Review: a single dose of oral naproxen or naproxen sodium reduced acute postoperative pain in adults.
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Comment↗
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[Biochemical studies on action mechnism of a new anti-inflammatory agent, naproxen (1). Effects of naproxen on changes in connective tissue components due to inflammation].
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Animals↗
Proceedings: Biochemical studies on the mechanism of action of a new anti-inflammatory agent, naproxen. 2. Effects of naproxen on mucopolysaccharase, protease and collagenolytic enzyme activities in inflamed tissues of filter paper-implanted rats.
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Animals↗
Bioavailability of naproxen sodium suppositories.
Bioavailability and absorption characteristics of naproxen sodium have been shown to be superior to that of naproxen in tablet formulations. In this study naproxen sodium suppositories were compared with naproxen tablets and naproxen suppositories with respect to plasma concentrations and bioavailability of naproxen. Eleven healthy volunteers participated in a randomized crossover study comparing naproxen sodium suppositories (equivalent to 500 mg naproxen) and naproxen suppositories (500 mg). Tmax (1.4 h) was significantly shorter after the administration of naproxen sodium suppositories than after naproxen tablets (2.4 h), whereas Cmax was higher after the tablet formulation. No difference was observed with respect to bioavailability and biologic half-life of naproxen. In a second crossover study in six volunteers suppositories containing either naproxen sodium or naproxen were compared. Tmax was shorter and Cmax significantly higher after administration of the sodium naproxen suppository formulation. The sodium naproxen suppositories were well tolerated and proved to be a safe and reliable way of administering naproxen, giving therapeutic naproxen concentrations within the 1st h after administration.
Adult↗
Naproxen removal from water by chlorination and biofilm processes.
Naproxen is an anti-inflammatory pharmaceutical that has been detected in natural and engineered aquatic environments. The primary aim of this research was to study chemical transformations of naproxen following chlorine oxidation, which is common in water and wastewater treatment systems. Synthetic waters containing elevated concentrations of naproxen were oxidized by free chlorine at naproxen:chlorine molar ratios of 0.02-3:1 and pH values of 5-9. The formation of naproxen products was dependent on pH, chlorine dosage and contact time. This study demonstrates that naproxen readily reacts with free chlorine and forms disinfection products. The formation of specific reaction products can vary depending on the characteristics of the water or wastewater and treatment operating conditions. More research is needed to identify intermediate and chemical reaction end products and to understand the reaction kinetics of naproxen chlorination for a range of water and wastewater treatment conditions. A secondary aim of this research was to study effects of naproxen and its chlorination products on biofilm processes, which are common in water and wastewater treatment systems and natural aquatic environments. A bioreactor was fed a naproxen solution and then fed a solution at the same naproxen concentration following contact with free chlorine. Results indicate that naproxen was not degraded biologically for the conditions of this study. In contrast, the naproxen solution containing products of chlorination caused an adverse response by discharging biomass from the bioreactor. Results therefore demonstrate that naproxen products of chlorination can adversely affect a biofilm process, which potentially can impact the performance of biofilm processes in natural and engineered aquatic environments. More research is needed to study naproxen chlorination reactions at low concentrations and in complex matrices, and to understand the toxicological relevance of naproxen and its products of chlorination in natural and engineered aquatic environments.
Anti-Inflammatory Agents, Non-Steroidal↗
Low molecular weight proteins as carriers for renal drug targeting: naproxen-lysozyme.
Low molecular weight proteins (LMWPs), such as lysozyme, may be suitable carriers to target drugs to the kidney. In this study the antiinflammatory drug naproxen was covalently bound to lysozyme (1:1). Pharmacokinetics of the conjugate, naproxen-lysozyme (nap-LYSO), were compared to that of an equimolar mixture of uncoupled naproxen with lysozyme in freely moving rats. Similar plasma kinetics and organ distribution for native lysozyme and the drug conjugate were observed (Clp = 1.2 and 1.1 ml/min; t1/2,beta = 85 and 75 min, respectively). In case of the uncoupled naproxen-lysozyme mixture, a monoexponential plasma disappearance of naproxen with a t1/2 of 2.8 hr was observed, coinciding with urinary excretion of naproxen metabolites (mainly 6-desmethylnaproxen sulfate; 6-DMN-S) between 2 and 8 hr after injection. Urinary recovery of total metabolites was 59% of the naproxen dose. In contrast, after injection of covalently bound naproxen, plasma levels of the parent drug were below the detection level, whereas naproxen was recovered as 6-DMN-S in urine over a period from 4 to 30 hr. However, only 8% of the administered dose was recovered as 6-DMN-S in urine, whereas 50% of the dose was recovered as naproxen metabolites in feces. Incubation experiments using purified renal tubular lysosomal lysates revealed that naproxen-lysozyme degradation ultimately results in a stable naproxen amino acid catabolite, naproxen-lysine (nap-lys). Hepatic uptake and biliary excretion of this catabolyte were demonstrated in isolated perfused rat livers. Further, an equipotent pharmacological activity relative to parent naproxen was observed.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
NO-naproxen modulates inflammation, nociception and downregulates T cell response in rat Freund's adjuvant arthritis.
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.
Animals↗
Stereoselective (S)- and (R)-naproxen glucuronosyl transferases of rat liver.
Stereoselective glucuronidation of naproxen, one of the 2-arylpropionic acids that are widely used as anti-inflammatory drugs, was investigated in chromatofocusing fractions of solubilized liver microsomes from 3-methylcholanthrene- (MC) and phenobarbital- (PB) treated rats. On chromatofocusing of solubilized microsomes of PB-treated rats, two naproxen glucuronosyltransferase (GT) fractions were separated. The fraction eluting at pH 8.7 preferentially conjugated (S)-naproxen (S/R ratio = 1.6) and the fraction eluting at pH 7.8 mostly conjugated (R)-naproxen (S/R ratio = 0.7). Chromatofocusing of solubilized microsomes from MC-treated rats also resulted in the separation of two naproxen GT fractions, eluting at pH 9.4 (S/R ratio 0.2) and at pH 8.7 (S/R ratio 0.8). These two fractions coincided with the elution of known MC-inducible GT activities assigned to a GT isozyme variously termed 4-nitrophenol GT or GT-I. Interestingly, kidney microsomes, known to contain a high constitutive expression of GT-I, preferentially glucuronidated (R)-naproxen (S/R ratio 0.2). The S/R ratio of 0.8, observed with the pI 8.7 fraction of MC-treated rat liver, may be explained by the presence of a mixture of naproxen GTs, consisting of (R)-naproxen GT (S/R ratio 0.2) and of (S)-naproxen GT (S/R ratio 1.6). The results suggest that naproxen is conjugated by at least 3 GT isozymes in rat liver; these have been operationally designated (S)-naproxen GTPB (S/R ratio 1.6), (R)-naproxen GTPB (S/R ratio 0.7), and (R)-naproxen GTMC (S/R ratio 0.2). The latter isozyme is probably identical to the previously characterized MC-inducible GT-I. Thus, (S)- and (R)-naproxen represent useful substrates to distinguish different GT isozymes.
Adult↗
Renal disposition and effects of naproxen and its l-enantiomer in the isolated perfused rat kidney.
Renal handling, metabolism and effects on kidney function of naproxen and its l-enantiomer were examined in the isolated perfused rat kidney (IPK). Urinary excretion rate of naproxen was much lower than the filtration rate, indicating extensive reabsorption. Naproxen is accumulated considerably in the IPK. This accumulation is concentration-dependent and is probably the result of active secretion of naproxen. Considerable amounts of desmethyl-naproxen were formed in the IPK. The kinetic behavior of the l-enantiomer of naproxen did not differ from naproxen. Addition of 37.5 to 3750 micrograms naproxen caused a decrease in urinary flow, glomerular filtration rate and fractional excretion of sodium, chloride, potassium, magnesium and calcium. The presence of prostaglandin E2 in the perfusate fully opposed the effects of naproxen on kidney function. Addition of 375 micrograms l-enantiomer of naproxen did not influence kidney function. Addition of very high doses (1 x 10(5) micrograms) of naproxen and its l-enantiomer to the IPK caused diuresis and increased the fractional excretion of sodium, chloride, potassium, glucose and calcium. We conclude that the pharmacokinetic behavior and the metabolism of naproxen in the IPK is probably not stereoselective; that relatively low doses of naproxen exert a specific, stereoselective effect on kidney function caused by inhibition of the prostaglandin E2 synthesis and that high doses of naproxen exert a nonstereoselective effect on kidney function.
Animals↗
Determination of naproxen and its metabolite O-desmethylnaproxen with their acyl glucuronides in human plasma and urine by means of direct gradient high-performance liquid chromatography.
Naproxen is metabolized in humans by O-demethylation, and by acyl glucuronidation to the 1-O-glucuronide. Naproxen, its metabolite and the conjugates can be measured directly by gradient high-performance liquid chromatographic analysis without enzymic deglucuronidation. The glucuronide conjugates were isolated by preparative chromatography from human urine samples. Mild acidic hydrolysis of one urinary conjugate resulted in naproxen. This conjugate was also formed by alkaline isomerization of isolated naproxen acyl glucuronide, indicating that the structure of this urinary conjugate must have been naproxen isoglucuronide (4-O-glucuronide). Mild acidic hydrolysis of another urinary conjugate resulted in O-desmethylnaproxen. This conjugate was also formed by alkaline isomerisation of isolated O-desmethylnaproxen acyl glucuronide, indicating that the structure of this urinary conjugate must have been O-desmethylnaproxen isoglucuronide (4-O-glucuronide). Calibriation curves were constructed by enzymic deconjugation of samples containing different concentrations of isolated naproxen acyl glucuronide, O-desmethylnaproxen acyl glucuronide, and the isoglucuronides of naproxen and O-desmethylnaproxen by mild acidic hydrolysis. The limit of quantitation of naproxen in plasma is 1.5 microgram/ml. The limits of quantitation in urine are: naproxen, O-desmethylnaproxen, naproxen acyl glucuronide and O-desmethylnaproxen acyl glucuronide, 1 microgram/ml; the isoglucuronide of naproxen and O-desmethylnaproxen, 1.5 microgram/ml. A pharmacokinetic profile of naproxen is shown, and some preliminary pharmacokinetic parameters of naproxen obtained from two human volunteers are given.
Acylation↗
Effect of a nitric oxide-releasing naproxen derivative on hypertension and gastric damage induced by chronic nitric oxide inhibition in the rat.
NSAIDs can elevate blood pressure through mechanisms such as renal vasoconstriction and sodium retention. These effects are particularly evident in hypertensive individuals. Nitric oxide-releasing NSAID derivatives have been shown to have greatly reduced toxicity in the gastrointestinal tract and kidney. We therefore evaluated the effects of a 4 week treatment with either naproxen or its nitric oxide-releasing derivative (NO-naproxen) on systemic arterial blood pressure and gastric damage in rats in which hypertension was induced by L-NAME. Rats received either L-NAME dissolved in the drinking water (400 mg/L) or tap water (control). Vehicle, naproxen (10 mg/kg) or an equimolar dose of NO-naproxen (14.5 mg/kg) were administered orally each day. After 4 weeks, blood pressure was measured, blood samples were taken for measurement of thromboxane synthesis, and gastric damage was evaluated by blind, macroscopic scoring. Both naproxen and NO-naproxen inhibited systemic cyclooxygenase activity by >90%. NO-naproxen-treated rats exhibited no significant gastric damage. The gastric damage produced by L-NAME alone was potentiated by naproxen but prevented by NO-naproxen. L-NAME treatment significantly increased blood pressure. In the absence of L-NAME, the naproxen group had significantly higher blood pressure than both the control and NO-naproxen groups. In rats receiving L-NAME, the same conclusions apply, but the concomitant administration of NO-naproxen was able to significantly reduce the blood pressure compared to L-NAME alone. Based on these results, we conclude that NO-naproxen may represent a safer alternative to standard NSAIDs in the treatment of inflammatory conditions in hypertensive patients.
Animals↗
Gabapentin and pregabalin can interact synergistically with naproxen to produce antihyperalgesia.
BACKGROUND: Gabapentin and pregabalin are anticonvulsants with antihyperalgesic effects in animal models of neuropathic and inflammatory nociception. This study characterized the manner in which gabapentin or pregabalin interacts with naproxen to suppress thermal hyperalgesia and inflammation in the carrageenan model of peripheral inflammation. METHODS: Gabapentin, pregabalin, naproxen, or a fixed-dose ratio of gabapentin + naproxen or pregabalin + naproxen was administered orally to rats after the induction of inflammation by intraplantar injection of lambda-carrageenan in one hind paw. Nociceptive thresholds were determined by the radiant heat paw-withdrawal test. Paw edema was measured by plethysmometry. Drug plasma concentrations were determined by a liquid chromatography-mass spectroscopy-mass spectroscopy method. RESULTS: Gabapentin, pregabalin, and naproxen alone reversed thermal hyperalgesia with ED50 values of 19.2, 6.0, and 0.5 mg/kg, respectively. Mixtures of gabapentin + naproxen in fixed-dose ratios of 50:1, 10:1, or 1:1 interacted synergistically to reverse carrageenan-induced thermal hyperalgesia. However, 1:50 gabapentin + naproxen produced only additive effects. No combination of gabapentin + naproxen decreased paw edema in a manner greater than additive. Plasma concentrations of gabapentin and naproxen were unaltered by the addition of the other drug. The mixture of 10:1 of pregabalin + naproxen interacted synergistically to reverse thermal hyperalgesia on the inflamed hind paw, whereas mixtures of 1:1 or 1:10 produced additive effects. CONCLUSIONS: These data suggest that gabapentin + naproxen and pregabalin + naproxen can interact synergistically or additively to reverse thermal hyperalgesia associated with peripheral inflammation. Therefore, the use of gabapentin or pregabalin in low-dose combinations with naproxen may afford therapeutic advantages for clinical treatment of persistent inflammatory pain.
Acetates↗
Sumatriptan and naproxen sodium for the acute treatment of migraine.
OBJECTIVE: To evaluate the efficacy and tolerability of treatment with a combination of sumatriptan 50 mg (encapsulated) and naproxen sodium 500 mg administered concurrently in the acute treatment of migraine. BACKGROUND: The pathogenesis of migraine involves multiple peripheral and central neural mechanisms that individually have been successful targets for acute (abortive) and preventive treatment. This suggests that multi-mechanism therapy, which acts on multiple target sites, may confer improved efficacy and symptom relief for patients with migraine. DESIGN AND METHODS: This was a multicenter, randomized, double-blind, double-dummy, placebo-controlled, four-arm study. Participants (n = 972) treated a single moderate or severe migraine attack with placebo, naproxen sodium 500 mg, sumatriptan 50 mg, or a combination of sumatriptan 50 mg and naproxen sodium 500 mg. In the latter two treatment arms, the sumatriptan tablets were encapsulated in order to achieve blinding of the study. RESULTS: In the sumatriptan plus naproxen sodium group, 46% of subjects achieved 24-hour pain relief response (primary endpoint), which was significantly more effective than sumatriptan alone (29%), naproxen sodium alone (25%), or placebo (17%) (P < .001). Two-hour headache response also significantly favored the sumatriptan 50 mg plus naproxen sodium 500 mg therapy (65%) versus sumatriptan (49%), naproxen sodium (46%), or placebo (27%) (P < .001). A similar pattern of between-group differences was observed for 2-hour pain-free response and sustained pain-free response (P < .001). The incidence of headache recurrence up to 24 hours after treatment was lowest in the sumatriptan plus naproxen sodium group (29%) versus sumatriptan alone (41%; P = .048), versus naproxen sodium alone (47%; P= .0035), and versus placebo (38%; P= .08). The incidences of the associated symptoms of migraine were significantly lower at 2 hours following sumatriptan 50 mg plus naproxen sodium 500 mg treatment versus placebo (P < .001). The frequencies and types of adverse events reported did not differ between treatment groups, with dizziness and somnolence being the most common. CONCLUSIONS: This is among the first prospective studies to demonstrate that multi-mechanism acute therapy for migraine, combining a triptan and an analgesic, is well tolerated and offers improved clinical benefits over monotherapy with these selected standard antimigraine treatments. Specifically, sumatriptan 50 mg (encapsulated) and naproxen sodium 500 mg resulted in significantly superior pain relief as compared to monotherapy with either sumatriptan 50 mg (encapsulated) or naproxen sodium 500 mg for the acute treatment of migraine. Because encapsulation of the sumatriptan for blinding purposes may have altered its pharmacokinetic profile and thereby decreased the efficacy responses, additional studies are warranted that do not involve encapsulation of the active treatments and assess the true onset of action of multi-mechanism therapy in migraine. This study did show that the combination of sumatriptan and naproxen sodium was well tolerated and that there was no significant increase in the incidence of adverse events compared to monotherapy.
Acute Disease↗
Effects of sulindac and naproxen on prostaglandin excretion in patients with impaired renal function and rheumatoid arthritis.
PURPOSE: The purpose of the current investigation was to study the influence of sulindac and naproxen on renal function and urinary excretion of the stable hydration product of prostacyclin, 6-keto-PGF1 alpha, in patients with arthritis and impaired renal function. PATIENTS AND METHODS: In a placebo-controlled, double-blind, cross-over design, the effects of 7 days of oral sulindac 200 mg twice a day were compared with naproxen 500 mg in the morning and 250 mg in the evening in 10 patients with polyarthritis and stable impaired renal function. Inulin and para-amino-hippurate sodium were used to calculate glomerular filtration rate and renal plasma flow. The excretion rate of 6-keto-PGF1 alpha was measured in urine collected overnight. After patients ingested drugs in the morning, urine was collected in fractions by spontaneous voiding. Venous blood samples were drawn repeatedly for assay of electrolytes, creatinine, proteins, hormones, and drugs. Grip strength and Ritchie articular index were recorded as indicators of symptomatic antiarthritic effectiveness. RESULTS: Naproxen decreased urine levels of 6-keto PGF1 alpha by 59% (p less than 0.01). Sulindac had no effect on renal prostaglandin excretion. Naproxen reduced the glomerular filtration rate and renal plasma flow by 18% (p less than 0.05) and 13% (p less than 0.05), respectively, while no significant change was observed during the sulindac treatment periods. Serum levels of creatinine and complement factor D were unaffected by either drug. Plasma renin activity decreased during naproxen and sulindac treatments by 38% (p less than 0.05) and 22% (p less than 0.05). No significant change in plasma aldosterone was observed during the two drug treatments, but urinary aldosterone declined significantly (p less than 0.05) by 34% with naproxen. Albuminuria decreased (p less than 0.05) during both naproxen (41%) and sulindac treatment (72%), while the albumin/creatinine clearance ratio decreased by 59% (p less than 0.05) only during treatment with sulindac. N-acetyl-beta-D-glucosaminidase in urine was not changed by either drug. Sulindac and naproxen had no discernible effects on base excess, excretion of water, sodium, or potassium, or on osmolal clearance. However, serum potassium increased slightly but significantly (p less than 0.01) during treatment with naproxen. Sulindac sulfide, the active metabolite of sulindac, could not be traced in the urine from any of the patients. Mean arterial blood pressure declined significantly (p less than 0.05) during sulindac treatment but did not change during treatment with naproxen. Both drugs produced equal clinical improvement as measured by grip strength and the Ritchie articular index. CONCLUSION: The results suggest that when sulindac and naproxen are given in clinical equipotent doses to patients with impaired renal function, sulindac does not affect renal prostaglandin synthesis or renal function, whereas naproxen induces suppression of renal prostaglandin synthesis and a further decrease in renal function.
6-Ketoprostaglandin F1 alpha↗
A randomized double-blind comparison of placebo, etodolac, and naproxen on gastrointestinal injury and prostaglandin production.
BACKGROUND: NSAIDs frequently cause gastrointestinal injury and increase the risk of ulcer complications. We compared an NSAID suggested to cause less gastric injury (etodolac) with a standard NSAID (naproxen) and a placebo in a 4-week double-blind trial assessing the effects on gastroduodenal injury, symptoms, and prostaglandin production in healthy volunteers. METHODS: Fifty-two healthy volunteers not taking NSAIDs, alcohol, antibiotics, bismuth, or anti-ulcer drugs: placebo, etodolac 400 mg, or naproxen 500 mg b.i.d. for 4 weeks. Endoscopies with biopsies were repeated at weeks 1 and 4. The number and dimensions of ulcers and erosions were recorded to quantitate injury. RESULTS: At week 1 the mean number and area of gastric ulcers per subject were greater with naproxen than placebo or etodolac (area: naproxen, 7.4 mm2; placebo, 0.6 mm2, p = 0.02 vs naproxen; etodolac, 2.1 mm2, p = 0.06 vs naproxen). Ulcer scores at week 4 were low and comparable in the three groups. The mean number and area of gastric erosions per subject were greatest with naproxen at both weeks 1 and 4 (week 4 area: naproxen, 58.3 mm2; placebo, 29.0 mm2; etodolac, 13.9 mm2, p < 0.02, naproxen vs placebo and vs etodolac). Placebo injury was presumably due to biopsies at prior endoscopy. Gastric mucosal prostaglandin E2 production did not change significantly from baseline after 1 or 4 weeks of treatment with placebo or etodolac, but did decrease significantly with naproxen (week 0, 1689; week 1, 479; week 4, 577 pg/mg protein). Gastrointestinal symptoms were present in only 1 (5%) of 20 visits in which endoscopy showed no erosions or ulcers vs 21 (26%) of 82 visits in which a mucosal defect was identified (p = 0.666). CONCLUSION: Gastric injury with 4 weeks of etodolac is comparable to that seen with placebo and significantly less than that occurring with naproxen, presumably due to the fact that etodolac does not suppress gastric mucosal prostaglandin production, whereas naproxen leads to a significant reduction.
Adult↗
Cytochromes P450, 1A2, and 2C9 are responsible for the human hepatic O-demethylation of R- and S-naproxen.
A preliminary report implicated cytochrome P450 (CYP) 2C9 in the human liver microsomal O-demethylation of S-naproxen, suggesting that this pathway may be suitable for investigation of human hepatic CYP2C9 in vitro. Kinetic and inhibitor studies with human liver microsomes and confirmatory investigations with cDNA-expressed enzymes were undertaken here to define the role of CYP2C9 and other isoforms in the O-demethylation of R- and S-naproxen. All studies utilised a newly developed sensitive and specific HPLC assay that measured the respective O-desmethyl metabolites of R- and S-naproxen in incubations of human liver microsomes and in COS cell lysates. Microsomal R- and S-naproxen O-demethylation kinetics followed Michaelis-Menten kinetics, with respective mean apparent Km values of 123 microM and 143 microM. Sulfaphenazole, a specific inhibitor of CYP2C9, reduced the microsomal O-demethylation of R- and S-naproxen by 43% and 47%, respectively, and the CYP1A2 inhibitor furafylline decreased R- and S-naproxen O-demethylation by 38% and 28%, respectively. R,S-Mephenytoin was a weak inhibitor of R- and S-naproxen O-demethylation, but other CYP isoform specific inhibitors (e.g., coumarin, diethyldithiocarbamate, quinidine, troleandomycin) had little or no effect on these reactions. cDNA-expressed CYP2C9 and CYP1A2 were both shown to O-demethylate R- and S-naproxen. Apparent Km values (92-156 microM) for the reactions catalysed by the recombinant enzymes were similar to those observed for human liver microsomal R- and S-naproxen O-demethylation. The data demonstrate that CYP2C9 and CYP1A2 together account for the majority of human liver R- and S-naproxen O-demethylation, precluding the use of either R- or S-naproxen as a CYP isoform-specific substrate in vitro and in vivo.
Aryl Hydrocarbon Hydroxylases↗
A comparison of valdecoxib and naproxen in the treatment of rheumatoid arthritis symptoms.
OBJECTIVES: The primary aim of this work was to compare the efficacy of valdecoxib 10, 20, and 40 mg QD with that of placebo and naproxen 500 mg BID in patients with rheumatoid arthritis (RA). The overall safety and tolerability profiles of valdecoxib and naproxen were also compared. METHODS: A 12-week, multicenter, randomized, double-blind, parallel-group, placebo- and active-controlled study was performed in patients with adult-onset RA whose disease was in a flare state after discontinuing NSAIDs or other analgesics. Patients were randomly assigned to valdecoxib 10, 20, or 40 mg QD, naproxen 500 mg BID, or placebo. The primary efficacy measures were the American College of Rheumatology (ACR) 20% responder index (ACR-20), physicians' assessments of tender/painful joint count and swollen joint count, and patients' and physicians' global assessments of disease activity. Adverse events, clinical laboratory data, and vital signs were assessed by the investigator and compared between treatment groups to evaluate overall tolerability and safety. RESULTS: A total of 1093 patients were randomized to receive either valdecoxib 10 mg QD (n=226), valdecoxib 20 mg QD (n=219), valdecoxib 40 mg QD (n=209), naproxen 500 mg BID (n=219), or placebo (n=220). At all time points, the proportion of ACR-20 responders was significantly higher in the valdecoxib groups than the placebo group at weeks 2 (10 mg, P<0.001; 20 mg, P=0.008; 40 mg, P= 0.004), 6 (all, P<0.001), and 12 (10 mg, P=0.006; 20 mg, P=0.004; 40 mg, P<0.001). Similarly, at all time points, the proportion of ACR-20 responders was significantly higher in the naproxen 500-mg group than the placebo group (all time points, P<0.001). In addition, mean changes in the number of tender/painful joint counts were significantly greater in the valdecoxib groups than the placebo group at weeks 2 (all, P<0.001), 6 (10 mg, P=0.002; 20 and 40 mg, P<0.001), and 12 (10 mg, P=0.004; 20 mg, P= 0.012; 40 mg, P<0.001). Naproxen treatment was also associated with greater reductions in tender/painful joint count than placebo (all, P<0.001). Mean changes in swollen joint count decreased at all time points in all groups, with significantly greater changes in the valdecoxib and naproxen treatment groups than the placebo group (valdecoxib 20 and 40 mg: week 6, P= 0.014 and P=0.003, respectively; naproxen: week 2, P=0.014; week 6, P=0.015; week 12, P=0.030). Physicians' global assessments of disease activity scores were significantly lower in the valdecoxib (10 mg: weeks 2 and 6, P<0.001; week 12, P=0.001; 20 and 40 mg: all weeks, P<0.001) and naproxen (all time points, P<0.001) treatment groups than the placebo group. Adverse events were reported by 45.5% patients in the placebo group, 51.8% in the valdecoxib 10 mg QD group, 58.0% in the valdecoxib 20 mg QD group, 56.9% in the valdecoxib 40 mg QD group, and 62.6% in the naproxen 500 mg BID treatment group. CONCLUSIONS: Valdecoxib 10, 20, and 40 mg QD were efficacious for treating the signs and symptoms of RA in these patients. The efficacy of valdecoxib 20 and 40 mg QD was not significantly different from that of naproxen 500 mg BID. Valdecoxib was generally well tolerated in this study.
Anti-Inflammatory Agents, Non-Steroidal↗
Effectiveness and mode of action of isopropyl myristate as a permeation enhancer for naproxen through shed snake skin.
The effectiveness and mode of action of isopropyl myristate (IPM) as an enhancer for the permeation of naproxen through shed snake skin have been investigated. The highest naproxen permeability was afforded by IPM (36.2 x 10(-4) cm h-1), followed by menthol (25.0 x 10(-4) cm h-1), oleic acid (11.1 x 10(-4) cm h-1), azone (7.3 x 10(-4) cm h-1) and control (1.4 x 10(-4) cm h-1). Whereas the permeability of un-ionized naproxen (47.4 x 10(-5) cm h-1) was much greater than that of ionized naproxen (1.11 x 10(-5) cm h-1), IPM-treatment of the intact skin increased the flux of ionized naproxen significantly more (50-fold) than that of un-ionized naproxen (15-fold). The large effect of pH on the permeation of naproxen through the intact stratum corneum became insignificant after extraction of lipids from the skin. Similar permeation of naproxen through intact and delipidized skin after IPM treatment indicated that the lipid barrier of the skin was largely impaired by IPM. Direct application of IPM to skin yielded a 2.6-fold higher naproxen permeability than the application of IPM as gel. A greater amount of naproxen was absorbed from 1% test gel (pH 5) containing IPM than from 10% commercial gel (pH 7) containing no IPM. These results show that use of IPM can significantly improve the bioavailability of naproxen in topical preparations.
Animals↗