Int J Pharm. 2000 May 10;200(2):161-79.
Structure and hydration properties of hydroxypropyl methylcellulose matrices containing naproxen and naproxen sodium.

Katzhendler I, Mader K, Friedman M.

Department of Pharmaceutics, School of Pharmacy, The Hebrew University of Jerusalem, PO Box 12065, 91120, Jerusalem, Israel.

The present study was conducted to obtain a deeper insight into the mechanism of drug release from HPMC matrices. The microstructure, mobility, internal pH and the state of water within the gel layer of hydrated HPMC matrices (having different molecular weights) containing naproxen sodium (NS) and naproxen (N) were studied using Electron Paramagnetic Resonance (EPR), Nuclear Magnetic Resonance (NMR) and Differential Scanning Calorimetry (DSC) techniques. The study show that matrices composed of various viscosity grades of HPMC are characterized by similar microviscosity values in spite of the difference in their molecular weight. The NMR and DSC results led to the conclusion that higher molecular weights of HPMC are characterized by higher water absorption capacity and higher swelling. Analysis of non-freezable water in HPMC(K4M)-NS system revealed that addition of NS to solution increased the fraction of water bound to K4M+NS compared with the equivalent solutions without NS. The results suggest that the drug is participating in the crystallization of water and leads to the formation of a three dimensional network structure that decreases the freedom of water in K4M+NS samples. Calculation of the number of hydration shells showed that up to 2.2 layers are involved in HPMC-NS hydration compared to 1.5 layers for HPMC gel without NS. This was explained based on the different water ordering in the gel induced by NS as results of its absorption to polymer surface. Microviscosity values measured by EPR for K4M/N and K4M/NS hydrated matrices were found to be higher for K4M/N matrices, especially at initial stage of hydration. Mobile compartment calculations showed lower values for K4M/N compared with K4M/NS matrices. pH measurements by EPR revealed that incorporation of N to HPMC matrix led to lower internal pH value inside the hydrated tablet compared with NS. This behavior led to lower solubility of N which dictates its surface erosion mechanism, compared with NS matrix that was characterized by higher internal pH value and higher drug solubility. These properties of HPMC/NS increased chain hydration and stability, and led to drug release by the diffusion mechanism.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10867246&dopt=Abstract Naproxen Naprosyn





Sheng Wu Gong Cheng Xue Bao. 2000 Jan;16(1):55-9.
[Enzymatic resolution of racemic naproxen in a low aqueous-organic biphase system]

[Article in Chinese]

Xin JY, Li SB, Xu Y, Wang LL, Shen RN.

OSSO, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences.

A stereoselective hydrolysis of the racemic naproxen methyl ester by immobilized lipase from Candida rugosa in a low aqueous-organic biphase system was studied. Support polar, water content, the logP value of organic phase and product inhibition effected the activity of immobilized enzyme. According to these reaction conditions, a low aqueous-organic biphase system for the continuous production of (S)-(+)-Naproxen was developed. The reaction was carried out in a continuous-flow closed-loop 50 mL stirred bioreactor packed with YWG-C6H5, a poorly polar synthetic support on which the lipase had been immobilized by adsorption. The aqueous phase was permanently remained in the reactor associated with the immobilized enzyme particles; the organic phase containing substrate was pumped through this reactor and emerged with the products. The continous-flow stirred bioreactor containing 75 mg lipase was allowed to operate continuously for 60 days at 30 degrees C with a 25% loss of activity, 900 mg of (S)-(+)-Naproxen (eep 95%) were producted.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10883277&dopt=Abstract Naproxen Naprosyn





Br J Pharmacol. 2000 Jul;130(6):1399-405.
NO-naproxen modulates inflammation, nociception and downregulates T cell response in rat Freund's adjuvant arthritis.

Cicala C, Ianaro A, Fiorucci S, Calignano A, Bucci M, Gerli R, Santucci L, Wallace JL, Cirino G.

Dipartimento di Farmacologia Sperimentale, Universita degli Studi di Napoli - Federico II, Napoli, Italy.

1. Anti-inflammatory non steroidal drugs releasing NO (NO-NSAIDs) are a new class of anti-inflammatory drugs to which has been added an NO-releasing moiety. These compounds have been shown to retain the anti-inflammatory, analgesic and antipyretic activity of the parent compound but to be devoid of gastrointestinal (GI) toxicity. 2. Freund's adjuvant (FA) arthritis was induced in rats by a single intraplantar injection into the right hindpaw of 100 microl of mycobacterium butirricum (6 mg ml(-1)). The effect of equimolar doses of naproxen (1, 3 and 10 mg kg(-1)) and NO-naproxen (1.5, 4.5 and 16 mg kg(-1)) was evaluated using two dosage regimen protocols: (i) preventive, starting oral administration of the drugs at the time of induction of arthritis and for the following 21 days (day 1 - 21); (ii) therapeutic, starting oral administration of the drugs 7 days after adjuvant injection and for the following 14 days (day 7 - 21). 3. Hindpaw swelling (days 3, 7, 11, 14, 17, 21) and nociception (days 15 and 21) were measured. On day 22 rats were sacrificed, draining lymph nodes were removed and T cells isolated. In vitro proliferation of T cells following stimulation with concanavalin A (0.5 - 5 microg ml(-1)) was measured using a tritiated thymidine incorporation assay. IL-2 receptor expression on T cells was measured by FACS analysis. 4. Naproxen and NO-naproxen showed similar activity in reducing oedema formation in the non-injected (controlateral) hindpaw. Both drugs showed anti-nociceptive effect. NO-naproxen was anti-nociceptive at a dose of 4.5 mg kg(-1) while naproxen showed the same extent of inhibition only at a dose of 10 mg kg(-1). 5. T cells were isolated and characterized by FACS analysis. Stimulation of isolated T cells with concanavallin A in vitro caused a significant increase in thymidine uptake. NO-naproxen at a dose of 4.5 mg kg(-1) inhibited T cell proliferation to the same extent as 10 mg kg(-1) of naproxen. 6. Inhibition of T cell proliferation was well correlated with reduced IL-2 receptor expression on T cells. In addition, NO-naproxen reduced both IL-1beta and TNFalpha plasma levels whilst naproxen reduced IL-1beta levels only. 7. In conclusion, both naproxen and NO-naproxen reduce inflammation and nociception associated with arthritis. In addition NO-naproxen interferes to a larger extent with cellular mechanism involved in T cell activation in rat adjuvant arthritis indicating that introduction of the NO moiety in the naproxen structure increases the effect at the level of the immune system.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10903982&dopt=Abstract Naproxen Naprosyn


uku.fi

Novel morpholinyl (4a) and piperazinylalkyl (4b-e) esters were synthesized and evaluated in vitro for their properties as bioreversible topically administered dermal prodrugs of naproxen. These ionizable prodrugs exhibited various aqueous solubilities and lipophilicities, depending on the pH of medium. As indicated by octanol-buffer partition coefficients (logP(app)) at pH 7.4, all of the prodrugs were significantly more lipophilic (logP(app)=0.7-3.9) than naproxen (logP(app)=0.3). Furthermore, the most aqueous of the soluble prodrugs (4b-d) were only 2-3-fold less soluble in an aqueous buffer of pH 7.4 ( approximately 30-50 mM) than was naproxen ( approximately 100 mM). At a pH of 5.0, prodrugs showed a generally higher aqueous solubility and similar logP(app) values, compared to naproxen. The chemical and enzymatic hydrolysis of prodrugs at 37 degrees C was investigated in aqueous buffer solutions (pH 5.0 and 7.4) and in 80% human serum (pH 7.4), respectively. The prodrugs showed moderate chemical stability (t(1/2)=15-150 days at pH 5.0), and they were hydrolyzed enzymatically to naproxen, with half-lives ranging from 0.4 to 77 min. In permeation studies using post-mortem human skin in vitro, the flux of naproxen was 6.5 and 1.6 nmol/cm(2). h in a saturated aqueous buffer vehicle of pH 7.4 and 5.0, respectively. Among the prodrugs, two piperazinyl derivatives (4c and 4d) resulted in a 9- and 4-fold enhancement of permeation, respectively, when compared to naproxen itself at pH 7.4. 4c also resulted in a significantly (4-fold) better permeation than naproxen at pH 5.0. In conclusion, piperazinyl esters improved skin permeation of naproxen and are promising prodrugs of naproxen for topical drug delivery.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10915963&dopt=Abstract Naproxen Naprosyn





Am J Physiol Heart Circ Physiol. 2000 Aug;279(2):H528-35.
Antihypertensive properties of a nitric oxide-releasing naproxen derivative in two-kidney, one-clip rats.

Muscara MN, McKnight W, Lovren F, Triggle CR, Cirino G, Wallace JL.

Department of Pharmacology and Therapeutics, University of Calgary, Calgary, Alberta, T2N 4N1, Canada.

Nonsteroidal anti-inflammatory drugs have been reported to exacerbate hypertension. In this study, we tested the hypothesis that a nitric oxide-releasing derivative of naproxen would ameliorate hypertension in the rat. Hypertension was induced by partially occluding one renal artery (the "2K,1C" model), and 2 wk later the rats started receiving naproxen, the nitric oxide-releasing derivative HCT-3012, or vehicle each day for 2 wk. Naproxen significantly exacerbated the hypertension. HCT-3012 significantly reduced blood pressure relative to both the naproxen- and vehicle-treated groups. Both naproxen and HCT-3012 markedly suppressed whole blood thromboxane B(2) synthesis. In studies of anesthetized rats, naproxen significantly enhanced the late hypertensive response to endothelin-1 and significantly blunted the early hypotensive response. In contrast, HCT-3102 did not affect either response to endothelin-1. In vitro, HCT-3012 significantly reduced the responsiveness of aortic rings to the contractile effects of phenylephrine. These studies suggest that HCT-3012 reduces blood pressure in hypertensive rats, not simply through the vasodilatory actions of the nitric oxide it releases, but through alterations in the responsiveness of the vasculature to endogenous pressor agents.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10924050&dopt=Abstract Naproxen Naprosyn


mwu.mukogawa-u.ac.jp

Uniform-sized molecularly imprinted polymers (MIPs) for (S)-naproxen and -ibuprofen selectively modified with hydrophilic external layer, restricted access media (RAM)-MIPs, have been prepared. First, the MIP for (S)-naproxen or -ibuprofen was prepared using 4-vinylpyridine and ethylene glycol dimethacrylate as a functional monomer and cross-linker, respectively, by a multistep swelling and thermal polymerization method. Next, a 1:1 mixture of glycerol monomethacrylate and glycerol dimethacrylate was used for hydrophilic surface modification, and it was added directly to the MIP for (S)-naproxen or -ibuprofen 4 h after the start of molecular imprinting. The obtained RAM-MIP material for (S)-naproxen or -ibuprofen was applied for direct serum injection assays of the drug by a column-switching system, consisting of a RAM-MIP material and conventional C18-silica column. However, leakage of the imprint molecule prevented accurate and precise assays of the drug. This problem has been overcome by using the RAM-MIP for (S)-naproxen for the assays of ibuprofen in rat plasma. The optimized column-switching system was applied successfully to the assay of ibuprofen in rat plasma after oral administration.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11080865&dopt=Abstract Naproxen Naprosyn





J AOAC Int. 2000 Nov-Dec;83(6):1489-92.
Assay of naproxen in rat serum by high-performance thin-layer chromatography/densitometry.

Guermouche MH, Atik N, Chader B.

Universite des Sciences et Technologies Houari Boumedienne, Institut de Chimie, Centre de Recherche en Analyse Physico-Chimique, Alger, Algeria.

A simple, sensitive, and reproducible high-performance thin-layer chromatographic method using densitometry is presented for the determination of naproxen in rat serum. Only 0.1 mL serum was used for extraction. Separations were performed on 10 x 10 cm plates coated with silica gel, with toluene-ethyl acetate-acetic acid (82 + 15 + 3) as the mobile phase. Benzophenone was used as the internal standard. Quantification was performed by densitometry at 260 nm. The response response for naproxen was linear (r = 0.992) over the range 2-100 mg/L. Method validation demonstrated good recoveries (92-96%), sensitivity (limit of quantitation, 1 mg/L), repeatability of sample application (4%), repeatability of the method (8%), and intermediate precision (5%). The procedure was applied to the quantitation of naproxen in rat serum.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11128159&dopt=Abstract Naproxen Naprosyn