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Clinical Trial
. 2005 Jan;59(1):80-4.
doi: 10.1111/j.1365-2125.2005.02226.x.

Bioavailability of diclofenac potassium at low doses

Burkhard Hinz  1 , Julia Chevts, Bertold Renner, Henrike Wuttke, Thomas Rau, Andreas Schmidt, Istvan Szelenyi, Kay Brune, Ulrike Werner
Affiliations
Clinical Trial

Bioavailability of diclofenac potassium at low doses

Burkhard Hinz et al. Br J Clin Pharmacol. 2005 Jan.

Abstract

Aim: Diclofenac-K has been recently launched at low oral doses in different countries for over-the-counter use. However, given the considerable first-pass metabolism of diclofenac, the degree of absorption of diclofenac-K at low doses remained to be determined. The aim of this study was to determine the bioavailability of low-dose diclofenac-K.

Methods: A randomized, three-way, cross-over study was performed in 10 subjects. Each received diclofenac-K, 22.5 mg via short-term i.v. infusion and orally at single doses of 12.5 mg and 25 mg.

Results: Mean (+/- SD) times to maximal plasma concentration (t(max)) of diclofenac were 0.48 +/- 0.28 h (12.5 mg) and 0.93 +/- 0.96 h (25 mg). The absolute bioavailability of diclofenac-K after oral administration did not differ significantly in the 12.5-mg and 25-mg dose group (63.1 +/- 12.6%vs. 65.1 +/- 19.4%, respectively). The 90% confidence intervals for the AUC(infinity) and AUC(t) ratios for the two oral regimes were 82.6, 103.4% (point estimate 92.4%) and 86.2, 112.9% (point estimate 98.6%), respectively. These values were within the acceptance criteria for bioequivalence (80-125%).

Conclusions: Our data indicate that diclofenac-K is rapidly and well absorbed at low dose, and are consistent with a rapid onset of action of the drug. Abbreviations AUC, area under plasma concentration-time curve; C(max), peak plasma concentration; CI, confidence interval; COX, cyclooxygenase; D, dose; F, absolute bioavailability; t(max), time to reach C(max).

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Figures

Figure 1
Figure 1
Mean diclofenac plasma concentration-time profiles (linear scale) following i.v. administration of 22.5 mg (▪) diclofenac-K (A) and single oral administration of 12.5 (▪) and 25 mg (▴) diclofenac-K (B). (C) The twin-peak pattern in three subjects who received 25 mg diclofenac-K. Values (A,B) are means (± SD) from 10 healthy subjects
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References

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