What is the dosage and administration of Mucomyst (Acetylcysteine)?

Mucomyst (Acetylcysteine) Dosage and Administration

For acetaminophen overdose, administer a loading dose of 140 mg/kg orally, followed by 70 mg/kg every 4 hours for 17 total maintenance doses, diluted to a 5% solution in diet cola or other diet soft drinks. 1

Acetaminophen Overdose Protocol

Immediate Actions

• Administer acetylcysteine immediately if ≤24 hours have elapsed from ingestion, without waiting for acetaminophen level results 1
• Empty the stomach promptly via lavage or ipecac-induced emesis (15 mL for children up to age 12,30 mL for adolescents/adults) 1
• If activated charcoal was given, perform lavage before acetylcysteine administration, as charcoal adsorbs acetylcysteine and reduces effectiveness 1

Dosing Regimen

Loading Dose:

• 140 mg/kg body weight orally 1
• Dilute 20% solution to 5% concentration (see preparation table below) 1

Maintenance Doses:

• 70 mg/kg every 4 hours for 17 total doses 1
• First maintenance dose given 4 hours after loading dose 1
• If patient vomits within 1 hour of any dose, repeat that dose 1

Solution Preparation

• Dilute 20% acetylcysteine solution with diet cola or diet soft drinks to achieve final 5% concentration 1
• For gastric/Miller-Abbott tube administration, water may be used as diluent 1
• Prepare dilutions freshly and use within 1 hour 1
• Unopened 20% vials can be refrigerated up to 96 hours after opening 1

Example dosing by weight:

• 70-79 kg patient: Loading dose = 11 grams (55 mL of 20% solution + 165 mL diluent = 220 mL total); Maintenance dose = 5.5 grams (28 mL of 20% solution + 82 mL diluent = 110 mL total) 1

Monitoring and Laboratory Assessment

• Draw baseline labs before treatment: acetaminophen level, SGOT, SGPT, bilirubin, PT, creatinine, BUN, glucose, electrolytes 1
• Obtain acetaminophen level ≥4 hours post-ingestion (levels before 4 hours are unreliable) 1
• Repeat liver function tests, coagulation studies, and metabolic panel daily if acetaminophen level is potentially toxic 1

Treatment Duration Decisions Based on Acetaminophen Levels

Continue full 17-dose course if:

• Pretreatment level is clearly toxic (above solid line on Rumack-Matthew nomogram: >200 µg/mL at 4 hours or >50 µg/mL at 12 hours) 1
• Pretreatment level could not be obtained 1
• Level is above the "possible toxicity" line (25% below the toxic line) 1

May discontinue if:

• Pretreatment level is clearly non-toxic (below broken line on nomogram) AND overdose occurred ≥4 hours before the level was drawn 1

Obtain second level if:

• Initial level was non-toxic but time of ingestion was unknown or <4 hours (peak may not occur until 4+ hours post-ingestion) 1

Alternative Administration Route

• For patients persistently unable to retain oral medication, administer via duodenal intubation 1
• Acetylcysteine solution is NOT approved for parenteral injection 1

Mechanism of Action in Acetaminophen Toxicity

• NAC primarily works by increasing glutathione synthesis (from 0.54 to 2.69 µmol/g/h), providing substrate for detoxification of acetaminophen's toxic metabolite (N-acetyl-p-benzoquinoneimine) 2
• NAC does NOT form significant direct adducts with the toxic metabolite; virtually all NAC-acetaminophen conjugates originate from metabolism of glutathione-acetaminophen adducts 2
• NAC acts as a free-radical scavenger and glutathione precursor 3, 4

Mucolytic Use (Non-Overdose Indications)

• NAC is widely used as a mucolytic agent for chronic respiratory diseases including cystic fibrosis, COPD, and bronchial asthma 3, 5
• The drug has bronchorrheic effects when aerosolized and expectorant/mucoregulator actions when given orally 3
• NAC demonstrates antioxidant and anti-inflammatory properties by reducing TNF-α, IL-6, and IL-1β through NF-κB suppression 4

Safety Profile

• NAC has a well-established safety profile with uncommon toxicity dependent on route and dosage 4
• Adverse effects are rare even in combination with other treatments 5
• The medication is inexpensive and easily accessible 5