ACETADOTE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ACETADOTE (ACETADOTE).
Acetylcysteine serves as a precursor to glutathione, replenishing hepatic glutathione stores and enhancing the detoxification of the toxic metabolite N-acetyl-p-benzoquinoneimine (NAPQI) in acetaminophen overdose.
| Metabolism | Acetylcysteine is metabolized in the liver to cysteine and other metabolites, and undergoes extensive first-pass metabolism. It is also partially metabolized to glutathione. |
| Excretion | Renal: 60-80% as unchanged drug and metabolites (sulfate, glucuronide, cysteine, N-acetylcysteine conjugates). Fecal: minor (less than 3%). |
| Half-life | Terminal elimination half-life: 5.6 hours (range 4.1-7.6). In acetaminophen overdose, half-life may be prolonged (up to 20 hours) due to saturation of metabolic pathways. |
| Protein binding | 50-83% (primarily to albumin, and to a lesser extent alpha1-acid glycoprotein). |
| Volume of Distribution | 0.33-0.47 L/kg. Distributes primarily to extracellular fluid; penetrates hepatocytes (site of action) and renal tubular cells. |
| Bioavailability | Oral: 6-10% (extensive first-pass metabolism, primarily to cysteine and glutathione). IV: 100% (bioequivalent to oral when adjusted for bioavailability). |
| Onset of Action | IV: within 15-30 minutes (peak plasma levels). Oral: 60 minutes (peak plasma levels at 1-2 hours). Clinical effect (protection from hepatotoxicity) requires early administration (within 8-10 hours post-overdose). |
| Duration of Action | IV: 4-6 hours (maintains therapeutic levels with continuous infusion). Oral: 4-6 hours per dose. Clinical duration of protective effect is dependent on maintaining adequate hepatic glutathione levels; repeated doses are needed for 72 hours in overdose protocols. |
Intravenous loading dose of 150 mg/kg over 60 minutes, then 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours (total 300 mg/kg over 21 hours). Oral: 140 mg/kg loading dose, then 70 mg/kg every 4 hours for 17 doses.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment recommended for renal impairment; acetylcysteine is renally eliminated, but no GFR-based modifications established. Monitor for fluid overload in oliguric patients. |
| Liver impairment | No specific Child-Pugh-based adjustments. In severe hepatic impairment (e.g., fulminant hepatic failure), consider cautious use due to potential for fluid overload; no dose reduction recommended. |
| Pediatric use | Same weight-based regimen as adults: IV loading 150 mg/kg over 60 min, then 50 mg/kg over 4 h, then 100 mg/kg over 16 h. Oral: 140 mg/kg loading, then 70 mg/kg every 4 h for 17 doses. |
| Geriatric use | No specific dose adjustment; use standard dosing. Monitor for fluid overload and renal function in elderly patients, as they are more prone to volume-related complications. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ACETADOTE (ACETADOTE).
| Breastfeeding | Acetylcysteine is excreted into human milk in low amounts; the milk-to-plasma ratio is not established. Based on limited data, it is considered compatible with breastfeeding. However, caution is advised, and the infant should be monitored for potential adverse effects such as diarrhea or rash. |
| Teratogenic Risk | Acetadote (acetylcysteine) is classified as FDA Pregnancy Category B. There are no adequate and well-controlled studies in pregnant women. Animal studies have not demonstrated teratogenic effects, but risks cannot be ruled out. Use during pregnancy only if clearly needed, especially in the first trimester for acetaminophen overdose. |
■ FDA Black Box Warning
None.
| Serious Effects |
["History of hypersensitivity to acetylcysteine or any component of the formulation.","Significant electrolyte abnormalities (e.g., hypernatremia) when using intravenous form."]
| Precautions | ["Hypersensitivity reactions: Anaphylactoid reactions (bronchospasm, urticaria, angioedema) may occur, especially with intravenous administration.","Fluid overload: Intravenous administration may cause volume overload, particularly in patients with heart failure or renal impairment.","Electrolyte disturbances: Intravenous formulation contains sodium; monitor serum sodium in patients at risk for hypernatremia.","Nausea and vomiting: Common adverse effects; may require antiemetic therapy."] |
| Food/Dietary | No significant food interactions. However, maintain adequate hydration and avoid alcohol to reduce hepatotoxicity risk. N-acetylcysteine may be mixed with fruit juice if oral administration is used to improve palatability. |
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| Fetal Monitoring | Monitor maternal liver function tests, prothrombin time, and acetaminophen levels. During prolonged infusion, monitor for hypersensitivity reactions (bronchospasm, hypotension). Fetal monitoring should include heart rate and uterine activity when administered near term due to risk of anaphylactoid reactions. |
| Fertility Effects | No known adverse effects on fertility. Animal studies have not shown impaired fertility. However, no specific human data are available. |
| Clinical Pearls | Acetadote (N-acetylcysteine) is the antidote for acetaminophen overdose. Administer within 8-10 hours of ingestion for maximum efficacy. Monitor for anaphylactoid reactions, especially with rapid infusion. Use a 5% dextrose solution for dilution; do not use sterile water. Consider weight-based dosing for pediatric patients. |
| Patient Advice | Take the full course of treatment as prescribed, even if you feel well. · Inform your doctor immediately if you experience rash, itching, or difficulty breathing. · Do not consume alcohol during treatment as it may worsen liver damage. · Follow a bland diet to reduce gastrointestinal distress; avoid spicy or fatty foods. · Attend all follow-up appointments to monitor liver function. |