Arzneimittelforschung. 1975 Feb;25(2A):288-91.
[Effect of naproxen on the semiconservative DNA synthesis and DNA repair of various cell systems]

[Article in German]

Klein G.

d-2-(6'Methoxy-2'-naphthyl)-propionic acid (naproxen) in different concentrations was investigated as to its influence on the semiconservative DNA synthesis and DNA repair of human lymphocytes and mouse speen cells. As could be shown, there was a slight diminuation of the DNA synthesis. In view of a desired antiproliferating effect in the treatment of rheumatic diseases this fact could certainly prove useful. Additionally, with a naproxen concentration of 30 ppm, a diminuation of the endonuclease activity in mouse spleen cells could be shown. With naproxen concentrations higher than 60 ppm a slight lowering of the exonuclease and polymerase activities in mouse spleen cells as well as in human lymphocytes were observed. With naproxen in a concentration of 120 ppm, all three enzymes of the excision repair investigated showed a distinct loss of activity. Results of investigations on ligase activity will be presented separately. Under the administration of naproxen, late effects on the genetic material are rather improbable, as long as the substance is not admininstered concomitantly with agents which have a direct effect on the DNA.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1173775&dopt=Abstract Naproxen Naprosyn





Scand J Rheumatol. 1977;6(3):155-7.
Naproxen concentrations in serum, synovial fluid, and synovium.

Jalava S, Saarimaa H, Anttila M, Sundquist H.

Naproxen levels in serum, synovial fluid and synovium of eighteen patients with "classical" or "definite" rheumatoid arthritis and chronic knee effusion were studied. After oral administration of 250 mg naproxen twice daily, naproxen levels in synovial fluid were found to be more than half as high as in serum. Even in synovium itself naproxen levels were appreciable.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=929122&dopt=Abstract Naproxen Naprosyn





Clin Biochem. 1979 Apr;12(2):66-7.
An ultraviolet spectrophotometric procedure for the routine determination of naproxen.

Holzbecher M, Ellenberger HA, Marsh JM, Boudreau S.

1. A procedure for the routine assay of Naproxen in serum by ultraviolet spectrophotometry is presented. The absorption coefficient (A1 1% cm) of Naproxen in methanol at 261 nm was found to be 216. 2. The Naproxen procedure appears to be relatively free from interferences of commonly coadministered medications. Salicylate interference is eliminated by a modified procedure. 3. Concentrations of Naproxen in a limited number (40) of clinical samples ranged from non-detected to 12.5 mg/dl. The therapeutic concentration appears to be 4 to 6 mg/dl (174-260 mumol/L).

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=445798&dopt=Abstract Naproxen Naprosyn





Analyst. 1994 Apr;119(4):697-701.
Second-derivative spectrophotometric determination of naproxen in the presence of its metabolite in human plasma.

Panderi I, Parissi-Poulou M.

Department of Pharmacy, University of Athens, Greece.

A second-derivative spectrophotometric method for the determination of naproxen in the absence or presence of its 6-desmethyl metabolite in human plasma is described. The method consists of direct extraction of the non-ionized form of the drug with pure diethyl ether and determination of the naproxen by measuring the peak amplitude (mm) in the second-order derivative spectrum at a wavelength of 328.2 nm. The efficiency of the extraction procedure expressed by the absolute recovery was 94.6 +/- 0.7% (mean +/- s) for the concentration range tested, and the limit of quantification attained according to the IUPAC definition was 2.42 mg l-1. The linear dynamic range for naproxen was 5.0-100.0 mg l-1, the correlation coefficient for the calibration graphs was excellent, r = 0.99993 (n = 6), the precision (Sr) was better than 4.58% and the accuracy was satisfactory (Er < 2.32%). The results obtained by the proposed method were in good agreement with those found by an HPLC method.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8024123&dopt=Abstract Naproxen Naprosyn





Acta Pharmacol Toxicol (Copenh). 1978 Oct;43(4):266-72.
Inhibition of prostaglandin synthesis in rat brain.

Abdel-Halim MS, Sjoquist B, Anggard E.

Rats were injected with one of five drugs alleged to inhibit brain prostaglandin (PG) synthesis: indomethacin, diclofenac, naproxen, aspiring and paracetamol. Animals were killed after 30 min. and the endogenous formation of PGF2alpha and PGE2 in brain homogenates was measured by mass fragmentography using deuterium labelled PGF2alpha and PGE2 as internal standards. Diclofenac, indomethacin, and naproxen inhibited dose dependently, the synthesis of PGF2alpha. The ED50 for diclofenac was 0.4 mg/kg, for indomethacin 1 mg/kg and for naproxen 2 mg/kg. In equieffective doses indomethacin had the longest duration. The time taken for the inhibition to decline to half its maximal value was 32 hrs for indomethacin and about 15 hrs for diclofenac and naproxen. Under the present conditions aspirin and paracetamol failed to produce significant reduction of PG synthesis in the rat brain homogenates in doses up to 100 mg/kg.

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Clin Pharmacol Ther. 1979 Jan;25(1):61-6.
Effect of naproxen on the steady-state serum concentration and anticoagulant activity of warfarin.

Jain A, McMahon FG, Slattery JT, Levy G.

The purpose of this investigation was to determine whether the anti-inflammatory drug naproxen interacts with warfarin during prolonged administration of both drugs. Healthy adults received oral doses of warfarin daily for 26 days. Naproxen, 375 mg twice daily, was given from the eleventh through the twentieth days. Naproxen administration had no apparent effect on the steady-state concentrations of free and total (free and protein-bound) warfarin in serum, despite a small but statistically significant increase of the warfarin-free fraction in serum. There was no apparent difference between the prothrombin times (at a constant daily dose of warfarin) observed before, during, and after administration of naproxen.

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Am J Med. 1987 Sep 28;83(3B):67-73.
Effects of concurrent sucralfate administration on pharmacokinetics of naproxen.

Caille G, du Souich P, Gervais P, Besner JG, Vezina M.

Pharmacology Department, Faculty of Medicine, University of Montreal, Quebec, Canada.

Sucralfate has been reported to protect the gastroduodenal mucosa against a variety of agents and is known to adsorb bile salts. Since gastrointestinal side effects can seriously compromise the efficacy of nonsteroidal anti-inflammatory drug therapy, and since it seems reasonable to assume that sucralfate may adsorb nonsteroidal anti-inflammatory drugs, the influence of sucralfate on the pharmacokinetic parameters of naproxen was assessed in 12 healthy volunteers. To do so, the pharmacokinetic profile of naproxen, administered alone or with sucralfate, singly or repeatedly (twice daily for five days), was compared. No significant difference was observed with any pharmacokinetic parameter between the single administration of naproxen alone or with sucralfate. However, a significantly lower maximum plasma concentration was attained with the repeated administration of naproxen in combination with sucralfate, compared with the repeated administration of naproxen alone. When single- and multiple-dose administration were compared, significant differences were observed in the maximum plasma concentration and the cumulative area under the curve. These results suggest an accumulation of naproxen after five days' administration. This accumulation, however, is not altered by the administration of sucralfate. The results of this study suggest that when naproxen is administered with sucralfate, only a delay in naproxen's absorption may occur, confirmed by a lower maximum plasma concentration, a longer time to reach the maximum plasma concentration, a similar elimination half-life, and equivalence in bioavailability. The clinical importance of such a delay has yet to be proved; however, it is unlikely that the clinical efficacy of naproxen will be altered, since the amount of drug absorbed remains the same.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3661612&dopt=Abstract Naproxen Naprosyn