Hydrochloric Acid

(BAN, rINN)

💊 Chemical information

Acide chlorhydrique; Acidum Hydrochloricum; Acidum hydrochloridum; Clorhídrico, ácido; E507; Kloorivetyhappo; Kwas solny; Kyselina chlorovodíková; Saltsyra; Salzsäure; Sósav; Suolahappo; Vandenilio chlorido ru _ gštis; Vetykloridihappo.
HCl = 36.46.
CAS — 7647-01-0.
ATC — A09AB03; B05XA13.
ATC Vet — QA09AB03; QB05XA13.

Pharmacopoeias.

Chin., Eur., Int., Jpn, Swiss, and Viet. include various concentrations. Also in USNF.

Ph. Eur. 6.2 (Hydrochloric Acid, Concentrated; Acidum Hydrochloridum Concentratum; Hydrochloric Acid BP 2008). It contains 35.0 to 39.0% w/w of HCl. A clear, colourless, fuming liquid. Miscible with water. Store below 30° in stoppered containers of glass or other inert material.

Ph. Eur. 6.2 (Hydrochloric Acid, Dilute; Acidum Hydrochloridum Dilutum). It contains 9.5 to 10.5% w/w of HCl prepared by mixing hydrochloric acid 274 g with water 726 g.

USNF 26 (Hydrochloric Acid). It contains 36.5 to 38.0% w/w of HCl. A colourless, fuming liquid having a pungent odour. It ceases to fume when it is diluted with 2 volumes of water. Store in airtight containers.

USNF 26 (Diluted Hydrochloric Acid). It contains 9.5 to 10.5% w/v of HCl and may be prepared by mixing hydrochloric acid 226 mL with sufficient water to make 1000 mL. A colourless, odourless liquid. Store in airtight containers.

💊 Adverse Effects

Hydrochloric acid is highly irritant and corrosive and ingestion has proved fatal. The corrosive effect causes chemical burns and severe pain. There may be violent vomiting, haematemesis, and circulatory collapse; acids can also produce intravascular coagulation and haemolysis. Ulceration may lead to perforation and patients can suffer strictures and pyloric stenosis. Asphyxiation may result from laryngeal oedema. Inhalation of acid fumes or aspiration of ingested acids may cause pneumonitis.
1. WHO. Chlorine and hydrogen chloride. Environmental Health Criteri
21. Geneva: WHO, 1982. Available at: http:// www.inchem.org/documents/ehc/ehc/ehc21.htm (accessed 16/06/04
2. Munoz Munoz E, et al. Massive necrosis of the gastrointestinal tract after ingestion of hydrochloric acid. Eur J Surg 2001; 167: 195–8.

💊 Treatment of Adverse Effects

Treatment of ingestion is mainly symptomatic. Gastric lavage and activated charcoal are not generally appropriate and emetics must not be used. Small amounts of water or milk may be given to dilute the acid but larger volumes may increase the risk of emesis and hence of further damage. Neutralising agents are not recommended because of the possibility of heat being produced during exothermic reactions, which may increase the injury further. Opioid analgesia may be required for pain. Endoscopy should be performed and surgical intervention may be necessary. There is little evidence to support the value of corticosteroids in preventing stricture formation. Acid burns of the skin should be flooded immediately with water and the washing should be copious and prolonged. Any affected clothing should be removed while flooding is being carried out. For burns in the eye, the lids should be kept open and the eye flushed with a steady stream of water at room temperature or sodium chloride 0.9%. A few drops of a local anaesthetic solution will relieve lid spasm and facilitate irrigation.

💊 Uses and Administration

Hydrochloric acid has been used as an escharotic. It has been used in the diluted form for the treatment of achlorhydria and other gastrointestinal disorders. It has also been given intravenously in the management of metabolic alkalosis. An acid perfusion test using hydrochloric acid has been used in the diagnosis of oesophageal disorders. When taken orally, it should be sipped through a straw to protect the teeth.

Homoeopathy.

Hydrochloric acid has been used in homoeopathic medicines under the following names: Acidum hydrochloricum; Muriaticum acidum; Hydrochloridum acidum; Chlorhydricum acidum; Acidum muriaticum; Ac. mur.

Diagnosis and testing.

References and comments on the use of an acid perfusion test in the diagnosis of oesophageal disorders,1-5 such as gastro-oesophageal reflux disease and oesophageal motility disorders. The test involves intraoesophageal perfusion of 0.1M hydrochloric acid; subsequent development of pain indicates an acid-sensitive oesophagus. This test has also been used in the differential diagnosis of angina.2
1. Sladen GE, et al. Oesophagoscopy, biopsy, and acid perfusion test in diagnosis of "reflux oesophagitis". BMJ 1975; 1: 71–6
2. Anonymous. Angina and oesophageal disease. Lancet 1986; i: 191–2
3. Hewson EG, et al. Acid perfusion test: does it have a role in the assessment of non cardiac chest pain? Gut 1989; 30: 305–10
4. de Caestecker JS, Heading RC. Acid perfusion in the assessment of non-cardiac chest pain. Gut 1989; 30: 1795–7
5. Howard PJ, et al. Acid perfusion is a good screening test for symptomatic oesophageal reflux. Gut 1989; 30: A1445.

Pregnancy.

Heartburn during pregnancy may be due to reflux of alkaline duodenal contents. A dilute solution of hydrochloric acid (pH 2) taken after meals and at bedtime produced improvements in heartburn in pregnant women.1
1. Anonymous. Heartburn in pregnancy. Drug Ther Bull 1990; 28: 11–12.

💊 Preparations

Proprietary Preparations

Pol.: Mixtura Pepsini. Multi-ingredient: Ital.: Gastro-Pepsin; S.Afr.: Sentinel Ulcer Mixture.
Published May 08, 2019.