Eur J Drug Metab Pharmacokinet. 1984 Oct-Dec;9(4):359-63.
In vivo plasma protein binding interaction between valproic acid and naproxen.

Grimaldi R, Lecchini S, Crema F, Perucca E.

The effect of naproxen on the kinetics of free and total plasma valproic acid (VPA) was investigated in 6 normal volunteers by using a recently developed simple ultrafiltration technique associated with an immuno-enzymatic assay (Free Level System I, Syva). Each subject received a single oral dose of sodium valproate on two occasions: a) on a control day and b) during concurrent treatment with naproxen (500 mg b.i.d. for 5 consecutive days). Naproxen caused a slight but significant decrease in total plasma VPA levels but left free VPA levels essentially unchanged. The free VPA fraction increased with increasing total VPA concentrations: at equivalent values of total VPA, however, the free fraction was higher in the presence of naproxen. It is concluded that naproxen exerts a moderate displacing effect on protein bound VPA, thereby increasing the clearance of total drug but leaving essentially unchanged the clearance of free drug.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6442704&dopt=Abstract Naproxen Naprosyn





J Clin Pathol. 1995 Jan;48(1):61-3.
Chemical gastritis induced by naproxen in the absence of Helicobacter pylori infection.

McCarthy CJ, McDermott M, Hourihane D, O'Morain C.

Department of Gastroenterology, Meath/Adelaide Hospitals, Trinity College, Dublin, Ireland.

AIM--To evaluate the histological changes that occur in the antral mucosa of healthy male subjects before and after one week of naproxen administration, using a chemical gastritis score according to the Helicobacter pylori status. METHODS--Nineteen male subjects (mean age 31 years) underwent two endoscopies: one before and the other after one week of naproxen treatment (1 g daily). Antral biopsy specimens were assessed for the presence of H pylori infection and for chemical gastritis, defined as the presence of foveolar hyperplasia, muscle fibres in the lamina propria, oedema, and vasodilatation, in the absence of acute or chronic inflammatory cell infiltrate. RESULTS--Of the 19 subjects, eight had H pylori infection. After one week of naproxen treatment, none of those with H pylori infection developed chemical gastritis, while five of 11 (45%) of those without H pylori infection did. In the absence of H pylori infection there was no evidence of inflammation, either before or after naproxen administration. CONCLUSIONS--A different pattern of antral histological change occurs following naproxen administration. This pattern is related to the presence or absence of H pylori infection, suggesting that H pylori status should be determined in histological studies of subjects taking non-steroidal anti-inflammatory drugs.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7706522&dopt=Abstract Naproxen Naprosyn





J Bone Miner Res. 1990 Oct;5(10):1029-35.
Effect of naproxen on cancellous bone in ovariectomized rats.

Lane N, Coble T, Kimmel DB.

Syntex Labs, Palo Alto, CA 94305.

Nonsteroidal anti-inflammatory drugs (NSAIDs) affect bone metabolism in vitro and in vivo. They delay but do not alter the outcome of healing processes in bone. In some bone loss models, they block bone resorption and slow the rate of loss. We studied the effect of naproxen, a potent NSAID, on cancellous bone of the proximal tibial metaphysis of 6-month-old adult female ovariectomized rats. Animals were ovariectomized, divided into groups, and fed standard diets differing only in naproxen content for 42 days. The rats of the groups ate 2.0, 5.5, 12.7, and 32 mg naproxen per kg body weight per day, respectively. Serum levels of naproxen were determined. Bone volume, mineralizing surface, osteoblast activity, osteoclast surface, and bone resorption rate were determined by bone histomorphometric techniques. The rats' dose-related serum naproxen levels ranged from 4 to 28 micrograms/ml. Naproxen inhibited up to 70% of the bone loss occurring after ovariectomy at a serum level of 4 micrograms/ml. We deduced that naproxen blocked bone resorption in ovariectomized rats by slowing osteoclast activity at all doses. In contrast, naproxen slowed bone formation only at serum levels greater than 20 micrograms/ml in ovariectomized rats. These findings may have clinical relevance in helping to prevent postmenopausal bone loss in women.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2080715&dopt=Abstract Naproxen Naprosyn





Biochim Biophys Acta. 1992 May 7;1131(1):78-82.
Inhibition of endothelial cell prostaglandin H synthase gene expression by naproxen.

Zyglewska T, Sanduja R, Ohashi K, Loose-Mitchell DS, Sanduja SK, Wu KK.

Department of Medicine, University of Texas Medical School at Houston 77030.

Naproxen is a potent anti-inflammatory drug whose action is attributed to inhibition of prostaglandin biosynthesis. In view of our recent discovery that aspirin and sodium salicylate are capable of reducing cellular levels of prostaglandin H (PGH) synthase mRNA, we have evaluated the effect of naproxen on PGH synthase protein and mRNA levels in cultured human umbilical vein endothelial cells (HUVEC). PGH synthase mRNA levels were quantified by a competitive polymerase chain reaction (PCR) assay; protein was assessed by Western blotting. Naproxen decreased the PGH synthase protein level in HUVEC in a concentration-dependent manner. It abolished entirely the 70 kDa PGH synthase subunit at 5 micrograms/ml. It appears more effective in blocking interleukin-1 inducible PGH synthase levels. Naproxen also inhibited the synthase mRNA level in a concentration-dependent manner; levels were reduced by 33% at 5 micrograms/ml and 60% at 30 micrograms/ml naproxen. These results indicate that naproxen, like the salicylates, inhibits PGH synthase levels in cultured endothelial cells either by inhibiting transcription of the PGH synthase gene or by destabilizing its messenger RNA.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1581362&dopt=Abstract Naproxen Naprosyn





Sex Transm Dis. 1994 Nov-Dec;21(6):338-44.
Effects of Cetyltrimethylammonium naproxenate on the adherence of Gardnerella vaginalis, Mobiluncus curtisii, and Lactobacillus acidophilus to vaginal epithelial cells.

Catalanotti P, Rossano F, de Paolis P, Baroni A, Buttini G, Tufano MA.

Istituto di Microbiologia, Cattedra di Microbiologia Clinica, Facolta di Medicina e Chirurgia, Seconda Universita degli Studi, Naples, Italy.

BACKGROUND AND OBJECTIVES: A decreased concentration or total disappearance of Lactobacillus acidophilus in the vagina constitutes a frequent observation in bacterial vaginosis. GOAL OF THE STUDY: Cetyltrimethylammonium naproxenate has been evaluated in vitro to detect antiadhesive properties at subinhibitory concentrations for Gardnerella vaginalis and Mobiluncus curtisii to vaginal epithelial cells (VEC). STUDY DESIGN: Bacterial strains 14C- and or 3H-labeled were tested for adherence and competition to binding sites in VECs before and after treatment at sub-MIC with cetyltrimethylammonium naproxenate. RESULTS: In control tests of adherence, G. vaginalis and M. curtisii had their maximal adhesion at pH 5.4, L. acidophilus at pH 4.4. Preincubation of G. vaginalis and M. curtisii with cetyltrimethylammonium naproxenate 2.5 mg/mL (subinhibitory concentration) at pH 5.4 reduced adherence to VECs respectively by 48.3% and 34.1%. The same treatment of L. acidophilus showed no statistically significant difference. Treatment of VECs alone did not modify adherence. Competition tests between L. acidophilus and G. vaginalis and between L. acidophilus and M. curtisii showed that, in small quantities, L. acidophilus could compete with G. vaginalis and M. curtisii for binding sites in VECs at pH 4.4, when pretreated with cetyltrimethylammonium naproxenate. At a higher pH (4.8 and 5.4), L. acidophilus in higher quantities did not compete for binding sites occupied by G. vaginalis and M. curtisii. CONCLUSIONS: Cetyltrimethylammonium naproxenate at subinhibitory concentrations modifies the adhesiveness of G. vaginalis and M. curtisii to VECs, reducing it by 48.3% and 34.1%, respectively. Adhesion of L. acidophilus to VECs is not impaired by pretreatment with cetyltrimethylammonium naproxenate at pH 4.4, even if they are in low number and compete for binding sites against pathogens. At higher pH levels, L. acidophilus did not compete for binding sites occupied by G. vaginalis and M. curtisii.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7871448&dopt=Abstract Naproxen Naprosyn





Farmaco. 1995 Dec;50(12):867-74.
Preparation and characterisation of polyphosphazene-based controlled release systems for naproxen.

Caliceti P, Lora S, Marsilio F, Veronese FM.

Department of Pharmaceutical Sciences, Centro di Studio di Chimica del Farmaco e dei Prodotti Biologicamente Attivi del CNR University of Padova, Italy.

A new polyphosphazene polymer suitable for preparation of naproxen controlled release systems has been prepared by non complete substitution of the chlorine at the phosphorus atoms of polydichlorophosphazene with phenylalanine ethyl ester and imidazole. Polymeric disks obtained by solvent evaporation were found to maintain their integrity for months either "in vivo" and "in vitro" after incubation in buffer, although the intrinsic viscosity undergoes a rapid decrease. The release rate of naproxen from the films was found to depend on thickness of the matrixes and amount of entrapped drug. "In vitro" release spikes, corresponding to initial in plasma burst after subcutaneous implantation of the films in rats, have been observed with high concentrations of drug in the matrixes. On the other end decreasing the drug concentrations in the polymer matrixes, the naproxen release approximates a zero order kinetic and a controlled release is obtained for weeks. Scanning electron microscopy showed that the disks giving spikes in drug release are characterised by the presence of naproxen crystals on the matrix surface. "In vivo" studies are demonstrating that the initial naproxen concentration spike is useful in the treatment of acute models of inflammation, while a more constant and lasting release is successful in chronic inflammation models. The degradation profile of this new polyphosphazene as well as preliminary pharmacological data are also reported.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8634078&dopt=Abstract Naproxen Naprosyn





Hum Exp Toxicol. 1994 Dec;13(12):831-8.
Lipid peroxidation and chemiluminescence during naproxen metabolism in rat liver microsomes.

Yokoyama H, Horie T, Awazu S.

Department of Biopharmaceutics, Tokyo College of Pharmacy, Japan.

1. Rat liver microsomal suspension containing NADPH and MgCl2 was incubated at 37 degrees C with naproxen, a non-steroidal anti-inflammatory drug. Thiobarbituric acid reactive substances (TBA-RS), high molecular weight protein aggregates and fluorescent substances were formed in the microsomal suspension. 2. Chemiluminescence was produced from the microsomal suspension. This chemiluminescence production was well correlated to the TBA-RS formation, indicating that the chemiluminescence production was closely associated with the lipid peroxidation. 3. The addition of SKF-525A to the microsomal suspension inhibited the production of TBA-RS, chemiluminescence and 6-demethylnaproxen (6-DMN), the oxidative product of naproxen. Further, the antioxidant, alpha-tocopherol and singlet oxygen quenchers like histidine, dimethylfuran and 1,4-diazabicyclo[2,2,2]octane strikingly inhibited the productions of chemiluminescence and TBA-RS. 4. Neither naproxen nor 6-DMN caused lipid peroxidation in the absence of NADPH. Thus, lipid peroxidation and chemiluminescence during the oxidation of naproxen in liver microsomes was suggested to be provoked by reactive oxygen species and an origin of chemiluminescence was shown to be singlet oxygen.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7718302&dopt=Abstract Naproxen Naprosyn