Naproxen

Oral🕒 Plan

Route dataTripSit

🧬 Receptor activityPHDC

Mechanism of actionPH

As with other non-selective NSAIDs, naproxen exerts it's clinical effects by blocking COX-1 and COX-2 enzymes leading to decreased prostaglandin synthesis. Although both enzymes contribute to prostaglandin production, they have unique functional differences. The COX-1 enzymes is constitutively active and can be found in normal tissues such as the stomach lining, while the COX-2 enzyme is inducible and produces prostaglandins that mediate pain, fever and inflammation. The COX-2 enzyme mediates the desired antipyretic, analgesic and anti-inflammatory properties offered by Naproxen, while undesired adverse effects such as gastrointestinal upset and renal toxicities are linked to the COX-1 enzyme.
Naproxen has pharmacologic actions similar to those of other prototypical nonsteroidal anti-inflammatory agents (NSAIAs). The drug exhibits anti-inflammatory, analgesic, and antipyretic activity. The exact mechanisms have not been clearly established, but many of the actions appear to be associated principally with the inhibition of prostaglandin synthesis. Naproxen inhibits the synthesis of prostaglandins in body tissues by inhibiting cyclooxygenase; at least 2 isoenzymes, cyclooxygenase-1 (COX-1) and -2 (COX-2) (also referred to as prostaglandin G/H synthase-1 (PGHS-1) and -2 (PGHS-2), respectively), have been identified that catalyze the formation of prostaglandins in the arachidonic acid pathway. Naproxen, like other prototypical NSAIAs, inhibits both COX-1 and COX-2. Although the exact mechanisms have not been clearly established, NSAIAs appear to exert anti-inflammatory, analgesic, and antipyretic activity principally through inhibition of the COX-2 isoenzyme; COX-1 inhibition presumably is responsible for the drugs' unwanted effects on GI mucosa and platelet aggregation.
The anti-inflammatory, analgesic, and antipyretic effects of naproxen and other nonsteroidal anti-inflammatory agents (NSAIAs), including selective inhibitors of COX-2 (e.g., celecoxib, rofecoxib), appear to result from inhibition of prostaglandin synthesis. While the precise mechanism of the anti-inflammatory and analgesic effects of NSAIAs continues to be investigated, these effects appear to be mediated principally through inhibition of the COX-2 isoenzyme at sites of inflammation with subsequent reduction in the synthesis of certain prostaglandins from their arachidonic acid precursors. Naproxen stabilizes lysosomal membranes and inhibits the response of neutrophils to chemotactic stimuli. The drug does not possess glucocorticoid or adrenocorticoid-stimulating properties.
Naproxen lowers body temperature in patients with fever. Although the mechanism of the antipyretic effect of nonsteroidal anti-inflammatory agents is not known, it has been suggested that suppression of prostaglandin synthesis in the CNS (probably in the hypothalamus) may be involved.
Naproxen-induced inhibition of prostaglandin synthesis may result in decreased frequency and intensity of uterine contractility. Prostaglandins E2 and F2alpha increase the amplitude and frequency of uterine contractions in pregnant women; current evidence suggests that primary dysmenorrhea is also mediated by these prostaglandins. Whether the increased production of prostaglandins associated with primary dysmenorrhea is mediated by COX-1 or COX-2 remains to be determined. Blood concentrations of a metabolite of prostaglandin F2alpha have been found to decrease in women with dysmenorrhea who were receiving naproxen. Therapy with naproxen has been effective in relieving menstrual pain and has reduced blood loss in women with menorrhagia, probably by inhibiting the formation of these prostaglandins. Administration of naproxen during late pregnancy may prolong gestation by inhibiting uterine contractions.

PharmacodynamicsPH

Naproxen is an established non-selective NSAID and is useful as an analgesic, anti-inflammatory and antipyretic. Similar to other NSAIDs, the pharmacological activity of naproxen can be attributed to the inhibition of cyclo-oxygenase, which in turn reduces prostaglandin synthesis in various tissues and fluids including the synovial fluid, gastric mucosa, and the blood. Although naproxen is an effective analgesic, it can have unintended deleterious effects in the patient. For instance, naproxen can adversely affect blood pressure control. A study found that use of naproxen induced an increase in blood pressure, although the increase was not as significant as that found with ibuprofen use. Further, studies have found that the risk of upper gastrointestinal bleeding is on average four-fold higher for individuals taking NSAIDs. Other factors that increase the risk of upper gastrointestinal bleeding include concurrent use of corticosteroids or anticoagulants, and a history of gastrointestinal ulcers.

Pharmacokinetics

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