NALFON
Clinical safety rating: caution
Comprehensive clinical and safety monograph for NALFON (NALFON).
Fenoprofen, a propionic acid derivative, nonselectively inhibits cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), reducing prostaglandin synthesis.
| Metabolism | Primarily hepatic via glucuronidation and hydroxylation; minor involvement of CYP2C9. |
| Excretion | Renal: 90% (mostly as glucuronide conjugates and unchanged drug; unchanged drug ~1-5%); Fecal: <5%; Biliary: negligible. |
| Half-life | 3-4 hours (terminal half-life in healthy adults; prolonged in elderly and hepatic impairment). |
| Protein binding | 99% (primarily to albumin). |
| Volume of Distribution | 0.15-0.2 L/kg (small, reflecting high protein binding and limited extravascular distribution). |
| Bioavailability | Oral: ~100% (well absorbed; slight first-pass effect). |
| Onset of Action | Oral: 30 minutes (analgesic effect). |
| Duration of Action | 4-6 hours (analgesic effect). |
NALFON (fenoprofen) 200-600 mg orally 3-4 times daily; maximum dose 3200 mg/day.
| Dosage form | TABLET |
| Renal impairment | Creatinine clearance 30-80 mL/min: reduce dose to 200 mg every 6-8 hours. Creatinine clearance <30 mL/min: avoid use. |
| Liver impairment | Child-Pugh class A or B: use with caution, reduce dose by 50%. Child-Pugh class C: contraindicated. |
| Pediatric use | Not recommended for pediatric use; safety and efficacy not established. |
| Geriatric use | Start at lowest effective dose (200 mg 3-4 times daily); monitor renal function and gastrointestinal bleeding risk. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for NALFON (NALFON).
| Breastfeeding | NALFON is excreted into breast milk in low concentrations; the M/P ratio is not specifically known but expected to be low. Due to potential adverse effects in neonates (e.g., renal impairment, gastrointestinal effects), caution is advised. Recommend avoiding use during breastfeeding, especially in preterm or low-birth-weight infants. |
| Teratogenic Risk | NSAIDs including NALFON are associated with increased risk of fetal renal dysfunction, oligohydramnios, and premature closure of the ductus arteriosus, particularly in the third trimester. First trimester exposure may be associated with a small increased risk of cardiac defects and gastroschisis, but data are limited. Avoid use after 30 weeks gestation due to risk of premature ductus arteriosus closure. |
■ FDA Black Box Warning
Nonsteroidal anti-inflammatory drugs (NSAIDs) cause an increased risk of serious cardiovascular thrombotic events, including myocardial infarction and stroke, which can be fatal. This risk may occur early in treatment and may increase with duration of use. NALFON is contraindicated in the setting of coronary artery bypass graft (CABG) surgery.
| Serious Effects |
["History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs","In the setting of CABG surgery","Advanced renal disease"]
| Precautions | ["Cardiovascular thrombotic events","Gastrointestinal bleeding, ulceration, and perforation","Renal toxicity including renal papillary necrosis","Hepatic toxicity","Hypertension","Anaphylactoid reactions","Exacerbation of asthma"] |
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| Fetal Monitoring | Monitor maternal renal function, blood pressure, and signs of bleeding. In pregnancy, fetal monitoring with ultrasound for oligohydramnios and ductus arteriosus Doppler if used beyond 20 weeks. Assess for premature ductus arteriosus closure in third trimester. |
| Fertility Effects | Nonsteroidal anti-inflammatory drugs (NSAIDs) like NALFON may impair female fertility by inhibiting ovulation through prostaglandin synthesis inhibition; this effect is reversible upon discontinuation. No known effect on male fertility at therapeutic doses. |