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At least 19 recordsLinked to original sources

Comparison of the antinociception produced by two oral formulations of ibuprofen: ibuprofen effervescent vs ibuprofen tablets.

OBJECTIVE: The aim of this study was to compare the dose-related effects of both ibuprofen tablets and ibuprofen effervescent [placebo, 400 and 800 mg ibuprofen (Aktren)] on phasic pain. PATIENTS: Twenty volunteers participated in this randomized, double-dummy, fivefold crossover study. METHODS: Measurements were obtained before and 15, 60 and 240 min after drug administration. Pain was produced by CO2 pulses applied to the left nostril. Subjects rated the intensity of the painful stimuli by means of a visual analogue scale. In addition, chemosomatosensory event-related potentials were recorded. RESULTS: In line with previous work, ibuprofen produced a dose-related decrease in pain-related potential amplitudes P1N1, indicating its antinociceptive effects. Higher plasma concentrations of ibuprofen were reached 15-40 min after administration of the effervescent while ibuprofen tablets had a tmax 60-90 min after administration. In addition, 60 min after intake of the effervescent a prolongation of the latencies of the potentials was observed, possibly reflecting superior antinociceptive properties when compared to ibuprofen tablets. In addition, the effervescent appeared to have more consistent effects on intensity estimates compared to ibuprofen tablets.

Administration, Oral↗

Codeine 20 mg increases pain relief from ibuprofen 400 mg after third molar surgery. A repeat-dosing comparison of ibuprofen and an ibuprofen-codeine combination.

A combination of 20 mg codeine base and ibuprofen 400 mg was compared with ibuprofen 400 mg in a randomised double-blind cross-over study of multiple doses in 25 patients after 2-stage bilateral third molar removal. The combination produced significantly greater pain relief and doubled the hours of minimum pain intensity and maximal relief on the day of surgery. The patients rated the combination significantly better than ibuprofen alone, and the combination was preferred by 16 of the 22 patients expressing a preference. There was no significant increase in side-effect incidence with the combination. The 30% increase in analgesic effect may be of clinical benefit, and this trial design, cross-over with multiple dosing in out-patients, may be a sensitive test for analgesics, potentially more predictive of side-effect problems than single-dose studies.

Adult↗

Preliminary pharmacokinetic study of ibuprofen enantiomers after administration of a new oral formulation (ibuprofen arginine) to healthy male volunteers.

The pharmacokinetics of ibuprofen enantiomers were investigated in a crossover study in which seven healthy male volunteers received single oral doses of 800 mg racemic ibuprofen as a soluble granular formulation (sachet) containing L-arginine (designated trade name: Spedifen), 400 mg (-)R-ibuprofen arginine or 400 mg (+)S-ibuprofen arginine. Plasma levels of both enantiomers were monitored up to 480 minutes after drug intake using an enantioselective analytical method (HPLC with ultraviolet detection) with a quantitation limit of 0.25 mg/l. Substantial inter-subject variability in the evaluated pharmacokinetic parameters was observed in the present study. After (+)S-ibuprofen arginine, the following mean pharmacokinetic parameters +/-SD were calculated for (+)S-ibuprofen: tmax 28.6 +/- 28.4 min; Cmax 36.2 +/- 7.7 mg/l; AUC 86.4 +/- 14.9 mg.h/l; t1/2 105.2 +/- 20.4 min. After (-)R-ibuprofen arginine, the following mean pharmacokinetic parameters were calculated for (+)S-ibuprofen and (-)R-ibuprofen, respectively: tmax 90.0 +/- 17.3 and 50.5 +/- 20.5 min; Cmax 9.7 +/- 3.0 and 35.3 +/- 5.0 mg/l; AUC 47.0 +/- 17.2 and 104.7 +/- 27.7 mg.h/l; t1/2 148.1 +/- 63.6 and 97.7 +/- 23.3 min. After racemic ibuprofen arginine, the following mean pharmacokinetic parameters were calculated for (+)S- and (-)R-ibuprofen, respectively: tmax 30.7 +/- 29.1 and 22.9 +/- 29.8 min; Cmax 29.9 +/- 5.6 and 25.6 +/- 4.4 mg/l; AUC 105.1 +/- 23.0 and 65.3 +/- 15.0 mg.h/l; t1/2 136.6 +/- 20.7 and 128.6 +/- 45.0 min. Tmax values of S(+)- and (-)R-ibuprofen after a single dose of 400 mg of each enantiomer did not differ significantly from the corresponding parameters obtained after a single dose of 800 mg of racemic ibuprofen arginine, indicating that the absorption rate of (-)R- and (+)S-ibuprofen is not different when the two enantiomers are administered alone or as a racemic compound. An average of 49.3 +/- 9.0% of a dose of the (-)R-ibuprofen arginine was bioinverted into its antipode during the study period (480 minutes post-dosing). The percent bioinversion during the first 30 minutes after (-)R-ibuprofen arginine intake averaged 8.1 +/- 3.9%. The mean AUC of (+)S-ibuprofen calculated after 800 mg racemic ibuprofen arginine (105.1 +/- 23.0 mg.h/l) was lower than the mean AUC value obtained by summing the AUCs of (+)S-ibuprofen after administration of 400 mg (+)S-ibuprofen arginine and 400 mg (-)R-ibuprofen arginine (133.4 +/- 26.6 mg.h/l). In conclusion, the administration of Spedifen resulted in very rapid absorption of the (+)S-isomer (eutomer) with tmax values much lower than those observed for this isomer when conventional oral solid formulations such as capsules or tablets of racemic ibuprofen are administered. This characteristic is particularly favourable in those conditions in which a very rapid analgesic effect is required.

Adult↗

A randomized, double-blind, placebo-controlled comparison of the analgesic efficacy, onset of action, and tolerability of ibuprofen arginate and ibuprofen in postoperative dental pain.

BACKGROUND: Because of its enhanced pharmacokinetic characteristics, ibuprofen arginate might be expected to provide faster pain relief than standard ibuprofen formulations in patients experiencing acute pain. OBJECTIVE: This study assessed the analgesic efficacy, speed of onset, and tolerability of ibuprofen arginate compared with a commercially available form of ibuprofen in patients with postoperative dental pain. METHODS: Patients were randomized to receive ibuprofen arginate 200 or 400 mg, ibuprofen 200 or 400 mg, or placebo in this multicenter, double-blind, double-dummy, parallel-group trial. Patients were observed for 6 hours after administration of a single dose of study medication. A repeated-dose, open-label phase followed. Pain intensity and pain relief were measured using traditional verbal descriptor scales; onset of analgesia was assessed using 2 stopwatches to measure the time to achievement of specific pain relief criteria. RESULTS: A total of 498 patients (219 men, 279 women; mean age, 21.5 years) participated in this study. Baseline pain was moderate in 388 patients (78%) and severe in 110 patients (22%). Meaningful pain relief was reached after a median of 29 and 28 minutes with ibuprofen arginate 200 and 400 mg, respectively, and after 52 and 44 minutes with ibuprofen 200 and 400 mg, respectively (all, P < 0.05). The percentages of patients who achieved meaningful pain relief within the first hour after treatment were 77.6% and 83.7% for ibuprofen arginate 200 and 400 mg, respectively, 61.0% and 63.0% for ibuprofen 200 and 400 mg, respectively, and 39.8% for placebo. The differences between ibuprofen arginate and ibuprofen were statistically significant (both doses, P < 0.05). Significantly greater numbers of patients achieved meaningful pain relief with ibuprofen arginate 400 mg compared with placebo from 20 minutes through 6 hours and with ibuprofen arginate 200 mg from 30 minutes through 6 hours (P < 0.05). Compared with placebo, a greater number of patients achieved meaningful pain relief with ibuprofen 400 mg from 45 minutes through 6 hours; with ibuprofen 200 mg. the corresponding interval was from I through 6 hours. After the first hour, pain reduction was similar for the similar doses of the 2 ibuprofen preparations. Median remedication times with both doses of ibuprofen arginate were similar to those with both doses of ibuprofen, ranging from 4.0 to 5.2 hours. Adverse-event profiles were similar between the 2 active medications. CONCLUSIONS: Ibuprofen arginate was effective in this population of patients experiencing moderate to severe pain after surgical extraction of > or = 1 impacted third molar, with 16 to 24 minutes' faster time to meaningful pain relief than with ibuprofen. The 2 formulations had similar tolerability profiles.

Adult↗

Stereoselective metabolism of ibuprofen in humans: administration of R-, S- and racemic ibuprofen.

Using stable isotope methodology, we studied the effect of the enantiomeric composition of dosage form on ibuprofen metabolism. Eight healthy human subjects received racemic ibuprofen (800 mg) plus S-[aromatic-2H4]ibuprofen (10 mg), R-ibuprofen (600 mg) plus S-[aromatic-2H4]ibuprofen (10 mg) and S-ibuprofen (600 mg) orally on separate occasions in random order. Stereoselective gas chromatography-mass spectrometry was used to quantify deuterated and nondeuterated ibuprofen in serum up to 24 h postdose. Urinary excretion of the stereoisomeric forms of carboxyibuprofen, hydroxyibuprofen and ibuprofen glucuronide were determined up to 24 h postdose by stereoselective high performance liquid chromatography. The metabolism of ibuprofen enantiomers was not influenced by the enantiomeric composition of the dose. For racemic ibuprofen, the mean clearances (+/- S.D.) of S-ibuprofen, R-ibuprofen inversion and R-ibuprofen noninversion were 87.4 +/- 25.9, 57.3 +/- 31.0 and 56.3 +/- 29.0 ml/min, respectively. The fractional inversion of ibuprofen was significantly greater (P less than .05) using the stereochemical composition of the urinary metabolites (0.63 +/- 0.05) vs. the method using the clearance of deuterated S-ibuprofen (0.51 +/- 0.08) after the dose of racemate. Unreliable estimates of fractional inversion were obtained when the S-ibuprofen and racemic ibuprofen doses were combined. Metabolite formation clearances suggested that S-ibuprofen is preferred over R-ibuprofen in the formation of hydroxyibuprofen, carboxyibuprofen and ibuprofen glucuronide. Product stereoselectivity in the formation of the four diastereomers of carboxyibuprofen was modest in favor of SS- and RR-carboxyibuprofen for S- and R-ibuprofen, respectively.

Adult↗

Ibuprofen arginate provides effective relief from postoperative dental pain with a more rapid onset of action than ibuprofen.

Ibuprofen is a safe and effective analgesic, but some formulations have a slow onset of action. Ibuprofen arginate is a rapidly absorbed salt designed to promote more rapid onset of analgesia. A clinical trial was conducted in 226 patients with postoperative dental pain to assess the analgesic efficacy and speed of onset of the arginine salt of ibuprofen compared with one of the commercially available forms of ibuprofen. Patients were administered a single dose of either ibuprofen arginate (200 mg or 400 mg), ibuprofen (200 mg or 400 mg), or placebo in this double-blind, randomized trial. To determine the onset of action of the study medication patients were required to note time to "any" pain relief and then time to "meaningful" pain relief, using the two-stopwatch method. Pain intensity and relief were assessed using traditional categorical scales over a 6-h period. Meaningful pain relief was achieved in 42 min and 24 min for ibuprofen arginate 200 mg and 400 mg, respectively, compared with 50 min and 48 min for ibuprofen 200 mg and 400 mg, respectively ( P<0.05). The results for the measurements of analgesic effectiveness [sum of pain intensity difference, total pain relief (TOTPAR), peak pain relief and overall evaluation of treatment] all showed that both doses of ibuprofen arginate and both doses of ibuprofen were significantly better than placebo and both 200-mg and 400-mg ibuprofen arginate doses were significantly better than ibuprofen 200 mg for peak pain relief. Mean plasma ibuprofen concentrations at 30 min and 60 min, respectively, were: ibuprofen arginine 200 mg, 13.9 micro g/ml and 15.7 micro g/ml; ibuprofen arginine 400 mg, 29.5 micro g/ml and 29.3 micro g/ml; ibuprofen 200 mg 2.5 micro g/ml and 5 micro g/ml; ibuprofen 400 mg, 2.3 micro g/ml and 7.4 micro g/ml. ( P<0.05). Adverse event profiles were similar across treatment groups. These results overall suggest that ibuprofen arginate when taken at doses equivalent to commercially available ibuprofen formulations produces analgesia that is faster in onset.

Adult↗

Comparative pharmacology of S(+)-ibuprofen and (RS)-ibuprofen.

Racemic ibuprofen, which contains equal quantities of R(-)-ibuprofen and S(+)-ibuprofen, has been used as an anti-inflammatory and analgesic agent for over 30 years. Although the S(+)-enantiomer is capable of inhibiting cyclooxygenase (COX) at clinically relevant concentrations, R(-)-ibuprofen is not a COX inhibitor. The two enantiomers of ibuprofen are therefore different in terms of their pharmacological properties and may be regarded as two different 'drugs'. They also differ in terms of their metabolic profiles. For example, R(-)-ibuprofen becomes involved in pathways of lipid metabolism and is incorporated into triglycerides along with endogenous fatty acids. S(+)-Ibuprofen does not appear to become involved in these unusual metabolic reactions, which is why S(+)-ibuprofen is regarded as being metabolically 'cleaner' than racemic ibuprofen. When racemic ibuprofen is given to humans, a substantial fraction of the dose of R(-)-ibuprofen (50%-60%) undergoes 'metabolic inversion' to yield S(+)-ibuprofen. On this basis, it has been argued that to obtain clinical effects that are comparable to those of a given dose of racemic ibuprofen, the dose of S(+)-ibuprofen would need to be about 75% of the dose of the racemate. However, this 'pharmacokinetic' rationale does not take into account the fact that inversion is not instantaneous, that there is variability in the extent of inversion between individuals, and that the kinetics of inversion may differ depending on the dosing situations. For example, the extent of inversion appears to be reduced when the racemate is given to patients experiencing acute pain. Recent studies have demonstrated that the clinical benefits of racemic ibuprofen can be derived from the administration of the single S(+)-enantiomer at a dose that is half that of the racemate. For example, 200 mg of S(+)-ibuprofen has been found to be superior or at least equivalent to 400 mg of the racemate in the relief of dental pain. Possible explanations for this higher than expected efficacy of S(+)-ibuprofen are considered.

Anti-Inflammatory Agents, Non-Steroidal↗

Pharmacokinetics of S(+)- and R(-)-ibuprofen in volunteers and first clinical experience of S(+)-ibuprofen in rheumatoid arthritis.

S(+)-, R(-)- or racemic ibuprofen was administered orally to volunteers in doses of 150 mg, 300 mg and 500 mg pure S(+)-, 300 mg pure R(-)- and 600 mg racemic ibuprofen. The pharmacokinetic parameters in humans showed that S(+)-ibuprofen was not inverted to R(-)-ibuprofen, whereas R(-)-ibuprofen was inverted to S(+)-ibuprofen to a variable degree. S(+)-ibuprofen and R(-)-ibuprofen given alone more rapidly reached significantly higher maximal plasma concentrations than after the same doses of the racemic compound. The elimination half-lives and clearance values for all three forms of ibuprofen were comparable. The mean residence time of S(+)-ibuprofen after R(-)- and racemic ibuprofen was significantly longer than after administration of the pure S(+)-enantiomer. Judged by the AUC, the bioavailability of S(+)-ibuprofen was independent of the dose within the range tested. Administration of S(+)-ibuprofen to 6 rheumatic patients showed that the pharmacokinetic behaviour of S(+)-ibuprofen in patients was similar to that found in volunteers. S(+)-ibuprofen proved to be an effective analgesic antirheumatic drug in the dose range 1 to 1.5 g/day.

Adult↗

Preliminary toxicokinetic study with different crystal forms of S (+)-ibuprofen (dexibuprofen) and R,S-ibuprofen in rats.

The aim of the study was to gain information on the plasma concentration-time profiles of both ibuprofen (CAS 15687-27-1) enantiomers in the rat after single oral application of two different crystal forms of S (+)-ibuprofen (dexibrufen, CAS 51146-56-6) and racemic ibuprofen in order to optimize blood-sampling times in a subsequent subchronic toxicity study. The application of either commercial racemic ibuprofen or recrystallised S (+)-ibuprofen (60 mg/kg) to two groups of 4 rats per blood sampling term was carried out in order to define Cmax and tmax and AUC of the plasma-concentrations of the ibuprofen enantiomers. The crystals of commercial (manufactured according to an usual manufacturing procedure) and recrystallised (S(+)- and racemic ibuprofen were different in respect to their shape and size. The recrystallised crystal species of S (+)- and racemic ibuprofen has better galenic (tabletting-) properties and tablets containing the modified S (+)-ibuprofen species showed favorable clinical results. The toxicokinetic behaviour of the recrystallised species was investigated in comparison to the commercial crystal species because of its slightly but significantly slower dissolution rate in simulated gastric and enteric juice. As the AUC0-24 h S-(+)-ibuprofen and the AUC0-24 h, R-(-)-ibuprofen after application of commercial and recrystallised crystal species were not different, the crystal form apparently did not exert an influence on the extent of absorption of S-(+)-ibuprofen and racemic ibuprofen in the rat. The rat has a high inversion capacity and the inversion of R-(-)-ibuprofen after application of commercial and recrystallised racemic ibuprofen was nearly complete in this study. The effects of crystallinity on solubility in simulated media in vitro did not correlate to the findings on the extent of absorption in the rat in vivo.

Animals↗

Analgesic efficacy of a hydrocodone with ibuprofen combination compared with ibuprofen alone for the treatment of acute postoperative pain.

Hydrocodone is a semisynthetic opioid with analgesic and antitussive properties qualitatively similar to other opioid agonists. Ibuprofen is a nonsteroidal antiinflammatory agent with analgesic and antipyretic activity and is an effective, primarily peripheral-acting antiinflammatory analgesic. The objective of this clinical trial was to determine the additive analgesic effect of the combination of 15 mg hydrocodone bitartrate with 400 mg ibuprofen, relative to 400 mg ibuprofen alone and placebo, in the treatment of postoperative pain. The single-dose analgesic efficacy of the combination of hydrocodone bitartrate with ibuprofen was compared with ibuprofen alone and placebo in 120 patients with moderate or severe postoperative pain after abdominal surgery. Analgesia was measured during the 6-hour period after dosing based on onset of relief, hourly and summary variables, and duration of effect. A significantly greater proportion of patients treated with the hydrocodone/ibuprofen combination reported onset of relief compared with ibuprofen or placebo; however, the distribution functions for time to onset of relief did not differ among treatments. Hydrocodone with ibuprofen and ibuprofen alone were significantly more effective than placebo for all measures of analgesia. The combination of hydrocodone with ibuprofen was significantly superior to ibuprofen for all hourly analgesic evaluations, weighted sum of pain intensity differences (SPID), total pain relief (TOTPAR), and global rating of study medication. No patients in the hydrocodone with ibuprofen group required analgesic remedication during the 6-hour study period, compared with 25% and 82% in the ibuprofen and placebo groups, respectively. The analgesic superiority of 15 mg hydrocodone bitartrate combined with 400 mg ibuprofen compared with 400 mg ibuprofen alone was demonstrated across many efficacy variables.

Adolescent↗

Effect of ibuprofen in patients with severe sepsis: a randomized, double-blind, multicenter study. The Ibuprofen Study Group.

OBJECTIVE: To evaluate the safety and physiologic actions of ibuprofen in patients with severe sepsis. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: Three university hospital medical ICUs. PATIENTS: Twenty-nine patients with clinical evidence of sepsis and the need for hemodynamic monitoring with a pulmonary artery flotation catheter. INTERVENTIONS: Thirteen patients received placebo and 16 received ibuprofen that consisted of 600 mg (n = 11) or 800 mg (n = 5) iv over 20 mins, followed by three 800-mg doses administered as a rectal solution every 6 hrs. The initial iv dose was given within 4 hrs of the presumptive diagnosis of sepsis. MEASUREMENTS AND MAIN RESULTS: The peak circulating total ibuprofen concentration after the iv dose (49.4 +/- 4.5 micrograms/mL, mean +/- SEM) was higher than peak concentrations after the three rectal doses (17.0 +/- 2.7, 16.4 +/- 3.0, 16.0 +/- 3.1 micrograms/mL). Both routes of ibuprofen administration were well tolerated. Frequent monitoring for gastrointestinal bleeding and assessment of renal and hepatic function failed to demonstrate significant differences between ibuprofen and placebo. Because a trend for reduced creatinine clearance was observed at 8 hrs in the ibuprofen group, nephrotoxicity of this drug in sepsis cannot be excluded. Temperature decreased significantly within 4 hrs of the initial dose of investigational therapy in patients who received ibuprofen (38.5 +/- 0.3 degrees to 37.0 +/- 0.2 degrees C, p less than .001). However, despite this significant change in temperature, we were unable to detect significant differences in hemodynamic and respiratory values or survival when ibuprofen-treated patients were compared with controls. CONCLUSIONS: Ibuprofen was well tolerated when administered iv and rectally to patients with severe sepsis, although drug absorption was poor with the rectal route. Significant antipyretic effects of ibuprofen were demonstrated. Although an excellent safety profile characterized ibuprofen in this study, the absence of ibuprofen-associated toxicity may have been secondary to poor rectal absorption of the drug. Our results support the continued clinical investigation of ibuprofen in sepsis, using an all-intravenous route of administration.

Administration, Rectal↗

Direct determination of ibuprofen and ibuprofen acyl glucuronide in plasma by high-performance liquid chromatography using solid-phase extraction.

A method for the simultaneous determination of ibuprofen and its labile, reactive metabolite, ibuprofen acyl glucuronide, in plasma is described. Reversed-phase high-performance liquid chromatography (HPLC) employed a C18 column using methanol-10 mM trifluoroacetic acid as the mobile phase with ultraviolet detection at 225 or 214 nm. It is essential that blood is handled rapidly and plasma is acidified upon collection prior to freezing. Plasma samples first are deproteinated with acetonitrile, the supernatant is diluted with phosphate buffer, and ibuprofen, ibuprofen glucuronide, and ibufenac (internal standard) are initially isolated by solid-phase extraction on C18 cartridges. Upon elution, the residue is evaporated, dissolved and injected onto the HPLC system. Recovery is 94 +/- 8 and 70 +/- 9% for ibuprofen glucuronide and ibuprofen, respectively. The measurable concentration range is linear from 0.1 to 10 micrograms/ml for ibuprofen glucuronide and from 0.5 to 100 micrograms/ml for ibuprofen. The method is satisfactory for the analysis of ibuprofen and ibuprofen glucuronide from pharmacokinetic studies in humans. The direct determination of ibuprofen glucuronide allows accurate measurement of this conjugate at low levels relative to the parent compound, ibuprofen, a distinct advantage compared to previously employed indirect methods.

Chromatography, High Pressure Liquid↗

Pharmacokinetics and absolute bioavailability of ibuprofen after oral administration of ibuprofen lysine in man.

The lysine salt of d,l-2-(4-isobutylphenyl)-propionic acid (ibuprofen lysine) was administered as a single oral dose of 500 mg by means of commercially available coated tablets (Imbun).* To assess the absolute bioavailability of ibuprofen after its oral application as a lysine salt, intravenous injections of ibuprofen solutions containing 200 mg and 400 mg of the drug served as reference application. In a partially randomized cross-over design, 8 healthy male volunteers received three different single dose administrations which were separated by wash-out periods of 4 days each. Ibuprofen plasma concentrations were determined by HPLC using direct injection, pre-column enrichment and column switching techniques. From the results of intravenous injections one can deduce linear ibuprofen pharmacokinetics within the considered dosage range, with corresponding AUC0-infinity values of 3786 micrograms * min ml-1 and 7260 micrograms * min ml-1 for the 200 mg and 400 mg doses, respectively. The values of plasma clearances as well as those of different volumes of distribution showed remarkable constancy after evaluation from both intravenous injections. The absorption of orally administered ibuprofen lysine proved to be rapid, resulting in a mean peak plasma level (Cmax) of 31 micrograms ml-1 ibuprofen and in a mean time to peak (tmax) of 45 min. The absolute bioavailability of ibuprofen amounts to 102.7 per cent, indicating a complete absorption of ibuprofen when administered as its lysine salt. Drug tolerability was excellent for the oral administration of ibuprofen lysine as well as for the intravenous treatments with ibuprofen free acid. Only mild and transient adverse drug reactions such as mild burning or dragging sensation during injection or mild redness at the site of injection were reported.

Administration, Oral↗

Magnesium hydroxide in ibuprofen tablet reduces the gastric mucosal tolerability of ibuprofen.

GOAL: The study was designed to compare the gastrointestinal tolerability of a magnesium hydroxide-containing ibuprofen tablet (buffered ibuprofen) and the conventional ibuprofen tablet in healthy volunteers. BACKGROUND: Magnesium hydroxide has been shown to increase the rate of absorption of ibuprofen. METHODS: A double blind, randomized, 2-period crossover study design was used. Twenty healthy men ingested 800 mg ibuprofen 3 times daily either in conventional tablets (2 doses of 400 mg) or in tablets containing magnesium hydroxide (2 doses of 400 mg ibuprofen and 200 mg magnesium hydroxide). On the 5th day only the morning dose was administered. Endoscopy was performed at baseline and on the 5th day in both treatments 2 hours after the last dose, and gastric pH was determined. In addition, plasma concentrations of ibuprofen were determined up to 90 minutes. RESULTS: The magnesium hydroxide-containing formulation increased the number of subjects evincing erosions in gastric corpus and antrum. In the gastric corpus 2 and 7 volunteers had erosions after conventional and buffered ibuprofen, respectively (P = 0.08). In the gastric antrum 5 and 13 volunteers showed erosions after conventional and buffered ibuprofen, respectively (P = 0.02). There was a trend toward faster absorption of ibuprofen when given together with magnesium hydroxide. The difference was not however statistically significant. CONCLUSIONS: Prolonged use of magnesium hydroxide together with high doses of ibuprofen should be avoided, because the combination may incur a higher risk of gastrointestinal irritation.

Acid-Base Equilibrium↗

The relationship between the pharmacokinetics of ibuprofen enantiomers and the dose of racemic ibuprofen in humans.

Ibuprofen is a chiral drug which is used clinically as a racemate. The pharmacological properties of ibuprofen reside almost exclusively with the S(+)-enantiomer. However, a portion of R(-)-ibuprofen is metabolically inverted to its pharmacologically active, mirror-image form. To investigate the influence of increasing dose of racemic ibuprofen on the pharmacokinetics of its individual enantiomers, four healthy male volunteers were given racemic ibuprofen (200, 400, 800, and 1200 mg), orally, on four occasions. The study was conducted using a balanced cross-over design. The extent of absorption of ibuprofen, as assessed by the total urinary recovery of ibuprofen and its metabolites, was extensive and independent of the administered dose. At all four doses, the area under the total and unbound plasma concentration-time curves (AUC and AUCu, respectively), and the unbound fraction in plasma, were significantly greater for the S(+)-enantiomer. With increasing ibuprofen dose, there was a less than proportional increase in the AUC of each enantiomer, while the AUCu for both enantiomers increased in direct proportion to the administered dose. The time-averaged unbound fraction of each enantiomer increased significantly with increasing dose, which caused the non-linearity between AUC and dose. It was predicted that the metabolic intrinsic clearance of each enantiomer, and the fraction of R(-)-ibuprofen which was metabolically inverted to S(+)-ibuprofen, was independent of the administered dose.

Adult↗

Renal handling and effects of S(+)-ibuprofen and R(-)-ibuprofen in the rat isolated perfused kidney.

1. The renal handling and effects of S(+)- and R(-)-ibuprofen have been studied in the isolated perfused kidney (IPK) of the rat. 2. Both ibuprofen enantiomers were extensively reabsorbed and accumulated in the kidney in a concentration-dependent manner. No pharmacokinetic differences were observed between the two enantiomers. 3. S(+)-ibuprofen concentrations ranging from 0.25 to 25 micrograms ml-1 (1.2 to 120 microM) caused a decrease in urinary flow, glomerular filtration rate (GFR) and electrolyte excretion. Urinary pH and excretion of glucose were not influenced. R(-)-ibuprofen concentrations ranging from 2.5 to 25 micrograms ml-1 (12 to 120 microM) also decreased urinary flow and electrolyte excretion. This decrease, however, was less than observed with S(+)-ibuprofen. GFR, urinary pH and glucose excretion were not affected by R(-)-ibuprofen. Prostaglandin E2 (PGE2) concentrations of 133 ng ml-1 reversed the effects on renal function of both enantiomers. 4. Very high S(+)- and R(-)-ibuprofen concentrations (greater than 400 micrograms ml-1) resulted in an increase in urinary flow and fractional excretion of sodium, chloride, potassium, glucose and calcium. 5. It is concluded that the pharmacokinetic behaviour of ibuprofen in the kidney is not stereoselective. Relatively high concentrations of both enantiomers increased the urinary flow and electrolyte excretion in a nonstereoselective manner. Lower concentrations of S(+)-ibuprofen decreased urinary flow and electrolyte excretion. The pharmacologically inactive R(-)-ibuprofen was also able to affect renal function in a similar way, but at different concentrations. These effects on renal function are probably caused by inhibition of PGE2 synthesis.

Animals↗

A controlled comparative study of ibuprofen arginate versus conventional ibuprofen in the treatment of postoperative dental pain.

The analgesic efficacy of an arginine salt of ibuprofen was compared to one of the commercially available forms of conventional ibuprofen in a 500-patient clinical trial in postoperative dental pain. Patients were administered a single dose of ibuprofen arginate (200 mg or 400 mg), conventional ibuprofen (200 mg or 400 mg), orplacebo in this double-blind, randomized, parallel-group trial. Results demonstrated that ibuprofen arginate was a safe and effective analgesia that was superior to conventional ibuprofen in both the amount of pain relief achieved and the time to onset of pain relief. Onset of analgesia, assessed as the median amount of time to achieve meaningful pain relief, was reached after 32 and 31 minutes with ibuprofen arginate 200 and 400 mg, respectively, and 64 and 58 minutes with conventional ibuprofen 200 and 400 mg, respectively (p < 0.05). Patients treated with ibuprofen arginate rated its overall effectiveness higher than those patients treated with conventional ibuprofen. Adverse event profiles were similar across all treatment groups.

Adolescent↗