Evaluation of the efficacy and dose-response relationship of dexibuprofen (S(+)-ibuprofen) in patients with osteoarthritis of the hip and comparison with racemic ibuprofen using the WOMAC osteoarthritis index.

OBJECTIVE: Treatment with non-steroidal anti-inflammatory drugs is the most common pharmacological therapy of rheumatic diseases. For the symptomatic treatment of painful disorders a dose-response relationship of the NSAID should be a basic requirement, which is difficult to be proven in studies because rheumatic diseases are heterogenous in terms of clinical involvement. The aim of this double-blind randomized trial was to compare the isolated active enantiomer dexibuprofen (S(+)-ibuprofen) with the double dose of racemic ibuprofen and to show a dose-response relationship of dexibuprofen in painful osteoarthritis of the hip. METHODS: 178 patients were randomly assigned to dexibuprofen 600/1,200 mg or racemic ibuprofen 2,400 mg daily. The primary endpoint was the improvement of the WOMAC osteoarthritis index after 15 days of therapy. The analysis was by intention to treat. RESULTS: The evaluation of the WOMAC OA index showed statistically significant equivalence of dexibuprofen 400 mg t.i.d. compared with racemic ibuprofen 800 mg t.i.d. by a Mann-Whitney statistic of 0.578 and the corresponding lower bound of the 95% confidence interval of 0.498. The test for superiority of dexibuprofen was borderline significant with p = 0.055. Dexibuprofen 400 mg t.i.d. and dexibuprofen 200 mg t.i.d. showed a statistically significant dose-response relationship in improving the WOMAC OA index (p = 0.023). Patients suffered from adverse drug reactions, mainly gastrointestinal disorders, 13.34% on dexibuprofen 200 mg, 15.25% on dexibuprofen 400 mg and 16.94% on racemic ibuprofen 800 mg. CONCLUSIONS: The active enantiomer dexibuprofen (S(+)-ibuprofen) proved to be an effective non-steroidal anti-inflammatory drug with a significant dose-response relationship in patients with painful osteoarthritis of the hip. Compared with racemic ibuprofen half of the daily dose of dexibuprofen shows at least equivalent efficacy. In contrast to pharmacokinetic data, the additional administration of R(-)-ibuprofen in form of racemate does not contribute to the clinical efficacy of racemic ibuprofen.

The duration of antidiuretic response of two desmopressin nasal sprays.

The duration of antidiuretic response and pharmacokinetics of desmopressin were investigated in 16 healthy, male overhydrated volunteers after intranasal administration of 20 microg desmopressin (dDAVP). The antidiuretic activity was determined by measuring urine osmolality and diuresis over a period of 24 hours. Both study preparations were equally effective regarding a rapid onset of activity and a highly reproducible extent of effect. Urine osmolalities, analyzed as areas under the time curve (AUCosm) were similar for both nasal sprays. Urine volumes were comparable. Bioequivalence was assessed for the primary criterion AUCosm by a calculated mean ratio (test/reference) of 100.9% (90% confidence interval ranging from 88.0% to 115.6%). Plasma levels of desmopressin, measured by a specific and sensitive radioimmunoassay method, were already detectable 20 minutes after administration. The mean time courses showed a similar shape with increased concentration levels for the test preparation. Consequently maximum desmopressin plasma concentrations were different, showing high interindividual variability. However, the times of reaching maximum plasma concentrations were similar. AUC(0-24h) was significantly raised after treatment with the test preparation (mean ratio of 127.9%; 90% confidence interval ranging from 106.6% to 153.5%). A subanalysis of the 2 reference batches with the two-sided t-test procedure for parallel groups resulted in a mean ratio of 83.1% with a 90% confidence interval ranging from 67.2% to 102.7%. The estimated ratios of the 2 batches of the reference preparation were borderline to the equivalence range. In conclusion, both study preparations had the same pronounced biological effect with different desmopressin bioavailabilities.

Pharmacokinetics of dexibuprofen administered as 200 mg and 400 mg film-coated tablets in healthy volunteers.

The pharmacokinetic properties of 2 film-coated preparations containing 200 mg and 400 mg dexibuprofen were compared in a single-dose, crossover study in 16 healthy, male volunteers. Dexibuprofen was absorbed rapidly (tmax 2.1 - 2.2 hours) reaching maximum concentrations of 12.4 microg/ml (200 mg), respectively 12.0 microg/ml (400 mg dose adjusted). For the characteristics AUC(0-12h) and AUC(0-infinity) arithmetic means of 49.2 (microg) x (h/ml)(200 mg) and 48.2 (microg) x (h/ml)(400 mg dose-adjusted), respectively 50.5 (microg) x (h/ml)(200 mg), and 49.2 (microg) x (h/ml)(400 mg) were calculated. No relevant differences for the pharmacokinetic characteristics terminal half-life, clearance, volume of distribution, and mean residence time were observed. A linear dose-relationship was shown over the investigated dose range. Mean ratios after dosage adjustment of the test preparation using the "2 one-sided t-tests" procedure were calculated. Bioequivalence was assessed for AUC(0-12h) with a mean ratio of 97.7% (90% CI: 92.4 - 103.3%), for AUC(0-infinity) with 97.1% (90% CI: 91.4 - 103.1%), and for Cmax with 97.5% (90% CI: 91.7 - 103.8%). Both dexibuprofen preparations were well tolerated. No changes in hematological and biochemical parameters were detected.

A comparative study of pharmacodynamics and bioavailability of 2 different desmopressin nasal sprays.

The antidiuretic effect and pharmacokinetics were investigated in 16 healthy, male overhydrated volunteers after intranasal administration of 20 microg desmopressin. The antidiuretic activity was measured by determination of urine osmolality and diuresis every 15 minutes over a period of 8 hours. Both study preparations were equally effective regarding a rapid onset of activity and a highly reproducible magnitude of effect. Urine osmolalities, analyzed as area under the time curve (AUCosm) and maximum urine osmolalities were similar for both nasal sprays. Urine volume, analyzed as area under the time curve, was raised after treatment with the test preparation. Bioequivalence was assessed for the primary criterion AUCosm by a calculated mean ratio (test/reference) of 102.8% and a 90% confidence interval ranging from 95.4% to 110.8%. Plasma levels of desmopressin, measured by a specific and sensitive radio-immunoassay method, were already detectable 20 minutes after administration. The mean time curves were parallel at different concentration levels. The maximum desmopressin plasma concentrations of both preparations were comparable, showing high interindividual variability. The times of reaching maximum plasma concentrations were similar. Desmopressin bioavailability was increased after treatment with the test preparation (mean ratio of 130.8% and a 90% confidence interval ranging from 109.9% to 155.7%). Both preparations showed a pronounced biological effect with similarly raised urine osmolalities. The detected differences in bioavailability seem to have no direct correlation to the biological response.