Diffusion of intramuscular ketoprofen into the cerebrospinal fluid

Pharmacokinetics and Pharmacodynamics of (S)-Ketoprofen Co-Administered with Caffeine: A Preclinical Study in Arthritic Rats

The purpose of the present study was to determine whether caffeine modifies the pharmacokinetics and pharmacodynamics of (S)-ketoprofen following oral administration in a gout-type pain model. 3.2 mg/kg of (S)-ketoprofen alone and combined with 17.8 mg/kg of caffeine were administered to Wistar rats and plasma levels were determined between 0.5 and 24.0 h. Additionally, antinociception was evaluated based on the protocol of the PIFIR (pain-induced functional impairment in the rat) model before blood sampling between 0.5 and 4.0 h. Significant differences in C_max, AUC_0-24, and AUC_0-∞ values were observed with caffeine administration (p < 0.05). Also, significant differences in E_max, T_max, and AUC_0-4 values were determined when comparing the treatments with and without caffeine (p < 0.05). By relating the pharmacokinetic and pharmacodynamic data, a counter-clockwise hysteresis loop was observed regardless of the administration of caffeine. When the relationship between AUCe and AUCp was fitted to the sigmoidal E_max model, a satisfactory correlation was found (R² > 0.99) as well as significant differences in E_max and EC₅₀ values (p < 0.05). With caffeine, E_max and EC₅₀ values changed by 489.5% and 695.4%, respectively. The combination studied represents a convenient alternative for the treatment of pain when considering the advantages offered by using drugs with different mechanisms of action.

The Cerebrospinal Fluid Distribution of Postoperatively Administred Dexketoprofen and Etoricoxib and Their Effect on Pain and Inflammatory Markers in Patients Undergoing Hip Arthroplasty

BACKGROUND AND OBJECTIVE

Based on earlier literature, etoricoxib may have a delayed analgesic effect in postoperative setting when analgesic efficacy of nonselective nonsteroidal anti-inflammatory drug dexketoprofen is rapid. This may be caused by slow penetration of etoricoxib into the central nervous system (CNS). Therefore we decided to determine the plasma and cerebrospinal fluid (CSF) pharmacokinetics and pharmacodynamics of dexketoprofen and etoricoxib in patients with hip arthroplasty.

METHODS

A total of 24 patients, scheduled for an elective primary hip arthroplasty were enrolled. After surgery, 12 subjects were randomized to received a single intravenous dose of dexketoprofen, and 12 subjects were given oral etoricoxib. Paired blood and CSF samples were taken up to 24 h for measurement of drug concentrations, interleukin (IL)-6, IL-1ra and blood for interleukin 10.

RESULTS

In CSF the highest measured concentration (C max) of dexketoprofen was 4.0 (median) ng/mL (minimum-maximum 1.9-13.9) and time to the highest concentration (t max) 3 h (2-5), and for etoricoxib C max 73 ng/mL (36-127) and t max 5 h (1-24), respectively. Opioid consumption during the first 24 postoperative hours was similar in the two groups. Dexketoprofen and etoricoxib had a similar effect on the postoperative inflammatory response. No significant differences considering pain relief or adverse events were found between the two groups.

CONCLUSION

Dexketoprofen and etoricoxib entered the CNS readily, already at 30 min after administration dexketoprofen was detected in the CSF in most subjects and etoricoxib after 60 min. A single dose of dexketoprofen and etoricoxib provided a similar anti-inflammatory and analgesic response after major orthopaedic surgery.

A Dose-Finding Study of Dexketoprofen in Patients Undergoing Laparoscopic Cholecystectomy: A Randomized Clinical Trial on Effects on the Analgesic Concentration of Oxycodone

Background

Dexketoprofen has been shown to provide efficient analgesia and an opioid-sparing effect after orthopedic surgery. In this dose-finding study, we evaluated the analgesic efficacy and opioid-sparing effect of dexketoprofen administered intravenously (i.v.) after laparoscopic cholecystectomy (LCC).

Methods

Twenty-four patients undergoing LCC were randomized to receive dexketoprofen 10 or 50 mg i.v. 15 min before the end of the surgery. Subjects were provided with 0.2 mg/kg of oxycodone at anesthesia induction. In the recovery room, pain was assessed with an 11-point numerical rating scale (NRS; score of 0 = no pain, score of 10 = most severe pain) every 10 min. When the NRS score was ≥3/10 at rest or ≥5/10 at wound compression, a plasma sample was taken for analysis of oxycodone [to determine the minimum effective concentration (MEC)], its metabolites, and dexketoprofen. After that, subjects were titrated with oxycodone 2 or 3 mg i.v. every 10 min until the NRS score was <3/10 at rest and <5/10 at wound compression. At this point, a second plasma sample was taken for analysis of oxycodone [minimum effective analgesic concentration (MEAC)], its metabolites, and dexketoprofen.

Results

At the onset of pain, the plasma oxycodone concentrations (MEC) were similar in the two groups: median 60 ng/mL (range 37–73) in the 10 mg group and median 52 ng/mL (range 24–79) in the 50 mg group. At the time of pain relief, the MEACs were 98 ng/mL (range 59–150) in the 10 mg group and 80 ng/mL (range 45–128) in the 50 mg group. The total doses of oxycodone needed to achieve pain relief were similar: 0.11 mg/kg (range 0–0.33) in the 10 mg group and 0.08 mg/kg (range 0–0.24) in the 50 mg group. Eleven subjects developed mild desaturation or a decreased respiratory rate after oxycodone titration.

Conclusion

In the present double-blinded, randomized clinical trial, the need for a rescue opioid analgesic, oxycodone, was similar with the two dose levels of dexketoprofen—10 and 50 mg i.v.—after LCC.

Intermittent hypoxia-induced cardiorespiratory long-term facilitation: A new role for microglia

Intermittent hypoxia induces plasticity in neural networks controlling breathing and cardiovascular function. Studies demonstrate that mechanisms causing cardiorespiratory plasticity rely on intracellular signalling pathways that are activated by specific neurotransmitters. Peptides such as serotonin, PACAP and orexin are well-known for their physiological significance in regulating the cardiorespiratory system. Their receptor counterparts are present in cardiorespiratory centres of the brainstem medulla and spinal cord. Microglial cells are also important players in inducing plasticity. The phenotype and function of microglial cells can change based on the physiological state of the central nervous system. Here, we propose that in the autonomic nuclei of the ventral brainstem the relationship between neurotransmitters and neurokines, neurons and microglia determines the overall neural function of the central cardiorespiratory system.

Intermittent Hypoxia-Induced Spinal Inflammation Impairs Respiratory Motor Plasticity by a Spinal p38 MAP Kinase-Dependent Mechanism

Inflammation is characteristic of most clinical disorders that challenge the neural control of breathing. Since inflammation modulates neuroplasticity, we studied the impact of inflammation caused by prolonged intermittent hypoxia on an important form of respiratory plasticity, acute intermittent hypoxia (three, 5 min hypoxic episodes, 5 min normoxic intervals) induced phrenic long-term facilitation (pLTF). Because chronic intermittent hypoxia elicits neuroinflammation and pLTF is undermined by lipopolysaccharide-induced systemic inflammation, we hypothesized that one night of intermittent hypoxia (IH-1) elicits spinal inflammation, thereby impairing pLTF by a p38 MAP kinase-dependent mechanism. pLTF and spinal inflammation were assessed in anesthetized rats pretreated with IH-1 (2 min hypoxia, 2 min normoxia; 8 h) or sham normoxia and allowed 16 h for recovery. IH-1 (1) transiently increased IL-6 (1.5 ± 0.2-fold; p = 0.02) and inducible nitric oxide synthase (iNOS) (2.4 ± 0.4-fold; p = 0.01) mRNA in cervical spinal homogenates, (2) elicited a sustained increase in IL-1β mRNA (2.4 ± 0.2-fold; p < 0.001) in isolated cervical spinal microglia, and (3) abolished pLTF (-1 ± 5% vs 56 ± 10% in controls; p < 0.001). pLTF was restored after IH-1 by systemic NSAID administration (ketoprofen; 55 ± 9%; p < 0.001) or spinal p38 MAP kinase inhibition (58 ± 2%; p < 0.001). IH-1 increased phosphorylated (activated) p38 MAP kinase immunofluorescence in identified phrenic motoneurons and adjacent microglia. In conclusion, IH-1 elicits spinal inflammation and impairs pLTF by a spinal p38 MAP kinase-dependent mechanism. By targeting inflammation, we may develop strategies to manipulate respiratory motor plasticity for therapeutic advantage when the respiratory control system is compromised (e.g., sleep apnea, apnea of prematurity, spinal injury, or motor neuron disease).

Relationship between blood levels and the anti-hyperalgesic effect of ketoprofen in the rat

The relationship between blood levels of ketoprofen and its anti-hyperalgesic effects was examined in rat using the carrageenan-evoked thermal hyperalgesia model. Female adult Wistar rats were injected with carrageenan into the plantar surface of the right hind paw. Immediately after, rats were administered with ketoprofen po and hindpaw withdrawal latency measured and micro-whole blood samples were obtained over six hours via a cannula inserted in the caudal artery. Ketoprofen levels were measured by HPLC. Ketoprofen concentration increased in a dose-dependent manner and was reflected in dose-dependent anti-hyperalgesic effect. The pharmacokinetic and pharmacodynamic parameters expressed as mean ± s.e.m. following administration of 1, 3.2, and 10 mg/kg ketoprofen were: Cmax 1.27 ± 0.08, 3.44 ± 0.20 and 11.76 ± 0.81 μg/mL; AUClast 4.16 ± 0.17, 11.63 ± 0.65 and 28.15 ± 1.32 μg h/mL; and Emax observed (AUCE ): 65.41 ± 7.79, 92.06 ± 6.46 and 98.42 ± 7.53%. A direct relationship between blood concentrations and the anti-hyperalgesic effect of ketoprofen followed a maximum effect model equation. The results indicate that the anti-hyperalgesic effect of ketoprofen in the carrageenan pain model can be predicted by the pharmacokinetic properties of ketoprofen.

Plasma and cerebrospinal fluid pharmacokinetics of flurbiprofen in children

AIMS

This study was designed to characterize paediatric pharmacokinetics and central nervous system exposure of flurbiprofen.

METHODS

The pharmacokinetics of flurbiprofen were studied in 64 healthy children aged 3 months to 13 years, undergoing surgery with spinal anaesthesia. Children were administered preoperatively a single dose of flurbiprofen intravenously as prodrug (n= 27) or by mouth as syrup (n= 37). A single cerebrospinal fluid (CSF) sample (n= 60) was collected at the induction of anaesthesia, and plasma samples (n= 304) before, during and after the operation (up to 20 h after administration). A population pharmacokinetic model was built using the NONMEM software package.

RESULTS

Flurbiprofen concentrations in plasma were well described by a three compartment model. The apparent bioavailability of oral flurbiprofen syrup was 81%. The estimated clearance (CL) was 0.96l h(-1) 70 kg(-1) . Age did not affect the clearance after weight had been included as a covariate. The estimated volume of distribution at steady state (V(ss) ) was 8.1 l 70 kg(-1) . Flurbiprofen permeated into the CSF, reaching concentrations that were seven-fold higher compared with unbound plasma concentrations.

CONCLUSIONS

Flurbiprofen pharmacokinetics can be described using only weight as a covariate in children above 6months, while more research is needed in neonates and in younger infants.

Ketoprofen pharmacokinetics, efficacy, and tolerability in pediatric patients

The NSAID ketoprofen is used widely in the management of inflammatory and musculoskeletal conditions, pain, and fever in children and adults. Pharmacokinetic studies show that drug exposure after a single intravenous dose is similar in children and adults (after dose normalization), and thus similar mg/kg bodyweight dosing may be used in children and adults. Ketoprofen crosses the blood-brain barrier and therefore has the potential to cause central analgesic effects. Ketoprofen has been investigated in children for the treatment of pain and fever, peri- and postoperative pain, and inflammatory pain conditions. The results of four clinical trials in febrile conditions with the oral syrup formulation indicate that ketoprofen is as effective as acetaminophen (paracetamol) and ibuprofen, allowing children to rapidly return to daily activities with improvements in sleep quality and appetite. Studies of ketoprofen in the management of postoperative pain indicate that ketoprofen is a highly effective analgesic when administered perioperatively for a variety of surgical types, by a variety of routes, and whether given preoperatively or postoperatively. For adenoidectomy, intravenous ketoprofen provided superior postoperative analgesic efficacy compared with placebo. Analgesic efficacy was similar with intravenous, intramuscular, or rectal routes of administration, but oral administration just before surgery was inferior to intravenous administration in this setting. In patients undergoing a tonsillectomy, intravenous ketoprofen was superior to intravenous tramadol in terms of the need for postoperative rescue analgesia, but did not remove the need for rescue opioid therapy in these patients. Intravenous ketoprofen had superior postoperative analgesic efficacy to placebo when given as an adjuvant to epidural sufentanil analgesia after major surgery. Oral ketoprofen has shown efficacy in the treatment of juvenile rheumatoid arthritis. Ketoprofen is generally well tolerated in pediatric patients. Most of the adverse events reported are mild and transient, and are similar to those observed with other NSAIDs. Long-term tolerability has not yet been fully established in children, but data from three studies in >900 children indicate that oral ketoprofen is well tolerated when administered for up to 3 weeks after surgery. In conclusion, ketoprofen is effective and well tolerated in children for the control of post-surgical pain and for the control of pain and fever in inflammatory conditions.

A critical appraisal of COX-2 selective inhibition and analgesia: how good so far?

The development of COX-2 selective inhibitors has opened a new era of clinical investigation in NSAIDs. Discussion of the established concepts of inflammation and therapeutical uses of these drugs has changed the rationale for its clinical use and therapeutic labeling of these drugs. A comprehensive discussion across basic science and clinical areas involved in each of these concepts is presented. This led to a remarkable re-evaluation of our insights on their traditionally proposed mechanisms of analgesia, their side-effects, and the clinical indication of NSAIDs as "over the counter" pain killers. This may shift physicians toward a more rational use of this drug class.

Cerebrospinal Fluid Distribution of Ketoprofen after Intravenous Administration in Young Children

OBJECTIVE

The purpose of this study was to evaluate the cerebrospinal fluid (CSF) distribution of an NSAID, ketoprofen, in children. Ketoprofen concentrations were determined from the CSF, plasma and protein-free plasma samples.

METHODS

Children (n = 21), aged 13-94 months, were given intravenous ketoprofen (1 mg/kg) prior to surgery under spinal anaesthesia. Single venous blood and CSF samples from each patient were collected simultaneously 7-67 minutes after the drug administration. Ketoprofen concentrations in the samples were determined using gas chromatography-mass spectrometry.

RESULTS

Ketoprofen entered the CSF and was detectable in all samples. However, CSF delivery was limited; the ratio of ketoprofen concentration in CSF to plasma remained below 0.006 at all times. Ketoprofen was highly bound (> 98%) to plasma proteins. The free ketoprofen fraction was not in equilibrium with the CSF, and no clear peak drug concentration in the CSF was observed.

CONCLUSION

This study shows that ketoprofen is able to enter the CSF of children, which enables central analgesic effects of ketoprofen. However, the slow distribution of ketoprofen into the CSF and the apparently low absolute concentrations has to be taken into account when central analgesic effects are desired.

COX-dependent mechanisms involved in the antinociceptive action of NSAIDs at central and peripheral sites

Despite the diverse chemical structure of aspirin-like drugs, the antinociceptive effect of NSAIDs is mainly due to their common property of inhibiting cyclooxygenases involved in the formation of prostaglandins. Prostaglandins are potent hyperalgesic mediators which modulate multiple sites along the nociceptive pathway and enhance both transduction (peripheral sensitizing effect) and transmission (central sensitizing effect) of nociceptive information. Inhibition of the formation of prostaglandins at peripheral and central sites by NSAIDs thus leads to the normalisation of the increased pain threshold associated with inflammation. The contribution of peripheral and central mechanisms to the overall antinociceptive action of NSAIDs depends on several factors including the location of the targets of drug action, the site of drug delivery and the uptake and distribution to the site of action. The present work reviews the data on the regulation and location of cyclooxygenases at central and peripheral sites of the nociceptive pathway and focuses on the role of COX in the generation and maintenance of pain hypersensitivity. Experimental and clinical evidences are used to evaluate the significance of the peripheral and central antihyperalgesic effects of NSAIDs.

Comparison of the antinociceptive activity of two new NO-releasing derivatives of the NSAID S-ketoprofen in rats

1 Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase (COX) enzymes inducing analgesic, anti-inflammatory and antipyretic actions. They are not devoid of severe side effects and so, the search for new compounds with similar or higher effectiveness and a lower incidence of undesired actions is important. Nitric oxide (NO)-releasing NSAIDs resulted from this search. 2 We have compared the antinociceptive effectiveness of cumulative doses of two new NO-releasing derivatives of S-ketoprofen, HCT-2037 and HCT-2040, using the recording of spinal cord nociceptive reflexes in anesthetized and awake rats and after intravenous and oral administration. 3 S-ketoprofen and HCT-2040 were equieffective in reducing responses to noxious mechanical stimulation after i.v. administration in anesthetized animals (ID50s: 1.3+/-0.1 and 1.6+/-0.2 micromol kg(-1) respectively), but did not modify wind-up. HCT-2037 was two-fold more potent (ID50 of 0.75+/-0.1 micromol kg(-1)) in responses to mechanical stimuli and very effective in reducing wind-up (63+/-17% of control; P<0.01; MED: 0.4 micromol kg(-1)), indicating a greater activity than the parent compound. 4 In awake animals with inflammation, HCT-2037 p.o. fully inhibited mechanical allodynia, 91+/-12% reduction, and hyperalgesia, 94+/-8% reduction. Equivalent doses of S-ketoprofen only partially reduced either allodynia (50+/-11%) or hyperalgesia (40+/-4%). The effect on responses to noxious thermal stimulation was similar for the two compounds. 5 We conclude that the molecular changes made in the structure of S-ketoprofen including an NO moiety in its structure, improve the antinociceptive profile of the compound opening new perspectives in a safer use of NSAIDs as analgesic drugs.

Evidence for a central mechanism of action of S-(+)-ketoprofen

It has been observed that some non-steroidal anti-inflammatory drugs (NSAIDs) may act through several mechanisms, in addition to central inhibition of prostaglandin synthesis. These other mechanisms include the L-arginine-nitric oxide (L-arginine-NO) pathway, as well as endogenous opiate and serotonergic mechanisms. Some of these mechanisms can explain the efficacy of NSAIDs in chronic pain conditions such as rheumatoid arthritis. The present study was designed to elucidate the involvement of the above pathways/mechanisms in the antinociceptive effect of S-(+)-ketoprofen at supraspinal and spinal levels. S-(+)-ketoprofen induced dose-dependent antinociception in the pain-induced functional impairment model in the rat. The antinociceptive effect of S-(+)-ketoprofen was not altered by i.t. or intracerebroventricula (i.c.v.) pre-treatment with L-arginine (29.6 microg/site) and L-nitro-arginine-monomethylester (L-NAME) (21.1 microg/site) and neither was the effect of S-(+)-ketoprofen modified by the opiate antagonist, naloxone (1 mg/kg, s.c.). In marked contrast, both i.c.v. administration of the 5-hydroxytryptamine (5-HT)(1)/5-HT(2)/5-HT(7) receptor antagonist, methiothepin (1.5 microg/site), and i.t. administration of the 5-HT(3)/5-HT(4) receptor antagonist, tropisetron (0.9 microg/site), significantly inhibited the S-(+)-ketoprofen-induced antinociceptive effect. These data suggest that the antinociceptive response to S-(+)-ketoprofen involves serotoninergic mechanisms via both supraspinal 5-HT(1)/5-HT(2)/5-HT(7) receptors and 5-HT(3) receptors located at spinal level. A role of the L-arginine-NO and opiate systems in S-(+)-ketoprofen-induced antinociception in the pain-induced functional impairment model in the rat model seems unlikely.

Effects of preoperative administration of ketoprofen on anesthetic requirements and signs of postoperative pain in dogs undergoing elective ovariohysterectomy

OBJECTIVE

To determine the effects of preoperative administration of ketoprofen on anesthetic requirements and signs of postoperative pain in dogs undergoing elective ovariohysterectomy.

DESIGN

Randomized, controlled clinical trial.

ANIMALS

22 clinically normal client-owned dogs.

PROCEDURE

60 minutes before induction of anesthesia, 11 dogs were given ketoprofen (2 mg/kg [0.9 mg/lb], i.m.), and the other 11 were given saline (0.9% NaCl) solution. Dogs were premedicated with glycopyrrolate, acepromazine, and butorphanol and anesthetized with thiopental; anesthesia was maintained with isoflurane. Ovariohysterectomy was performed by an experienced surgeon, and butorphanol was given 15 minutes before completion of the procedure. Objective behavioral scores and numerical pain scores at rest and with movement were recorded every 2 hours for 12 hours after surgery and then every 4 hours for an additional 12 hours.

RESULTS

Preoperative administration of ketoprofen did not reduce the dose of thiopental required to induce anesthesia or the end-tidal concentration of isoflurane required to maintain anesthesia. Activity levels and median objective behavioral scores were significantly higher 4 and 6 hours after surgery in dogs given ketoprofen than in dogs given saline solution. However, mean numerical pain scores in dogs given ketoprofen were not significantly different from scores for dogs given saline solution at any time.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that preoperative administration of ketoprofen does not reduce anesthetic requirements in dogs undergoing elective ovariohysterectomy but may reduce signs of pain after surgery. Results also suggest that the objective behavioral score may be a more sensitive measure of acute postoperative pain than traditional numerical pain scores.

Diffusion of ketoprofen into the cerebrospinal fluid of young children

BACKGROUND

The objective was to examine whether or not ketoprofen enters the cerebrospinal fluid after a single oral dose of 1 mg.kg-1 syrup, and to find out what is the lowest plasma concentration that will achieve a measurable level in the cerebrospinal fluid.

METHODS

We measured ketoprofen concentrations both in plasma and cerebrospinal fluid of 10 young and healthy children (aged 9-86 months) after surgery with spinal anaesthesia. Samples of cerebrospinal fluid were collected 30 min after drug administration, at the same time as venous blood samples. A validated high-performance liquid chromatography method with a lower limit of 0.02 microg x ml(-1) was used to detect ketoprofen concentrations in cerebrospinal fluid and plasma.

RESULTS

Ketoprofen was detectable in the cerebrospinal fluid only in the child who had the highest plasma concentration, 7.4 microg x ml(-1), while at plasma concentrations 6.5 microg x ml(-1) or less, cerebrospinal fluid (CSF) concentrations remained unmeasurable. The detected CSF/plasma ratio was 0.008.

CONCLUSIONS

These results indicate that ketoprofen at a dose of 1 mg x kg(-1) is too low to produce measurable CSF levels within 30 min of oral administration.

The effect of ketoprofen on recovery after tonsillectomy in children: a 3-week follow-up study

OBJECTIVE

To evaluate recovery after tonsillectomy in children, and to determine the safety and efficacy of ketoprofen in pain treatment after discharge.

STUDY DESIGN

A prospective, longitudinal study in 102 children undergoing tonsillectomy.

METHODS

All children underwent tonsillectomy under a same general anesthesia. At discharge, all patients were prescribed ketoprofen capsules at a dose of 3-5 mg(-1) kg(-1) per 24 h for postoperative pain control at home, with paracetamol or paracetamol-codeine tablets for rescue analgesia. At home, the patients recorded pain and analgesic consumption each day for the first week after surgery. At 3 weeks, patients recorded the total analgesic requirement, duration of pain, and all adverse events during recovery and return to normal daily activities.

RESULTS

The median of pain cessation was 9 days (range 1-20 days) and the median duration of analgesic treatment was 10 days (4-19 days). More than 50% of the patients needed rescue analgesic daily during the first week after tonsillectomy. Ketoprofen combined with paracetamol or paracetamol-codeine provided sufficient analgesia for most children. However, the analgesic action of drugs was too short to achieve pain relief, which allow undisturbed sleep during the first postoperative nights. A return back to normal daily activities took place after 9 days (2-26 days). The influence of age for pain pattern was negligible. Five patients needed electrocautery to stop postoperative bleeding. No other serious adverse-events occurred.

CONCLUSIONS

The main problem after tonsillectomy is significant pain that may last 9 days or longer after surgery. Ketoprofen combined with paracetamol-codeine seems to provide a sufficient analgesia, but before ketoprofen may be recommended for children during tonsillectomy a larger study is needed to show whether or not ketoprofen increases the hemorrhage rate.

Cyclooxygenase-1 vs. cyclooxygenase-2 inhibitors in the induction of antinociception in rodent withdrawal reflexes

Non-steroidal antiinflammatory drugs (NSAIDs) inhibit the cyclooxygenase (COX) enzyme and so they are effective analgesic, antiinflammatory and antipyretic drugs. The discovery of COX-2 led to the search for new NSAIDs with a selective action over this isoenzyme. The experiments performed to date have shown either more, less or no different efficacy of new COX-2 selective NSAIDs when compared to the non-selective inhibitors, probably because the comparison has not been performed under similar conditions. We have therefore compared the analgesic activity of six NSAIDs with different selectivity for the COX isoenzymes. The experiments were performed using the recording of spinal cord nociceptive reflexes in anaesthetised rats and in awake mice. The non-selective COX inhibitors, such as dexketoprofen trometamol, were effective in reducing nociceptive responses both in normal and monoarthritic rats (ED50s: 0.31 and 3.97 micromol/kg, respectively), and in mice with paw inflammation (12.5 micromol/kg, p < 0.01). The COX-1 selective inhibitor SC-58560 showed efficacy in normal rats (ED50: 0.8 micromol/kg) and in mice with paw inflammation (15 micromol/kg, p < 0.05), but not in monoarthritic rats. The COX-2 selective inhibitors celecoxib (105 micromol/kg) and rofecoxib (128 micromol/kg) however, were not effective in any of the groups studied. We conclude that inhibition of both COX isoenzymes is needed to achieve an effective analgesia in inflammation.

Effect of caffeine on antinociceptive action of ketoprofen in rats

BACKGROUND

To assess a possible synergistic antinociceptive interaction, the antinociceptive effects of ketoprofen (KET), and caffeine (CAF) administered either separately or in combinations were determined in a model of arthritic pain.

METHODS

Antinociceptive activity was assayed using "ellipsis pain-induced functional impairment in the rat" (PIFIR model). The antinociceptive efficacies were evaluated using several dose-response curves and time courses. The antinociceptive effects from the combination that produced the greater effect were compared with the maximal antinociceptive effect of either morphine, acetylsalicylic acid (ASA), or KET alone. The animals were administered with 0.05 mL intra-articular (i.a.) of uric acid to induce nociception. Groups of six rats received orally either ASA, morphine (MOR), KET, CAF, or a combination KET + CAF (24 combinations).

RESULTS

ASA (ED(50) 465.2 +/- 1.5 mg/kg), MOR (ED(50) 71.0 +/- 1.6 mg/kg), and KET (ED(50) 7.2 +/- 1.4 mg/kg) alone induced dose-dependent antinociception, whereas CAF alone showed no activity at the assayed doses. Nine combinations showed various degrees of potentiation (p <0.01), while the remainder exhibited the antinociceptive effect of KET only. Combinations of 17.8 mg/kg CAF with either 1.0, 1.8, 3.2, 5.6, or 10.0 mg/kg KET yielded the highest antinociceptive potentiations. For example, antinociceptive effect was 125.6 +/- 21.4 area units (au) with KET (3.2 mg/kg) alone, but the combination with CAF (17.8 mg/kg) showed 309.5 +/- 10.3 au. The median effective dose (ED(50)) of KET alone was 7.2 +/- 1.4 mg/kg, whereas the ED(50) of KET + CAF 17.8 mg/kg was 0.4 +/- 0.6 mg/kg: KET in the presence of CAF was approximately 18 times more potent than the analgesic drug without CAF.

CONCLUSIONS

These results showed that CAF was able to potentiate the analgesia of KET, but only at selected dose combinations: CAF in the doses of 10.0 and 17.8 mg/kg was able to potentiate the analgesic effect of KET, the most efficacious drug combination being CAF 17.8 mg/kg + KET 3.2 mg/kg. The combination of analgesic drugs and CAF can produce better antinociceptive effects than the analgesic drug alone. This knowledge will permit the selection of the therapeutically most effective combination ratio of drugs, employing lower doses of each drug.

A comparative experimental study of the effects of diclofenac and ketoprofen on the small-bowel mucosa of canines

The aim of this experimental study was to investigate the effect of diclofenac sodium and ketoprofen, two non-steroidal anti-inflammatory drugs (NSAIDs) with different excretion pathways, and the role of other enteric factors during simultaneous administration of these drugs on the development of mucosal lesions of the small intestine in canines. Twenty-five animals were divided into three groups. Group I included 10 canines, 5 with diclofenac sodium (group Ia) and 5 with ketoprofen administration (group Ib). Group II included 5 animals in which a segment of ileum was surgically isolated from the rest of the small intestine. Group III included 10 animals in two subgroups of 5; a segment of ileum was surgically isolated in both subgroups; groups IIIa received diclofenac and group IIIb ketoprofen. Histological examination of the specimens taken revealed macroscopic and microscopic mucosal lesions in 5/5 animals in group Ia, whereas none of the 5 animals in group Ib had any lesions. Group II did not reveal any mucosal lesions. Three out of 5 animals (60%) administered diclofenac in group IIIa had intestinal mucosal lesions, but none of the 5 revealed lesions in the isolated loop of ileum. No lesions were observed in the isolated loop or in the rest of the intestinal mucosa in the animals in group IIIb. Our results suggest that NSAIDs produce intestinal mucosal lesions not only when administered per mouth but also after intramuscular administration. Diclofenac, unlike ketoprofen, was responsible for the development of lesions in the intestinal mucosa. The role of drugs and/or their metabolites in the intestine and certain other factors must still be determined.

The clinical effect of ketoprofen after arthroscopic subacromial decompression: a randomized double-blind prospective study

The purpose of the study was to evaluate the clinical effect of ketoprofen after arthroscopic subacromial decompression (ASD). The design was randomized, prospective, and double-blind, with a placebo control group. Forty-one consecutive patients with subacromial impingement syndrome, were randomized to treatment with ketoprofen 200 mg once daily or placebo for 6 weeks following ASD. For additional analgesia, patients used paracetamol if necessary. Clinical follow-up was performed at 6 weeks and at 2 years postoperatively. At the 6-week follow-up, the patients treated with ketoprofen had a statistically significant increase in UCLA total score (P<.05), range of movement (P<.05), and satisfaction (P<.05), and they had significantly less pain (P<.05). There was no statistical difference between the ketoprofen and placebo groups regarding strength. Patients receiving ketoprofen had significantly less need for additional analgesia (P<.05). At the 2-year follow-up, there were no differences in the scores between the ketoprofen and placebo group.

The NSAID dexketoprofen trometamol is as potent as mu-opioids in the depression of wind-up and spinal cord nociceptive reflexes in normal rats

The aim of this study was to examine the potency of the antinociceptive effects of the non-steroidal antiinflammatory drug (NSAID), Dexketoprofen Trometamol (the active enantiomer of ketoprofen) on spinal cord nociceptive reflexes. These effects were compared with those of the mu-opioid receptor agonist fentanyl in normal animals. The experiments were performed in male Wistar rats anaesthetised with alpha-chloralose. The nociceptive reflexes were recorded as single motor units in peripheral muscles, activated by mechanical and electrical stimulation. Both dexketoprofen and fentanyl inhibited responses evoked by mechanical and electrical stimulation with doses in the same nanomolar range (dexketoprofen ID50s: 100 and 762 nmol kg-1 and fentanyl: 40 and 51 nmol kg-1, respectively). Dexketoprofen and fentanyl also significantly inhibited wind-up. Since fentanyl has been shown to be some 1000 times more potent than morphine in this type of experiments, we conclude that dexketoprofen has central analgesic actions in normal animals and depresses nociceptive responses with a potency similar to that of mu-opioid agonists.

Central and peripheral actions of the NSAID ketoprofen on spinal cord nociceptive reflexes

Ketoprofen is a non-steroidal antiinflammatory drug (NSAID) which provides effective analgesia in situations of pain provoked by tissue inflammation. However, the location of its analgesic effects, (peripheral tissues versus central nervous system), have not been clearly identified and separated. In the present study the effectiveness of ketoprofen was examined in two different types of experiments: (i) Open field behavioural tests in conscious rats, and (ii) spinal cord nociceptive reflexes (single motor units) activated by electrical and thermal stimulation in chloralose anaesthetised rats. The experiments were performed in rats with carrageenan-induced inflammation of one hindpaw, or of one knee joint. The administration of ketoprofen significantly inhibited the reduction of exploratory movements caused by inflammation in open field experiments. Ketoprofen was also effective in depressing reflex activity evoked by electrical and noxious thermal stimulation of the skin, either in inflamed tissue or in normal tissue of monoarthritic animals. It was also effective in the reduction of reflex wind-up; a phenomenon in which the activity of spinal cord neurones increases progressively with high frequency electrical stimulation. We therefore conclude that ketoprofen has central as well as peripheral analgesic activity.

The effects of a nonsteroidal antiinflammatory drug (ketoprofen) on morphine respiratory depression: a double-blind, randomized study in volunteers

Nonsteroidal antiinflammatory drugs (NSAIDs) decrease the postoperative requirements for opioid analgesic medication. To determine whether NSAIDs potentiate the respiratory effects of opioids, we studied the effects of ketoprofen (K), an NSAID, on respiratory depression induced by morphine (M) in volunteers. After ethics committee approval, 12 healthy male volunteers received infusions of K (1.5 mg/kg), M (0.1 mg/ kg), and KM (1.5 mg/kg + 0.1 mg/kg) in a double-blind, randomized, three-treatment, three-period cross-over trial. During the three sessions, CO2 rebreathing challenges for ventilatory and occlusion pressure responses to CO2 were performed immediately before and 10, 70, 130, 190, and 250 min after drug infusion over 10 min. Venous blood samples for plasma drug concentrations were withdrawn at the same times. Comparisons were made on slopes of ventilatory and occlusion pressure responses to CO2. Venous blood samples confirmed that morphine plasma concentrations were similar when subjects had received morphine alone and when they had received the combination of drugs. Morphine alone induced a respiratory depression with a decrease in both ventilatory and occlusion pressure responses to CO2. Ketoprofen alone did not produce any respiratory effects. The combination of drugs induced a decrease in ventilatory responses to CO2, but intergroup comparisons showed that this was significantly less marked than the decrease induced by morphine alone. In conclusion, for similar morphine plasma concentrations, respiratory depression was less marked with the combination of drugs than with morphine alone. Therefore, ketoprofen may reduce the respiratory depression induced by morphine.

Mechanisms of actions of opioids and non-steroidal anti-inflammatory drugs

Opioids and non-steroidal anti-inflammatory drugs (NSAIDs) are the commonest drugs used to treat pain. Opioids mimic the actions of endogenous opioid peptides by interacting with mu, delta or kappa opioid receptors. The opioid receptors are coupled to G1 proteins and the actions of the opioids are mainly inhibitory. They close N-type voltage-operated calcium channels and open calcium-dependent inwardly-rectifying potassium channels. This results in hyperpolarization and a reduction in neuronal excitability. They also decrease intracellular cAMP which modulates the release of nociceptive neurotransmitters (e.g. substance P). Inhibition of prostaglandin synthesis by cyclooxygenase is the principal mode of the analgesic and anti-inflammatory actions of NSAIDs. Cyclo-oxygenase is inhibited irreversibly by aspirin and reversibly by other NSAIDs. The widespread inhibition of cyclo-oxygenase is responsible for many of the adverse effects of these drugs. NSAIDs also reduce prostaglandin production within the CNS. This is the main action of paracetamol.

Ketoprofen, a non-steroidal anti-inflammatory drug prevents the late-onset reduction of muscarinic receptors in gerbil hippocampus after transient forebrain ischemia

Ischemia-induced hippocampal late-onset reduction of muscarinic acetylcholine receptors (LORMAR) begins as late as 7 days after transient forebrain ischemia in the gerbil, but it precedes to completion of neuronal death in the CA1 region. We previously reported that post-ischemic administration of cyclosporin A prevented LORMAR with suppression of astroglial and microglial activation. In the present study, we showed that the chronic post-ischemic administration of a non-steroidal anti-inflammatory drug, ketoprofen (5 mg/kg, subcutaneously, twice a day for 14 days) significantly reduced LORMAR both 14 days and 21 days after 5-min transient ischemia. This protective effect of ketoprofen against LORMAR suggests that the non-steroidal anti-inflammatory drugs is clinically efficacious in the treatment of LORMAR, a sequela of cerebral ischemia.

Stereoselective inhibition of rat brain cyclooxygenase by dexketoprofen

Although it has been assumed that the effects of nonsteroidal antiinflammatory drugs (NSAIDs) are mainly the result of their action on local synthesis of prostaglandins, there is growing evidence to suggest that they may also exert a central analgesic action. Some authors have suggested that inhibition of prostaglandin synthesis in the brain could contribute to the analgesic action. The effect of dexketoprofen trometamol (tromethamine salt of the enantiomer (+)-S-ketoprofen) on prostaglandin synthesis was investigated in rat brain fragments and in cyclooxygenase preparations from rat brain microsomes. Effects of the (-)-R-enantiomer and the racemic mixture were also evaluated. Significant levels of prostaglandin F2 alpha (PGF2 alpha) were synthesized in rat brain fragments after 10 min of incubation at 37 degrees C. Dexketoprofen was found to be a potent inhibitor of this PGF2 alpha production in rat brain (IC50 = 6.2 nM), and it completely suppressed PGF2 alpha production at 1 microM concentration. In addition, inhibition of PGF2 alpha synthesis by dexketoprofen was highly stereoselective since the enantiomer (-)-R-ketoprofen was significantly less potent (IC50 = 294 nM); with this enantiomer, even at high concentrations such as 1 microM, less than 60% inhibition was achieved. These results correlated with those obtained in the study of racemic ketoprofen and its enantiomers on cyclooxygenase activity of rat brain microsomes, where dexketoprofen also inhibited enzymatic activity stereoselectively. IC50 values obtained for dexketoprofen, (-)-R-ketoprofen, and rac-ketoprofen were 3.5 microM, 45.3 microM, and 5.8 microM, respectively. The above results could be related to the potent analgesic effect of dexketoprofen observed in vivo, which was also stereoselective. Taken together, these findings suggest that prostaglandin synthesis inhibition in rat brain by dexketoprofen could be associated, at least in part, with the analgesic effect of this NSAID.

Severe forms of neurocysticercosis: treatment with albendazole

Study of 22 patients with the severe form of neurocysticercosis treated with albendazole (ABZ) administered in 6 different schedules ranging from 15 to 30 mg/kg/day for 21 to 60 days. Dextrochloropheniramine and ketoprofen were the adjuvant drugs. Multiple symptoms were observed in 90.9% of patients. Intracranial hypertension was manifested in 90.9%. Hydrocephaly occurred in 86.4%. Evolution was satisfactory in 10 patients, 8 died and 4 had sequelae. Tomographic studies showed the appearance of an isolated IVth ventricle in 9 patients, after ventriculoperitoneal shunt, before ABZ treatment in 3 of them, during in 5 and after treatment in one. Median clinical follow-up duration was 10 months for the patients who died and 3-4 years for survivors. In 3 patients there was an increase in cyst size during the administration of the 15 mg/kg/day ABZ dose, which was not observed in any patient when the 30 mg/kg/day dose was used.

Preclinical and clinical development of dexketoprofen

Dexketoprofen trometamol is a water-soluble salt of the dextrorotatory enantiomer of the nonsteroidal anti-inflammatory drug (NSAID) ketoprofen. Racemic ketoprofen is used as an analgesic and an anti-inflammatory agent, and is one of the most potent in vitro inhibitors of prostaglandin synthesis. This effect is due to the S(+)-enantiomer (dexketoprofen), while the R(-)-enantiomer is devoid of such activity. The pharmacokinetic profile of ketoprofen and its enantiomers was assessed in several animals species and in human volunteers. In humans, the relative bioavailability of oral dexketoprofen trometamol (12.5 and 25 mg, respectively) is similar to that of oral racemic ketoprofen (25 and 50 mg, respectively), as measured in all cases by the area under the concentration-time curve values for S(+)-ketoprofen. Dexketoprofen trometamol, given as a tablet, is rapidly absorbed, with a time to maximum plasma concentration (tmax) of between 0.25 and 0.75 hours, whereas the tmax for the S-enantiomer after the racemic drug, administered as tablets or capsules prepared with the free acid, is between 0.5 and 3 hours. Peak plasma concentrations of 1.4 and 3.1 mg/L are reached after administration of dexketoprofen trometamol 12.5 and 25 mg, respectively. From 70 to 80% of the administered dose is recovered in the urine during the first 12 hours, mainly as the acyl-glucuronoconjugated parent drug. No R(-)-ketoprofen is found in the urine after administration of dexketoprofen [S(+)-ketoprofen], confirming the absence of bioinversion of the S(+)-enantiomer in humans. in animal studies, the anti-inflammatory potency of dexketoprofen was always equivalent to that demonstrated by twice the dose of ketoprofen. Similarly, animal studies showed a high analgesic potency for dexketoprofen trometamol. The R(-)-enantiomer demonstrated a much lower potency, its analgesic action being apparent only in conditions where the metabolic bioinversion to the S(+)-enantiomer was significant. The gastric ulcerogenic effect of dexketoprofen at various oral doses (1.5 to 6 mg/kg) in the rat do not differ from those of the corresponding double doses (3 to 12 mg/kg) of racemic ketoprofen. Repeated (5-day) oral administration of dexketoprofen as the trometamol salt causes less gastric ulceration than was observed after the acid form of both dexketoprofen and the racemate. In addition, single dose dexketoprofen as the free acid at 10 to 20 mg/kg does not show a significant intestinal ulcerogenic effect in rats, while racemic ketoprofen 20 or 40 mg/kg is clearly ulcerogenic to the small intestine. The analgesic efficacy of oral dexketoprofen trometamol 10 to 20 mg is superior to that of placebo and similar to that of ibuprofen 400 mg in patients with moderate to serve pain after third molar extraction. The time to onset of pain relief appeared to be shorter in patients treated with dexketoprofen trometamol than in those treated with ibuprofen 400 mg. Dexketoprofen trometamol was well tolerated, with a reported incidence of adverse events similar to that of placebo.

Pharmacokinetics of ketoprofen in healthy horses and horses with acute synovitis

The pharmacokinetic properties of a single intravenous dose of ketoprofen (2.2 mg/kg) in plasma and synovial fluid were compared in four healthy animals and four horses with experimentally induced acute synovitis. Synovitis was induced by the injection of a 1% solution of sterile carrageenan into the left intercarpal joint. Ketoprofen was administered at the same time as carrageenan infection. The plasma disposition followed a biexponential equation or a two-compartment model in most horses. The plasma harmonic mean half-life in healthy horses (0.88 h) was longer than in horses with synovitis (0.55 h). Synovial fluid concentrations of ketoprofen in healthy horses approximated those in plasma by 3 h post-dose. In horses with synovitis, synovial fluid concentrations approximated plasma concentrations by 1 h. Synovial fluid concentrations of ketoprofen in horses with synovitis were 6.5 times higher than those in healthy horses at 1 h. The area under the synovial fluid concentration curve for horses with synovitis was greater than in healthy horses. These data suggest that the inflamed joint serves as a site of sequestration for ketoprofen. Furthermore, these results indicate that plasma pharmacokinetics may be altered by inflammation in a peripheral compartments such as the joint.

Non-steroidal anti-inflammatory drugs and spinal nociceptive processing

Non-steroidal anti-inflammatory drugs have a direct action on spinal nociceptive processing in vivo with a relative order of potency which correlates with their capacity as inhibitors of cyclooxygenase activity. However, recent clinical surveys and new in vivo evidence strongly suggest that for some of these agents, centrally mediated analgesia may also be achieved by additional mechanisms, which are independent of prostaglandin synthesis inhibition. In this review we explore the likelihood for such mechanisms following an extensive survey of existing data. The implications of these mechanisms are discussed in the light of our current understanding of spinal nociceptive processing.

The spinal actions of nonsteroidal anti-inflammatory drugs and the dissociation between their anti-inflammatory and analgesic effects

The traditional classification of nonsteroidal anti-inflammatory drugs (NSAIDs) as exclusively 'peripherally acting' agents is no longer valid. For many of these agents there is a growing body of evidence in favour of an additional central mechanism for their anti-inflammatory and analgesic effects. This view is further supported by the recent discovery that a substantial component of the hyperalgesia and allodynia that characterise postinjury hypersensitivity occurs in the CNS, notably the spinal dorsal horn. An important corollary is that inhibition of central nociceptive processing may represent an important analgesic mode of action for those NSAIDs that are effective in the management of pain after tissue injury. Historically, attempts to group this heterogeneous class of compounds into a single entity are largely derived from the observation that the majority of clinically useful NSAIDs are weak organic acids (pKa 3 to 5), bind extensively to plasma albumin (= 99%), and inhibit (to varying degrees) prostaglandin synthesis. However, the significance of these various unifying features is becoming increasingly obscure. While inhibition of prostaglandin synthesis apparently remains an important analgesic mode of action for NSAIDs both in the periphery and the CNS, other mechanisms should be considered. Some NSAIDs, in addition to their effects on prostaglandin synthesis, also affect the synthesis and activity of other neuroactive substances believed to have key roles in processing nociceptive input within the dorsal horn. It has been argued that these other actions, in conjunction with inhibition of prostaglandin synthesis, may synergistically augment the effects of NSAIDs on spinal nociceptive processing. Despite much effort, it remains a formidable task to assess the significance of these differential mechanisms upon clinical pain states. In the meantime, however, it may be possible, on the basis of in vivo studies, to evaluate the impact of putative spinal analgesic mechanisms that are unrelated to inhibition of prostaglandin synthesis. This approach has recently been extended to include the identification of pharmacokinetic and clinical correlates of these derived in vivo parameters, and in this way attempt to demonstrate clinical relevance.

The effect of diclofenac and ketoprofen on halothane MAC in rabbit

Non-steroidal anti-inflammatory drugs obviously act also on the central nervous system. We, therefore, studied the effect of diclofenac 3 mg/kg and ketoprofen 4 mg/kg on the minimum alveolar concentration (MAC) of halothane in 10 New Zealand White rabbits. After determination of halothane MAC, total doses of NSAIDs were administered intravenously as three subdoses: 12.5%, 37.5% and 50% of the total dose. Depth of anaesthesia did not increase significantly after the first two doses with either drug. With ketoprofen, halothane MAC increased after subdose 3 from 1.52 (SD 0.42) vol% to 1.9 (SD 0.36) vol% (p < 0.01). With diclofenac, halothane MAC increased after subdose 3 from 1.44 (SD 0.18) vol% to 1.60 (SD 0.39) vol% (ns). With both drugs, large interindividual differences of MAC appeared after full doses of NSAIDs.

Protein binding of indomethacin in human cerebrospinal fluid

The binding of the non-steroidal anti-inflammatory drug indomethacin to proteins in human cerebrospinal fluid (CSF), drawn during lumbar puncture from 10 patients affected by lumbosciatica, was measured by equilibrium dialysis and spectrofluorimetry. Similar binding studies on human serum albumin solutions (0.5 and 1 g/L) were performed using the same techniques. The mean binding percentage of indomethacin determined by equilibrium dialysis was 40%. The results obtained by both techniques allowed us to conclude that the binding of indomethacin in CSF was essentially due to albumin.

The pharmacokinetics of total and unbound concentrations of tenoxicam in synovial fluid and plasma

Tenoxicam is a nonsteroidal antiinflammatory drug with an elimination half-life of 60-80 hours; it is administered once daily. Tenoxicam concentrations were measured in plasma (10 samples) and synovial fluid (6 samples) over a 24-hour dosage interval at steady state in 10 subjects with arthritis who had been taking the drug at a dosage of 20 mg/day for at least 2 weeks. Total tenoxicam concentrations in synovial fluid were always less than those in plasma, and there was little fluctuation in plasma or synovial concentrations over the dosage interval, although there was substantial inter-subject variation in both concentrations. There was a significant relationship between the tenoxicam dosage when expressed as mg/kg of body weight and the average steady-state total concentration of tenoxicam in plasma (r = 0.80, P = 0.006); this accounted for a substantial proportion of the intersubject variation. The mean +/- SD steady-state concentrations in synovial fluid and plasma were 3.9 +/- 1.8 micrograms/ml and 9.2 +/- 3.7 micrograms/ml, respectively, yielding a mean +/- SD synovial fluid: plasma ratio of 0.43 +/- 0.12. Synovial fluid:plasma ratios of total tenoxicam correlated with synovial fluid:plasma ratios of albumin (r = 0.71, P = 0.02). The synovial fluid:plasma ratio of unbound tenoxicam was 0.90 +/- 0.3 (95% confidence interval 0.68-1.11), which was not significantly different from a value of 1 (t = -1.09, P = 0.31).

Pharmacokinetics of diflunisal in patients

There are few pharmacokinetic data available on the disposition of diflunisal in patients; this study, therefore, looked at the oral absorption, distribution and elimination of this drug. Ten pharmacokinetic profiles obtained from 8 patients showed a maximum plasma diflunisal concentration of 62.0 +/- 26.5 mg/L after 2.76 +/- 1.87 hours, and an area under the plasma concentration-time curve (AUC) of 678.3 +/- 362.3 mg/L.h. Significant intra- and intersubject variability was observed in this group of patients. Analysis of biliary secretion of diflunisal in 4 patients suggested a biliary elimination and subsequent enterohepatic circulation ranging between 2.4 and 15.1%. The AUC for diflunisal in synovial fluid collected from 66 patients was about 70% of that for plasma. In none of 28 patients studied could any trace of diflunisal be observed in cerebrospinal fluid, even though the sensitivity of the assay allowed detection of concentrations as low as 0.01 mg/L.

Anatomical mapping of brain sites involved in the antinociceptive effects of ketoprofen

Ketoprofen, a non-steroidal anti-inflammatory drug, has analgesic effects in animals and humans through a peripheral as well as a central action. This study was designed to determine which brain sites are involved in the central analgesic action of ketoprofen, by using the hot-plate test. Latencies to the first hindpaw lick were recorded in animals receiving local cerebral injections of ketoprofen (10 micrograms in 0.3 microliters) or a control solution (saline). Nineteen brain sites were tested. A significant analgesia was obtained in the 8 following sites: central gray, centro-medial nucleus of the thalamus, nucleus reuniens, dorso-lateral geniculate nucleus, medial geniculate nucleus, dorso-medial and ventro-medial nuclei of the hypothalamus, posterior hypothalamic nucleus and lateral vestibular nucleus. A slight analgesia, which did not reach significance, was observed in three structures: dorsal raphé, raphé magnus and ventral postero-medial thalamic nucleus. No analgesia was observed in other sites: centro-lateral nucleus of the thalamus, posterior thalamic nuclear group, parafascicular nucleus, bed nucleus of the stria terminalis, mesencephalic tegmentum, nucleus of the tractus solitarius, spinal trigeminal complex, and brainstem reticular formation. Therefore ketoprofen seems to be centrally active mostly at the level of several integrative and non-specific structures.

Plasma and cerebrospinal fluid concentrations of indomethacin in humans. Relationship to analgesic activity

Plasma and cerebrospinal fluid (CSF) concentrations of indomethacin have been determined in 52 patients hospitalized for nerve-root compression pain. Samples of blood and CSF were collected at the same time in each subject, 0.5 to 12 h after a single intramuscular injection of 50 mg indomethacin. Analgesic effect was assessed by the absolute and percentage variation in Huskisson's visual analogue scale between dosing and sampling. According to its high lipid solubility, indomethacin rapidly crossed the blood-brain barrier, being detected in CSF 0.5 h after administration. After attainment of equilibrium within 2 h, the CSF level exceeded the free plasma level. Since the drug was extensively bound to serum albumin (99.7 +/- 0.1%), this phenomenon may represent a slight degree of binding of indomethacin in CSF. The analgesic activity was not related to either the plasma or CSF concentration of indomethacin.

Central analgesic effect of ketoprofen in humans: electrophysiological evidence for a supraspinal mechanism in a double-blind and cross-over study

The aims of this study were: (1) to test the hypothesis of a central analgesic effect of the aspirin-like drug ketoprofen and (2) to attempt to differentiate between a spinal and a supraspinal mechanism in this possible central action. The threshold of the nociceptive flexion reflex from the biceps femoris muscle elicited by sural nerve stimulation was studied before and after a double-blind, cross-over and randomized intravenous injection of ketoprofen (100 mg in 5 ml saline) and saline (5 ml) in 2 groups of volunteers. The first one was composed of 10 normal subjects while the second consisted of 8 paraplegic patients with complete spinal section of traumatic origin. In normal subjects, ketoprofen injection resulted in a rapid and significant increase (+68%) of the threshold of the nociceptive reflex, while saline injection produced a slow increase of only 17% of this threshold. In contrast, in paraplegic patients, neither ketoprofen nor saline produced any significant change in the nociceptive reflex threshold. A supraspinal involvement in the central analgesic effect of this drug is discussed.

Clinical pharmacokinetics of nonsteroidal anti-inflammatory drugs in the cerebrospinal fluid

The pharmacokinetics of nonsteroidal anti-inflammatory drugs (NSAIDs) in the cerebrospinal fluid (CSF) is of clinical interest as it may be related to some of their properties and side-effects. Two types of NSAIDs can be described with respect to their concentration and time course in CSF: in the first type, the transfer across the blood-brain barrier seems to be controlled by simple physico-chemical factors. These drugs (oxyphenbutazone, indomethacin, ketoprofen) are characterized by a high lipophilicity. At steady state, their free plasma concentrations correspond to their CSF concentrations. The second group consists of more hydrophilic compounds (salicylates); there is no correlation between plasma concentrations and CSF concentration. Further investigation needs to be carried out on CNS side-effects and the antialgesic activity of salicylates in relation on their CSF distribution.

The diffusion of pirprofen into the cerebrospinal fluid in man

We have measured the concentrations of pirprofen at various times in plasma and cerebrospinal fluid (CSF) samples, drawn during diagnostic myelography from 28 patients affected by sciatica. After intramuscular injection of 400 mg plasma concentrations of pirprofen reached a peak in 60 min then fell slowly. In contrast, the CSF concentration rose until 12 h and then fell. Pirprofen rapidly crossed the blood-brain barrier and was detectable in CSF at 15-30 min after injection. These results support the suggested hypothesis of a central analgesic action of pirprofen along with the known peripheral one. A new sensitive HPLC method was developed for measuring the concentration of pirprofen in the CSF.