Drugs for Acne Vulgaris

DRUGS FOR ACNE VULGARIS

Acne vulgaris is the most common skin disease in adolescent boys and girls. Under androgenic stimulation the sebaceous follicles of face and neck produce excess of sebum and get colonized by bacteria and yeast (Propionibacterium acnes, Staph. epidermidis, Pityrosporum ovale). Bacterial lipases produce fatty acids which irritate the follicular ducts causing retention of secretions and hyperkeratosis— ‘comedones’ are formed which may rupture into the dermis causing inflammation and pustulation.

1. TOPICAL THERAPY

Benzoyl peroxide

It is one of the most effective and widely used drugs in acne: gradually liberates oxygen (in the presence of water) which kills bacteria, especially anaerobic/microaerophilic ones: used almost exclusively for acne because of its high efficacy against P. acnes and additional keratolytic and comedolytic properties. P. acnes or other bacteria do not develop resistance to benzoyl peroxide. It induces mild desquamation, the comedone caps are shed and production of irritant fatty acids in the sebum is reduced. Benzoyl peroxide is a mild irritant of the skin—burning and stinging sensation is often felt initially, localized erythema may occur. Most patients gradually develop tolerance to these actions; if not, use should be discontinued. Avoid contact with eyes, lips, mucous membranes and denuded skin. It can bleach hair and coloured fabric.

Adverse effects are excessive dryness of skin, marked scaling, erythema, edema and contact sensitization (in 1–2% patients). It is used as 5– 10% cream, gel or lotion; duration and frequency of application is guided by the degree of irritation produced and tolerated; start with 15 min once daily.

PERSOL, PERNOX, BENZACAC 2.5% and 5% gel; in PERSOL FORTE 10% cream with sulfur ppt. 5%.

Retinoic acid (all trans vitamin A acid, Tretinoin)

It is a potent comedolytic: promotes lysis of keratinocytes, prevents horny cells from binding to each other, hence comedones, which are horny impactions in follicles, cannot form. Epidermal cell turnover is stimulated resulting in peeling. No antibacterial action is exerted. It is highly efficacious in acne, but response is delayed (may take 6–10 weeks). Tretinoin has the potential to irritate the skin; start with the lower concentration applied once daily.

Side effects are feeling of warmth, stinging, excessive redness, edema and crusting. Used as a 0.025–0.05% gel or cream, it can be alternated with benzoyl peroxide (one in the morning the other at night), but both should not be applied together because benzoyl peroxide accelerates degradation of tretinoin. Teratogenic risk with topical retinoic acid is minor because of low blood levels produced; but it should be used during pregnancy only if essential.

Tretinoin has been shown to prevent photo-ageing of skin. Dry scaly surface, mottling, wrinkles, rough and leathery texture, sagging of loose skin that develop due to excessive exposure to sun are arrested and pigmented spots tend to fade. However, the risk benefit ratio of long-term prophylactic therapy is not clear.

EUDYNA 0.05% cream. RETINOA 0.025% and 0.05% cream.

Adapalene

It is a newer synthetic tretinoin-like drug which binds directly to the nuclear retinoic acid receptor and modulates keratinization and differentiation of follicular epithelial cells. It also exerts anti-inflammatory action; comedone formation is suppressed. In acne vulgaris it is as effective but less irritating than tretinoin. It remains stable in the presence of benzoyl peroxide; can be combined with it.

ADAFERIN, ADAPEN, ADAPLE, ACLENE 0.1% gel; apply once daily at bed time.

Tazarotene is another topical retinoid with therapeutic effect in acne vulgaris as well.

Topical Antibiotics

Clindamycin, erythromycin and tetracyclines are less effective against P. acnes than benzoyl peroxide. They are appropriate for cases with inflamed papules, rather than in noninflamed comedones. They do not irritate skin but can cause sensitization.

Erythromycin: ACNEDERM 2% lotion and oint; ERYTOP 3% lotion and cream; ACNESOL 4% gel, 2% lotion, ACNELAKZ 4% lotion and gel with zinc acetate 2%.

Clindamycin: CLINDACA, CLINCIN 1% gel.

Nadifloxacin is a newer topical quinolone broadspectrum antibiotic which has exerted therapeutic benefit in inflamed acne and folliculitis.

NADIBACT, NADOXIN 1% cream for topical application.

Azelaic acid

It is a natural product from Pityrosporum ovale that has been developed for topical treatment of acne. Many aerobic and anaerobic microorganisms, especially P. acnes present on acne bearing skin are inhibited. Azelaic acid reduces cutaneous bacterial density, free fatty acid content of skin surface lipids and proliferation of keratinocytes. Used as 10%, 20% cream, its efficacy in acne approaches that of

benzoyl peroxide, but response is delayed. It has also benefited melasma.

AZIDERM 10%, 20% cream

II. SYSTEMIC THERAPY

Systemic use of drugs in acne is indicated only in severe cases with cysts and pustules which are likely to form scars.

Antibiotics

Tetracycline, minocycline or erythromycin have been used. After initial control, smaller maintenance doses may be continued for months. However, long-term systemic antibiotic therapy has its own complications. Recently risk of intracranial hypertension after use of tetracyclines for > 2 months has been emphasized.

Isotretinoin

(13cis retinoic acid) is an orally administered retinoid that reduces production of sebum (skin bacteria decrease secondarily), corrects abnormal keratinization of follicles and causes dramatic improvement. A 20 week course of 0.5–1 mg/kg daily brings about remission in most cases of cystic acne. Relapses occur after variable intervals; can be treated similarly. Side effects are frequent—cheilitis, dryness of skin, eyes, nose and mouth, epistaxis, pruritus, conjunctivitis, paronychia, rise in serum lipids and intracranial tension, and musculoskeletal symptoms. Therefore, it should be reserved for unresponsive cases of severe acne.

Isotretinoin is highly teratogenic; upto 25% exposed foetuses had birth defects—craniofacial, heart and CNS abnormalities (ACCUTANE embryopathy). It is contraindicated in women likely to become pregnant during therapy and one month after. The t½ of isotretinoin is ~18 hours, and it is not accumulated like other retinoids.

ISOTROTIN 10, 20 mg cap, IRET 20 mg cap.

Isotretinoin is also effective in the prevention and treatment of skin cancers. Oral leucoplakia, actinic keratoses and other premalignant lesions can be treated, but benefitrisk ratio is not clear.