Clinical pharmacokinetics of ketoprofen after single intravenous administration as a bolus or infusion

Prediction of Tissue-Plasma Partition Coefficients Using Microsomal Partitioning: Incorporation into Physiologically based Pharmacokinetic Models and Steady-State Volume of Distribution Predictions

Drug distribution is a necessary component of models to predict human pharmacokinetics. A new membrane-based tissue-plasma partition coefficient (K _p) method (K _p,mem) to predict unbound tissue to plasma partition coefficients (K _pu) was developed using in vitro membrane partitioning [fraction unbound in microsomes (f _um)], plasma protein binding, and log P The resulting K _p values were used in a physiologically based pharmacokinetic (PBPK) model to predict the steady-state volume of distribution (V _ss) and concentration-time (C-t) profiles for 19 drugs. These results were compared with K _p predictions using a standard method [the differential phospholipid K _p prediction method (K _p,dPL)], which differentiates between acidic and neutral phospholipids. The K _p,mem method was parameterized using published rat K _pu data and tissue lipid composition. The K _pu values were well predicted with R ² = 0.8. When used in a PBPK model, the V _ss predictions were within 2-fold error for 12 of 19 drugs for K _p,mem versus 11 of 19 for K_p,dPL With one outlier removed for K _p,mem and two for K _p,dPL, the V _ss predictions for R ² were 0.80 and 0.79 for the K _p,mem and K _p,dPL methods, respectively. The C-t profiles were also predicted and compared. Overall, the K _p,mem method predicted the V _ss and C-t profiles equally or better than the K _p,dPL method. An advantage of using f _um to parameterize membrane partitioning is that f _um data are used for clearance prediction and are, therefore, generated early in the discovery/development process. Also, the method provides a mechanistically sound basis for membrane partitioning and permeability for further improving PBPK models. SIGNIFICANCE STATEMENT: A new method to predict tissue-plasma partition coefficients was developed. The method provides a more mechanistic basis to model membrane partitioning.

Prediction of sustained fetal toxicity induced by ketoprofen based on PK/PD analysis using human placental perfusion and rat toxicity data

AIM

We encountered a case of fetal toxicity due to ductus arteriosus (DA) constriction in a 36-week pregnant woman who had applied multiple ketoprofen patches. The aim of the present study was to present the case and develop a model to predict quantitatively the fetal toxicity risk of transdermal administration of ketoprofen.

METHODS

Human placenta perfusion studies were conducted to estimate transplacental pharmacokinetic (PK) parameters. Using a developed model and these parameters, human fetal plasma concentration profiles of ketoprofen administered to mothers were simulated. Using pregnant rats, DA constriction and fetal plasma drug concentration after ketoprofen administration were measured, fitted to an Emax model, and extrapolated to humans.

RESULTS

Transplacental transfer value at the steady state of ketoprofen was 4.82%, which was approximately half that of antipyrine (passive marker). The model and PK parameters predicted almost equivalent mother and fetus drug concentrations at steady state after transdermal ketoprofen administration in humans. Maximum DA constriction and maximum plasma concentration of ketoprofen after administration to rat dams were observed at different times: 4 h and 1 h, respectively. The model accurately described the delay in DA constriction with respect to the fetal ketoprofen concentration profile. The model with effect compartment and the obtained parameters predicted that use of multiple ketoprofen patches could potentially cause severe DA constriction in the human fetus, and that fetal toxicity might persist after ketoprofen discontinuation by the mother, as observed in our case.

CONCLUSION

The present approach successfully described the sustained fetal toxicity after discontinuing the transdermal administration of ketoprofen.

A physiologically based pharmacokinetic model to predict the pharmacokinetics of highly protein-bound drugs and the impact of errors in plasma protein binding

Predicting the pharmacokinetics of highly protein-bound drugs is difficult. Also, since historical plasma protein binding data were often collected using unbuffered plasma, the resulting inaccurate binding data could contribute to incorrect predictions. This study uses a generic physiologically based pharmacokinetic (PBPK) model to predict human plasma concentration-time profiles for 22 highly protein-bound drugs. Tissue distribution was estimated from in vitro drug lipophilicity data, plasma protein binding and the blood: plasma ratio. Clearance was predicted with a well-stirred liver model. Underestimated hepatic clearance for acidic and neutral compounds was corrected by an empirical scaling factor. Predicted values (pharmacokinetic parameters, plasma concentration-time profile) were compared with observed data to evaluate the model accuracy. Of the 22 drugs, less than a 2-fold error was obtained for the terminal elimination half-life (t1/2 , 100% of drugs), peak plasma concentration (Cmax , 100%), area under the plasma concentration-time curve (AUC0-t , 95.4%), clearance (CLh , 95.4%), mean residence time (MRT, 95.4%) and steady state volume (Vss , 90.9%). The impact of fup errors on CLh and Vss prediction was evaluated. Errors in fup resulted in proportional errors in clearance prediction for low-clearance compounds, and in Vss prediction for high-volume neutral drugs. For high-volume basic drugs, errors in fup did not propagate to errors in Vss prediction. This is due to the cancellation of errors in the calculations for tissue partitioning of basic drugs. Overall, plasma profiles were well simulated with the present PBPK model. Copyright © 2016 John Wiley & Sons, Ltd.

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 randomized, controlled clinical trial of ketoprofen for sickle-cell disease vaso-occlusive crises in adults

Vaso-occlusive crisis (VOC) is the primary cause of hospitalization of patients with sickle-cell disease. Treatment mainly consists of intravenous morphine, which has many dose-related side effects. Nonsteroidal antiinflammatory drugs have been proposed to provide pain relief and decrease the need for opioids. Nevertheless, only a few underpowered trials of nonsteroidal antiinflammatory drugs for sickle-cell VOC have been conducted, and conflicting results were reported. We conducted a phase 3, double-blind, randomized, placebo-controlled trial with ketoprofen (300 mg/day for 5 days), a nonselective cyclooxygenase inhibitor, for severe VOC in adults. A total of 66 VOC episodes were included. The primary efficacy outcome was VOC duration. The secondary end points were morphine consumption, pain relief, and treatment failure. Seven VOC episodes in each group were excluded from the analysis because of treatment failures. No significant between-group differences were observed for the primary outcome or the secondary end points. Thus, although ketoprofen was well-tolerated, it had no significant efficacy as treatment of VOC requiring hospitalization. These findings argue against its systematic use in this setting.

Pilot Study of Relative Bioavailability of Two Oral Formulations of Ketoprofen 25 mg in Healthy Subjects. A Fast-Dissolving Lyophilized Tablet as Compared to Immediate Release Tablet

The pharmacokinetics of ketoprofen from a fast-dissolving lyophilized tablet (LT), which need not be swallowed, as compared to an immediate release (IR) tablet as reference after single oral dose (25 mg) administration was determined in six healthy subjects aged between 25-40 years using a randomized crossover design. In this study, the rate and extent of absorption of ketoprofen were found to be very different after administration of the LT and the IR tablet. The rate of absorption of ketoprofen from LT was significantly faster than that of IR tablet and had significantly higher Cmax (by about 50%) and earlier tmax (by 15 min), whereas the extent of absorption expressed by AUC was about 68% higher as compared to the IR tablet. The relative bioavailability (frel) of the LT compared with the IR tablet was 168%. The difference between the two formulations for half-life and MRT were statistically significant (p<0.05). The tolerance of the two tested formulations was excellent. Ketoprofen LT remained physically and chemically stable for 12 months at 25 degrees C and 60% relative humidity.

Ketoprofen and tramadol for analgesia during early recovery after tonsillectomy in children

BACKGROUND

Pain following tonsillectomy is often intense. Nonsteroidal anti-inflammatory drugs and opioids are effective, but both can cause adverse effects. Tramadol may be a viable alternative for post-tonsillectomy pain. This study was designed to compare the analgesic effects of ketoprofen and tramadol during the early recovery period after tonsillectomy.

METHODS

Forty-five ASA class I children (9-15 years) were randomized to receive either saline, ketoprofen (2 mg.kg(-1)) or tramadol (1 mg.kg(-1)) after induction of anesthesia. Upon completion of surgery, the study treatment was continued as a 6 h intravenous (i.v.) infusion of another dose of saline, ketoprofen (2 mg.kg(-1)) or tramadol (1 mg.kg(-1)). Postoperatively, each patient received rescue analgesia with patient-controlled analgesia (PCA) device programmed to deliver 0.5 microg.kg(-1) bolus doses of fentanyl. Postoperative pain was assessed using Visual Analog Scale (VAS) during swallowing. Intraoperative blood loss was measured.

RESULTS

The total number of requests of PCA-fentanyl was significantly less in ketoprofen group compared with tramadol and placebo groups (P = 0.035 and P = 0.049, respectively, in pairwise comparisons) and the VAS scores for pain were significantly lower in ketoprofen group compared with tramadol (P = 0.044) or placebo groups (P = 0.018) during the first six postoperative hours. Measured intraoperative blood loss was greater in ketoprofen-treated patients than in those receiving placebo (P = 0.029).

CONCLUSION

A dose of 4 mg.kg(-1) of i.v. ketoprofen provided good pain relief with moderate supplemental PCA-fentanyl requirements during the first six postoperative hours after tonsillectomy in children whereas the effects of 2 mg.kg(-1) of i.v. tramadol did not differ from those of placebo.

Pharmacokinetics of intravenous and rectal ketoprofen in young children

OBJECTIVE

To evaluate the relative bioavailabilities of ketoprofen after intravenous and rectal administration to young children.

DESIGN

Open-label prospective parallel-group study.

PATIENTS

Participants were 28 children aged 7 to 93 months.

METHODS

Eighteen children received a single intravenous injection of ketoprofen 1 mg/kg, and ten children, weight 16-24 kg, received a 25mg ketoprofen suppository. Venous blood samples were collected at selected times after administration, ranging from 2 minutes to 8 hours for the intravenous group and from 30 minutes to 8 hours for the suppository group. A validated high performance liquid chromatography method was used to measure plasma ketoprofen concentrations.

RESULTS

In the intravenous group, the maximum plasma concentration of ketoprofen ranged between 10.5 and 22.2 mg/L, and in the suppository group, following dose normalisation to 1 mg/kg of ketoprofen, between 3.8 and 7.4 mg/L. In the intravenous group, area under the concentration-time curve from zero to infinity ranged between 9.2 and 23.5 mg x h/L, and in the suppository group after dose normalisation between 8.8 and 12.9 mg x h/L. The bioavailability of ketoprofen from the suppository was about 73%. Volume of distribution was 0.04-0.10 L/kg in the intravenous group and 0.08-0.16 L/kg in the suppository group. The terminal half-life was comparable in both study groups, ranging between 0.7 and 3.0 hours in the intravenous group and between 1.2 and 2.9 hours in the suppository group.

CONCLUSION

Absorption of ketoprofen after rectal administration is reasonably rapid and predictable. Because the bioavailability of rectal ketoprofen is also relatively high, a suppository may be used in children in whom the drug cannot be given intravenously or by mouth.

Pharmacodynamics, chiral pharmacokinetics and PK-PD modelling of ketoprofen in the goat

There have been few studies of the pharmacodynamics of nonsteroidal antiinflammatory drugs (NSAIDs) using PK-PD modelling, yet this approach offers the advantage of defining the whole concentration-effect relationship, as well as its time course and sensitivity. In this study, ketoprofen (KTP) was administered intravenously to goats as the racemate (3.0 mg/kg total dose) and as the single enantiomers, S(+) KTP and R(-) KTP (1.5 mg/kg of each). The pharmacokinetics and pharmacodynamics of KTP were investigated using a tissue cage model of acute inflammation. The pharmacokinetics of both KTP enantiomers was characterized by rapid clearance, short mean residence time (MRT) and low volume of distribution. The penetration of R(-) KTP into inflamed (exudate) and noninflamed (transudate) tissue cage fluids was delayed but area under the curve values were only slightly less than those in plasma, whereas MRT was much longer. The S(+) enantiomer of KTP penetrated less readily into exudate and transudate. Unidirectional inversion of R(-) to S(+) KTP occurred. Both rac-KTP and the separate enantiomers produced marked inhibition of serum thromboxane B2 (TxB2) synthesis (ex vivo) and moderate inhibition of exudate prostaglandin E2 (PGE2) synthesis (in vivo); pharmacodynamic variables for S(+) KTP were Emax (%) = 94 and 100; IC50 (microg/mL) = 0.0033 and 0.0030; N = 0.45 and 0.58, respectively, where Emax is the maximal effect, IC50 the plasma drug concentration producing 50% of Emax and N the slope of log concentration/effect relationship. The IC50 ratio, serum TxB2:exudate PGE2 was 1.10. Neither rac-KTP nor the individual enantiomers suppressed skin temperature rise at, or leucocyte infiltration into, the site of acute inflammation. These data illustrate for KTP shallow concentration-response relationships, probable nonselectivity of KTP for cyclooxygenase (COX)-1 and COX-2 inhibition and lack of measurable effect on components of inflammation.

Pharmacokinetics of a 24-hour intravenous ketoprofen infusion in children

BACKGROUND

No pharmacokinetic data are available with respect to the plasma concentration of ketoprofen during intravenous infusion in children.

METHODS

We present here the pharmacokinetics of ketoprofen after a 10-min intravenous infusion of 1 mg/kg followed by a 24-h infusion of 4 mg/kg in 18 children aged 7 months to 16 years. Venous blood samples were collected at 5 min, 1, 2, 4, 24 h following the loading dose, and then 1, 2 and 4 h after the end of the infusion. A validated HPLC method was used to measure plasma levels of ketoprofen.

RESULTS

The steady state plasma concentration of ketoprofen was 2.0 microg/mL (range 1.3-2.7 microg/mL). The clearance of ketoprofen was 0.09 L x h(-1) x kg(-1) (range 0.06-0.13 L x h(-1) x kg(-1)). The distribution volume was 0.16 L/kg (range 0.12-0.21 L/kg). The terminal half-life was 1.3 h (range 0.8-1.7 h).

CONCLUSION

The pharmacokinetics of ketopofen in children is similar to that reported in adults. Our results indicate that ketoprofen is a feasible drug for continuous intravenous infusion in acute pain treatment in children.

Parenteral ketoprofen for pain management after adenoidectomy: comparison of intravenous and intramuscular routes of administration

BACKGROUND

Different parenteral routes of administration of NSAIDs such as ketoprofen have not been properly compared in children. This study was designed to compare the analgesic efficacy of intravenous and intramuscular ketoprofen for pain management in children after day-case adenoidectomy.

METHODS

A total of 120 children, aged 1-9 years, who were scheduled to undergo adenoidectomy, were randomized to receive ketoprofen 2 mg/kg either intravenously with intramuscular placebo (n = 40) or ketoprofen 2 mg/kg intramuscularly with intravenous placebo (n = 40), or both intravenous and intramuscular placebo (n = 40) at induction of anesthesia. The study design was prospective and double-blind with parallel groups. Pain was assessed at rest and during swallowing using the Maunuksela pain scale during 3 h after surgery, and fentanyl i.v. was given for rescue analgesia.

RESULTS

Children in the Placebo group needed significantly more doses of fentanyl (72 doses) than either children in the intravenous group (47 doses) or children in the intramuscular group (51 doses) (P = 0.021). In addition, a higher proportion of children in the Placebo group than in the two ketoprofen groups (P = 0.03) demanded rescue analgesic. No difference in the need for rescue analgesia or in pain scores was found between the two ketoprofen groups. Children in the intravenous group had less pain than children in the Placebo group. The difference was significant during swallowing at 1 h after surgery (P = 0.046) and for the worst pain observed during swallowing for 3 h after surgery (P = 0.022). There were no differences between the three groups with respect to operation times, amount of perioperative bleeding, or rate or extent of adverse events.

CONCLUSION

The efficacy of intravenous and intramuscular ketoprofen was similar, and they both differed from placebo.

Human variability in glucuronidation in relation to uncertainty factors for risk assessment

The appropriateness of the default uncertainty factor for human variability in kinetics has been investigated for glucuronidation using an extensive database of substrates metabolised primarily by this pathway. Inter-individual variability was quantified for 15 compounds from published pharmacokinetic studies (after oral and intravenous dosing) in healthy adults and other subgroups using parameters relating to chronic exposure (metabolic and total clearances, area under the plasma concentration time-curve (AUC)) and acute exposure (C(max)). Low inter-individual variability (about 30-35%) was found for all parameters (clearance corrected or not corrected for body weight, metabolic clearance, oral AUC and C(max)) after either iv or oral administration to healthy adults. The overall variability of 31% for glucuronidation in healthy adults supported the validity of the default kinetic uncertainty factor of 3.16 for this group, because it would cover more than 99% of individuals. Comparisons between potentially sensitive subgroups and healthy adults using differences in means and variability indicated that neonates showed the greatest impairment of glucuronidation, and that the 3.16 kinetic default factor applied to the mean data for adults would be inadequate for this subpopulation. The in vivo data have been used to derive pathway-related default factors for compounds eliminated largely via glucuronidation.

Comparison of intravenous and oral ketoprofen for postoperative pain after adenoidectomy in children

One hundred children, aged 1-9 yr, undergoing adenoidectomy were randomized to receive ketoprofen 1 mg kg-1 either i.v. with an oral placebo (n = 40) or ketoprofen 1 mg kg-1 orally with an i.v. placebo (n = 40), or both oral and i.v. placebo (n = 20). The study design was prospective and double blind with parallel groups. The pain was assessed at rest and during swallowing using the Maunuksela pain scale (0 = no pain, 10 = worst possible pain) after surgery for 3 h. Fentanyl 0.5 microgram kg-1 i.v. was given for rescue analgesia. Children in the i.v. group needed significantly less doses (1, 1-3; median and 10th/90th percentiles) of rescue analgesic compared with the oral group (2, 1-3; P = 0.024). Of those who needed rescue analgesic, three out of 30 children in the i.v. group required three or more doses of fentanyl compared with 10 out of 28 children in the oral group. There were no differences between the groups with respect to pain scores, operation times, perioperative bleeding or frequency of adverse events.

Morphine-sparing effect of ketoprofen after abdominal surgery

In a double-blind, placebo-controlled clinical trial (power of 80% to detect a 30% reduction in morphine consumption, P < 0.05), we have determined that the administration of two doses of intravenous ketoprofen 100 mg, one at the end of surgery and the second 12 hours postoperatively, was associated with a significant reduction in morphine consumption at eight (P = 0.028), 12 (P = 0.013) and 24 hours (P = 0.013) but not four hours (P = 0.065) postoperatively, as compared to placebo, when assessed by patient-controlled analgesia. There was no difference between the groups in pain scores or in the incidence of nausea and vomiting. One patient in the placebo group suffered from excessive sedation while one patient from the ketoprofen group suffered from transient oliguric renal failure. There were no other adverse effects. The results of this study show that ketoprofen does provide a morphine-sparing effect in the management of postoperative pain after abdominal surgery.

Pharmacokinetic parameters and milk concentrations of ketoprofen after administration as a single intravenous bolus dose to lactating goats

Six clinically normal lactating does were administered ketoprofen (2.2 mg/kg intravenously (i.v.)). Blood and milk samples were collected prior to and for 24 h after drug administration. Drug concentrations in serum and milk were determined by high performance liquid chromatography. Pharmacokinetic parameters from each goat were combined to obtain mean estimates (mean +/- SD) of half-life of elimination (t1/2beta) of 0.32 +/- 0.14 h, systemic clearance (Cl) of 0.74 +/- 0.12 L/kg x h, and volume of distribution at steady state (V(ss)) of 0.23 +/- 0.051 L/kg. In milk, ketoprofen was unmeasurable by the method employed (level of detection 25 ng/mL) for all samples.

Effects of regional analgesia and/or a non-steroidal anti-inflammatory analgesic on the acute cortisol response to dehorning in calves

The effect of using a non-steroidal anti-inflammatory analgesic (ketoprofen) on the plasma cortisol response in calves dehorned with or without regional analgesia was determined. One hundred calves divided into 10 groups, four control and six dehorned, were used. Blood samples were taken before and after dehorning and plasma cortisol concentrations were measured. Dehorning caused a marked rise in plasma cortisol concentrations which returned to pretreatment levels after seven hours. The animals given ketoprofen before dehorning had a cortisol response similar to the dehorned animals for the first 1.3 hours after dehorning but then the plasma cortisol concentration returned to pretreatment levels. When animals were given a regional analgesic and ketoprofen the plasma cortisol concentrations were similar to control animals which had not been dehorned, with a small increase in plasma cortisol concentrations for the first hour after dehorning and then a rapid return to pretreatment values. This response was significantly lower than that seen in calves which received only regional analgesia. The results of this study suggest that a systemic analgesic should be combined with regional analgesia if the distress associated with dehorning is to be abolished.

Percutaneous absorption of ketoprofen from different anatomical sites in man

PURPOSE

The purpose of this study was to investigate the percutaneous absorption of ketoprofen applied topically to different anatomical sites on the body.

METHODS

The study design was a randomized, four-way crossover in 24 healthy male subjects. One gram of ketoprofen 3% gel (30 mg dose) was applied every six hours for 25 doses over a 100 cm2 of the back, arm, and knee. A 0.5 ml of ketoprofen solution (60 mg/ml) was applied to the back as a reference treatment. Plasma and urine samples were obtained for the assay of racemic ketoprofen and ketoprofen enantiomers (S and R), respectively.

RESULTS

The relative bioavailabilities of ketoprofen gel were 0.90 +/- 0.50, 1.08 +/- 0.63, and 0.74 +/- 0.38 when applied to the back, arm, and knee, respectively. The plasma ketoprofen C(max) for gel applied to the back and arm are similar (p > 0.05) but C(max) was lower when applied to the knee (p < 0.05). The time to C(max) ranged from 2.7 to 4.0 hours and was similar for gel treatments on the back and arm, but no longer for the knee treatment. The fraction of dose excreted in urine as total S and R enantiomers ranged from 5.41 to 9.10%.

CONCLUSIONS

The percutaneous absorption of ketoprofen was similar when applied to either the back or arm but was lower when applied to the knee.

[Comparative study of buprenorphine and its combination to ketoprofen or propacetamol for postoperative analgesia in urologic surgery]

OBJECTIVE

To compare the analgesic effect of subcutaneous buprenorphine alone and in combination with propacetamol and ketoprofen following urologic surgery.

STUDY DESIGN

Open randomized clinical trial.

PATIENTS

Sixty ASA II/III patients undergoing urologic surgery.

METHODS

The patients were randomized into three groups to receive either buprenorphine (0.3 mg subcutaneous) on demand (group 1, n = 20), or a combination of buprenorphine (0.3 mg)-propacetamol (2 g)-ketoprofen (100 mg) by intravenous route over 2 hours followed by an infusion of propacetamol (2 g) and ketoprofen (100 mg) at a constant rate over. The remaining 22 hours (group 2, n = 20), or the same loading dose as in group 2 prolonged by a continuous infusion of buprenorphine (0.3 mg), propacetamol (2 g) and ketoprofen (100 mg) over the same period (group 3, n = 20). Visual analogue scale pain scores (0-10) were assessed every hour during the 24 hours of the study. When the VAS score exceeded 5, an additional dose of 0.3 mg of buprenorphine was administered.

RESULTS

Groups were similar for age, surgery, anaesthesia and initial pain levels. Compared to group 1, the onset of analgesia was earlier in groups 2 and 3 at the 1st hour (P < 0.05); the level of analgesia was lower at the 3rd hour (P < 0.05). The maintenance of this analgesia level required constant buprenorphine administration. Buprenorphine requirements were decreased to 56% and 37% in groups 2 and 3 respectively, compared to group 1 (P < 0.05). Incidence of nausea and vomiting was lowered to 15% in group 3 (P < 0.05).

CONCLUSION

A combination of buprenorphine, propacetamol and ketoprofen provides effective postoperative analgesia with a low incidence of nausea and vomiting and decreased requirements of buprenorphine.

Pharmacokinetics and pharmacodynamics of ketoprofen in calves applying PK/PD modelling

The pharmacokinetics (PK) and pharmacodynamics (PD) of ketoprofen (KTP) were studied in calves following intravenous administration of the drug racemate at a dose rate of 3 mg/kg. To evaluate the anti-inflammatory properties of KTP, a model of acute inflammation, consisting of surgically implanted subcutaneous tissue cages stimulated by intracaveal injection of carrageenan, was used. No differences were observed between disposition curves of KTP enantiomers in plasma, exudate or transudate. This indicates that in calves KTP pharmacokinetics is not enantioselective. S(+)- and R(-)- KTP each had a short elimination half-life (t1/2 beta) of 0.42 +/- 0.08 h and 0.42 +/- 0.09 h, respectively. The volume of distribution (Vd) was low, values of 0.20 +/- 0.06 L/kg and 0.22 +/- 0.06 L/kg being obtained for R(-) and S(+)KTP, respectively. Body clearance (ClB) was high, correlating with the short elimination half-life, 0.33 +/- 0.03 L/kg/h [R(-)KTP] and 0.32 +/- 0.04 L/kg/h [S(+)-KTP]. KTP pharmacodynamics was evaluated by determining the effects on serum thromboxane (TxB2), exudate prostaglandin (PGE2), leukotriene (LTB4) and beta-glucuronidase (beta-glu) and bradykinin (BK)-induced oedematous swelling. Effect-concentration inter-relationships were analysed by PK/PD modelling. KTP did not affect exudate LTB4, but inhibition of the other variables was statistically significant. The mean EC50 values for inhibition of serum TxB2, exudate PGE2 and beta-glu and BK-induced swelling were 0.118, 0.086, 0.06 and 0.00029 microgram/mL, respectively. These data indicate that KTP exerted an inhibitory action, not only as expected, on eicosanoid (TxB2 and PGE2) synthesis but also on exudate beta-glu and BK-induced oedema. The EC50 values for these actions indicate that they are likely to contribute to the overall anti-inflammatory effects of KTP in calves. However, claims that KTP inhibits 5-lipoxygenase and thereby blocks the production of inflammatory mediators such as LTB4 were not substantiated. PK/PD modelling has proved to be a useful tool for analysing the in vivo pharmacodynamics of KTP and for providing new approaches to elucidating its mechanism(s) of action.

Comparison of parenteral diclofenac and ketoprofen for postoperative pain relief after maxillofacial surgery

Non-steroidal anti-inflammatory drugs (NSAID) effectively reduce the need for opioid analgesia after various types of surgery. The efficacy of diclofenac and ketoprofen to relieve pain after maxillofacial surgery was compared in the present study. In a randomized and double-blind fashion, 90 ASA I-II patients (16-60 yrs) were studied, divided into three groups: Thirty patients received 1.0 mg.kg-1 diclofenac i.v. after general anaesthesia induction, before surgical incision, and four hours later the same dose was given i.m. Thirty patients received ketoprofen 1.35 mg.kg-1 i.v. and i.m., as above, and a third group of 30 patients received a comparable volume of saline i.v. and i.m. The patients received supplemental analgesia using a patient controlled analgesia apparatus; the rescue medication consisted of 0.03 mg.kg-1 oxycodone i.v. (four-hour maximum dose was 0.4 mg.kg-1) during the 24-hour follow-up. The three groups were comparable regarding the type of maxillofacial surgery (osteotomies vs. soft tissue surgery). Overall, there was a lower need for i.v. oxycodone during the 24-hour period in the diclofenac group (269 doses) than in the ketoprofen group and in the saline group (388 doses, each) (P < 0.01). The significantly lower number of oxycodone administrations in the diclofenac group was a result of a distinguishable difference, particularly during the first four hours after surgery. There was no statistically significant difference in the incidence of side effects of the analgesic therapy between the three groups.

NSAID use and efficacy in the emergency department: single doses of oral ibuprofen versus intramuscular ketorolac

OBJECTIVE

To compare the clinical efficacy of single doses of intramuscular ketorolac and oral ibuprofen in the emergency department (ED) treatment of acute pain.

DESIGN

A retrospective analysis of data collected during a prospective survey of pain management efficacy. The design was noninterventional, and therapy was selected by the treating physician independent of the trial.

SETTING

Urban teaching hospital adult patient emergency department.

PARTICIPANTS

A convenience sample of ED patients in acute pain.

INTERVENTIONS

Patients received ibuprofen 800 mg po (n = 95), or ketorolac 60 mg im (n = 30) as a single dose. Therapy was selected by the treating physician and was not influenced by the study.

RESULTS

Data collected were a 100-mm visual analog pain scale at patient arrival and discharge, verbal description of pain relief, patient demographics, pain management data, and discharge diagnosis. Baseline pain intensity was higher in patients receiving ketorolac (77 mm median) than in those receiving ibuprofen (65 mm, p = 0.02). Pain relief was similar (p = 0.29) with either treatment when assessed by visual analog scale or patient definition of pain relief.

CONCLUSIONS

A single dose of either nonsteroidal antiinflammatory drug produced similar pain relief in the general ED population during clinical treatment of pain. Ketorolac should not necessarily be considered a more effective analgesic than ibuprofen in these commonly used doses.

Pharmacokinetics of ketoprofen in rats: effect of age and dose

The effects of age and dose on the pharmacokinetics of ketoprofen were evaluated in young adult and senescent male Fischer 344 rats following intravenous administration of 2.5 and 10 mg kg-1. Plasma concentrations were measured by HPLC and free ketoprofen determined by equilibrium dialysis. The glucuronidation of ketoprofen was investigated in a preparation of rat liver microsomes and kinetic analysis of UDP-glucuronyltransferase was carried out by determining the initial rate of metabolic activity as a function of ketoprofen concentration. Mean plasma clearance CLfree and steady-state volume of distribution Vssfree calculated from unbound plasma ketoprofen concentrations were significantly lower in the aged rat, suggesting reduced metabolic activity and decreased ketoprofen binding to tissue components, respectively. Plasma protein binding demonstrated an age-dependent decline due to decreases in both albumin concentration and binding affinity. Thus, plasma clearance CL and steady-state volume of distribution Vss changes were insignificant when total plasma concentrations were examined, due to the greater free fraction of ketoprofen in the plasma of senescent rats. The maximal rate of ketoprofen glucuronidation by hepatic microsomes was reduced whereas the affinity of the metabolic enzymes for the compound was unaffected by age. Dose had a marked effect on the disposition of ketoprofen as well. Saturation of elimination pathways and tissue binding sites contributed to significant declines in CLfree and Vssfree with increasing dose. Likewise, concentration-dependent plasma protein binding occurred, reflecting saturation of albumin binding. Thus, changes in the pharmacokinetic parameters based on total drug concentrations were offset by the increase in the unbound fraction of ketoprofen.