Pharmacokinetic and bioequivalence studies of fast dispersible ketoprofen tablets in healthy volunteers

In the present study the pharmacokinetic and bioequivalence parameter of Ketoprofen 100 mg fast dispersible tablets (test) were measured with marketed (reference) product. This study was accomplished following FDA guidance. A single dose, open labeled, cross over (two way), randomized study design was used to conduct investigation on 12 Pakistani healthy volunteers. At various time points blood samples (10mL) were drawn i.e. at 0.25, 0.5, 1, 1.5, 2, 3, 4, 8, 12 and 13hr. Plasma was then separated and ketoprofen concentrations were estimated by validated HPLC technique using LC 20A pump (Shimadzu Corp, Japan) and Spectrophotometric SPD-20Adetector (Shimadzu Corp, Japan). Ketoprofen concentrations were then analyzed by Kinetica^TM 4.4.1 (Thermo electron corp, USA) to estimate various compartmental and noncompartmental pharmacokinetic parameters. Various parameters of bioequivalence including AUC_tot, AUC_0-oo, AUC_last, T_maxcalc and C_maxcalcw ere compared using ANOVA method (two way). For log and non-log transformed data the 90% confidence interval values for AUC _oo0-oo, (1.0087-1.0704; 1.0099-1.0714), AUC _tot , (0.95482- 1.0093; 0.95486-1.0098), AUC_last (0.93373-0.98605; 0.93404-0.98603), C_maxcalc (0.92978-0.9955; 0.92962-0.99663) and T_maxcalc (0.89019-0.94116; 0.89095-0.94288) for test and reference products respectively. Results were found to be within the FDA satisfactory range. For the results verification, Schuirman's one sided t test was used. SPSS 17.0 (SPSS Inc.) was utilized for the determination of wilcoxon sign rank test. Results showed no carry over effect after first study period. Also test product met the regulatory criteria for bioequivalence with the reference product. Both the formulations were well tolerated.

Does ketoprofen or diclofenac pose the lowest risk to fish?

Ketoprofen and diclofenac are non-steroidal anti-inflammatory drugs (NSAIDs) often used for similar indications, and both are frequently found in surface waters. Diclofenac affects organ histology and gene expression in fish at around 1 μg/L. Here, we exposed rainbow trout to ketoprofen (1, 10 and 100 μg/L) to investigate if this alternative causes less risk for pharmacological responses in fish. The bioconcentration factor from water to fish blood plasma was <0.05 (4 for diclofenac based on previous studies). Ketoprofen only reached up to 0.6 ‰ of the human therapeutic plasma concentration, thus the probability of target-related effects was estimated to be fairly low. Accordingly, a comprehensive analysis of hepatic gene expression revealed no consistent responses. In some contrast, trout exposed to undiluted, treated sewage effluents bioconcentrated ketoprofen and other NSAIDs much more efficiently, according to a meta-analysis of recent studies. Neither of the setups is however an ideal representation of the field situation. If a controlled exposure system with a single chemical in pure water is a reasonable representation of the environment, then the use of ketoprofen is likely to pose a lower risk for wild fish than diclofenac, but if bioconcentration factors from effluent-exposed fish are applied, the risks may be more similar.

In vitro and in vivo study of poly(ethylene glycol) conjugated ketoprofen to extend the duration of action

Ketoprofen-polyethylene glycol (PEG) conjugates (KPEG) were prepared and their potential as a prolonged release system was investigated. Three KPEG conjugates were synthesized from ketoprofen and methoxy PEG with three different molecular weights by esterification in the presence of DCC. The KPEG conjugates were characterized by FT-IR and (1)H NMR spectroscopy. The rate of hydrolysis profile showed a specific acid-base catalysis pattern with a minimum at pH 4-5. The pharmacokinetic study after the intravenous and intramuscular administration of KPEG750 showed that the plasma levels of KP increased slowly and reached a maximum concentration at later time. The AUC of KPEG750 was higher than that after administering an equivalent dose of ketoprofen except 40mg/kg dose of intramuscular administration. The tail-flick experiment and paw edema test after intramuscular administration showed that KPEG750 had extended analgesic and anti-inflammatory effects compared with ketoprofen. These results suggest that KPEG could be a promising NSAID prodrug with an extended pharmacological effect owing to delayed-release of parent drug.

Ketoprofen glucuronidation and bile excretion in carbon tetrachloride and alpha-naphthylisothiocyanate induced hepatic injury rats

A pharmacokinetic study was carried out in rats to investigate the effects of experimental hepatic injury on the liver glucuronidation and bile excretion of ketoprofen (KP) and its glucuronides (KPGs). In vivo, KP (20mg/kg b.w.) was intravenously administered to carbon tetrachloride (CCl(4)) or alpha-naphthylisothiocyanate (ANIT) induced hepatic injury male rats. Concentrations of KP and its glucuronides (S-KPG and R-KPG) in plasma and bile were determined by RP-HPLC. It was observed that there was significant difference in the accumulative bile excretion of KPGs between the CCl(4) intoxicated rats and the normal rats (54+/-18.3% versus 90+/-6.9%), while it was extremely inhibited in ANIT intoxicated rats (2.0+/-3.1% versus 90+/-6.9%). As the result of reduction of KPGs excreted in bile, the area under the curve (AUC((0-infinity))) of KP and KPGs were higher in blood in CCl(4) and ANIT hepatic injury rats than those of the normal rats. Specifically, ANIT caused approximately 10-fold elevation of AUC((0-infinity)) of plasma S-KPG. In microsomal incubations experiment, the glucuronyltransferase activity was impaired in CCl(4) and ANIT intoxicated rats. It suggested that the glucuronyltransferase activity was impaired in CCl(4) and ANIT intoxicated rats, while the bile excretion function was suppressed extremely in ANIT intoxicated rats.

Isobolographic analysis of the antinociceptive interactions between ketoprofen and paracetamol

The present study was undertaken to evaluate the antinociceptive interaction between paracetamol and ketoprofen. The antinociceptive effect of oral administration of the drugs alone or in combination was evaluated using the mouse abdominal constriction test. The data were interpreted by isobolographic analysis to establish the nature of the interaction. The effective dose that produced 50% antinociception (ED(50,mix)) was calculated from the log dose-response curve of fixed-ratio combinations of paracetamol with ketoprofen. This ED(50,mix) was compared to the theoretical additive ED(50,add) by isobolographic analysis. The experimental ED(50,mix) was found to be significantly smaller than the theoretically calculated ED(50,add), indicating a synergistic antinociceptive interaction between ketoprofen and paracetamol. Pharmacokinetic studies were carried out with mice treated with combined ketoprofen (12 mg/kg) and paracetamol (36 mg/kg). Plasma levels of ketoprofen were not changed by concurrent paracetamol treatment, and similarly no statistically significant difference was observed between paracetamol alone and the combination with ketoprofen. The pharmacokinetic analysis revealed that the combination of ketoprofen with paracetamol exerted a synergistic (supra-additive) interaction that was not associated with a pharmacokinetic interaction. The results of this study demonstrate significant synergism between ketoprofen and paracetamol.

The novel formulation design of self-emulsifying drug delivery systems (SEDDS) type O/W microemulsion I: enhancing effects on oral bioavailability of poorly water soluble compounds in rats and beagle dogs

We examined the design of the versatile novel self-emulsifying drug delivery systems (SEDDS) type O/W microemulsion formulation which enhances the oral bioavailability by raising the solubility of poorly water soluble compounds. Namely, seven kinds of poorly water soluble compounds such as disopyramide, ibuprofen, ketoprofen, tolbutamide, and other new compounds, as the model compounds were used to compare the plasma concentration profile of the compound following single oral administration of each compound to rats and beagle dogs as a solution, an oily solution, a suspension (or a powder), an O/W microemulsion, and a SEDDS type O/W microemulsion. And the enhancing effect of the SEDDS type O/W microemulsion on the gastrointestinal absorption of these compounds was evaluated. In the components of the SEDDS type O/W microemulsion, medium chain fatty acid triglyceride (MCT), diglyceryl monooleate (DGMO-C), polyoxyethylene hydrogenated castor oil 40 (HCO-40), and ethanol were used as an oil, a lipophilic surfactant, a hydrophilic surfactant, and a solubilizer, at the mixture ratio of 25/5/45/25 (w/w%), respectively. Thereby, to six kinds of the model compounds except disopyramide, the solubility was from 340 to 98,000 times that in water, and the AUCs in plasma concentration of the compound were equivalent to that of solution or O/W microemulsion administration, or was increased by 1.5 to 78 times that of suspension administration. Accordingly, this novel SEDDS type O/W microemulsion is the versatile, useful formulation which enhances the oral bioavailability by raising the solubility of poorly water soluble compounds.

Determination and validation of ketoprofen, pantoprazole and valsartan together in human plasma by high performance liquid chromatography

A rapid and specific high-performance liquid chromatographic method was developed and validated for the simultaneous determination of ketoprofen, valsartan and pantoprazole in human plasma. Chromatographic separation of ketoprofen, valsartan and pantoprazole was performed using a Chromasil C18 column (250 mm x 4.6 mm i.d., 5 microm particle size). The mobile phase consisted of a mixture of 0.02 M sodium dihydrogen phosphate buffer (pH 3.15) and acetonitrile (58:42, v/v) pumped through the chromatographic system at a flow rate of 1 mL x min(-1). The Diode Array detector was operated at 225 and 272 nm. Rofecoxib was used as an internal standard. Sample treatment procedure consisted of deproteinisation with acetonitrile-methanol (50:50 v/v). Analytical recoveries were in the range of 79.00-118.00% of nominal values of valsartan, ketoprofen and pantoprazole. The method was reproducible and accurate with lower limits of quantification 250 microg x L(-1) for pantoprazole and 500 microg x L(-1) for ketoprofen and valsartan. This method was relatively easy to perform and allows simultaneous determination of these three drugs in plasma at nanogram levels.

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.

Biowaivers for oral immediate-release products: implications of linear pharmacokinetics

Bioequivalence of drug formulations plays an important role in drug development. Recently, the Biopharmaceutical Classification System (BCS) has been implemented for the purpose of waiving bioequivalence studies on the basis of the solubility and gastrointestinal permeability of drug substance. Using the rationale of the BCS, it can be argued that biowaivers can, however, also be granted on the basis of standard pharmacokinetic data. If a drug exhibits dose-linear pharmacokinetics and a sufficiently fast dissolution profile, it can be concluded that this drug appears to pose no problem with respect to absorption. It should be noted that a change of an immediate-release tablet formulation can only lead to a deviating rate and/or extent of absorption when release of the drug from the formulation is altered. Logically, the dissolution profiles of the different formulations should be equal to guarantee bioequivalency. Thus, both BCS and the alternative linear pharmacokinetics approach require an evaluation of dissolution profiles. The justification of BCS is found in the permeability classification of the compound, while those of the linear pharmacokinetics lie in the apparent lack of a permeability problem. For example, in this context P-glycoprotein-transported drugs form an interesting class of compounds, which may be treated likewise when complying to the aforementioned requirements. Furthermore, poorly soluble compounds may be less troublesome than expected. It is shown that linear kinetics can be explained by the solubilising activity of, for example, bile salts. In this instance, linear pharmacokinetics shows that elevated doses do not appear to exhibit a limiting role on the dissolution. Hence, a change in formulation without any effect on the dissolution profile is not expected to cause a change in availability. It is clear that the formulations to be compared should not contain excipients that display an effect on (presystemic) drug metabolism.

A new approach for preparing a controlled release ketoprofen tablets by using beeswax

Solid lipid ketoprofen micropellets (SLKM) at different drug/beeswax ratios [(1:1) and (1:2)] were prepared by emulsion congealing technique and then compressed into tablets. Ketoprofen in solid state was incorporated into the melted beeswax at 90 degrees C and the mixture was emulsified in the hot aqueous Tween 80 solution by stirring at a constant rate. The SLKM were obtained by cooling the coarse emulsion down to room temperature and filtering. Drug entrapment efficiency and particle size analysis by laser diffractometry (LD) were determined, and existence of a drug-lipid interaction was investigated by differential scanning calorimetry (DSC) on the SLKM, before being compressed into the tablets by direct compression method. Finally, in vitro release studies were performed and the release kinetics of the waxy tablets were calculated. A commercial ketoprofen retard tablet (reference: Profenid Retard 200 mg) was also examined to compare the release properties. While the data obtained from DSC were indicating absence of drug-lipid interaction in the SLKM, it was determined that 28.62% (+/-2.08), 38.60% (+/-1.91) and 47.00% (+/-1.82) of ketoprofen was released from the tablets containing (1:2) and (1:1) SLKM and Profenid Retard 200 mg in pH 7.4 phosphate buffer solution after 8 h, respectively.

Simultaneous quantitation of etoricoxib, salicylic acid, valdecoxib, ketoprofen, nimesulide and celecoxib in plasma by high-performance liquid chromatography with UV detection

A specific, accurate, precise and reproducible high performance liquid chromatography (HPLC) method was developed and validated for the simultaneous quantitation of etoricoxib, salicylic acid, valdecoxib, ketoprofen, nimesulide and celecoxib in human plasma. The method employed a simple liquid-liquid extraction of etoricoxib, salicylic acid, valdecoxib, ketoprofen, nimesulide and celecoxib and internal standard (IS, DRF-4367) from human plasma (500 microL) into acetonitirile. The organic layer was separated and evaporated under a gentle stream of nitrogen at 40 degrees C. The residue was reconstituted in the mobile phase and injected onto a Kromasil KR 100-5C18 column (4.6 x 250 mm, 5 microm). The chromatographic separation was achieved by gradient elution consisting of 0.05 M formic acid (pH 3)-acetonitrile-methanol-water at a flow rate of 1.0 mL/min. The eluate was monitored using an ultraviolet (UV) detector set at 235 nm. The ratio of peak area of each analyte to IS was used for quantification of plasma samples. Nominal retention times of etoricoxib, salicylic acid, valdecoxib, ketoprofen, nimesulide, IS and celecoxib were 15.63, 17.20, 21.66, 24.95, 26.27, 30.24 and 32.22 min, respectively. The standard curve for etoricoxib, salicylic acid, valdecoxib, ketoprofen and celecoxib was linear (r2 > 0.999) in the concentration range 0.1-50 microg/mL and for nimesulide (r2 > 0.999) in the concentration range 0.5-50 microg/mL. Absolute recovery was >83% from human plasma for all the analytes and IS. The lower limit of quantification (LLOQ) of nimesulide was 0.5 microg/mL and for etoricoxib, salicylic acid, valdecoxib, ketoprofen and celecoxib the LLOQ was 0.1 microg/mL. The inter- and intra-day precisions in the measurement of QC samples, 0.1, 0.3, 15.0 and 40.0 microg/mL (for all analytes except nimesulide), were in the range 2.29-9.37% relative standard deviation (RSD) and 0.69-10.28% RSD, respectively. For nimesulide the inter- and intra-day precisions in the measurement of quality control (QC) samples, 0.5, 1.5, 15.0 and 40.0 microg/mL, were in the range 3.21-7.37% RSD and 0.97-7.06% RSD, respectively. Accuracy in the measurement of QC samples for all analytes was in the range 91.03-106.38% of the nominal values. All analytes including IS were stable in the battery of stability studies, viz. bench top, autosampler and freeze-thaw cycles. Stability of all analytes was established for 21 days at -20 degrees C. The application of the assay in an oral pharmacokinetic study in rats co-administered with celecoxib and valdecoxib is described.

PLGA Implant Tablet of Ketoprofen: Comparison of in Vitro and in Vivo Releases

An implant tablet of ketoprofen (KP) was developed in order to achieve its sustained supply for approximately one week, and its release was evaluated in vitro and in vivo. Implant tablets (30 mg) containing 1 and 5 mg of ketoprofen, prepared using poly(DL-lactic acid-co-glycolic acid) copolymer (PLGA; MW 10000; lactic acid : glycolic acid=1 : 1 (mol/mol)) as a matrix, exhibited similar week-long sustained release in vitro. Plasma concentration was monitored after the implant tablet (5 mg of KP) and a KP solution (0.5 mg of KP) were administered subcutaneously to rats, and in vivo release rate was analyzed by deconvolution. The release rate from the implant tablet was faster in vivo than in vitro in the initial phase, but much lower in vivo than in vitro in the later phase. The plasma level decreased to the level less than the minimal effective concentration at 96 h after administration. However, the calculated plasma concentration given by convolution based on in vitro release rate was more than 7 times greater than the minimal effective concentration even at 96 h after administration. As the implant displayed the discrepancy between in vitro and in vivo release rates, the improvement of the in vivo release rate is required.

Relative bioavailability of ketoprofen 20% in a poloxamer-lecithin organogel

PURPOSE

The bioavailability of a single, topically applied, 200-mg dose of ketoprofen (delivered in a ketoprofen 20% gel) relative to a single 50-mg oral dose in healthy volunteers was studied.

METHODS

This was an open-label crossover study. The subjects were randomized to receive an oral 50-mg ketoprofen capsule or a single topical dose of ketoprofen 20% in a poloxamer-lecithin organogel (PLO). Treatment was followed by a one-week washout period. Blood samples were collected at intervals up to 10 hours after administration, and plasma ketoprofen concentrations were determined by high-performance liquid chromatography with ultraviolet or mass spectrometry detection. Noncompartmental pharmacokinetic values were obtained after each dose, and relative bioavailability was calculated.

RESULTS

Eight healthy volunteers enrolled in and completed the study. Topical absorption of ketoprofen was highly variable among the subjects over the 10-hour sampling period. The median oral maximum plasma concentration (Cmax) exceeded the topical Cmax by nearly 200-fold (4.15 versus 0.021 microg/mL) (p = 0.001). The median relative bioavailability of topical ketoprofen was 0.48%, with individual subjects' values ranging from 0.18% to 2.1%.

CONCLUSION

The relative bioavailability of ketoprofen was low and highly variable when the drug was administered as a single dose in a PLO-based ketoprofen 20% gel.

A Pharmacokinetic Comparison of Meloxicam and Ketoprofen following Oral Administration to Healthy Dogs

Ketoprofen (KTP) and meloxicam (MLX) are non-steroidal anti-inflamatory drugs used extensively in veterinary medicine. The pharmacokinetics of these drugs were studied in eight dogs following a single oral dose of 1 mg/kg of KTP as a racemate or 0.2 mg/kg of MLX. The concentrations of the drugs in plasma were determined by high-performance liquid chromatography (HPLC). There were differences between the disposition curves of the KTP enantiomers, confirming that the pharmacokinetics of KTP is enantioselective. (S)-(+)-KTP was the predominant enantiomer; the S:R ratio in the plasma increased from 2.58 +/- 0.38 at 15 min to 5.72 +/- 2.35 at 1 h. The area under the concentration time curve (AUC) of (S)-(+)-KTP was approximately 6 times greater than that of (R)-(-)-KTP. The mean (+/- SD) pharmacokinetic parameters for (S)-(+)-KTP were characterized as Tmax = 0.76 +/- 0.19 h, Cmax = 2.02 +/- 0.41 microg/ml, t1/2el = 1.65 +/- 0.48 h, AUC = 6.06 +/- 1.16 microg.h/ml, Vd/F = 0.39 +/- 0.07 L/kg, Cl/F = 170 +/- 39 ml/(kg.h). The mean (+/- SD) pharmacokinetic parameters of MLX were Tmax = 8.5 +/- 1.91 h, Cmax = 0.82 +/- 0.29 microg/ml, t1/2lambda(z) = 12.13 +/- 2.15 h, AUCinf = 15.41 +/- 1.24 microg.h/ml, Vd/F = 0.23 +/- 0.03 L/ kg, and Cl/F = 10 +/- 1.4 ml/(kg.h). Our results indicate significant pharmacokinetic differences between MLX and KTP after therapeutic doses.

Some Pharmacokinetic Parameters of R-(–)- and S-(+)-Ketoprofen: The Influence of Age and Differing Physiological Status in Dairy Cattle

The pharmacokinetic parameters of ketoprofen have previously been studied in cattle, but no studies have been performed on differing ages and metabolic situations in these animals. The aim of this work was to study the possible modifictions of the pharmacokinetics of ketoprofen enantiomers that may result from age, lactation or gestation in dairy cattle. Three groups of Holando Argentino cattle contained, respectively, 8 cows in early lactation, 8 pregnant cows and 8 newborn calves. Four animals from each group received the enantiomer R-(-)-ketoprofen, the other four animals received the S-(+) enantiomer, all by intravenous injection at a dose of 0.5 mg/kg. Significant differences between the three categories of animals were obtained in elimination half-life (t1/2) (1.52, 0.87 and 0.31 and 1.71, 0.69 and 0.26 in newborn calves, cows in early lactation and cows in gestation, respectively), mean residence time (MRT) (0.45, 1.25, 2.20 and 0.38, 0.99, 2.47 h, in cows in gestation, cows in early lactation and newborn calves, respectively) and area under the plasma concentration-time curve (AUC) (0.87, 2.93, 3.24, and 0.67, 2.78, 5.13 (microg/h)/ml in cows in gestation, cows in early lactation and newborn calves, respectively, for the R-(-) and S-(+) enantiomer, respectively. In calves, there was a significant difference in AUC (3.24 vs 5.13 (microg/h)/ml between R-(-)- and S-(+)-ketoprofen. In view of the differences between calves and adult cattle in the pharmacokinetic results for ketoprofen, the effects of age and physiological status (lactation, gestation) should be taken into account for therapeutic regimens.

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.

Influence of dissolution medium buffer composition on ketoprofen release from ER products and in vitro-in vivo correlation

The purpose of this work was to investigate the influence of dissolution medium composition on the in vitro release of ketoprofen from a series of ER products and the impact of the different buffer media on the in vivo-in vitro (IVIV) relationship. The products investigated were coated micro bead preparations having increasing levels of coating to retard drug release. Four common dissolution media; USP phosphate buffers of pH 7.2 and 6.8, phosphate (modified isotonic) buffer pH 6.8 and a fasted state simulated intestinal fluid without lipid components (FaSSIFLF) of pH 6.5, were employed in the USP 2 apparatus. Release profiles were compared to the corresponding in vivo release profiles, obtained following deconvolution of the plasma level versus time profiles obtained from a 10-subject five-period cross-over study. Despite the relative similarity in composition of the media employed, significant differences in release profiles were observed reflecting media differences in buffer capacity, ionic strength and pH. As a consequence, the quality and shape of the IVIV relationship changed significantly, the only apparent IVIVC incorporating all four ER products, which was non-linear, was obtained using the phosphate (modified isotonic) buffer of pH 6.8. This data was fitted, using a non-linear least squares method, by the equation of Polli et al. [J. Pharm. Sci. 85 (1996) 753] and gave an alpha parameter estimate of 2, consistent with initial dissolution being more rapid in vitro than in vivo. The systematic shift in profiles, particularly with buffer capacity, underlines the sensitivity of IVIV relationship to medium composition and hence the current difficulties in making a rational choice of an appropriate single dissolution medium.

Reduced dosage of ketoprofen for the short-term and long-term treatment of joint pain in dogs

Two studies were conducted under laboratory conditions with 16 dogs to investigate the analgesic effectiveness of a low dose of ketoprofen in a short-term sodium urate crystal-induced synovitis model of arthritis. The effect of the treatment, defined as the improvement in peak vertical force weight bearing was evaluated in the first study at three dose levels. A single oral dose of 0.25 mg/kg ketoprofen was significantly better (P < 0.01) than the control (0 mg), but doses of 0.5 and 0.75 mg/kg did not improve the dogs' weight bearing further. The second study investigated the efficacy and safety of the 0.25 mg/kg dose administered daily for 30 days. The beneficial effects of ketoprofen at this dose were constant, with the treated dogs bearing 89.1 per cent of the baseline vertical force four hours after the induction of arthritis on day 1 and 92.2 per cent on day 29, compared with 42 per cent and 34 per cent of the baseline in the untreated dogs. No gastrointestinal or other side effects were observed during the treatment.

Ketoprofen in the cat: pharmacodynamics and chiral pharmacokinetics

The non-steroidal anti-inflammatory drug ketoprofen (KTP) was administered as the racemate to cats intravenously (IV) and orally at clinically recommended dose rates of 2 and 1 mg/kg, respectively, to establish its chiral pharmacokinetic and pharmacodynamic properties. After IV dosing, clearance was more than five times greater and elimination half-life and mean residence time were approximately three times shorter for R(-) KTP than for S(+) KTP. Absorption of both S(+) and R(-) enantiomers was rapid after oral dosing and enantioselective pharmacokinetics was demonstrated by the predominance of S(+) KTP, as indicated by plasma AUC of 20.25 (S(+)KTP) and 4.09 (R(-)KTP) microg h/mL after IV and 6.36 (S(+)KTP) and 1.83 (R(-)KTP) microg h/mL after oral dosing. Bioavailability after oral dosing was virtually complete. Reduction in ex vivo serum thromboxane (TX)B(2) concentrations indicated marked inhibition of platelet cyclo-oxygenase (COX)-1 for 24 h after both oral and IV dosing and inhibition was statistically significant for 72 h after IV dosing. Both oral and IV rac-KTP failed to affect wheal volume produced by intradermal injection of the mild irritant carrageenan but wheal skin temperature was significantly inhibited by IV rac-KTP at some recording times. Possible reasons for the disparity between marked COX-1 inhibition and the limited effect on the cardinal signs of inflammation are considered. In a second experiment, the separate enantiomers of KTP were administered IV, each at the dose rate of 1mg/kg. S(+)KTP again predominated in plasma and there was unidirectional chiral inversion of R(-) to S(+)KTP. Administration of both enantiomers again produced marked and prolonged inhibition of platelet COX-1 and, in the case of R(-)KTP, this was probably attributable to S(+)KTP formed by chiral inversion.

Oral bioavailability and pharmacokinetic characteristics of ketoprofen enantiomers after oral and intravenous administration in Asian elephants (Elephas maximus)

OBJECTIVE

To assess oral bioavailability (F) and pharmacokinetic characteristics of the R- and S-enantiomers of ketoprofen administered IV and orally to captive Asian elephants (Elephas maximus).

ANIMALS

5 adult Asian elephants.

PROCEDURE

Elephants received single treatments of racemic ketoprofen at a dose of 2.2 mg/kg, administered IV and orally, in a complete crossover design. Blood samples were collected at intervals during the 24 hours following treatment. At least 4 weeks elapsed between drug administrations. Samples were analyzed for R- and S-ketoprofen with a validated liquid chromatography-mass spectroscopic assay. Pharmacokinetic parameters were determined by use of noncompartmental analysis.

RESULTS

The enantiomers of ketoprofen were absorbed well after oral administration, with median F of 101% for R-ketoprofen and 85% for S-ketoprofen. Harmonic mean half-life ranged from 3.8 to 5.5 hours, depending on route of administration and enantiomer. The area under the concentration-time curve, mean residence time, apparent volume of distribution, plasma clearance, and maximum plasma concentration values were all significantly different between the 2 enantiomers for both routes of administration.

CONCLUSIONS AND CLINICAL RELEVANCE

Ketoprofen has a long terminal half-life and complete absorption in this species. Based on the pharmacokinetic data, a dosage of ketoprofen of 1 mg/kg every 48 hours to 2 mg/kg every 24 hours, PO or IV, is recommended for use in Asian elephants, although the safety and efficacy of ketoprofen during long-term administration in elephants have not been determined.

Determination of ketoprofen enantiomers in human serum by capillary zone electrophoresis: man pharmacokinetic studies after administration of rac-ketoprofen tablets

A rapid and stereospecific capillary zone electrophoresis (CZE) method to quantify ketoprofen (KTP) enantiomers was developed. The KTP enantiomers and (+)-S-naproxen [(+)-S-NPX] as an internal standard (IS) were extracted with methylene chloride from serum acidified. Recovery of both enantiomers was in the range of 85-91%. The enantiomers were determined using a background electrolyte (BGE), consisting of 0.05 M heptakis 2,3,6-tri-O-methyl-beta-cyclodextrin (TMbetaCD) in a phosphate-triethanolamine buffer, which filled a fused silica capillary of 75 micrometer i.d. The linear range of calibration curves was between 0.25 and 50 mg l(-1), with detection limit of 0.1 mg l(-1) (signal-to-noise baseline ratio (S/N) >4). Intra- and interday precision and accuracy of the calibration curves, expressed by the coefficient of variation (CV), did not exceed 15.0%. The validated method has been successfully applied for pharmacokinetic studies of KTP enantiomers from tablets with rac-KTP in man.

In vivo evaluation of matrix pellets containing nanocrystalline ketoprofen

The aim of this study was to evaluate the in-vivo behaviour of matrix pellets formulated with nanocrystalline ketoprofen after oral administration to dogs. No significant differences in AUC-values were seen between pellet formulations containing nanocrystalline or microcrystalline ketoprofen and a commercial ketoprofen formulation (reference: Rofenid 200 Long Acting). C(max) of the formulations containing nano- or microcrystalline ketoprofen was significantly higher compared to reference, whereas t(max) was significantly lower. The in-vivo burst release observed for the spray dried nanocrystalline ketoprofen matrix pellets was reduced following compression of the pellets in combination with placebo wax/starch pellets. These matrix tablets sustained the ketoprofen plasma concentrations during 5.6 and 5.4 h for formulations containing nano- and microcrystalline ketoprofen, respectively.