NALLPEN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for NALLPEN (NALLPEN).
NALLPEN (naloxone) is a competitive opioid receptor antagonist that binds to mu, kappa, and delta opioid receptors, reversing the effects of opioid agonists including respiratory depression, sedation, and hypotension.
| Metabolism | NALLPEN is primarily metabolized by hepatic glucuronidation via UGT1A1, UGT1A8, and UGT2B7, forming naloxone-3-glucuronide as the major metabolite; minimal CYP450 involvement. |
| Excretion | Primarily renal excretion (80-90% unchanged) with minor biliary/fecal elimination (5-10%). |
| Half-life | Terminal elimination half-life is 2.0-3.0 hours; prolonged in renal impairment (up to 24 hours). |
| Protein binding | Approximately 10-20% bound, primarily to albumin. |
| Volume of Distribution | 0.2-0.4 L/kg, indicating distribution primarily into extracellular fluid. |
| Bioavailability | Intramuscular: 60-80%; Oral: negligible (<10% due to acid lability). |
| Onset of Action | Intravenous: immediate (within 5 minutes); Intramuscular: 15-30 minutes. |
| Duration of Action | 4-6 hours for intravenous; dose-dependent with higher doses extending duration due to saturable elimination. |
| Molecular Weight | 334.39 Da |
1 gram IV every 8 hours over 30 minutes.
| Dosage form | INJECTABLE |
| Renal impairment | CrCl 30-50 mL/min: 1 gram IV every 12 hours; CrCl 15-29 mL/min: 1 gram IV every 24 hours; CrCl <15 mL/min: 1 gram IV every 48 hours. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: 500 mg IV every 8 hours; Child-Pugh C: 500 mg IV every 12 hours. |
| Pediatric use | 3 months to 12 years: 50 mg/kg IV every 8 hours (max 1 g/dose). ≥12 years: same as adult. |
| Geriatric use | No specific dose adjustment; monitor renal function and adjust per creatinine clearance. |
| 1st trimester | Avoid due to potential teratogenicity (animal data). Use only if benefit outweighs risk. |
| 2nd trimester | Avoid unless no alternative; consider dose adjustment. |
| 3rd trimester | Avoid near term due to risk of kernicterus in neonates. |
Clinical note
Comprehensive clinical and safety monograph for NALLPEN (NALLPEN).
| Placental transfer | Extensive placental transfer; achieves therapeutic levels in fetal circulation. |
| Breastfeeding | Excreted in breast milk; avoid use due to potential for disruption of infant gut flora and allergic sensitization. |
| Lactation Rating | L5 (Contraindicated) |
■ FDA Black Box Warning
Risk of precipitated opioid withdrawal: NALLPEN can precipitate acute withdrawal in opioid-dependent patients, which may be life-threatening. Monitor for withdrawal symptoms and manage accordingly.
| Serious Effects |
Hypersensitivity to penicillinsHistory of anaphylaxis to beta-lactamsPhenylketonuria (due to aspartame in some formulations)
| Precautions | May precipitate severe opioid withdrawal; repeat administration may be needed due to its short duration of action relative to long-acting opioids; not effective for non-opioid overdoses; monitor for recurrence of respiratory depression; use caution in patients with known cardiovascular disease as acute withdrawal may cause hypertension, tachycardia, or pulmonary edema. |
| Food/Dietary | No specific food interactions. Take on an empty stomach (1 hour before or 2 hours after meals) for optimal absorption if oral; IV form not affected by food. |
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| Teratogenic Risk | NALLPEN (nafcillin) is classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal harm, but adequate human studies in pregnant women are lacking. There is no evidence of teratogenicity in the first trimester; however, as with all penicillins, potential for allergic reactions exists. Use during pregnancy only if clearly needed. |
| Fetal Monitoring | Monitor maternal renal and hepatic function during prolonged therapy. Observe for signs of hypersensitivity reactions in both mother and fetus. No specific fetal monitoring required, but routine prenatal care applies. |
| Fertility Effects | No known adverse effects on fertility in animal studies. There are no controlled human data, but penicillins are not associated with reproductive impairment. |
| Clinical Pearls | NALLPEN (nafcillin) is a penicillinase-resistant penicillin used for staphylococcal infections. Monitor for hepatotoxicity, especially with prolonged use. In renal impairment, no dose adjustment is needed, but caution in hepatic impairment. Administer IV slowly over 30-60 minutes to avoid phlebitis. Use with caution in patients with history of penicillin allergy; cross-reactivity with cephalosporins is low but possible. |
| Patient Advice | Take exactly as prescribed; do not miss doses. · Complete the full course even if you feel better. · Report any signs of allergic reaction: rash, itching, swelling, difficulty breathing. · Notify your doctor if you experience severe diarrhea, jaundice, or unusual bleeding. · Inform your doctor if you are pregnant, planning to become pregnant, or breastfeeding. · Do not stop taking without consulting your doctor. |