Fenoprofen Explained

Fenoprofen, sold under the brand name Nalfon among others, is a nonsteroidal anti-inflammatory drug (NSAID). Fenoprofen calcium is used for symptomatic relief for rheumatoid arthritis, osteoarthritis, and mild to moderate pain. It has also been used to treat postoperative pain.^[1] It is available as a generic medication.^{[2] [3]}

Pharmacology

Decreases inflammation, pain, and fever, probably through inhibition of cyclooxygenase (COX-2 inhibitor) activity and prostaglandin synthesis.

Chirality and biological activity

Fenoprofen is chiral drug with one stereogenic center and exists as chiral twins. (S)-enantiomer has the desired pharmacological action where as the (R)-isomer is less active. It is observed that there is stereoselective bioconversion of the (R)- to (S)-fenoprofen. This stereoselective conversion is called chiral inversion.^{[4] [5]}

Contraindications

History of significantly impaired renal function; patients with known hypersensitivity to any component of the product; patients who have experienced asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs; treatment of perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.

Adverse effects

In October 2020, the U.S. Food and Drug Administration (FDA) required the drug label to be updated for all nonsteroidal anti-inflammatory medications to describe the risk of kidney problems in unborn babies that result in low amniotic fluid. They recommend avoiding NSAIDs in pregnant women at 20 weeks or later in pregnancy.^{[6] [7]}

Drug interactions

• Aminoglycosides (e.g. gentamicin): Plasma aminoglycoside levels may be elevated.
• Angiotensin-converting enzyme (ACE) inhibitors: Antihypertensive effect of ACE inhibitors may be diminished.
• Anticoagulants: Coadministration may prolong prothrombin time.
• Aspirin: Fenoprofen Cl may be increased; coadministration is not recommended.
• Diuretics: Patients treated with fenoprofen may be resistant to the effects of loop diuretics and thiazides.
• Hydantoins, sulfonamides, sulfonylureas: Fenoprofen may displace these drugs from their binding site.
• Lithium: Renal Cl of lithium may be reduced and plasma levels may be elevated, which may increase the risk of lithium toxicity.
• Methotrexate: May increase methotrexate levels.
• Phenobarbital: May decrease fenoprofen t. Dosage adjustments of fenoprofen may be required if phenobarbital is added or withdrawn.
• SSRIs (e.g. fluoxetine, citalopram): The risk of GI effects may be increased.

Laboratory test interactions

False elevation in free and total serum T 3 as measured by Amerlex-M kit.

Brand names

• UK Fenopron (Typharm Limited)

See also

• Ibuprofen
• Ketoprofen
• Thalidomide
• Chirality
• Chiral drugs
• Chiral inversion

External links

• Fenoprofen info from Drugs.com

Notes and References

1. Traa MX, Derry S, Moore RA . Single dose oral fenoprofen for acute postoperative pain in adults . The Cochrane Database of Systematic Reviews . 2011 . 2 . CD007556 . February 2011 . 21328296 . 4171001 . 10.1002/14651858.CD007556.pub2 .
2. Web site: 2022 First Generic Drug Approvals . U.S. Food and Drug Administration (FDA) . 3 March 2023 . https://web.archive.org/web/20230630003602/https://www.fda.gov/drugs/drug-and-biologic-approval-and-ind-activity-reports/2022-first-generic-drug-approvals . 30 June 2023 . live . 30 June 2023.
3. Web site: Competitive Generic Therapy Approvals . U.S. Food and Drug Administration (FDA) . 29 June 2023 . 29 June 2023 . 29 June 2023 . https://web.archive.org/web/20230629233651/https://www.fda.gov/drugs/generic-drugs/competitive-generic-therapy-approvals . live .
4. Rubin A, Knadler MP, Ho PP, Bechtol LD, Wolen RL . Stereoselective inversion of (R)-fenoprofen to (S)-fenoprofen in humans . Journal of Pharmaceutical Sciences . 74 . 1 . 82–84 . January 1985 . 3920382 . 10.1002/jps.2600740122 .
5. Caldwell J, Hutt AJ, Fournel-Gigleux S . The metabolic chiral inversion and dispositional enantioselectivity of the 2-arylpropionic acids and their biological consequences . Biochemical Pharmacology . 37 . 1 . 105–114 . January 1988 . 3276314 . 10.1016/0006-2952(88)90762-9 .
6. FDA Warns that Using a Type of Pain and Fever Medication in Second Half of Pregnancy Could Lead to Complications . U.S. Food and Drug Administration (FDA) . 15 October 2020 . 15 October 2020.
7. Web site: NSAIDs may cause rare kidney problems in unborn babies . U.S. Food and Drug Administration . 21 July 2017 . 15 October 2020.