The Pharmacological Basis of Therapeutics A Textbook of Pharmacology, Toxicology and Therapeutics for Physicians and Medical Students. By Prof. Louis Goodman and Prof. Alfred Gilman. Pp. xiii + 1383. (New York: The Macmillan Company, 1941.) 50s. net.

The Pharmacological Basis of Therapeutics

Fregert'sManual of Contact Dermatitisis packed with useful information and is highly recommended as a primer for those learning dermatology and as a brief refresher text for the practicing clinician. Of special usefulness to the clinician are tables of suitable patch test concentrations, a compilation of irritants and sensitizers in common occupations, and excellent discussions about where the more common allergens may be encountered. Every dermatologist would benefit from reading this succinct and well written manual.

Manual of Contact Dermatitis

Over the years, changes have had to be made in the list of topical drugs most frequently responsible for allergic contact dermatitis. The 4 most common sensitizers in Italy in the past have been penicillin, sulfonamide, promethazine and neomycin. Now the list is headed by neomycin, benzocaine and ethylenediamine. Antihistamines and parabens are less frequently observed as sensitizers. The increasing topical use of new drugs and additives, as well as older sensitizers, produces reactions to other substances, such as non-steroidal anti-inflammatory agents, some antimycotic drugs, propylene glycol and benzoyl peroxide.

Allergic contact dermatitis to some medicaments

Background. Isopropyl alcohol is a secondary alcohol, a structural isomer of propanol, that is widely used as an industrial solvent and as a preservative and antiseptic in the clinical environment. It is known to be a mild irritant for the eyes and mucous membranes, but is considered to be a weak and infrequent sensitizer.



Objectives. To show that isopropyl alcohol should be considered as a potential allergen in patients with eczema who have contact with this substance.



Materials and methods. We present a series of 1450 patients patch tested with isopropyl alcohol during the period 1992–2011.



Results. Forty-four patients showed an allergic response to isopropyl alcohol. Four cases presented as occupational hand eczema. Fourteen cases were seen in patients with leg ulcers. Twenty-six patients presented with eczematous lesions following the use of products containing isopropyl alcohol to disinfect previous skin lesions. Eighty-four per cent of the patients showed sensitization to three or more allergens. Relevance was present in 84% of the patients.



Conclusions. We report here the first large case series of contact allergy to isopropyl alcohol, which demonstrates that sensitization to this substance might not be as uncommon as previously thought.

Allergic contact dermatitis caused by isopropyl alcohol: a missed allergen?

Benzoyl peroxide (BP) is shown to be a weak allergen. Of 25 guinea pigs, only 5 were sensitized in the TINA lest. Before treatment, only 2 of 172 acne patients gave a positive patch test with 1% BP, but not with 0.1% BP. The following results suggest that BP is a strong irritant. The irritant potential ID50 in rabbis was 2.52% and thee IT50 was 2.31 days with 5% BP, 4.34 days with 1% and 8.35 days with 0.1% BP.



29% of acne patients and non-exposed controls had a positive patch lest with 5% BP. However, only 11 of 155 acne patients and clinical signs of intolerance, which settled despite continued use in 10 cases. The possible reasons for this dichotomy are explored. Neither the irritant nor allergenic properties of BP impaired its clinical use.

Allergic and irritant potential of benzoyl peroxide

Two laboratory assistants developed contact dermatitis from a disposable swab for pre-injection use, containing isopropyl alcohol 70% and propylene oxide 1%. Patch testing gave position allergic reactions to propylene oxide in both patients, one of whom also reacted to isopropyl alcohol. Testing of 25 control persons gave negative results.

Contact allergy to propylene oxide and isopropyl alcohol in a skin disinfectant swab

Sixteen patients with chronic leg ulcers were treated with 10% benzoyl peroxide gel for 6 weeks. At the end of the treatment, patch tests with 2 % benzoyl peroxide in petrolatum and 10 % in a gel showed that nine patients (56 %.| had become sensitized. This high sensitization rate is in good accord with the results obtained by experimental investigations using human maximization tests and repeated insult patch tests. A strong sensitizer such as benzoyl peroxide should not be used in the routine treatment of chronic leg ulcers, despite its good healing effect.

Ove Jensen

Papers

Contact allergy to propylene oxide and isopropyl alcohol in a skin disinfectant swab

Contact sensitization to benzoyl peroxide following topical treatment of chronic leg ulcers.