Epiduo®: composition and pharmaceutical form
Epiduo® comes as a gel. One gram of gel contains 1 mg of adapalene and 25 mg of benzoyl peroxide — two active substances in a single base.
The ratio is no accident: adapalene works at a very low concentration, while benzoyl peroxide requires a concentration orders of magnitude higher — this reflects the difference in their mechanisms rather than in their potency. The formulation includes propylene glycol, which can itself irritate the skin, something to bear in mind for those whose skin already reacts to topical products.
How Epiduo® works
The medicine contains two substances with different but complementary mechanisms. Adapalene is a chemically stable derivative of naphthalenecarboxylic acid with retinoid-like activity. It binds to specific nuclear retinoic acid receptors and acts as a potent modulator of epidermal cell differentiation and of the keratinisation process. Topical application brings the differentiation of epithelial cells back to normal and thereby reduces the number of microcomedones — the invisible foundation of future lesions.
Adapalene also has anti-inflammatory properties. In in vitro models it inhibits the chemotactic and chemokinetic response of human polymorphonuclear leucocytes, holds back the conversion of arachidonic acid into inflammatory mediators, and suppresses AP-1 factors and the expression of Toll-like receptors of type 2. Benzoyl peroxide handles the other part of the work: it has antibacterial action, above all against Propionibacterium acnes, which multiplies in the affected pilosebaceous follicle, and it also has an exfoliating and keratolytic action and reduces sebum production.
Indications
Epiduo® is used for the local treatment of acne vulgaris with comedones, papules and pustules.
The wording describes exactly the form of acne for which the combination of the two substances makes sense: comedones respond to adapalene, inflammatory elements to benzoyl peroxide. In other words, the medicine is designed for a mixed picture, where the skin has both blocked pores and inflamed nodules with pustules, and not just one of the two. The safety and efficacy of the medicine in children under 9 have not been studied, so it is not used in that age group.
Method of use and dosage
The gel is applied once a day in the evening to clean, dry skin, covering the whole area affected by acne rather than individual lesions. A thin layer is spread with the fingertips, avoiding the area around the eyes and the mouth. Evening application was not chosen at random: overnight the product works without sunlight, and the skin is not exposed to ultraviolet immediately after treatment.
The first signs of improvement usually appear between the first and the fourth week of treatment, and the overall length of the course is determined by the doctor from the clinical picture. If irritation occurs there are three routes, and the choice depends on its severity: adding moisturising creams that do not promote the formation of comedones; applying the gel less often, for example every other day; or stopping use temporarily or altogether. That is precisely why treatment is started under medical supervision rather than pushed through by eye.
Contraindications
The list of contraindications consists of a single point.
- hypersensitivity to the active substances or to any excipient of the medicine.
Special warnings and precautions
The gel is not applied to damaged or cracked skin — cuts, grazes — or to skin with eczema. Contact of the product with the eyes, mouth, nostrils and mucous membranes should be avoided; if it gets into an eye, the eye is washed immediately with warm water. If an allergy to any component develops, use is stopped.
Practical warnings
- excessive sun and ultraviolet exposure is avoided during treatment;
- the medicine contains propylene glycol, which may irritate the skin;
- the gel must not reach dyed materials — fabrics and hair: bleaching or a change of colour is possible;
- irritation most often peaks in the first week of use and then passes on its own;
- with marked irritation it is more sensible to reduce the frequency of application than to drop the treatment at once;
- the influence on the ability to drive and operate machinery has not been tested, since it does not apply to this medicine.
Drug interactions
No specific interaction studies with other medicines have been carried out. Experience with adapalene and benzoyl peroxide separately indicates that there are no known interactions with other products applied to the skin at the same time.
Even so, two limitations matter. Other retinoids, benzoyl peroxide or products with a similar mechanism of action should not be used at the same time — that would double one and the same effect. Exfoliating, irritating and drying cosmetics are used with caution: together with the gel they intensify irritation. Systemic interactions are not to be expected: absorption of adapalene through human skin is low, and benzoyl peroxide penetrates poorly and is completely converted into benzoic acid, which is eliminated rapidly.
Pregnancy and breastfeeding
In animal studies with adapalene given orally at high, systemically acting doses, reproductive toxicity was observed. Clinical experience with topical adapalene and benzoyl peroxide in pregnant women is limited and, although the few available data do not indicate harm with use in early pregnancy, because of the small volume of data and the possibility of slight penetration of adapalene through the skin the medicine is not used during pregnancy. If pregnancy occurs unexpectedly, treatment is stopped.
No studies of the passage of the medicine into milk in animals or humans after application to the skin have been carried out. No influence on the breastfed child is expected, since the systemic action of the medicine in a breastfeeding woman is negligible, so it may be used during this period. On one condition: the gel is not applied to the breast area, so that the child does not come into contact with it.
Adverse effects
Practically all the adverse reactions are local and predictable: they reflect the exfoliating and irritating action of both components.
- common: dry skin, irritant contact dermatitis, a burning sensation, skin irritation, redness, peeling;
- uncommon: itching of the skin, sunburn;
- frequency not known: allergic contact dermatitis, facial itching, burning skin pain, blisters on the skin;
- frequency not known, beyond the skin: swelling of the eyelids and a feeling of tightness in the throat — these reports came in after the medicine reached the market.
What matters is the pattern over time: if redness, dryness, peeling, burning and stinging pain in the skin appear after application, their intensity is usually mild or moderate. The signs of local intolerance reach their peak during the first week of use and then pass on their own. That is what distinguishes the skin's normal adaptation from an allergic reaction, in which case the medicine must be withdrawn.
Overdose
The medicine is intended exclusively for external use once a day. Applying more gel or applying it more often does not speed up the result, it only intensifies the irritation.
If the medicine is swallowed accidentally, suitable symptomatic treatment is given. The product information provides for no special measures, but it is worth telling a doctor what happened, especially if a child swallowed the gel. For the same reason the tube is kept where children cannot reach it — the gel has no repellent taste or smell that would stop a child.
How to get a prescription for Epiduo® online
Epiduo® is a prescription-only medicine: the doctor determines whether the combination of adapalene with benzoyl peroxide suits your particular form of acne and how long to use it. During the online consultation the doctor will go through the nature of the lesions, clarify what you have already used and assess whether the skin will not prove too sensitive for such a combination.
If the medicine is suitable, the doctor will issue an electronic prescription and explain the routine: how to apply the gel, what to expect in the first week and what to do if the irritation turns out stronger than expected.
