General
Acetylcysteine is available in rubber stoppered glass vials containing 4, 10, or 30 mL. The 20% solution may be diluted to a lesser concentration with either Sodium Chloride Injection, Sodium Chloride Inhalation Solution, Sterile Water for Injection, or Sterile Water for Inhalation. The 10% solution may be used undiluted.
Acetylcysteine does not contain an antimicrobial agent, and care must be taken to minimize contamination of the sterile solution. If only a portion of the solution in a vial is used for inhalation, store the remainder in a refrigerator and use within 96 hours.
Nebulization-face mask, mouth piece, tracheostomy
When nebulized into a face mask, mouth piece, or tracheostomy, 1 to 10 mL of the 20% solution or 2 to 20 mL of the 10% solution may be given every 2 to 6 hours; the recommended dose for most patients is 3 to 5 mL of the 20% solution or 6 to 10 mL of the 10% solution 3 to 4 times a day.
Nebulization tent, Croupette
In special circumstances it may be necessary to nebulize into a tent or Croupette, and this method of use must be individualized to take into account the available equipment and the patient's particular needs. 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 10% or 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 to 2 mL of a 10% to 20% solution may be given as often as every hour.
When used for the routine nursing care of patients with tracheostomy, 1 to 2 mL of a 10% to 20% solution may be given every 1 to 4 hours by instillation into the tracheostomy.
Acetylcysteine may be introduced directly into a particular segment of the bronchopulmonary tree by inserting (under local anesthesia and direct vision) a small plastic catheter into the trachea. Two to 5 mL of the 20% solution may then be instilled by means of a syringe connected to the catheter.
Acetylcysteine may also be given through a percutaneous intratracheal catheter. One to 2 mL of the 20% or 2 to 4 mL of the 10% solution every 1 to 4 hours may then be given by a syringe attached to the catheter.
Diagnostic Bronchograms
For diagnostic bronchial studies, two or three administrations of 1 to 2 mL of the 20% solution or 2 to 4 mL of the 10% solution should be given by nebulization or by instillation intratracheally, prior to the procedure.
Administration of Aerosol
Materials
Acetylcysteine may be administered using conventional nebulizers made of plastic or glass. Certain materials used in nebulization equipment react with acetylcysteine. The most reactive of these are certain metals (notably iron and copper) and rubber. Where materials may come into contact with acetylcysteine solution, parts made of the following acceptable materials should be used: glass, plastic, aluminum, anodized aluminum, chromed metal, tantalum, sterling silver, or stainless steel. Silver may become tarnished after exposure, but this is not harmful to the drug action or to the patient.
Nebulizing Gases
Compressed tank gas (air) or an air compressor should be used to provide pressure for nebulizing the solution. Oxygen may also be used but should be used with the usual precautions in patients with severe respiratory disease and CO2 retention.
Apparatus
Acetylcysteine is usually administered as fine nebulae and the nebulizer used should be capable of providing optimal quantities of a suitable range of particle sizes.
Commercially available nebulizers will produce nebulae of acetylcysteine satisfactory for retention in the respiratory tract. Most of the nebulizers tested will supply a high proportion of the drug solution as particles of less than 10 microns in diameter. Mitchell2 has shown that particles less than 10 microns should be retained in the respiratory tract satisfactorily.
Various intermittent positive pressure breathing devices nebulized acetylcysteine with a satisfactory efficiency including: No. 40 De Vilbiss (The De Vilbiss Co., Somerset, Pennsylvania), and the Bennett Twin-Jet Nebulizer (Puritan Bennett Corp., Oak at 13th., Kansas City, Missouri).
The nebulized solution may be inhaled directly from the nebulizer. Nebulizers may also be attached to the plastic face masks or plastic mouthpieces. Suitable nebulizers may also be fitted for use with the various intermittent positive pressure breathing (IPPB) machines. The nebulizing equipment should be cleaned immediately after use because the residues may clog the smaller orifices or corrode metal parts.
Hand bulbs are not recommended for routine use in nebulizing acetylcysteine because their output is generally too small. Also, some hand-operated nebulizers deliver particles that are larger than optimum for inhalation therapy.
Acetylcysteine should not be placed directly into the chamber of a heated (hot pot) nebulizer. A heated nebulizer may be part of the nebulization assembly to provide a warm saturated atmosphere if the acetylcysteine aerosol is introduced by means of a separate unheated nebulizer. Usual precautions for administration of warm saturated nebulae should be observed.
The nebulized solution may be breathed directly from the nebulizer. Nebulizers may also be attached to plastic face masks, plastic face tents, plastic mouth pieces, conventional plastic oxygen tents, or head tents. Suitable nebulizers may also be fitted for use with the various intermittent positive pressure breathing (IPPB) machines.
The nebulizing equipment should be cleaned immediately after use, otherwise the residues may occlude the fine orifices or corrode metal parts.
Prolonged Nebulization
When three fourths of the initial volume of acetylcysteine solution has been nebulized, a quantity of Sterile Water for Injection, USP (approximately equal to the volume of solution remaining) should be added to the nebulizer. This obviates any concentration of the agent in the residual solvent remaining after prolonged nebulization.
Compatibility
The physical and chemical compatibility of acetylcysteine solutions with certain other drugs that might be concomitantly administered by nebulization, direct instillation, or topical application has been studied.
Acetylcysteine should not be mixed with certain antibiotics. For example, the antibiotics, tetracycline hydrochloride, oxytetracycline hydrochloride, and erythromycin lactobionate, were found to be incompatible when mixed in the same solution. These agents may be administered from separate solutions if administration of these agents is desirable.
The supplying of these data should not be interpreted as a recommendation for combining acetylcysteine with other drugs. The table is not presented as positive assurance that no incompatibility will be present, since these data are based only on short-term compatibility studies done in the Mead Johnson Research Center. Manufacturers may change their formulations, and this could alter compatibilities. These data are intended to serve only as a guide for predicting compounding problems.
If it is deemed advisable to prepare an admixture, it should be administered as soon as possible after preparation. Do not store unused mixtures.
IN VITRO COMPATIBILITY1 TESTS OF ACETYLCYSTEINE
1. The rating, Incompatible, is based on the formation of a precipitate, a change in clarity, immiscibility, or a rapid loss of potency of acetylcysteine or the active ingredient of the PRODUCT AND/OR AGENT in the admixture.
The rating, Compatible, means that there was no significant physical change in the admixture when compared with a control solution of the PRODUCT AND/OR AGENT, and that there was no predicted chemical incompatibility. All of the admixtures have been tested for short-term chemical compatibility by assaying for the concentration of acetylcysteine after mixing.
2. The active ingredient in the PRODUCT AND/OR AGENT was also assayed after mixing. Some of the admixtures developed minor physical changes which were considered to be insufficient to rate the admixture Incompatible. These are listed in footnotes 3, 4, and 5.
3. A strong odor developed after storage for 24 hours at room temperature.
4. The admixture was a slightly darker shade of yellow than a control solution of the PRODUCT AND/OR AGENT.
5. A light tan color developed after storage for 24 hours at room temperature.
6. Entries are final concentrations. Values in parentheses relate volumes of acetylcysteine solutions to volume of test solutions.
RATIO TESTED6
PRODUCT AND/OR AGENT
COMPATIBILITY
ACETYLCYSTEINE
PRODUCT
RATING
OR AGENT
ANESTHETIC, GAS
Halothane
Compatible
20%
Infinite
Nitrous Oxide
Compatible
20%
Infinite
ANESTHETIC, LOCAL
Cocaine HCl
Compatible
10%
5%
Lidocaine HCl
Compatible
10%
2%
Tetracaine HCl
Compatible
10%
1%
ANTIBACTERIALS (A parenteral form of each antibiotic was used)
Bacitracin2,3 (mix and use at once)
Compatible
10%
5,000 U/mL
Chloramphenicol Sodium Succinate
Compatible
20%
20 mg/mL
Carbenicillin Disodium2 (mix and use at once)
Compatible
10%
125 mg/mL
Gentamicin Sulfate2
Compatible
10%
20 mg/mL
Kanamycin Sulfate2 (mix and use at once)
Compatible
10%
167 mg/mL
Compatible
17%
85 mg/mL
Lincomycin HCl2
Compatible
10%
150 mg/mL
Neomycin Sulfate2
Compatible
10%
100 mg/mL
Novobiocin Sodium2
Compatible
10%
25 mg/mL
Penicillin G Potassium2 (mix and use at once)
Compatible
10%
25,000 U/mL
Compatible
10%
100,000 U/mL
Polymyxin B Sulfate2
Compatible
10%
50,000 U/mL
Cephalothin Sodium
Compatible
10%
110 mg/mL
Colistimethate Sodium2 (mix and use at once)
Compatible
10%
37.5 mg/mL
Vancomycin HCl2
Compatible
10%
25 mg/mL
Amphotericin B
Incompatible
4% - 15%
1 - 4 mg/mL
Chlortetracycline HCl2
Incompatible
10%
12.5 mg/mL
Erythromycin Lactobionate
Incompatible
10%
15 mg/mL
Oxytetracycline HCl
Incompatible
10%
12.5 mg/mL
Ampicillin Sodium
Incompatible
10%
50 mg/mL
Tetracycline HCl
Incompatible
10%
12.5 mg/mL
BRONCHODILATORS
Isoproterenol HCl2
Compatible
3%
0.5%
Isoproterenol HCl2
Compatible
10%
0.05%
Isoproterenol HCl2
Compatible
20%
0.05%
Isoproterenol HCl
Compatible
13.3% (2 parts)
0.33% (1 part)
Isoetharine HCl
Compatible
13.3% (2 parts)
(1 part)
Epinephrine HCl
Compatible
13.3% (2 parts)
0.33% (1 part)
CONTRAST MEDIA
Iodized Oil
Incompatible
20%/20 mL
40%/10 mL
DECONGESTANTS
Phenylephrine HCl2
Compatible
3%
0.25%
Phenylephrine HCl
Compatible
13.3% (2 parts)
0.17% (1 part)
ENZYMES
Chymotrypsin
Incompatible
5%
400 γ/mL
Trypsin
Incompatible
5%
400 γ/mL
SOLVENTS
Alcohol
Compatible
12%
10% - 20%
Propylene Glycol
Compatible
3%
10%
STEROIDS
Dexamethasone Sodium Phosphate
Compatible
16%
0.8 mg/mL
Prednisolone Sodium Phosphate5
Compatible
16.7%
3.3 mg/mL
OTHER AGENTS
Hydrogen Peroxide
Incompatible
(All ratios)
Sodium Bicarbonate
Compatible
20% (1 part)
4.2% (1 part)
General
Regardless of the quantity of acetaminophen reported to have been ingested, administer acetylcysteine immediately if 24 hours or less have elapsed from the reported time of ingestion of an overdose of acetaminophen. Do not await results of assays for acetaminophen level before initiating treatment with acetylcysteine. The following procedures are recommended:
The stomach should be emptied promptly by lavage or by inducing emesis with syrup of ipecac. Syrup of ipecac should be given in a dose of 15 mL for children up to age 12 and 30 mL for adolescents and adults followed immediately by drinking copious amounts of water. The dose should be repeated if emesis does not occur in 20 minutes.
In the case of a mixed drug overdose activated charcoal may be indicated. However, if activated charcoal has been administered, lavage before administering acetylcysteine treatment. Activated charcoal adsorbs acetylcysteine in vitro and may do so in patients and thereby may reduce its effectiveness.
Draw blood for predetoxification acetaminophen plasma assay and baseline SGOT, SGPT, bilirubin, prothrombin time, creatinine, BUN, blood sugar and electrolytes.
Administer the loading dose of acetylcysteine, 140 mg per kg of body weight. (Prepare acetylcysteine for oral administration as described in the Dosage Guide and Preparation table).
Determine subsequent action based on predetoxification plasma acetaminophen information. Choose ONE of the following four courses of therapy.
Predetoxification plasma acetaminophen level is clearly in the toxic range (See Acetaminophen Assays - Interpretation and Methodology below):Administer a first maintenance dose (70 mg/kg acetylcysteine) 4 hours after the loading dose. The maintenance dose is then repeated at 4-hour intervals for a total of 17 doses. Monitor hepatic and renal function and electrolytes throughout the detoxification process.
Predetoxification acetaminophen level could not be obtainedProceed as in A.
Predetoxification acetaminophen level is clearly in the non-toxic range (beneath the dashed line on the nomogram) and you know that acetaminophen overdose occurred at least 4 hours before the predetoxification acetaminophen plasma assaysDiscontinue administration of acetylcysteine.
Predetoxification acetaminophen level was in the non-toxic range, but time of ingestion was unknown or less than 4 hoursBecause the level of acetaminophen at the time of predetoxification assay may not be a peak value (peak may not be achieved before 4 hours post-ingestion), obtain a second plasma level in order to decide whether or not the full 17-dose detoxification treatment is necessary.
If the patient vomits an oral dose within 1 hour of administration, repeat that dose.
In the occasional instances where the patient is persistently unable to retain the orally administered acetylcysteine, the antidote may be administered by duodenal intubation.
Repeat SGOT, SGPT, bilirubin, prothrombin time, creatinine, BUN, blood sugar and electrolytes daily if the acetaminophen plasma level is in the potentially toxic range as discussed below.
Preparation of Acetylcysteine for Oral Administration
Oral administration requires dilution of the 20% solution with diet cola or other diet soft drinks, to a final concentration of 5% (see Dosage Guide and Preparation table). If administered via gastric tube or Miller-Abbott tube, water may be used as the diluent. The dilutions should be freshly prepared and utilized within one hour. Remaining undiluted solutions in opened vials can be stored in the refrigerator up to 96 hours. ACETYLCYSTEINE IS NOT APPROVED FOR PARENTERAL INJECTION.