Monthly Compounding Update
  Gentamicin 40 mg/mL for Inhalation
  There has been increasing interest in using inhaled antibiotics post lung transplantation and for a number of lower respiratory tract infections.
Loyd V. Allen, Jr., PhD
Professor Emeritus, College of Pharmacy, University of Oklahoma, Oklahoma City
Gentamicin 40 mg/mL for Inhalation
Gentamicin (equivalent
to 5.97 g gentamicin
Sodium bisulfite
Disodium EDTA
Sodium hydroxide and/or
hydrochloric acid
Sterile Water for Injection
4.0 g

320 mg
10 mg
qs to pH

qs   100 mL
US Pharmacist

Method of Preparation: Note—This formulation should be prepared according to strict aseptic compounding technique in a laminar airflow hood in a cleanroom or via isolation barrier technology by a compounding pharmacist who is validated in aseptic compounding. This is a high-risk preparation.

Calculate the quantity of each ingredient for the amount to be prepared. Accurately weigh or measure each ingredient. Dissolve the sodium bisulfite and disodium edetic acid (EDTA) in about 90 mL of Sterile Water for Injection previously heated to 60ºC to 70ºC. Cool and add the gentamicin sulfate; mix until dissolved. Using sodium hydroxide and/or hydrochloric acid, adjust the pH to 4.0 to 5.5 and mix well. Add sufficient Sterile Water for Injection to final volume and mix well. Sterile-filter into sterile containers, then package and label.

Use: This preparation has been used for susceptible infections involving the lungs.

Packaging: Package in sterile containers.

Labeling: Keep out of reach of children. Discard after ____ [time period].

Stability: Refer to USP <797> for the beyond-use date for this preparation.1

Quality Control: Quality-control assessment can include weight/volume, physical observation, pH, specific gravity, osmolality, assay, color, clarity, particulate matter, and sterility.2,3

Discussion: Gentamicin inhalation has been used in the treatment of susceptible infections of the lung. Inhaled antibiotics may provide an effective suppressive antibiotic therapy with an acceptable safety profile for adult patients with stable noncystic fibrosis (non-CF) bronchiectasis and chronic bronchial infection.4

Inhaled antibiotics have been used to treat chronic airway infections since the 1940s, with the earliest experience involving aerosolizing antibiotics designed for parenteral administration. Over the past decade, there has been a growing interest in the use of inhaled antibiotics for other lower respiratory tract infections, such as non-CF bronchiectasis, ventilator-associated pneumonia, chronic obstructive pulmonary disease, and mycobacterial disease, and in the post–lung transplantation setting.5

Gentamicin sulfate is an aminoglycoside antibiotic occurring as the sulfate salt, or a mixture of such salts, of the antibiotic substances produced by the growth of Micromonospora purpurea. Commercially, it is a mixture of the sulfate salts of gentamicin C1, C2, and C1A. It occurs as a white to buff powder that is soluble in water, but insoluble in alcohol. The pH of the injection is between 3.0 and 5.5. Gentamicin sulfate has a potency equivalent of not less than 590 mcg of gentamicin per milligram calculated on the dried basis. It should be preserved in tight containers.1,6

Disodium EDTA (disodium ethylenediaminetetraacetate, edetic acid disodium, C10H14N2Na2O8, MW 336.21) occurs as an odorless, white, crystalline powder with a slightly acidic taste. It is soluble 1 g in 11 mL of water, slightly soluble in 95% ethanol, and practically insoluble in chloroform and ether. The pH of a 1% w/v solution in carbon dioxide–free water is in the range of 4.3 to 4.7. Disodium EDTA also occurs as the dihydrate (C10H14N2Na2O8.2H2O, MW 372.2). It melts at 252ºC with some decomposition.7

Sodium bisulfite (sodium hydrogen sulfite, NaHSO3, MW 104.07) occurs as a white, crystalline powder. It is soluble 1 in 3.5 parts of water and in 70 parts of 95% alcohol. Generally, most substances sold as sodium bisulfite contain significant but variable amounts of sodium metabisulfite; sodium metabisulfite is less hygroscopic and more stable during storage and shipment. Sodium bisulfite is generally used as an antioxidant in solutions of intermediate pH.8

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1. U.S. Pharmacopeia 38/National Formulary 3. Rockville, MD: U.S. Pharmacopeial Convention, Inc; 2014:559-611,1940.
2. Allen LV Jr. Standard operating procedure for particulate testing for sterile products. IJPC. 1998;2:78.
3. Allen LV Jr. Standard operating procedure: quality assessment for injectable solutions. IJPC. 1999;3:406-407.
4. Brodt AM, Stovold E, Zhang L. Inhaled antibiotics for stable non-cystic fibrosis bronchiectasis: a systematic review. Eur Respir J. 2014;44:382-393.
5. Quon BS, Goss CH, Ramsey BW. Inhaled antibiotics for lower airway infections. Ann Am Thorac Soc. 2014;11:425-434.
6. McEvoy GK. AHFS Drug Information 2012. Bethesda, MD: American Society of Health-System Pharmacists; 2012:58-64.
7. Cantor SL, Shah S. Disodium edetate. In: Rowe RC, Sheskey PJ, Cook WG, Fenton ME, eds. Handbook of Pharmaceutical Excipients. 7th ed. Washington, DC: American Pharmaceutical Association; 2012:274-276.
8. Kabir MA, Reo JP. Sodium metabisulfite. In: Rowe RC, Sheskey PJ, Quinn ME, eds. Handbook of Pharmaceutical Excipients. 6th ed. Washington, DC: American Pharmaceutical Association; 2009:654-656.