Nonproprietary Names

USP:Strong Ammonia Solution
PhEur:Ammonia Solution, Concentrated USP-NF: Strong Ammonia Solution

Synonyms

Ammoniaca; ammoniacum; ammoniae solution concentrata; aqua ammonia; concentrated ammonia solution; spirit of hartshorn; stronger ammonia water.

Chemical Name and CAS Registry Number

Ammonia [7664-41-7]

Empirical Formula and Molecular Weight

NH3 17.03

Structural Formula

See Section 4.

Functional Category

Alkalizing agent.

Applications in Pharmaceutical Formulation or Technology

Technology Ammonia solution is typically not used undiluted in pharmaceutical applications. Generally, it is used as a buffering agent or to adjust the pH of solutions. Most commonly, ammonia solution (the Ammonia Solution concentrated form) is used to produce more dilute ammonia solutions. Therapeutically, dilute ammonia solution is used as a reflex stimulant in ‘smelling salts’, as a rubefacient, and as a counterirritant to neutralize insect bites or stings.(1)

Description

Strong ammonia solution occurs as a clear, colorless liquid having an exceedingly pungent, characteristic odor. The PhEur 6.0 states that concentrated ammonia solution contains not less than 25.0% and not more than 30.0% w/w of ammonia (NH3). The USP32– NF27 states that strong ammonia solution contains not less than 27.0% and not more than 31.0% w/w of ammonia (NH3). See also Section 17.

Pharmacopeial Specifications

See Table I. Table I: Pharmacopeial specifications for ammonia solution. Test PhEur 6.0 USP32–NF27 Identification Characters Appearance of solution Oxidizable substances Pyridine and related substances þ þ þ þ42 ppm þ — — þ — Carbonates 460 ppm — Chlorides 41 ppm — Sulfates 45 ppm — Iron 40.25 ppm — Heavy metals 41 ppm 40.0013% Residue on evaporation 420 mg/L — Limit of nonvolatile residue — 40.05% Assay (of NH3) 25.0–30.0% 27.0–31.0%

Typical Properties

Solubility Miscible with ethanol (95%) and water. Specific gravity 0.892–0.910

Stability and Storage Conditions

On exposure to the air, ammonia solution rapidly loses ammonia. Ammonia solution should be stored in a well-closed container, protected from the air, in a cool, dry place. The storage temperature should not exceed 208C.

Incompatibilities

Ammonia solution reacts vigorously with sulfuric acid or other strong mineral acids and the reaction generates considerable heat; the mixture boils.

Method of Manufacture

Ammonia is obtained commercially chiefly by synthesis from its constituent elements, nitrogen and hydrogen, which are combined under high pressure and temperature in the presence of a catalyst. Ammonia solution is produced by dissolving ammonia gas in water.

Safety

Ingestion of strong solutions of ammonia is very harmful and causes severe pain in the mouth, throat, and gastrointestinal tract as well as severe local edema with cough, vomiting, and shock. Burns to the esophagus and stomach may result in perforation. Inhalation of the vapor causes sneezing, coughing, and, in high concentration, pulmonary edema. Asphyxia has been reported. The vapor is irritant to the eyes. Strong solutions are harmful when applied to the conjunctiva and mucous membranes. Topical application of even dilute ammonia solutions, used to treat insect bites, has caused burns, particularly when used with a subsequent dressing.(2–4) When used as an excipient, ammonia solution is generally present in a formulation in a highly diluted form.

Handling Precautions

Observe normal precautions appropriate to the circumstances and quantity of material handled. Care should be used in handling strong or concentrated ammonia solutions because of the caustic nature of the solution and the irritating properties of its vapor. Before containers are opened, they should be well cooled. The closure should be covered with a cloth or similar material while opening. Ammonia solution should not be tasted and inhalation of the vapor should be avoided. Ammonia solution should be handled in a fume cupboard. Eye protection, gloves, and a respirator are recommended.

Regulatory Status

Included in the FDA Inactive Ingredients Database (oral suspensions, topical preparations). Included in nonparenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Non-medicinal Ingredients. 17 Related Substances Dilute ammonia solution. Dilute ammonia solution Synonyms Ammonia water Specific gravity 0.95–0.96 Comments Several pharmacopeias include monographs for dilute ammonia solution. The JP XV, for example, states that ammonia water contains not less than 9.5% and not more than 10.5% w/v of ammonia (NH3).

Comments

Where ‘ammonia solution’ is prescribed therapeutically, dilute ammonia solution should be dispensed or supplied. The EINECS number for ammonia solution is 231-635-3. 19 Specific References 1 Frohman IG. Treatment of physalia stings. J Am Med Assoc 1996; 197: 733. 2 Beare JD et al. Ammonia burns of the eye: an old weapon in new hands. Br Med J 1988; 296: 590. 3 Payne MP, Delic JI. Ammonia.Toxicity Review 24. London: HMSO, 1991; 1–12. 4 Leduc D et al. Acute and long term respiratory damage following inhalation of ammonia. Thorax 1992; 47: 755–757.

General References

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Author

PJ Sheskey.

Date of Revision

10 January 2009.