BRANDS OF NAPROXEN IN KENYA
Naprin, Unijules Life Sciences Ltd
NAPROXEN MODE OF ACTION:
Naproxen is a propionic acid derivative. It acts as an anti-inflammatory agent, analgesic and has anti-pyretic activity in man. By its action on cyclo-oxygenase, naproxen inhibits prostaglandin synthesis (as do other NSAIDs). Naproxen exhibits its anti-inflammatory effect even in adrenalectomised animals, indicating that its action is not mediated through the pituitary-adrenal axis. As with other NSAIDs, however, the exact mechanism of its anti-inflammatory action is not known.
Naproxen is indicated for the treatment of:
- Rheumatoid arthritis.
- Osteoarthritis (degenerative arthritis).
- Ankylosing spondylitis.
- Juvenile rheumatoid arthritis.
- Acute gout.
- Acute musculoskeletal disorders.
DOSAGE AND ADMINISTRATION
Rheumatoid arthritis, osteoarthritis and ankylosing spondylitis:
500mg-1g daily in two doses at twelve hourly intervals, or alternatively, if 1g daily is needed this can be administered as two 500mg doses or as a single dose. The size of the morning and evening doses can be adjusted on the basis of the predominant symptoms (ie night time pain or morning stiffness)
Initially 750mg followed by 250mg every 8 hours until the attack has passed.
Acute musculoskeletal disorders and dysmenorrhoea:
Initially 500mg followed by 250mg every 6-8 hours as necessary to a maximum of 1250mg daily after the first day.
Children over 5 years:
For juvenile rhematoid arthritis 10mg/kg a day taken in two doses every 12 hours.
The elderly are at increased risk of the serious consequences of adverse reactions. If an NSAID is considered necessary, the lowest effective dose should be used and for the shortest possible duration. The patient should be monitored regularly for GI bleeding during NSAID therapy. Studies indicate that although total plasma concentration of naproxen is unchanged, unbound plasma fraction of naproxen is increased in the elderly. The implication of this finding for naproxen dosing is unknown. As with other drugs used in the elderly it is prudent to use the lowest effective dose. Dosage should be reduced in the elderly where there is an impairment of renal function.
Undesirable effects may be minimised by using the lowest effective dose for the shortest duration necessary to control symptoms.
Method of Administration
For oral administration. Tablets should be swallowed whole and not broken or crushed. To be taken preferably with or after food.
Patients with active gastrointestinal bleeding or peptic ulceration, known hypersensitivity to naproxen, naproxen sodium or any other ingredient in the formulation.
Active, or history of recurrent peptic ulcer/haemorrhage (two or more distinct episodes of proven ulceration or bleeding).
NSAIDs are contraindicated in patients who have previously shown hypersensitivity reactions (e.g. asthma, rhinitis, angioedema or urticaria) in response to ibuprofen, aspirin, or other non-steroidal anti-inflammatory drugs.
Severe heart failure, hepatic failure and renal failure.
During the last trimester of pregnancy.
History of gastrointestinal bleeding or perforation, related to previous NSAIDs therapy.
- Naproxen is highly protein-bound hence patients receiving hydantoins, anticoagulants or a highly protein-bound sulfonamide should be closely monitored for signs of overdosage of these drugs. No interactions have been observed in clinical studies with naproxen and sulfonylureas, but caution is nevertheless advised since interaction has been seen with other non-steroidal agents of this class.
- NSAIDs, including naproxen, have been reported to increase steady state plasma lithium levels by inhibition of renal lithium clearance. Decreased elimination of lithium. It is recommended that these levels are monitored whenever initiating, adjusting or discontinuing naproxen.
- Anti-hypertensives: Reduced anti-hypertensive effect. Concomitant administration of naproxen with beta blockers such as propranolol may reduce their antihypertensive effect and may increase the risk of renal impairment associated with the use of ACE inhibitors or angiotensin II receptor antagonists.
- Probenecid given concurrently increases naproxen plasma levels and extends its half-life considerably.
- Decreased elimination of methotrexate. Caution is advised when methotrexate is administered concurrently, due to the possible enhancement of its toxicity as naproxen, like other NSAIDs, has been reported to reduce tubular secretion of methotrexate in an animal model.
- The natriuretic effect of furosemide has been reported to be inhibited by some drugs of this class. Naproxen therapy should be temporarily withdrawn 48 hours before adrenal function tests are performed as it may artifactually interfere with some tests for 17-ketogenic steroids. Similarly, naproxen may interfere with some assays of urinary 5-hydroxyindoleacetic acid.
- NSAIDs may exacerbate cardiac failure, reduce GFR and increase plasma cardiac glycoside levels when co-administered with cardiac glycosides.
- As with all NSAIDs, caution is advised when ciclosporin is co-administered because of the increased risk of nephrotoxicity.
- NSAIDs should not be used for 8-12 days after mifepristone administration as NSAIDs can reduce the effects of mifepristone.
- As with all NSAIDs, caution should be taken when co-administering with corticosteroids because of the increased risk of gastrointestinal ulceration or bleeding .
- Other analgesics including cyclooxygenase-2 selective inhibitors: Avoid concomitant use of two or more NSAIDs (including aspirin) as this may increase the risk of adverse effects.
- Diuretics: NSAIDs may reduce the effect of diuretics and antihypertensive medicinal products. The risk of acute renal insufficiency, which is usually reversible, may be increased in some patients with compromised renal function (e.g. dehydrated patients or elderly patients) when angiotensin II receptor antagonists are combined with NSAIDs. Therefore, the combination should be administered with caution, especially in the elderly. Patients should be adequately hydrated and consideration should be given to monitoring of renal function after initiation of concomitant therapy, and periodically thereafter. Diuretics can increase the risk of nephrotoxicity of NSAIDs.Anti-coagulants: NSAIDs may enhance the effects of anti-coagulants, such as warfarin.
- Quinolone antibiotics: Animal data indicate that NSAIDs can increase the risk of convulsions associated with quinolone antibiotics. Patients taking NSAIDs and quinolones may have an increased risk of developing convulsions.
- Anti-platelet agents and selective serotonin reuptake inhibitors (SSRls): Increased risk of gastrointestinal bleeding .
- Tacrolimus: Possible increased risk of nephrotoxicity when NSAIDs are given with tacrolimus.
- Zidovudine: Increased risk of haematological toxicity when NSAIDs are given with zidovudine. There is evidence of an increased risk of haem arthroses and haematoma in HIV(+) haemophiliacs receiving concurrent treatment with zidovudine and ibuprofen.
- Bisphosphonates: concomitant use of bisphosphonates and NSAIDs may increase the risk of gastric mucosal damage.
- Colestyramine: colestyramine delays the absorption of naproxen. Naproxen should be taken at least one hour before or four to six hours after colestyramine.
- Acetylsalicylic acid: Clinical pharmacodynamic data suggest that concomitant naproxen usage for more than one day consecutively may inhibit the effect of low-dose acetylsalicylic acid on platelet activity and this inhibition may persist for up to several days after stopping naproxen therapy. The clinical relevance of this interaction is not known.
Renal impairment and cystitis
Clinical | Pharmacokinetic data
Pregnancy Category: C
Routes of Administration: Oral
Bioavailability: 95% (by mouth)
Protein Binding: 99%
Metabolosim: Liver (to 6-desmethylnaproxen)
Onset of Action: Not Available
Elimination Half life: 12–17 hours (adults)
Legal Status | Dosage forms & Strengths
OTC / Rx-only
Narcotic Drugs and Psychotropic Substances (Control ) Act Schedule:
This Drug is not Subject to DDA drugs Act
Dosage Forms | Strengths:
|CompTox Dashboard (EPA)|
- Todd, Peter A., and Stephen P. Clissold. “Naproxen.” Drugs 40.1 (1990): 91-137.
- Davies, Neal M., and Keith E. Anderson. “Clinical pharmacokinetics of naproxen.” Clinical pharmacokinetics 32.4 (1997): 268-293.
- Harrington, Peter J., and Eric Lodewijk. “Twenty years of naproxen technology.” Organic Process Research & Development 1.1 (1997): 72-76.