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NAPROXEN (Naprosyn, Naprosyn EC, Naprosyn Suspension, Anaprox/Anaprox DS, Naprelan)

Naproxen is a NSAID (non-steroidal anti-inflammatory drug) with anti-inflammatory, antipyretic, and analgesic effects with the sodium (Na) salt being more rapidly absorbed for faster desired analgesia. It exerts these medical properties by prostaglandin synthesis inhibition. The sodium salt is naproxen Na (Anaprox) which achieves peak blood levels in 1-2 hours versus the 2-4 hours of naproxen. Anaprox and Anaprox DS (the double strength) find indication especially in menstrual pain. A delayed release formulation, naproxen EC (Naprosyn EC) has an enteric coating- pH sensitive- which forms as a prohibitive barrier not to dissolve in the stomach but instead the small intestine, thus delaying the action, which is further delayed if taken with food.

INDICATIONS



Naproxen is indicated for analgesic relief in patients with rheumatoid arthritis(RA), osteoarthritis, (OA, DJD), juvenile rheumatoid arthritis(JRA), ankylosing spondylitis(AS) tendonitis, bursitis, and acute gout. Relief in RA is evidenced by reduced joint swelling, reduced morning stiffness, duration, and increased mobility. The degree of response in RA is not dependent upon age, sex, severity, or duration of RA.

Osteoarthritic patients experience reduced joint pain or tenderness, increased joint range of motion, increased mobility, and improved capacity to perform normal activities of daily living. Patients with ankylosing spondylitis report decreased night pain, morning stiffness, and rest pain. Acute gout patients have found reduction of the inflammatory symptoms of joint swelling and heat within 24-48 hours of beginning naproxen. Naproxen has proven efficacy in relieving pain in postoperative orthopedic and episiotomy procedures along with uterine contractions and dysmenorrhea with onsets of relief within 30 minutes for naproxen Na or 60 minutes with naproxen and lasting up to 12 hours.

In RA polypharmacy (combinations of medications) of naproxen and gold salts can be used safely to enhance results. The addition of steroids however provides no additional benefit and has thus led to the postulation of the “steroid sparing effect" of naproxen.

SIDE EFFECTS



Naproxen should be avoided in patients with asthma, urticaria, or have a history of any allergic response to aspirin or other NSAIDs, or in patients undergoing or have had cardiac bypass grafts(CABG) procedures As with all NSAIDs ,naproxen may increase risk of serious cardiovascular(CV) thrombosis events, MI(myocardial infarction) or stroke(CVA). When necessary to be treated with both, the smallest dose and shortest duration should be employed.

Naproxen may enhance existing or lead to new presentations of hypertension. It may reduce the effects of the loop (furosemide) or thiazide (hydrochlorothiazide) diuretics. Increased risks of bleeding, ulcerations, and stomach or intestinal perforation may occur with this medication. Prolonged use of this and other NSAIDs may cause renal(kidney) papillary necrosis and other renal diseases, especially in those patients with liver functional diseases, dehydrated patients , heart failure , and the elderly. This and other NSAIDs must be avoided in late pregnancy due to the possibility of premature closure of the ductus arteriosus, Since the drug is extensively metabolized in liver, prolonged use may lead to elevated liver enzymes with rare, but severe reactions including necrosis and failure.

The hematological (on the blood) effects include amenia either due to the platelet adherence blocking component and bleeding or the erythropoieses (blood formation). A benefit of naproxen versus aspirin is the fact that the altering platelet function of naproxen is of shorter duration and reversible upon withdrawal of the medication.

Dermatological effects include exfoliate dermatitis (significant large surface areas of shedding of the skin), Stevens - Johnson syndrome which may require hospitalization and supportive treatment. The skin reactions may manifest underlying hypersensitivity which could herald more serious medical systemic reactions. With such presentations such as rash, blistering, intense itching(pruritis) warmth (local or with fever), the medication should be discontinued and the physician contacted, Gastrointestinal symptoms such as nausea, upper right quadrant pain with flu-like symptoms, fatigue and jaundice may be indicative of liver toxicity.

DOSAGE



The dosing of naproxen, its sodium and enteric coated form is generally bid pc(twice daily with food)for the indications noted. Naproxen is available in 250, 375, or 500mg tablets and suspension as 125mg/5cc (teaspoonful). The sodium salt is either 275mg or the DS(double strength) as 550mg per tablet. The enteric coasted “EC" is available as 375 and 500 and should be swallowed whole, NOT CRUSHED OR CHEWED. The pediatric suspension is based upon body weight at the approximate following doses;

13kg (29lb) 62.5mg (half teaspoonful) twice daily

25kg(55lb) 125mg twice daily

38kg (84 lb) 187.5mg twice daily

REFRENCES

The RX Consultant, Pain Management, May 2000, Vol IX, Number 5

MPR, Monthly Prescribing Reference, 2011 Edition, Pain Management Guide

PDR, Physician Desk Reference, PDR 61 Edition, 2007

COMMENTS

My personal experiences with naproxen and its various formulation has been helpful in treating both the adult and pediatric patients, For the acute gout or tendonitis fascitis patients, I find the medication is well tolerated, with ease of compliance at only twice daily and of favorable response. It is a good replacement for the OTC formulation when higher daily doses are required for the acute inflammation then possibly delivered by the OTC products. The suspension is pleasant tasting and also well tolerated in my pediatric population.



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