In recent years, due to a better understanding of the pathogenesis of acne, new therapeutic modalities have been designed. One of these is the recently approved 4% minocycline foam for topical treatment. This article presents a simplified understanding of the new medication along with formulation and profile.

What is acne vulgaris?

Acne by definition is a multifactorial chronic inflammatory disease of pilosebaceous units. Various clinical presentations include seborrhoea, comedones, erythematous papules and pustules, less frequently nodules, deep pustules or pseudocysts, and ultimate scarring in a few of them. Therefore, successful management of acne needs careful selection of anti-acne agents according to clinical presentation and individual patient needs.

The conventional therapies

1. Topical therapy- It is useful in mild and moderate acne, as monotherapy, in combination and also as maintenance therapy.
2. Benzoyl peroxide- It is an effective topical agent for many years and is available in different formulations (washes, lotions, creams, and gels) and concentrations (2.5–10%).
3. Topical retinoids- They should be used as the first-line therapy, alone or in combination, for mild-to-moderate inflammatory acne and is also a preferred agent for maintenance therapy. Tretinoin, adapalene, tazarotene, isotretinoin, metretinide, retinaldehyde, and β-retinoyl glucuronide are currently available topical retinoids.
4. Topical antibiotics- Erythromycin and clindamycin in concentrations of 1-4% are the most popular in the management of acne and available in a variety of vehicles and packaging.

Other topical/new agents

Combination therapy:

1. Benzoyl peroxide can be combined with tretinoin and found to be superior to monotherapy.
2. A combination of topical retinoid and topical antimicrobial is more effective in reducing both inflammatory and non-inflammatory acne lesions than either agent used alone.
3. Topical clindamycin and benzoyl peroxide applied once daily and fixed clindamycin phosphate 1.2% and tretinoin 0.025% in aqueous-based gel formulation used once daily are both found to be an effective treatment for acne.

Other agents include:

• Salicylic acid
• Azelaic acid
• Lactic acid/Lactate lotion
• Tea tree oil 5%

Systemic antibiotics

Oral antibiotics are indicated in mainly moderate-to-severe inflammatory acne. Tetracyclines and derivatives still remain the first choice. Macrolides, co-trimoxazole, and trimethoprim are other alternatives for acne.

Tetracycline (500 mg–1 g/day), doxycycline (50–200 mg/day), minocycline (50–200 mg/day), lymecycline (150–300 mg/day), erythromycin (500 mg–1 g/day), co-trimoxazole, trimethoprim, and recently azithromycin (500 mg thrice weekly) are being used successfully in acne. Minocycline and doxycycline are more effective than tetracycline and erythromycin.

Hormonal therapy

It may be needed in female patients with severe seborrhoea, clinically apparent androgenetic alopecia, seborrhoea/acne/hirsutism/alopecia and with proven ovarian or adrenal hyperandrogenism.

1. Oral contraceptives
2. Spironolactone
3. Cyproterone acetate
4. Flutamide

Various topical and systemic drugs are available to treat acne, which may sometimes confuse the treating dermatologist. The evidence-based studies and inputs from various practising dermatologists have led to a consensus of the use of topical agents, topical antibiotics and combination therapy of the above including oral antibiotics and hormone therapy.

New drug formulation: Minocycline foam 4%

Topical minocycline foam 4% has recently been accepted and approved by the FDA in January 2020 for the treatment of inflammatory lesions of non-nodular, moderate to severe acne vulgaris (acne) in patients aged ≥9 years. It was developed to minimise systemic minocycline absorption and toxicity, and its high lipid content allows efficient drug movement through sebum and into affected sites.

In a study published recently in the American Journal of Clinical Dermatology, a 12-week, phase III clinical trial with once-daily topical minocycline foam 4% significantly improved both inflammatory and non-inflammatory lesions relative to foam vehicle in patients aged ≥9 years with moderate to severe acne and was reported by most patients to be satisfactory or highly satisfactory to use. Reports from a dermal safety study showed that topical minocycline foam 4% did not have any effects related to phototoxicity, photoallergy, skin sensitisation and skin irritation.

Drug availability and dosage

1. The drug is available as 40 mg minocycline and is supplied in 30 g aerosol cans.
2. It is to be applied to the acne-affected areas once daily, 1 hour before bedtime.

Drug reactions

Studies have shown to have no adverse effects of topical minocycline. Although, in cases of allergic reactions and hypersensitivity, the usage has to be stopped immediately and anti-inflammatory therapy needs to be started. The patient can be advised other drug combinations discussed earlier.