Aminobenzoic Acid

(USAN, rINN)
Aminobenzoic Acid Chemical formula
Synonyms: Acide 4-Aminobenzoïque; Acidum 4-aminobenzoicum; Amben; 4-Aminobensoesyra; 4-Aminobentsoehappo; 4-aminobenzoesav; Aminobenzoico, ácido; 4-Aminobenzoine˙ru _ gštis; Kwas 4aminobenzoesowy; Kyselina 4-aminobenzoová; PAB; PABA; Pabacidum; Para-aminobenzoic Acid; Vitamin Bx; Vitamin H′. 4Aminobenzoic acid.
Cyrillic synonym: Аминобензойная Кислота.

💊 Chemical information

Chemical formula: C7H7NO2 = 137.1.
CAS — 150-13-0.
ATC — D02BA01.
ATC Vet — QD02BA01.

Pharmacopoeias.

In Eur. and US.

Ph. Eur. 6.2

(4-Aminobenzoic Acid; Aminobenzoic Acid BP 2008). White or slightly yellow crystalline powder. Slightly soluble in water; freely soluble in alcohol; it dissolves in dilute solutions of alkali hydroxides. Protect from light.

USP 31

(Aminobenzoic Acid). White or slightly yellow, odourless crystals or crystalline powder. It discolours on exposure to air or light. Slightly soluble in water and in chloroform; freely soluble in alcohol and in solutions of alkali hydroxides or carbonates; sparingly soluble in ether. Store in airtight containers. Protect from light.

💊 Adverse Effects and Precautions

Adverse skin reactions such as local irritation and contact dermatitis have been reported after the topical use of aminobenzoate sunscreens. Aminobenzoate sunscreens should not be used by those with a history of photosensitivity or hypersensitivity reactions to structurally related drugs such as sulfonamides, thiazide diuretics, and ester-type local anaesthetics. Aminobenzoic acid may stain clothing. Early reports of such reactions led to the removal of these compounds from sunscreen preparations (many are now described as ‘PABA-free’), although padimate O still appears to be widely used.2Patients allergic to aminobenzoic acid may also react to structurally related allergens such as para-aminobenzoic acid ester anaesthetics, sulfonamides, and paraphenylenediamine in hair dyes.1,2 Skin reactions (vitiligo) have also been reported with oral aminobenzoic acid3 and the adverse effects associated with the former use of high oral doses for various conditions have been highlighted.4
1. Scheuer E, Warshaw E. Sunscreen allergy: A review of epidemiology, clinical characteristics, and responsible allergens. Dermatitis 2006; 17: 3–11. Correction. ibid.; 162
2. Mackie BS, Mackie LE. The PABA story. Australas J Dermatol 1999; 40: 51–3
3. Hughes CG. Oral PABA and vitiligo. J Am Acad Dermatol 1983; 9: 770
4. Worobec S, LaChine A. Dangers of orally administered paraaminobenzoic acid. JAMA 1984; 251: 2348.

💊 Pharmacokinetics

If given orally, aminobenzoic acid is absorbed from the gastrointestinal tract. It is metabolised in the liver and excreted in the urine as unchanged drug and metabolites.

💊 Uses and Administration

Aminobenzoic acid is applied topically as a sunscreen. Aminobenzoic acid and its derivatives effectively absorb light throughout the UVB range but absorb little or no UVA light. Aminobenzoate sunscreens may therefore be used to prevent sunburn, but are unlikely to prevent drugrelated or other photosensitivity reactions associated with UVA light; combination with a benzophenone may give some added protection against such photosensitivity. Aminobenzoic acid has sometimes been included as a member of the vitamin-B group, but deficiency of aminobenzoic acid in man or animals has not been found. Aminobenzoic acid has been used with bentiromide in the PABA or BTPABA test of pancreatic function.

💊 Preparations

USP 31: Aminobenzoic Acid Gel; Aminobenzoic Acid Topical Solution.
Published October 31, 2018.