Triderm®: composition and pharmaceutical form
Triderm® comes in two topical forms — cream and ointment. One gram of cream or ointment contains 0.5 mg of betamethasone as the dipropionate, 10 mg of clotrimazole and 1 mg of gentamicin as the sulfate.
The combination of three active substances defines what the medicine is for. It is not simply a hormonal ointment nor simply an antifungal: one formulation brings together a corticosteroid, an antifungal component and an antibiotic, each with its own task.
How Triderm® works
The medicine's properties come from the combined action of three substances. Betamethasone dipropionate belongs to the potent corticosteroids: applied to the skin it gives a rapid and lasting anti-inflammatory and anti-itch effect and constricts the blood vessels. Gentamicin is an aminoglycoside antibiotic with a broad antibacterial spectrum.
Clotrimazole belongs to the imidazole group with a broad antifungal spectrum: it inhibits the development of the fungi that cause skin disease and works at the level of the fungal cell wall. Resistance to clotrimazole is rare — it has been noted in Candida guilliermondi, while repeated contact with strains of Candida albicans and Trichophyton mentagrophytes did not produce resistant forms.
Indications
The cream and the ointment are used for the symptomatic treatment of inflammatory skin changes that respond to corticosteroids, when they are complicated by a secondary infection caused by organisms sensitive to gentamicin and clotrimazole.
Clotrimazole has proved effective in the local treatment of fungal involvement of the inguinal folds, the perineum, the feet and glabrous skin. It acts on Trichophyton rubrum, Trichophyton mentagrophytes, Epidermophyton floccosum and Microsporum canis, on candidiasis caused by Candida albicans and on pityriasis versicolor caused by Malassezia furfur. Sensitive to gentamicin are group A streptococci, Staphylococcus aureus including some penicillinase-producing strains, and also gram-negative bacteria — Pseudomonas aeruginosa, Escherichia coli, Proteus vulgaris, Klebsiella pneumoniae.
Method of use and dosage
A thin layer of cream or ointment is applied to the affected areas and the surrounding skin twice a day, morning and evening. The medicine must be applied regularly, and the length of treatment depends on the size and location of the lesions and on the response to therapy.
| Situation | Timeframe |
|---|---|
| Fungal involvement of the inguinal folds, the perineum, glabrous skin and candidiasis | 2 weeks |
| Fungal involvement of the feet | 4 weeks |
| First signs of improvement | the redness and itching disappear, usually on the third to fifth day |
| No improvement within a week (feet, within 2 weeks) | review the diagnosis |
| Symptoms persisting after 2 weeks (feet, after 4) | stop the treatment and prescribe another |
| Maximum duration | using it for more than 4 weeks is not recommended |
The medicine is prescribed to adults and children over 12; in children under 12 it is not recommended. For the ointment the timing guide is the same: if there is no improvement after 3–4 weeks, the diagnosis must be reviewed.
Contraindications
There are many restrictions, and they concern both the composition and the sites of application.
- hypersensitivity to betamethasone dipropionate, clotrimazole or gentamicin, and also to other corticosteroids, imidazole derivatives, aminoglycoside antibiotics or any excipient;
- viral skin infections, for example chickenpox and herpes;
- rosacea and acne vulgaris;
- primary bacterial and fungal skin infections;
- wounds and damaged skin;
- the skin of the face;
- the area of the anus and the genitals, as well as perioral dermatitis;
- prolonged use.
Special warnings and precautions
If irritation, allergy or secondary infection appears, the medicine is withdrawn and suitable treatment prescribed. Prolonged topical use can lead to the growth of strains resistant to gentamicin and other aminoglycosides; besides, cross-allergy to antibiotics of this group is known. The medicine is not applied in the eyes, around them or on the mucous membranes.
Why "more and for longer" is the wrong approach
Both the corticosteroid and gentamicin are absorbed through the skin, and under occlusive dressings systemic absorption rises. Hence the risk of systemic corticosteroid effects, including suppression of adrenal cortex function, and of gentamicin — oto- and nephrotoxicity, especially in people with impaired kidney function. Application to a large body surface, in large amounts and under occlusive dressings is therefore avoided. Particular caution is needed in psoriasis: topical corticosteroids in this disease can be dangerous — as tolerance develops a relapse is possible, and there is a risk of generalised pustular psoriasis and of general toxic action through the broken integrity of the skin.
Children and excipients
- in children, suppression of the hypothalamic-pituitary-adrenal axis after topical corticosteroids occurs more often than in adults, because of the greater ratio of skin surface to body weight;
- in children on topical corticosteroids, Cushing's syndrome, slowed growth, reduced weight gain and raised intracranial pressure have been described;
- the signs of adrenal insufficiency are a low plasma cortisol and the absence of a response to ACTH stimulation;
- the signs of raised intracranial pressure are a bulging fontanelle, headache and bilateral papilloedema;
- the cream contains cetostearyl alcohol and may cause a local skin reaction, for example contact dermatitis;
- the cream contains propylene glycol and may irritate the skin.
Drug interactions
No interactions with other medicines are known.
That, however, does not remove the need for caution when other products are applied topically to the same area at the same time: combining several active preparations on one area of skin increases irritation, and occlusion under a dressing increases absorption. Such combinations are worth discussing with the doctor.
Pregnancy and breastfeeding
There are no data on the safety of use in pregnant women, but corticosteroids and gentamicin are known to be capable of absorption through the skin. The medicine is therefore used during pregnancy only when the potential benefit to the mother outweighs the potential risk to the mother, the foetus or the newborn. Since potent corticosteroids showed a teratogenic effect in animal studies, use during pregnancy must be brief and limited to a small area of skin.
Whether the active substances are absorbed with topical application in amounts sufficient to pass into breast milk is unknown. The decision to stop breastfeeding or to withdraw the medicine is taken with its importance for the mother in mind. The medicine is not applied to the skin of the breasts while breastfeeding.
Adverse effects
The main reactions are burning, redness, weeping and itching at the site of application. In addition, the effects typical of each of the three components separately are possible.
- from betamethasone: burning, itching, irritation, dryness of the skin, folliculitis, excessive hair growth, steroid acne, skin depigmentation;
- from betamethasone: perioral dermatitis, allergic contact dermatitis, maceration of the skin, secondary infections, skin atrophy, striae and miliaria;
- from clotrimazole: redness, burning, formation of blisters, peeling, oedema, itching, urticaria and general irritation of the skin;
- from gentamicin: skin irritation with redness and itching, which usually does not require stopping treatment;
- hypersensitivity reactions are grounds for interrupting treatment immediately;
- when betamethasone passes into the blood, systemic effects typical of corticosteroids are possible;
- systemic reactions arise above all with prolonged use, application to a large surface and in children;
- hypochromic anaemia has also been described.
Hence the practical conclusion: this is a medicine for short courses on a limited area. As soon as the timeframe and the area grow, so does the likelihood of systemic rather than local problems.
Overdose
Excessive or prolonged topical use of corticosteroids can suppress the hypothalamic-pituitary-adrenal axis with the development of secondary adrenal insufficiency and systemic effects, including Cushing's syndrome. The acute manifestations of hypercortisolism are transient; if necessary the electrolyte balance is corrected and, in chronic poisoning, the corticosteroid dose is lowered gradually.
Overdose of clotrimazole in topical use is unlikely: after 6 hours under an occlusive dressing with isotope-labelled clotrimazole, no detectable amounts of radioactive material were found in the serum of study participants. Excessive or prolonged topical use of gentamicin can lead to the appearance of resistant bacterial strains and also to hearing and kidney damage. If non-susceptible organisms grow, the medicine is withdrawn and appropriate treatment prescribed.
How to get a prescription for Triderm® online
Triderm® is a prescription-only medicine: it contains a potent corticosteroid and an antibiotic, and the list of places where it must not be applied is longer than the list of indications. During the online consultation the doctor will go through the nature of the lesions, clarify where the affected areas are and decide whether the combination of three components is really needed here.
If the medicine is suitable, the doctor will issue an electronic prescription, determine the length of the course and explain when the result should be reassessed and at which signs treatment should be stopped.
