5 min resulted in a short-term burst of activity (<8 min) and a long-lasting (>120 min) neuronal hyper-responsiveness to stimulation of the dura and periorbital skin (group 1). Infusion of naproxen (1 mg/kg) 2 h after IS (group 1) brought all measures of neuronal responsiveness back to the baseline values recorded prior to IS, and depressed ongoing spontaneous activity well below baseline. When given preemptively 1 h before IS (group 2), naproxen blocked the short-term burst of activity and every long-term measure of neuronal hyper-responsiveness that was studied in the central neurons. The same preemptive treatment, however, failed to block IS-induced short-term bursts of activity in C-unit meningeal nociceptors (group 3). The results suggest that parenteral administration of naproxen, unlike triptan therapy, can exert direct inhibition over central trigeminovascular neurons in the dorsal horn. Though impractical as a routine migraine therapy, parenteral NSAID administration should be useful as a non-narcotic rescue therapy for migraine in the setting of the emergency department.

Mechanistic Approaches to Volume of Distribution Predictions: Understanding the Processes

PURPOSE

To use recently developed mechanistic equations to predict tissue-to-plasma water partition coefficients (Kpus), apply these predictions to whole body unbound volume of distribution at steady state (Vu(ss)) determinations, and explain the differences in the extent of drug distribution both within and across the various compound classes.

MATERIALS AND METHODS

Vu(ss) values were predicted for 92 structurally diverse compounds in rats and 140 in humans by two approaches. The first approach incorporated Kpu values predicted for 13 tissues whereas the second was restricted to muscle.

RESULTS

The prediction accuracy was good for both approaches in rats and humans, with 64-78% and 82-92% of the predicted Vu(ss) values agreeing with in vivo data to within factors of +/-2 and 3, respectively.

CONCLUSIONS

Generic distribution processes were identified as lipid partitioning and dissolution where the former is higher for lipophilic unionised drugs. In addition, electrostatic interactions with acidic phospholipids can predominate for ionised bases when affinities (reflected by binding to constituents within blood) are high. For acidic drugs albumin binding dominates when plasma protein binding is high. This ability to explain drug distribution and link it to physicochemical properties can help guide the compound selection process.

Ketorolac analgesia for inguinal hernia repair is not improved by peripheral administration

PURPOSE

It has been suggested that ketorolac, a non-steroidal anti-inflammatory drug (NSAID) available for parenteral use, may result in prolonged (24 hr) postoperative analgesia through a peripheral mechanism when added to local anesthetic infiltration. Our objective was to assess this effect by controlling for systemic absorption of the drug.

METHODS

This randomized, double-blind trial studied 40 men undergoing elective inguinal hernia repair under spinal anesthesia. All patients received 19 mL of lidocaine 1% infiltrated in the operative field before incision. Patients were randomized into two groups of 20. The surgical site group received ketorolac 30 mg added to the lidocaine infiltration. In the control group, ketorolac 30 mg was injected subcutaneously in the contralateral abdominal wall. Numeric rating scores (0-10) of pain at rest and with movement were recorded at the time of discharge from the recovery room and at 24 hr postoperatively. Time to first analgesia, postoperative iv morphine use, total time in the recovery room, and total oral analgesic use in the first 24 hr were also compared.

RESULTS

There were no significant differences between groups with respect to any of the measured variables. In both groups, pain scores were low at rest (1.9 +/- 1.4 vs 2.2 +/- 1.8, surgical site and systemic groups, respectively) and moderate with movement (5.3 +/- 2.2, 5.0 +/- 1.8) after anesthetic recovery. Pain scores were similar at 24 hr (1.1 +/- 1.3, 1.9 +/- 1.6 at rest; 5.7 +/- 2.0, 6.2 +/- 2.2 with movement).

CONCLUSION

Adding ketorolac to lidocaine infiltration for hernia repair does not improve or prolong postoperative analgesia compared to systemic administration.

Dexamethasone suppresses peripheral prostanoid levels without analgesia in a clinical model of acute inflammation

PURPOSE

The therapeutic effects of glucocorticoids are generally attributed to suppression of multiple signaling pathways involved in the inflammatory response leading to decreased levels of inflammatory mediators at the site of injury. This study evaluated the in vivo relationship between levels of prostanoids at the site of tissue injury and analgesia after dexamethasone administration in a clinical model of tissue injury.

METHODS

Subjects were administered dexamethasone 4 mg or placebo 12 hours and 1 hour before the removal of 2 mandibular third molars. A microdialysis probe was implanted at each surgical site for measurement of immunoreactive prostaglandin E2 (PGE(2)) or immunoreactive thromboxane B(2) (TxB(2)), and pain was measured concurrently. Subjects received either ketorolac 30 mg intravenously or placebo at pain onset.

RESULTS

PGE(2) was detectable in the first postoperative sample, decreased over the next hour and then increased coincident with the onset of postoperative pain. Administration of dexamethasone suppressed PGE(2) levels in samples collected at pain onset in comparison to placebo and significantly suppressed TxB(2) at the surgical site but without any effect on pain report. Subsequent administration of ketorolac significantly reduced pain while decreasing both PGE(2) and TxB(2) levels at the surgical site.

CONCLUSION

The lack of an analgesic effect for dexamethasone while reducing both PGE(2) and TxB(2) at the site of injury in comparison to ketorolac analgesia accompanied by greater reductions in levels of these prostanoids suggests that glucocorticoids at this dose do not suppress PGE(2) release sufficiently to attenuate peripheral sensitization of nociceptors after tissue injury.

Age-stratified pharmacokinetics of ketorolac tromethamine in pediatric surgical patients

Published data suggest that ketorolac pharmacokinetics are different in children than in adults. We sought to better characterize ketorolac pharmacokinetics in children. Thirty-six children, aged 1-16 yr, were stratified into four age groups: 1-3 yr, 4-7 yr, 8-11 yr, and 12-16 yr. Each child received 0.5 mg/kg of ketorolac tromethamine IV after completion of elective surgery. A maximum of 16 venous blood samples (mean, 13 +/- 2) were collected at predetermined times up to 10 h after drug administration. Plasma ketorolac concentrations were measured by high-performance liquid chromatography after solid-phase extraction. Individual concentration-versus-time relationships were best fit to a two-compartment pharmacokinetic model by using SAAM II. Body weight-normalized pharmacokinetic variables did not differ among the age groups and were similar to those reported for adults, including a volume of distribution at steady state of 113 +/- 33 mL/kg (mean +/- SD) and an elimination clearance of 0.57 +/- 0.17 mL x min(-1) x kg(-1). Our study demonstrates that a single dose of ketorolac (0.5 mg/kg) results in plasma concentrations in the adult therapeutic concentration range for 6 h in most children. Our data provide no evidence that children require either larger weight-adjusted doses or shorter dosing intervals than adults to provide similar plasma drug concentrations.

IMPLICATIONS

The literature suggests that ketorolac disposition differs between children and adults. We characterized ketorolac pharmacokinetics in 36 children. Body weight-normalized two-compartment pharmacokinetic variables did not differ among pediatric patients <17 yr old and were similar to adult values.