Acetylcysteine

For acetaminophen toxicity:
a) A 2–3 hour wait between activated charcoal and PO administration of acetylcysteine (NAC) is necessary. Give NAC as an initial oral loading dose of 140 mg/kg (dilute to 5% in dextrose or sterile water), followed by 70 mg/kg PO four times daily (q6h) for 7 treatments. With ingestion of massive quantities, some authors suggest using a 280 mg/kg loading dose and continuing treatment for 12–17 doses. May also be given IV after diluting to 5% and given via slow IV over 15–20 minutes. Additional therapy may include IV fluids, blood or Oxyglobin®, ascorbic acid and SAMe. (Wismer 2006)

For phenol toxicity:
a) 140 mg/kg PO or IV initially, then 50 mg/kg q4h for 3 days. May be partially effective to reduce hepatic and renal injury. Resultant methemoglobinemia should be treated with ascorbic acid or methylene blue. (Dorman & Dye 2005) 

For adjunctive treatment of hepatic lipidosis (see also Carnitine):
a) Identify underlying cause of anorexia and provide a protein replete feline diet, give acetylcysteine (NAC) at 140 mg/kg IV over 20 minutes, then 70 mg/kg IV q12h; dilute 10% NAC with saline 1:4 and administer IV using a 0.25 micron filter; correct hypokalemia and hypophosphatemia, beware of electrolyte changes with re-feeding phenomenon (Center 2006)

To help break up chondroids in the gutteral pouch:
a) Instill 20% solution (Foreman 1999) In neonatal foals to break up meconium refractory to repeated enemas:
a) 8 grams in 20 g sodium bicarbonate in 200 mL water (pH of 7.6), give as enema as needed to effect (Freeman 1999)
b) With foal in lateral recumbency, insert a 30 french foley catheter with a 30 cc bulb for a retention enema. Using gravity flow, infuse slowly 100– 200 mL of 4% acetylcysteine solution and retain for 30–45 minutes. IV fluids and pain medication should be considered. Monitor for possible bladder distention. (Pusterla et al. 2003)

For acetaminophen (Paracetamol) toxicity:
a) A 2–3 hour wait between activated charcoal and PO administration of acetylcysteine (NAC) is necessary. Give NAC as an initial oral loading dose of 140 mg/kg (dilute to 5% in dextrose or sterile water), followed by 70 mg/kg PO four times daily (q6h) for 7 treatments. With ingestion of massive quantities, some authors suggest using a 280 mg/kg loading dose and continuing treatment for 12–17 doses. May also be given IV after diluting to 5% and given via slow IV over 15–20 minutes. Additional therapy may include IV fluids, blood or Oxyglobin®, ascorbic acid and SAMe. (Wismer 2006)
b) 150 mg/kg PO or IV initially, then 50 mg/kg q4h for 17 additional doses (Bailey 1986)
c) Loading dose of 140 mg/kg PO, then 70 mg/kg PO every 6 hours for 7 treatments (Grauer & Hjelle 1988)

For phenol toxicity:
a) 140 mg/kg PO or IV initially, then 50 mg/kg q4h for 3 days. May be partially effective to reduce hepatic and renal injury. Resultant methemoglobinemia should be treated with ascorbic acid or methylene blue. (Dorman & Dye 2005)

For hepatotoxicity secondary to xylitol poisoning:
a) Acetylcysteine at 140–280 mg/kg loading dose IV, PO; followed by 70 mg/kg four times daily; vitamin K (phytonadione) at 1.25–2.5 mg/kg PO twice daily; plasma, SAMe at 20 mg/kg/day PO; vitamin E at 100–400 Units twice daily PO; and silymarin 20–50 mg/kg/day PO. (Talcott 2008)

For degenerative myelopathy:
a) 25 mg/kg PO q8h for 2 weeks, then q8h every other day. The 20% solution should be diluted to 5% with chicken broth or suitable diluent.
Used in conjunction with aminocaproic acid (500 mg per dog PO q8h indefinitely). Other treatments may include prednisone (0.25–0.5 mg/kg PO daily for 10 days then every other day), Vitamin C (1000 mg PO q12h) and Vitamin E (1000 Units PO q12h). Note: No treatment has been shown to be effective in published trials. (Shell 2003)

Effervescent tablet or Dispersible tablet: Adults and children above 6 years: One effervescent tablet of Acetylcysteine 600 mg a day (preferably in the evening). The duration of treatment should be 5 to 10 days in the acute treatment, whereas it may be continued in the chronic states for several months, according to the advice of the physician. Dissolve the tablets in a glass containing a small quantity of water, mixing it, if necessary, with a spoon. A palatable solution is thus obtained, which can be drunk directly from the glass.Effervescent Granules: Adults and children above 6 years: 1 sachet Acetylcysteine 200 mg or 2 sachets Acetylcysteine 100 mg, 2-3 times a day. Children (2-6 years of age): 1 sachet Acetylcysteine 100 mg from 2 to 4 times a day, according to the age. The duration of treatment should be 5 to 10 days in the acute treatment, whereas it may be continued in the chronic states for several months, according to the advice of the physician.Dissolve the contents of the sachets in a glass containing a small quantity of water; mixing it, if necessary, with a spoon. A palatable solution is thus obtained, which can be drunk directly from the glass.Nebuliser Solution: The 20% solution may be diluted to a lesser concentration with either Sodium Chloride for injection, Sodium Chloride for inhalation, sterile water for injection, or sterile water for inhalation. Adult: 5-10 ml of 10% or 20% solution by Nebuliser every 6-8 hr PRN. Children: 1-11 months: 1-2 ml of 20% or 2-4 ml of 10% solution by Nebuliser every 6-8 hr PRN. 12 months-11 years: 3-5 ml of 20% or 6-10 ml of 10% solution by Nebuliser every 6-8 hr PRN. Below 12 years: 5-10 ml of 10/20% solution by Nebuliser every 6-8 hr PRN. ** Diagnostic Bronchograms: 1-2 ml of 20% or 2-4 ml of 10% solution 2-3 times by Nebulisation or by instillation intratracheally prior to procedure.** Nebulisation tent or croupette: This form of administration requires very large volumes of the solution, occasionally as much as 300 ml during a single treatment period. If a tent or croupette must be used, the recommended dose is the volume of acetylcysteine (using 20%) that will maintain a very heavy mist in the tent or croupette for the desired period. Administration for intermittent or continuous prolonged periods, including overnight, may be desirable.** Direct Instillation: When used by direct instillation, 1-2 ml of a 20% solution may be given as often as every hour. When used for the routine nursing care of patients with tracheostomy, 1-2 ml of a 20% solution may be given every 1-4 hours by instillation into the tracheostomy.