Assays - Diclofenac

Comparison of UV and tandem mass spectrometric detection for the high-performance liquid chromatographic determination of diclofenac in microdialysis samples

Author: B.X. Mayer, K. Namiranian, P. Dehghanyar, R. Stroh, H. Mascher, M. Müller
Publisher: J Pharm Biomed Anal. 2003, 33, 745-754

High-performance liquid chromatography (HPLC) was used to analyse microdialysis samples obtained in vivo from human subcutaneous adipose tissue after topical application of the nonsteroidal anti-inflammatory drug diclofenac. For the reliable determination of diclofenac two different detection principles were applied in two different laboratories. One HPLC method utilized UV-detection at 280 nm, the other one used selected reaction monitoring mass spectrometry (MS). The HPLC-UV and -MS methods offered low limits of quantification of 10 and 1 ng/ml and an accuracy between 94.0 - 126.7 and 89.3 - 110.9 %, respectively. However, a comparison showed that the HPLC-UV method failed to determine diclofenac in biological matrices, as both false negative and positive values were found. HPLC-MS is clearly superior to HPLC-UV due to a much more selective detection, increased sensitivity and shorter run times.

Topical skin penetration of Diclofenac after single- and multiple-dose application

Author: P. Dehghanyar, M. Brunner, B.X. Mayer, K. Namiranian, H.J. Mascher, M. Müller
Publisher: Int. J. Clin. Pharm. Ther. 2004, 42, 353-359

Objective: Transdermal penetration of nonsteroidal anti-inflammatory drugs (NSAIDs) has been shown to be highly variable. The present study was performed to gain insight into the transdermal penetration process of topically applied diclofenac and to test whether transdermal absorption leads to pharmacologically effective concentrations in dermal tissue layers beneath the application site.
Material and method: Six healthy male volunteers participated in this 2-way crossover study and were assigned to 2 treatment groups. In the first group, diclofenac was applied in a therapeutic dose of 60 mg/100cm² 3 times daily for 4 days with subsequent occlusion with a plastic foil for 4 hours to enhance transdermal drug absorption. After a 1-week wash-out, diclofenac was applied at a single-dose of 300 mg/100cm² without occlusion. Diclofenac in both groups was applied on a previously shaven area of the thigh. Transdermal penetration was assessed employing in vivo microdialysis.
Results: After multiple-dose administration mean diclofenac concentrations of 0.48 ± 0.35 ng/ml were observed in subcutaneous tissue ( mean ± SEM). The mean AUC-subcutis/plasma-ratio of 0.08 ± 0.02 indicates redistribution of diclofenac from the systemic circulation to the tissue. After single-dose treatment, mean tissue concentrations were 24.26 ± 46.43 ng/ml with a mean AUCsubcutis/plasma ratio of 60.85 ± 57.59, which suggests direct tissue penetration of diclofenac.
Conclusions: Transdermal penetration of diclofenac after multiple as well as after single application of the present formulation is highly variable. In addition to other factors influencing the transdermal penetration process, dose and mode of administration are important factors determining whether pharmacologically effective local tissue concentrations are attained.

Diclofenac concentrations in defined tissue layers after topical administration

Author: M. Müller, H. Mascher, C. Kikuta, S. Schäfer, M. Brunner, G. Dorner, H.G. Eichler
Publisher: Clin Pharmacol Ther., 293 - 299, 1997

To date is is unclear whether therapeutic concentrations are attained in target tissues after topical administration of nonsteroidal anti-inflammatory drugs. Therefore this study in healthy volunteers was undertaken to measure diclofenac concentrations attained in defined tissue layers directly underlying the site of topical diclofenac application by in vivo microdialysis. Methods: In each experiment two microdialysis probes were inserted, one into a superficial (3.9 mm) and one into a deep (9.3 mm) tissue layer, in 20 healthy volunteers and calibrated in vivo. The distance between the surfaces of the skin and the tips of the microdialysis probes were measured by 7.5 MHz ultrasound. Diclofenac was administered topically as a single dose of approximately 300 mg/100cm². Concentration versus time profiles in tissue layers were monitored for 5 hours. Results: Concentration versus time profiles in tissue layers were obtained in 11 of 20 experiments. However, there was no correlation between area under the concentration curve (AUC) in a defined layer and the depth of probe insertion. In those experimets where concentration versus time profiles were obtained for bith probes mean AUC was 532 µg x min / ml for superficial layers, and 438 µg x min / ml for deep layers. Conclusion: We conclude that transdermal penetration of diclofenac, at least single doses, is not predictible and may strongly be influenced by individual skin properties.

The pharmacokinetics of a new sustained-release form of Diclofenac sodium in humans

Author: H.J. Mascher
Publisher: Drug Design and Delivery 4 (1989), 303-311

In the present study, two sustained release diclofenac preparations were administered every 12 hours over 4 days to ten human volunteers. Diurnal profiles were recorded on the 1st and 4th days, from which pharmacokinetic parameters were calculated: particular attention was given to cumulation. One, a newly develeped sustained release formulation, hat a MRT of 5.5 hours, and showed surprisingly small variation coefficients [AUC ss (72-84 hrs) Cmax (72-84 hrs)] after 7 administered doses; accordingly, the maximum concentrations were within a very narrow time window [tmax ss (72-84 hrs) range: 1.5 - 2.5 hours after administration]. Due to the selected release profiles with this formulation, there was no danger of cumulation in spite of administration every 12 hours [AUC 0-12 hrs, mean value 1555 ng/ml x h; AUC ss 72-84 hrs, mean value 1750 ng/ml x h].