How to use topical medications properly?

Current pharmaceutical technology has produced many types of drugs and many different routes of administration. Topical drugs are a very convenient preparation in the treatment of skin lesions. However, it also has some significant side effects. So how to use topical drugs correctly?

Antifungal drugs

Currently, there are many topical antifungal drugs available on the market, but their effectiveness and usage are not exactly the same. For example, nystatin and miconazole are particularly effective in treating yeast infections (such as Candida) but are not effective against filamentous fungi. Clotrimazole and ketoconazole have a fairly broad spectrum of action against fungi compared to the above two drugs, but are less effective than newer preparations such as terbinafine, ciclopirox olamine and butenafine. Topical antifungal drugs are often used in the treatment of superficial fungal infections such as tinea versicolor, ringworm, intertrigo, nail fungus, scalp fungus, etc.

It should be noted that in cases of scalp and nail fungus, topical antifungal drugs are often not effective enough and must be combined with oral medications. The effectiveness of topical antifungal drugs is usually achieved after at least 2 weeks of use, except in cases of tinea versicolor and ringworm, which can be effective after a few days. Intertrigo and athlete's foot are often caused by excessive local humidity, so treatment must combine antifungal drugs with local moisture-proofing measures. If there is ulceration due to bacterial superinfection, it is necessary to combine with antibiotics. In addition to the above indications, topical antifungal drugs are also indicated in the treatment of seborrheic dermatitis. Although the mechanism of the disease is not yet clearly understood, the use of topical antifungal drugs such as ketoconazole and ciclopirox olamine significantly reduces inflammation and scaling.

Caution should be exercised with topical medications.

Antibiotic

Although hundreds of different antibiotic preparations have been developed and used, very few of them can be used topically. Erythromycin and clindamycin ointments are commonly used to treat acne and folliculitis, while mupirocin, polymyxin, bacitracin, and neomycin ointments are commonly used to treat skin infections such as impetigo. Antibiotic ointments are also effective in preventing infection of skin wounds. Contact dermatitis is a common side effect of ointments containing polymyxin, bacitracin, and neomycin, so these drugs should be avoided if suitable alternatives are available. Some cases of severe allergic reactions such as Stevens-Johnson and Lyell syndromes due to topical antibiotics have also been recorded.

Corticoids

Topical corticosteroids have been used in practice since 1960, mainly in the treatment of inflammatory skin diseases such as atopic eczema, seborrheic dermatitis, contact dermatitis, dyshidrosis... Some other skin diseases such as cutaneous lymphoma, lupus erythematosus, psoriasis, lichen planus... also respond well to these drugs. The most dangerous side effect of topical corticosteroids is skin atrophy. This complication often occurs early with strong corticosteroids such as clobetasol propionate, fluocinolone acetonide... but can also occur with weak corticosteroids if used for a long time and continuously. The skin of the face, folds and thin skin areas often atrophy the fastest while the palms and soles of the feet often atrophy more slowly. Children are at high risk of skin atrophy. Using topical drugs in combination with systemic drugs or being exposed to sunlight after applying the drug also increases the risk of skin atrophy. Symptoms of skin atrophy include bruising, shiny skin, and ridges.

Other common side effects of topical corticosteroids include skin pigmentation disorders, hirsutism, acne, delayed wound healing, etc. Long-term use of corticosteroids in the skin around the eyes can also cause or aggravate cataracts and glaucoma. In addition, strong types, if used for a long time or over a large area, can also cause adrenal suppression. In a few cases, topical corticosteroids can also cause contact dermatitis, although these drugs have very strong anti-allergic effects.

The side effects of topical corticosteroids depend mainly on the intensity of the drug's effect and the duration of use. Meanwhile, the therapeutic effect of these drugs is proportional to the risk of causing side effects of the drug. Different brands of the same active ingredient with the same content can also have different therapeutic effects and risks of causing side effects. In addition, increasing the content of a corticosteroid active ingredient in a topical drug does not significantly increase the therapeutic effect of the drug, for example, the anti-inflammatory effect of 0.1% triamcinolone ointment is not significantly greater than that of 0.025% triamcinolone ointment.

Some things to note when choosing topical corticosteroids: Because topical corticosteroids have a high risk of causing side effects, it is necessary to accurately diagnose the disease before deciding to use these drugs. The choice of topical corticosteroids requires a balance between the effectiveness of treatment and the risk of side effects. Treatment of diseases such as Lichen planus and cutaneous lupus erythematosus often requires strong topical corticosteroids, because these diseases often have inflammatory lesions in the deep layers of the skin. Some diseases with inflammatory lesions that are too deep, such as sarcoidosis, often do not respond to topical corticosteroids because the side effects of the drug often appear before the main effect appears.

Diseases with superficial skin lesions such as psoriasis and atopic eczema often respond well to topical corticosteroids with medium potency. In cases of chronic dermatitis of the hands (such as psoriasis and atopic eczema), strong topical corticosteroids should be chosen and used for a short time to limit the risk of palmar atrophy. In general, in children, weak topical drugs such as hydrocortisone and clobetasone butyrate should be chosen.

Combination topical medications

There are currently many topical medications on the market that combine a corticosteroid, an antibiotic, and an antifungal. In general, the use of these medications should be limited as much as possible, because in many cases, the ingredients in the medication can interfere with each other's effectiveness. For example, in the case of skin fungus, preparations containing corticosteroids will aggravate the disease and reduce the effectiveness of antifungal medications.

According to SKDS - TH