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PubMed1997

Clinical pharmacokinetics of naproxen.

Naproxen is a stereochemically pure nonsteroidal anti-inflammatory drug of the 2-arylpropionic acid class. The absorption of naproxen is rapid and complete when given orally. Naproxen binds extensively, in a concentration-dependent manner, to plasma albumin. The area under the plasma concentration-time curve (AUC) of naproxen is linearly proportional to the dose for oral doses up to a total dose of 500 mg. At doses greater than 500 mg there is an increase in the unbound fraction of drug, leading to an increased renal clearance of total naproxen while unbound renal clearance remains unchanged. Substantial concentrations of the drug are attained in synovial fluid, which is a proposed site of action for nonsteroidal anti-inflammatory drugs. Relationships between the total and unbound plasma concentration, unbound synovial fluid concentration and therapeutic effect have been established. Naproxen is eliminated following biotransformation to glucuroconjugated and sulphate metabolites which are excreted in urine, with only a small amount of the drug being eliminated unchanged. The excretion of the 6-O-desmethylnaproxen metabolite conjugate may be tied to renal function, as accumulation occurs in end-stage renal disease but does not appear to be influenced by age. Hepatic disease and rheumatoid arthritis can also significantly alter the disposition kinetics of naproxen. Although naproxen is excreted into breast milk the amount of drug transferred comprises only a small fraction of the maternal exposure. Significant drug interactions have been demonstrated for probenecid, lithium and methotrexate.

Absorption↗
PubMed2005

Competitive binding of ibuprofen and naproxen to bovine serum albumin : modified form of drug-drug displacement interaction at the binding site.

The competitive binding characteristics of ibuprofen and naproxen with respect to binding site on bovine serum albumin (BSA) was studied by equilibrium dialysis method at pH 7.4 and 25 degrees C. We studied the effect of one drug on the free concentration of another in vitro during concurrent administration. There was remarkable increase in free concentration of naproxen when ibuprofen (2x10(-5) M) was added to a 1:1 naproxen-BSA mixture (2x10(-5) M: 2x10(-5) M), suggesting that ibuprofen displaced naproxen from its binding sites. However free fraction of naproxen was not increased up to the level expected from direct competitive displacement. Free concentration of ibuprofen was hardly increased by naproxen when naproxen (2x10(-5) M) was added to the ibuprofen-BSA (1:1) mixture. But in both cases, in presence of ranitidine (site I specific probe), the free concentration of the displaced drug increased more prominently compared to that in absence of ranitidine. This result suggests that, ibuprofen displaces naproxen and vice versa from its high affinity binding site (site II) and the displaced drug rebounds to its low affinity binding site (site I) on BSA molecule. This form of modified displacement has been arbitrarily referred to as site-to-site displacement.

Animals↗
PubMed2006

Evaluation of the comparative efficacy and tolerability of rofecoxib and naproxen in children and adolescents with juvenile rheumatoid arthritis: a 12-week randomized controlled clinical trial with a 52-week open-label extension.

OBJECTIVE: To compare the safety and efficacy of rofecoxib* to naproxen for the treatment of juvenile rheumatoid arthritis (JRA). METHODS: This was a 12-week, multicenter, randomized, double-blind, double-dummy, active comparator-controlled, non-inferiority study with a prespecified 52-week open-label active comparator-controlled extension. Children (ages 2-11 yrs) and adolescents (ages 12-17 yrs) received lower-dose (LD)-rofecoxib [0.3 mg/kg/day up to 12.5 mg/day (base study only)]; or higher-dose (HD)-rofecoxib (0.6 mg/kg/day up to 25 mg/day) or naproxen 15 mg/kg/day as oral suspensions. Adolescents received daily rofecoxib (LD) 12.5 (base study only) or (HD) 25 mg, or naproxen 15 mg/kg/day (maximum 1,000 mg/day) as tablets. The primary endpoint was the time-weighted average proportion of patients meeting the American College of Rheumatology Pediatric-30 (ACR Pedi 30) response criteria. A prespecified bound for the 95% confidence interval for the ratio of the percentage of ACR Pedi 30 responders was used to assess non-inferiority of treatment response between groups. Safety was assessed throughout the study. RESULTS: A total of 310 patients ages 2-17 years (181 (3/4) age 11) were randomized to receive LD-rofecoxib (N=109), HD-rofecoxib (N=100), or naproxen (N=101). The ACR Pedi 30 response rates following 12 weeks of treatment were 46.2%, 54.5%, and 55.1%, respectively. The relative rates of response compared to naproxen were 0.81 (95% CI 0.61, 1.07) and 0.98 (95% CI 0.76, 1.26) for LD- and HD-rofecoxib, respectively. Both rofecoxib doses were not inferior to naproxen. Patients (N=227) entering the extension received HD-rofecoxib or naproxen with efficacy maintained during the extension. All treatments were generally well tolerated throughout the study. CONCLUSION: Daily treatment of JRA patients with rofecoxib up to 12.5 or 25 mg was well tolerated, providing sustained clinical effectiveness comparable to naproxen 15 mg/kg. *On September 30, 2004, Merck & Co., Inc. announced the voluntary worldwide withdrawal of rofecoxib from the market.

Adolescent↗
PubMed1985

Treatment of sports injuries with naproxen sodium and dextropropoxyphene napsylate.

Sixty-eight football players suffering from moderate to severe soft-tissue injuries were studies for up to 14 days. Treatment was either 550 mg naproxen sodium or 100 mg dextropropoxyphene napsylate initially and then 275 mg naproxen sodium or 100 mg dextropropoxyphene napsylate 4-times daily. Signs and symptoms were assessed daily on 4-point scales. The time taken for patients to return to training and be available for selection were recorded. The outcome of treatment of signs and symptoms was very similar for both groups, the only statistically significant difference detected being for the amount of swelling, which showed greater improvement in the naproxen sodium group on Days 2 to 6. Patients in the naproxen sodium group returned to training approximately 1 day sooner than those in the dextropropoxyphene napsylate group. The majority of patients in both treatment groups did not require treatment for 14 days. The duration of treatment in the naproxen sodium group, however, was shorter, with 59% stopping medication by Day 10, as compared to 33% in the dextropropoxyphene napsylate group (p=0.03). Nine patients in the naproxen sodium group and 6 in the dextropropoxyphene napsylate group reported side-effects, all gastro-intestinal in origin. One patient in the former group was withdrawn because of the reaction. There were three further withdrawals. One patient in the naproxen sodium group was referred for surgery, 1 patient in the dextropropoxyphene napsylate group was lost to follow-up and the final patient withdrew because of lack of efficacy. Both treatments were effective and well tolerated but the patients in the naproxen sodium group showed a more beneficial response.

Adolescent↗
PubMed1986

Lithium interaction with sulindac and naproxen.

The interaction of lithium with sulindac and naproxen was studied in six sulindac-treated and seven naproxen-treated patients admitted to a geropsychiatry ward. Patients under a steady state lithium level received lithium for 3 days, then lithium + sulindac (300 mg/day) or naproxen (750 mg/day) for 6 days, and then lithium alone for 5 days. Sulindac failed to affect serum lithium levels and lithium clearance. The results with naproxen showed marked interindividual variations ranging from no increase to a 41.9% increase in serum lithium levels within 5 days. There was a corresponding decrease in lithium clearance in naproxen-treated patients. Patients undergoing lithium therapy might need a reduction of their lithium dosage following naproxen administration. More frequent serum lithium level determinations are required following initiation of naproxen therapy until the magnitude of the lithium-naproxen drug interaction can be adequately assessed in a given individual.

Aged↗
PubMed1980

Naproxen sodium (Anaprox): pharmacology, pharmacokinetics and drug interactions.

Naproxen sodium (Anaprox) is a potent antiinflammatory and analgesic agent. The drug has demonstrated a variety of biologic actions, including stabilization of lysosomal membranes, but most of its therapeutic activity is probably mediated through prostaglandin synthesis inhibition. The linkage between inhibition of prostaglandin synthesis and relief of dysmenorrhea has been documented in clinical studies, reported elsewhere in this supplement. Of relevance is the selective activity of naproxen sodium on uterine microsomal preparations. Once dissolved in biologic fluids, naproxen and naproxen sodium are chemically identical species and have the same biologic properties. Administration of naproxen as the sodium salt (Anaprox), however, permits more rapid absorption from the gastrointestinal tract. In either form, the drug is essentially completely absorbed. Its metabolic half-life averages 13 hours. The metabolism of naproxen is quite simple: it is excreted almost entirely in the urine as the native molecule, its oxidative 6-desmethyl metabolite and their respective conjugates. Naproxen is an acidic drug that is highly bound to plasma albumin. It may thus be expected to displace and transiently increase the tissue availability of other protein-bound drugs. In practice, however, potential interactions with both warfarin and tolbutamide have been evaluated and do not appear to be of clinical significance. Naproxen has a high therapeutic index and a shallow dose-response curve, so the effect of other drugs on its pharmacokinetics is not likely to have a large clinical impact.

Acid-Base Equilibrium↗
PubMed1995

Gastroduodenal tolerability of nabumetone versus naproxen in the treatment of rheumatic patients.

OBJECTIVE: The objective of this endoscopic, double-blind study was to evaluate the gastric tolerability of nabumetone, a novel nonsteroidal anti-inflammatory drug, compared with naproxen in patients with rheumatoid arthritis. METHODS: Patients with definite or classic rheumatoid arthritis as defined by ACR criteria were eligible for entry into the study if an initial endoscopy was normal or showed the presence of only one erosion or one or two submucosal hemorrhages. After a 7-day washout period, the patients were randomized to receive either nabumetone, 1 g, or naproxen, 500 mg, b.i.d. Blinding was achieved by the use of double dummies. Endoscopy was repeated after 4 wk of treatment. The primary efficacy parameters were Ritchie articular index, duration of morning stiffness, and global assessments. RESULTS: Gastric mucosal lesions of different degrees were observed in 9% (2/22) of nabumetone-treated patients and in 40% (12/30) of those who received naproxen (p = 0.01). One duodenal ulcer was found in a patient treated with nabumetone, and this patient had a history of duodenal ulcer. In the naproxen group, six patients were found to have an ulcer. Clinical evaluation of rheumatological symptomatology showed no statistical difference in relieving symptoms between the two drugs in the primary efficacy assessments. However, six nabumetone-treated patients dropped out because of lack of efficacy, compared with one in the naproxen group. Side effects were noted in three patients treated with nabumetone and in 14 treated with naproxen (p = 0.004). CONCLUSION: This study showed that nabumetone, 1 g daily, results in significantly less deterioration of gastric mucosa than naproxen, 500 mg daily, but the efficacy of naproxen, 1 g, appears to be more than that achieved with nabumetone, 1 g.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

Effects of celecoxib and naproxen on renal function in the elderly.

OBJECTIVE: To compare the effects of celecoxib, a cyclooxygenase 2-specific inhibitor, with the nonspecific cyclooxygenase 1 and 2 inhibitor naproxen on renal function in 29 healthy elderly subjects in a single-blind, randomized, crossover study. METHODS: Subjects received either celecoxib, 200 mg twice daily, for 5 days followed by celecoxib, 400 mg twice daily, for the next 5 days, or they received naproxen, 500 mg twice daily, for 10 days. After a 7-day washout, subjects were crossed over to receive the other regimen. RESULTS: After the first dose, the trend was for a greater decrease in glomerular filtration rate with naproxen (-5.31 mL/min per 1.73 m2) compared with celecoxib (-0.86 mL/min per 1.73 m2). The treatment difference became statistically significant on day 6 (-7.53 vs -1.11 mL/min per 1.73 m2 for naproxen and celecoxib, respectively; P=.004). Urinary prostaglandin E2 and 6-keto-prostaglandin F1alpha excretion was significantly reduced from baseline across the treatment interval with both celecoxib and naproxen (P< or =.04). There were no significant differences in prostaglandin excretion between these 2 agents (P> or =.07). Small, transient decreases (P<.05) in urinary sodium excretion were observed after the initiation of both celecoxib and naproxen treatment. Sodium excretion values returned to baseline by the end of the study. CONCLUSIONS: The results indicate that cyclooxygenase 2-specific inhibition in healthy elderly subjects may spare renal hemodynamic function, although the effects on sodium excretion, as well as urinary prostaglandin E2 and 6-keto-prostaglandin F1alpha excretion, appear to be similar to those of nonspecific cyclooxygenase inhibitors such as naproxen.

Aged↗
PubMed2001

Synthesis and cyclooxygenase inhibitory properties of novel (+) 2-(6-methoxy-2-naphthyl)propanoic acid (naproxene) derivatives.

Halomethylation of naproxene (1) occurs regioselectively in position 5 and subsequently--in situ or on treatment with silver nitrate--leads to naproxene-"dimers" with two naproxene units, 5,5'-connected through a ethenylene (3) and a methylene (4) bridge, respectively. Two of the new naproxene derivatives were screened for their cyclooxygenase inhibitory properties relative to naproxene. Both 5-chloromethyl naproxene (2) and 2-(5-((carboxyethyl)-2-methyloxynaphthyl)-6-methoxy-2-naphthyl)propanoic acid (4) were inactive in the concentration range of 0.1-10 mumole against both COX-1 and COX-2, indicating that bulky substituents in position 5 in naproxene are unfavourable for both COX-1 and COX-2 inhibition.

Cyclooxygenase 1↗
PubMed2000

Absence of pharmacokinetic interaction between orally co-administered naproxen sodium and diphenhydramine hydrochloride.

The potential for a pharmacokinetic interaction between naproxen and diphenhydramine was examined in a randomized three-way crossover design with a 1-week washout between dosing. Single oral doses of 220 mg of naproxen sodium and 50 mg of diphenhydramine hydrochloride were given separately and together to 30 healthy male and female subjects. Heparinized blood samples obtained for 48 h postdose were assayed for plasma naproxen and diphenhydramine concentrations using validated high-performance liquid chromatography (HPLC) and gas chromatography (GC) assay methods, respectively. The area under the plasma concentration-time curve (AUC), maximum plasma concentrations (C(max)), time of C(max) (T(max)) and terminal exponential half-life (t(1/2,z)), were analysed for significant treatment differences by analysis of variance (ANOVA). Based on absence of significant treatment effects on AUC and C(max), single-dose oral co-administration of 220 mg of naproxen sodium with 50 mg of diphenhydramine hydrochloride does not alter the pharmacokinetics of either naproxen or diphenhydramine. Significant treatment differences seen for naproxen T(max) (0.3 h, males only) and diphenhydramine t(1/2,z) (0.8 h, females only) were minor and are unlikely to have therapeutic consequences. Thus, efficacy and safety of concomitant naproxen and diphenhydramine should not be altered due to a pharmacokinetic interaction.

Adolescent↗
PubMed1977

Naproxen, aspirin, and codeine in postpartum uterine pain.

The analgesic efficacy of oral naproxen and its sodium salt was compared with that of aspirin and codeine in two separate trials involving 140 and 90 patients, respectively, with postpartum uterine pain in a single-dose, parallel, stratified, randomized, placebo-controlled, double-blind design. With 300 or 600 mg naproxen and with 275 mg naproxen sodium, significant analgesia, measured subjectively by pain intensity differences (PID), was prolonged at least 7 or 8 hr; onset tended to be delayed 2 hr or more. With 650 mg aspirin analgesia began within 1 hr and continued until the fifth hour, while with 60 mg codeine responses were indistinguishable from placebo responses throughout the 8-hr time course. Although time-effect patterns with naproxen sodium and aspirin were different, summed analgesic effects (SPID) showed equal efficacy and superiority over placebo (p less than 0.005). With each of the 2 doses of naproxen, SPID separation from placebo was comparable to that above (p less than 0.02 and 0.005, respectively), but analgesic dose response, though measurable, was not significant. Side effects were not significant with any of the treatments. It appears that naproxen and naproxen sodium are analgesics with efficacy equal to aspirin and may prove to be rational substitutes for currently available analgesics in some painful states in which longer pain relief would be desireable.

Adolescent↗
PubMed1980

Comparative analgesic effects of naproxen sodium, aspirin, and placebo.

The analgesic efficacy of a single 550-mg dose of naproxen sodium was compared with that of 650 mg aspirin and a placebo in a double-blind, parallel trial. The study was carried out in an industrial setting and included 201 adult patients with various acute pain states. Musculoskeletal pain was the most common type of pain treated. Pain intensity differences and patients' evaluation of pain relief indicated statistically significantly earlier and better analgesia with naproxen sodium than with both aspirin and placebo. The summed pain intensity differences (SPID) showed that naproxen sodium performed better than aspirin, which in turn did better than placebo. the difference between naproxen sodium and aspirin means for SPID was numerically equal to the difference between the aspirin and placebo means for SPID. Further, the incidence of side effects was less with naproxen sodium than with aspirin. The study demonstrated that naproxen sodium provided earlier and better pain relief than aspirin, that this effect was consistent over time, and that the incidence of side effects associated with naproxen sodium was less than with aspirin.

Adult↗
PubMed1990

Effects of various granulating systems on the bioavailability of naproxen sodium from polymeric matrix tablets.

Naproxen sodium and a cellulose ether derivative were granulated with either water or a poly(meth)acrylic acid ester copolymer aqueous dispersion to make three controlled-release matrix dosage forms. The different polymeric matrix systems contained hydroxypropyl methylcellulose (formulation A), hydroxypropyl cellulose:poly(meth)acrylic acid ester copolymer (formulation B), and hydroxypropyl methylcellulose:poly(meth)acrylic acid ester copolymer (formulation C). All three hydrophilic matrix tablets demonstrated identical in vitro dissolution rates. The three controlled-release formulations were compared with a marketed immediate-release naproxen sodium dosage form (formulation D) in a single-dose crossover study in six healthy volunteers. The AUC values for controlled-release dosage forms A and C were larger than those for formulations B and D. However, the reasons why the AUC for formulations A and C is larger than that for formulations B versus D can be explained differently. Formulations A and C more effectively maintain naproxen plasma levels than formulation D by reducing the amount of naproxen unbound to plasma proteins, therefore reducing naproxen available for urinary excretion. Naproxen sodium delivered from formulations A and C is also probably much better absorbed than from that from formulation B, possibly due to less drug entrapment. More importantly, although all three CR formulations had identical in vitro dissolution profiles, naproxen sodium plasma levels were better maintained (based on AUC) in subjects taking formulations A and C, which contained a lower polymer content and did not use hydroxypropyl cellulose. The tmax values were larger for the three controlled-release dosage forms. Also, the Cmax value for the conventional dosage form was nearly twofold higher than that observed for the controlled-release dosage forms.

Adult↗
PubMed1979

The effects of ibuprofen, indomethacin, aspirin, naproxen, and placebo on the gastric mucosa of normal volunteers: a gastroscopic and photographic study.

The effects of various nonsteroidal antiinflammatory drugs on the gastric mucosa were endoscopically evaluated in 40 normal volunteers. Eight groups, each containing five subjects were designed: aspirin (3600 mg/d); placebo; ibuprofen (1600 mg/d); ibuprofen (2400 mg/d); indomethacin (100 mg/d); indomethacin (150 mg/d); naproxen (500 mg/d); and naproxen (750 mg/d). All volunteers took medication for seven days and gastroscopy was carried out on day one and day eight. All findings were documented by photography. Severe gastric mucosal injury occurred with aspirin (P less than 0.05), both doses of indomethacin, and the higher dose of naproxen. Lesser changes were seen with the lower dose of naproxen, both doses of ibuprofen and placebo. The higher doses of ibuprofen, indomethacin, and naproxen caused a greater degree of gastric mucosal injury, but statistical significance was achieved only with naproxen (P less than 0.01). Subjective gastrointestinal complaints generally correlated with endoscopic pathology; however, nine volunteers had evidence of severe injury to the gastric mucosa with no symptomatology. This was confined to the patients on indomethacin, naproxen, and ibuprofen. Aspirin patients all had some degree of symptomatology but to a lesser degree than expected in view of the endoscopic findings.

Adult↗
PubMed2007

A randomized, double-blind, one-week study comparing effects of a novel COX-2 inhibitor and naproxen on the gastric mucosa.

CS-706 is a novel cyclooxygenase-2 (COX-2) inhibitor with potent analgesic, anti-inflammatory, and antitumor properties in animal models. This one-week, multicenter study was undertaken to assess the safety and tolerability of CS-706 and to compare the effects of CS-706 versus naproxen on acute gastrointestinal (GI) mucosal injury. Healthy men and women (n=160) without evidence of underlying gastroduodenal lesions were randomized to placebo, 100 mg CS-706 once daily, 200 mg CS-706 once daily, or 500 mg naproxen twice daily, administered for 7 days. On Day 8, subjects underwent a posttreatment upper GI endoscopy to assess development of gastroduodenal petechiae, erosions, and ulcers. Inhibition of COX-1 and COX-2 activity over the 24-hr postdose interval on Day 7 was determined in 48 subjects (12 per treatment group). CS-706 was safe and well tolerated. The extent of upper GI mucosal injury for both CS-706 dose groups was statistically significantly less than that for naproxen (P < 0.001) and was similar to placebo (P=0.615 and P=0.115 for 100 and 200 mg CS-706, respectively). No subject in placebo or either CS-706 treatment group had gastroduodenal ulcers, compared with 11 (28.2%) subjects treated with naproxen (P < 0.001). Both doses of CS-706 inhibited COX-2 activity to a similar extent as naproxen, whereas neither dose of CS-706 showed meaningful inhibition of platelet COX-1. In contrast, naproxen nearly completely inhibited COX-1 over the dosing interval. We conclude that CS-706, dosed up to 200 mg once daily, has an acute, upper GI toxicity profile similar to that of placebo and significantly superior to that of naproxen.

Adult↗
PubMed1984

Utility of naproxen in the differential diagnosis of fever of undetermined origin in patients with cancer.

The clinical utility of naproxen as an antipyretic agent was examined in the differential diagnosis of fever of undetermined origin in patients with cancer. Twenty-two patients with cancer and fever of undetermined origin for more than seven days were treated with naproxen to control fever when there was no evidence of infection after a careful initial evaluation, and in most cases, after failure of antibiotic therapy. In final analysis, none of five patients with infectious fever had responses to naproxen. In contrast, 14 of 15 patients with neoplastic fever showed a prompt, complete, and sustained lysis of fever within 24 hours after the initiation of naproxen treatment, and the patients also showed symptomatic improvement. One patient with neoplastic fever who did not have a response to naproxen had lysis of fever after the removal of necrotic tumor tissue. Two patients with fever from connective tissue disease had a partial lysis of fever in response to naproxen. These data suggest that naproxen specifically produces the lysis of neoplastic fever and, therefore, is a useful agent in assisting in the differential diagnosis of infectious fever and neoplastic fever in patients with cancer and fever of undetermined origin.

Adult↗
PubMed1988

Steady state pharmacokinetics of naproxen in young and elderly healthy volunteers.

The pharmacokinetic properties of naproxen (375 mg twice daily and 750 mg twice daily) were evaluated in 23 young (age range, 19 to 32 years) and 25 elderly (age range, 65 to 74 years) healthy male volunteers. After an initial screening examination, each subject received 15 doses of naproxen in this double-blind parallel study. Comparison of trough plasma naproxen concentrations (12 hours after each of the last two morning doses) verified steady state and provided no evidence of drug accumulation in either age or dosage group beyond that achieved after seven days of naproxen administration. Plasma naproxen concentrations determined at 0, 0.5, 1, 2, 4, 8, 12, and 24 hours after the final dose revealed no statistically significant differences between age groups, at either dosage, with respect to total area under the 12-hour time-concentration curve or peak plasma naproxen concentrations. Terminal plasma half-life was longer in the elderly group at each dosage, but these differences are probably not clinically important since the steady state area under the curve was similar in the two age groups. There were no statistically significant changes in serum creatinine levels (monitored as an indicator of kidney function) in either group at either dosage. These results suggest that advanced age per se does not alter naproxen pharmacokinetics in any clinically significant way.

Adult↗
PubMed1988

Kidney function during naproxen therapy in patients at risk for renal insufficiency.

The effects of naproxen on renal function in 34 patients with minimally elevated serum creatinine (Scr) or subnormal creatinine clearance (Ccr) were evaluated in a parallel-design study. All patients received open-label naproxen 375 mg twice daily for 2 weeks (phase I); patients were then randomly assigned to receive naproxen 750 mg twice daily (n = 26) or to continue naproxen 375 mg twice daily (n = 8) double-blind for an additional 2 weeks (phase II). Renal function was assessed by Scr, Ccr, and BUN measurements at baseline and at the end of each treatment phase. Neither treatment group had a clinically meaningful change in median laboratory values between baseline and the end of phase I, or between baseline and the end of phase II. During the first 2 weeks of treatment with naproxen 375 mg twice daily, there was no change in Scr. At the time of the first Scr measurement following the increase in naproxen dose to 750 mg twice daily, 13 of 26 patients had Scr levels of 1.1 mg/dL or higher, but four days later, only three patients had Scr levels of 1.1 mg/dL or higher, suggesting that a transient increase in Scr may accompany dosage increase. Chronic administration of naproxen 375 mg twice daily in patients at risk for renal insufficiency based on laboratory evidence of renal impairment was not associated with further deterioration in renal function. An increase in dosage to 750 mg twice daily in such patients appeared to be associated with only small, transient changes in laboratory measures of renal function.

Adult↗