Propylene Glycol

An Often Unrecognized Cause of Allergic Contact Dermatitis in Patients Using Topical Corticosteroids

Mohammed Al Jasser, MD; Nino Mebuke; Gillian de Gannes, MD, FRCPC

Skin Therapy Letter. 2011;16(5)

Abstract and Introduction

Abstract

Propylene glycol (PG) is considered to be a ubiquitous formulary ingredient used in many personal care products and pharmaceutical preparations. It is an organic compound commonly found in topical corticosteroids (CS). Cutaneous reactions to PG are mostly irritant, but allergic contact dermatitis to PG is well-documented. Cosensitization to PG and topical CS can occur, making it challenging to choose the appropriate topical CS in a PG-allergic patient. This review is aimed at guiding clinicians in the selection of a suitable topical corticosteroid when presented with patients allergic to PG.

Introduction

Propylene glycol (PG) is a colorless, viscous, nearly odorless liquid that is used as an intermediate for the synthesis of other chemicals.^[1,2] It is a multifunctional excipient that is used in many products as a solvent, vehicle, humectant, or emulsifier.^[3] The annual PG production and global demand are rapidly increasing.^[3] Vehicles for topical corticosteroid preparations commonly include PG for enhancing stratum corneum penetration. In addition to topical steroids, PG can also be found in other topical pharmacologic preparations, including antibacterials, antifungals, benzoyl peroxide, and emollients,^[1] Cutaneous reactions to PG have been recognized since 1952.^[1]

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Cite this: Propylene Glycol - Medscape - May 01, 2011.

Abstract and Introduction
Sources of PG
Allergic Contact Dermatitis to PG
PG and ACD to Topical Corticosteroids
Case Report
The Choice of a Topical CS in a PG-allergic Patient
Conclusion
References

Table 1. Patch test results to the 2010 North American Contact Dermatitis Group screening series
Ingredient	Day 3 (48 hours)	Day 7
Propylene glycol	++	++
Budesonide	++	++
Lanolin alcohol	++	++
Balsam of Peru	+	+
Glyceryl thioglycolate	-	+

Reactions were graded using a scoring system recommended by the International Contact Dermatitis Research Group: + = erythema and papules, ++ = edema or vesicles, +++ = bullae and/or erosions, – = no reaction.

Table 2. Propylene glycol-free topical corticosteroids available in Canada sorted by potency and structural class CR = cream, GL = gel, LO = lotion, OL = Oil, OC = oily cream, OI = ointment, SH = shampoo, SL = solution, SP = spray
Structural class	Class A: Hydrocortisone type	Class B: Triamcinolone acetonide type	Class C: Betamethasone type	Class D1: Betamethasone dipropionate type	Class D2: Methylprednisolone aceponate type
Class 7: Least potent	Hydrocortisone 0.5%, 1% [OI] (Cortoderm®) Hydrocortisone 1%, 2.5% [CR, LO]; 2.5% [SL] (Emo-Cort®)
Class 6: Low potency		Desonide 0.05% [OI] (Desocort®)
Class 5: Lower mid-strength		Fluocinolone acetonide 0.01% [OL] (Derma-Smoothe/FS®)		Betamethasone valerate 0.05% [OI] (Betaderm®) Betamethasone valerate 0.05% [CR, LO] (ratio-Ectosone) Betamethasone valerate 0.1% [CR] (Prevex® B, ratio-Ectosone) Betamethasone valerate 0.1% [LO] (Betaderm®, ratio-Ectosone, Valisone®)	Prednicarbate 0.1% [CR] (Dermatop®)
Class 4: Mid-strength		Triamcinolone acetonide 0.1% [OI, CR] (Aristocort®) Amcinonide 0.1% [CR, LO] Cyclocort®, ratio-Amcinonide)	Desoximetasone 0.05% [CR] (Topicort®) Diflucortolone valerate 0.1% [CR, OC, OI] (Nerisone®)
Class 3: Upper mid-strength		Triamcinolone acetonide 0.5% [CR] (Aristocort®)		Betamethasone valerate 0.1% [OI] (Betaderm®) Betamethasone dipropionate 0.05% [CR] (Diprosone®) Betamethasone dipropionate 0.05% [LO] (Diprosone®, ratio-Topisone)
Class 2: High potency		Amcinonide 0.1% [OI] (Cyclocort®, ratio-Amcinonide)	Desoximetasone 0.25% [CR]; 0.05% [GL] (Topicort®)	Betamethasone dipropionate 0.05% [OI] (Diprosone®, ratio-Topisone)
Class 1: Superpotent				Clobetasol propionate 0.05% [OI, LO] (ratio-Clobetasol) Clobetasol propionate 0.05% [SL] (Dermovate®) Clobetasol propionate 0.05% [SH, SP] (Clobex®)

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